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Table of Content

    10 August 2015, Volume 26 Issue 15
    Research on Grid Impact Suppression in Hydraulic Wind Turbine
    Ai Chao, Yan Guishan, Kong Xiangdong, Chen Lijuan
    2015, 26(15):  1989-1994. 
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    Taking a hydraulic wind turbine as the research object, mathematical models for wind turbine, fixed displacement pump-variable displacement motor of hydraulic system, synchronous generator and excitation system were established, for the problem of grid impact in hydraulic wind turbine. The mathematical models for impulse current and impact torque were derived. A suppression method for grid impact in hydraulic wind turbine was proposed, by the combination of generator speed control, excitation voltage control and quasi-synchronization monitoring. Using 30kV·A hydraulic wind turbine simulation platform as the simulation and experimental foundation, the grid impact suppression was researched. Simulation and experimental results show that the grid impact suppression proposed has good control effect for impulse current and impact torque, achieving the flexible grid-connection for generator.

    Analysis of Spool Cliping Force for 2D Electro-hydraulic Proportional Directional Valve
    Liu Guowen, Ruan Jian, Li Sheng, Meng Bin, Zuo Xiqing,
    2015, 26(15):  1995-1999. 
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    To solve clamping malfunction of the spool which was caused in the 2D electro-hydraulic proportional valve under high pressure situation,  applicating the theory of gap flow, the radial force of 2D valve under eccentric and non-eccentric situations was systematically analyzed and a computational formula of 2D valve clamping force was deduced.Using software MATLAB the analysis result was calculated to get the relationship between 2D valve clamping force and the eccentricity with the angle between the high pressure and low pressure holes. Based on the 2D valve's property, the improvement measures of solving spool clamping malfunction were put forward, The flow field of the spool surface was CFD simulated and analysed by using Fluent software. Based on the velocity vector and pressure distribution of the spool, the improvement measure of solving spool clamping malfunction is proved correct. The design philosophy of 2D electro-hydraulic proportional valve is improved, high pressure and large flow proportional control is achieved in improved 2D electro-hydraulic proportional valve.

    Analysis on Torque Characteristics of Harmonic Electromagnetic Movable Tooth Transmission
    Ren Yubo, Xu Lizhong, Liang Yongli
    2015, 26(15):  2000-2005. 
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    A new type of electromechanical integrated transmission system was presented, this transmission system working principles were analyzed, based on a small elastic deformation and deformation coordination assumptions, the stress of movable tooth was analyzed. The meshing force analysis model and algorithm were given under the theoretic status, in accordance with meshing force calculation sample the transmission device preliminary meshing force distribution characteristics were obtained. The transmission output torque was derived, the variation laws were studied,that indicated the relationship among output torque and transmission ratio, the number of turns, tooth radius, gap coefficient and stator slots.Based on this result,it can optimize the parameters of this transmission mechanism.

    Study  on  External  Features  of  Particle  Damping  Loss  Factor
    Hu Li, Tang Zhe, Xu Xian, Yang Qiliang
    2015, 26(15):  2005-2009. 
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    The principle of steady-state energy flow method to measure the damping loss factor was derived.Through this method,a certain type of particle damper damping  loss factor was carried on the experimental study.The vibration simulation of steel plate which was pasted with particle damper was compared with experimental research.The experimental results of the steady-state energy flow method show that,the particle damper damping loss factors vary with the changes of acceleration and present the obvious  “piecewise representation”  features. At  the same time,the  damping loss factors vary  with  the changes of  the frequency and present the obvious “ridge”  features. The reasons of  these features were analyzed in theory.

    Analysis of Influences of Gearbox Flexibility on Dynamic Characteristics
    He Jingliang, He Changran, Wu Xutang, Chen Yong,
    2015, 26(15):  2010-2015. 
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    To analyse the influences of gearbox flexibility on the dynamic characteristics, based on the theory of multi body dynamics, a transmission dynamic analysis model was built. After considering the flexibility deformation of the housing, gears and other parts, the influences of transmission system deformation on dynamic performance were analyzed by calculating mesh misalignment, contact stress, transmission errors, displacement and other relative parameters. In view of the weak parts in the transmission structure, the improvement measures were proposed.

    B-spline Surface Fitting Algorithm Based on Contour's Constraint Points
    Jiang Benchi, Han Jiang, Tian Xiaoqing, Xia Lian
    2015, 26(15):  2016-2021. 
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    Aiming at cross-sectional measured data, a B-spline surface fitting method was proposed. The original data points were denoised firstly, then vantage points of curvature were picked out and taken as the initial contour constraint points, and an initial curve interpolated with the constraint points was gained. After that, constraint points were added to the region whose fitting accuracy needed to be improved, until the B-spline curve could reach preset accuracy. Finally, subjecting to curve which contained the most constraint points, constraint points of the balance number were added to the rest of the curve, and average chord-length parameterization was conducted to construct a family of B-spline curves, and a B-spline fitting surface was obtained at last. Simulation results show that, this method can compress the number of control vertices of the surface model significantly with a high efficiency of surface reconstruction.

    Structure Reliability Analysis for Airborne Pod Frame Based on Generalized Grey Relational Method
    Hu Dongfang, Wang Zhuo, Ji Yuanhao
    2015, 26(15):  2021-2029. 
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    The grey system theory was adopted in the virtual design of airborne pod. Firstly, the gray relational mathematical model was constructed, then the Deng's grey relational method was used as an introduction to expound the generalized grey relational method for reliability evaluation of mechanical products and analyze the difference or relationship between them. The absolute grey correlation model was adopted to determine the relevant factors affecting the situation. Moreover, the analysis of relative grey correlation model was utilized to export the relative change rate for each evaluation index. All of these manners will eventually complete the reliability analysis of airborne pod frame, which can provide theoretical evidences for determining the best structure of airborne pod. 

    Robust  Design  of  Hydraulic  Slide  Valve  Internal Structure
    Wu Xiaofeng, Gan Weimin, Liu Chunjie, Wang Xiaojun
    2015, 26(15):  2030-2035,2040. 
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    In order to optimize the hydraulic valve controlled factors to reduce the sensitivity of  valve opening or closing operation performances  to the  noise factors,and to improve the reliability and stability of hydraulic valve,a robust design method was put forward for hydraulic valves.The dynamic characteristics of inner fluid were simulated when hydraulic valve was opening or closing based on CFD method.Effects of valve inner flow structure parameters,the spool  movement  speed,valve oil inlet and outlet pressure difference on transient flow force were analyzed,then the quantitative relationship  among the transient flow force and various parameters was acquired by using the  design of experiment method and response  surface function method.Finally,the internal flow structure parameters of slide valve were set as the  design variables,spool movement speed and pressure difference between inlet  and  outlet were set as the noise factors which were uncontrollable,transient flow force in hydraulic slide valve obeyed normal distribution and variances minimization was set as the target,a robust design  of  slide  valve faced to its operation  performance  was  executed.Results show that,the effects of noise factors   on transient flow force are  reduced by optimizing the structure parameters.

    Research on Micro Milling Burr Based on Grey Correlation Analysis Method
    Sun Shufeng, Zhang Qindong, Huang Ke, Wang Pingping, Yin Anchen
    2015, 26(15):  2036-2040. 
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    The influences of process factors on the burr generation of part machined were studied based on the grey correlation analysis method. Fault tree model of burr generation was set up. Burr generation was defined as top event and the factors influencing burr generation were defined as basic events. The sufficient and necessary basic events sets that led to top event occurrence were defined as minimal cut sets. The characteristic matrix and pattern vectors of typical faults were set up to calculate the generation rate of minimal cut sets and top event, importance of basic events and the correlation values of minimal cut sets separately. Micro milling experiments were carried out to verify the three minimal cut sets whose correlation values were No.1 ~ No.3. The experimental results are in conformity with the grey correlation calculation ones. Therefore, the grey correlation analysis method provides an effective method to predict and control micro milling burr.

    Steady-flow Characteristic of Gas Fuel Injection Device
    Wang Tianbo, Liu Liang, Chang Siqin, Zhu Jianhui
    2015, 26(15):  2041-2046. 
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    In order to reveal the injection characteristics of the gas fuel injection device, the 3-D steady flow situation simulation models of two kinds of injection devices in different action modes, and the other two kinds of devices in different sealing ways, were established. The steady-flow characteristics such as outflow speed, pressure loss, lateral force of poppet valve stem and back pressure of these models were compared by using Fluent. And the effective injection pressure (EIP) concept was also used to evaluate the injection efficiency of gas fuel injection device. The simulation results show that the outflow speed of pull-open injection device is higher than push-open injection device obviously under the same operating conditions. The injection efficiency of the pull-open injection device is about 56.0% high, on the other hand, the push-open injection device is 50.3% low. In general, the steady-flow characteristic of the pull-open injection device is better than that of the push-open one. The injection efficiency of the plane sealing pull-open injection device is as 55.2%.

    Isolated Substructure Model Updating Method Based on Local Vibration Test Response
    Guo Junlong, Ma Liyuan, Li Hui, Li Shilong
    2015, 26(15):  2046-2050. 
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    A new method of isolation substructure was proposed to update a local substructure based on local vibration test responses, aiming to solve the problems of the excessive identification parameters and low efficiency applied in large complex structure model updating. The method utilized the local structure's vibration test responses to construct the isolation substructure, in order to separate the substructure from the whole and constituted a simply independent structure, which could weaken the influence of the whole effectively. Then, the objective substructure was updated based on the responses of isolation substructure. Finally, a T shaped weld steel tube and the launch platform model were given to prove the effectiveness of the method. The results show that the proposed method contains fewer elements and can be updated easier with high efficiency, and it is well suitable for model updating of such large complex structure.

    ASTFA-BSS Method and Its Applications in Composite Fault Diagnosis for Gearbox
    Yang Yu, He Zhiyi, Li Zizhu, Cheng Junsheng
    2015, 26(15):  2051-2055,2061. 
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    Considering ASTFA method for decomposing the least number of single component as the optimization goal, and taking the physically meaningful instantaneous frequency of single component as constraint conditions, to make the components more reasonable, combining BSS, a BSS method was proposed based on the ASTFA, which was used to carry out composite fault diagnosis of the gearbox. In this method, the single-channel source signals were decomposed by AFTFA, then the dominant eigenvalue method was used to estimate the number of sources, and observed signals were restructured by the number of sources, finally the estimation of source signals was obtained through BSS. The experimental results show that the proposed method can separate the composite fault signal of the gearbox effectively, and achieve the composite fault diagnosis of the gearbox.

    Segmented Calibration of Transducer Based on Grey Neural Network
    He Weiming, Shui Hongwei, Song Xiaoqi, Gan Yi, Wang Zhonghou, IHARA Tohru
    2015, 26(15):  2056-2061. 
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    As large range and high precision transducer could not complete the calibration with just one experiment, an integrated modeling method was proposed, which incorporated optimized grey GM(1,1) and BP neural network to predict the missing values in calibration, and the segmented calibration of transducer was realized. Firstly, according to experimental data, traditional grey GM(1,1) model was established to predict the missing values, which were measured by both calibrated transducer and standard transducer. In addition, in order to weaken the scope of the sequence and improve mode prediction accuracy, the idea of center approach was used to optimize traditional grey GM(1,1) model. Finally, BP neural network was applied for modifying the residuals of optimized grey GM (1,1), realizing the prediction of the missing values in calibration with a high accuracy. The results show that the residual mean of the combined model of calibrated and standard transducer are 0.023% and 0.401% respectively, the effectiveness of the combined predicting model is proved, so it can be used to predict the missing values for the segmented calibration of transducer, and a new method is proposed to solve characteristic curve fitting problem, which is related to segmented calibration of large range and high precision transducer.

    Variable Precision Rough Set Decision-making Method for Quality Assessment of Cable Harness Wiring in Complex Mechatronic Products
    Wang Falin, Liao Wenhe, Guo Yu, Ju Chuanhai
    2015, 26(15):  2062-2069. 
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    For the current cable harness wiring mainly relied on the assembly workers' experience and made it difficult to get guaranteed quality problem, a VPRS decision-making method was proposed herein based on attribute weighted similarity measurement for cable harness wiring quality assessment. Firstly, a quality assessment model for cable harness wiring was established by overall considering multiple attributes of assesses objects. Secondly, the cable harness wiring quality assessment rules were formulated combined with the theory of VPRS on the basis of quality assessment model. Finally, similarity degrees among the current cable harness wiring status and all objects from the decision-making system were compared based on attribute weighted similarity, which could obtain the decision results of wiring quality, and complete the quality assessment. Example results show that the method presented can provide more realistic decision-making results compared to the traditional quality assessment method.

    Thermodynamic Analysis and Calculation on Hydraulic Steering Units of Aircraft Hydraulic System
    Li Jing, Tang Guichun, Cao Junfei, Shi Xianzhu
    2015, 26(15):  2070-2074,2080. 
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    A thermodynamic analysis method was adopted to hydraulic servo steering units in temperature controlling for reducing aircraft hydraulic systems failure. A hydraulic servo steering units can be simplified to a servo valve and an actuator cylinder.Based on the first law of thermodynamics, the thermodynamic model of hydraulic steering units for aircraft was established. And the thermodynamic differential equations set of the model were derived with lumped parameter method, and solved by Runge-Kutta method. Simulations of hydraulic servo steering thermodynamics model were carried out by employing MATLAB software. And the calculation results coincide with the experimental data. The model presented herein can be used to calculate the dynamic temperature of aircraft hydraulic systems.

    Theoretical and Experimental Study of Cooling Method for SMA Wire Actuators
    Wang Qi, Xu Zhiwei
    2015, 26(15):  2075-2080. 
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    For the purpose of shortening cooling time of SMA actuators and the ultimate goal of improving the response speed, a novel cooling system was designed to amplify heat transfer coefficient by utilizing forced convection between a SMA wire and cooling pipe. Using compressed air as a cooling air supply, airflow through the annulus channel driven by pressure drop achieved rapid cooling of a single wire without affecting the others. The numerical analysis of natural cooling and forced convection heat transfer theoretical models were established to provide help for system design, and experiments of natural cooling and forced convection were carried out on a SMA wire of 1mm in diameter. Contrastive analyses of the theoretical solutions and experimental results indicate that the theoretical models are accurate.

    Research on Service Methods for Ecosystem of Soft Material Cutter
    Fang Yunke, Huang Xuhong, Li Tao, Xu Yuanyuan, Chen Jixi, Gu Xinjian
    2015, 26(15):  2081-2089. 
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    In response to the real problems and changes in demands for the development of domestic cutter manufacturer, combining the theory of industrial ecosystem, manufacturers service innovation and knowledge management, considering the needs of soft material cutting manufacturing industry, the concept of the ecosystem of soft material cutter (ESMC) was proposed, the industrial chain model of the cutter industry was given, the knowledge structure of the cutter manufacturer was studied, also the feasibility was analyzed. Through further research, the service methods for the ESMC were put forward, that is, the sub-ecosystem of product services of the ESMC and the sub-ecosystem of multi-value chain services of the ESMC, so as to promote the prosperity and development of the industrial ecosystem.

    A High-speed Smooth Arc Transition and Look-ahead Control Algorithm for Continuous Short-segments
    Zhang Jun, Zhang Liqiang, Zhang Kai
    2015, 26(15):  2089-2095. 
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    A quadratic NURBS arc transition path in the adjacent segments which was everywhere curvature-continuous was proposed to solve the problems of the machine vibration and shocks caused by abrupt change of velocity and acceleration, and then the high-speed smooth transition was obtained. Based on the arc model, a look-ahead control algorithm was established. Under the conditions of the chord errors and machine dynamics, the algorithm aimed to achieve optimal transition velocity, and control acceleration/ deceleration by using the 7 section and 5 section mixed bidirectional S algorithm, and to avoid the motor starting/stopping frequently, then the high-speed transition was realized smoothly. The example demonstrates that the proposed algorithm can achieve more stable transition velocity, improve the machining efficiency and quality, and satisfy the demands of high-speed machining.

    A Module Partition Method for Product Redesign
    Zhou Kaijun, Gong Zhibing, Tong Yifei
    2015, 26(15):  2096-2102. 
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    In order to improve the defects in present methods of module partition, a unified product module partition mathematical model and solution processes were proposed. According to the characteristics of the mathematical model, a fitness function module was constructed based on the degree of polymerization and the degree of separation, then the matrix crossover genetic algorithm was applied for solving optimization module partition. Finally, taking astronomical dome products for example, the component integrated fuzzy similar matrix acquisition was illustrated, as well as the optimization algorithm for solving process. Practice has proved that this method is fast and effectives.

    Suporting Force Control Strategy of Transition Process for Stepping-type Advanced Supporting Equipment
    Mao Jun, Yang Zhenhua, Lu Jinnan, Xie Miao
    2015, 26(15):  2103-2108. 
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    To solve the problem of fluctuations of supporting force during transition process and improve the efficiency of support, using advanced electro-hydraulic proportional control technology, combining theoretical basis of valve control cylinder, a control strategy was put forward,that used spool displacement of the direction valve to control supporting force of cylinder groups. For the electro-hydraulic system of advanced supporting equipment, the mathematical model and simulation model of control system were established. The system simulation was carried out by AMESim software, the control effect of different control spool displacement curves was analyzed during supporting rack up and down. The results show that the spool displacement control curve that studys on volume increment principle is conform to the requirements of the actual working conditions. Combining experimental study of the prototype, the control law of experiments and simulation was analyzed and the reasonableness of the control strategy was verified.

    Intelligent Jig and Fixture Planning Algorithm Based on Analytical Hierarchy Process
    Ling Ping, Luo Chen, Su Chun
    2015, 26(15):  2109-2117. 
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    The locating feature recognition, analyses of three-dimensional model of the workpiece and automatic reasoning algorithms to locating scheme were studied. Model was simplified and the candidate locating features set were extracted based on rule-based reasoning and a hierarchical storage model of feature faces was proposed. Comprehensive evaluation normalized theory and standard deviation method theory were combined to achieve the quantitative comparison of importance of selected factors. The sorting and optimization of the multi-level positioning reference was achieved based on AHP, so that the combination weight vector of the candidate locating reference related to the optimal locating reference and the optimal locating scheme could be got through total sort by AHP. Finally, an example was provided to prove that the method of proposed jig and fixture planning is feasible and realistic.

    Regenerative Braking Control Strategy for PHEV Based on Optimal Braking Effect
    Gao Aiyun, Deng Xiaozhong, Zhang Mingzhu, Fu Zhumu
    2015, 26(15):  2118-2124. 
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    Based on the principles of the braking force distribution, a regenerative braking control strategy was proposed on the basis of the optimal braking effect and fuzzy control, where mechanical braking could cooperate with regenerative braking and front and rear wheel braking force were distributed reasonably. Taking the braking strength and the state of charge of batteries as inputs, and regarding the expected regenerative braking force as an output, a fuzzy controller was designed. The control strategy designed was simulated from parts performance, braking energy recovery and braking sense compared with the default control strategy in ADVISOR. At the same time, the hardware-in-the-loop simulation was developed to prove the simulation results in ADVISOR effective. The results show that the control strategy presented can assure the driver of satisfactory braking sense based on the braking stability, and improve energy efficiency at the same time and at last achieve optimal braking effect.

    Vibration Analysis and Experimental Test of a Boom System of Truck Mounted Concrete Pump
    Liu Rongsheng, Li Hui, Gao Yingjie, Yang Yulin
    2015, 26(15):  2125-2129. 
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    An analytic method was applied to study the vibration performance of the 52-meter-long five-boom system of truck mounted concrete pump. The combination of Lagrange's equations of the second kind and assumed mode method was utilized to establish the flexible multi-body dynamics equation of the boom system. Based on the dynamic model, modal analysis was implemented and numerically solved by MATLAB, and the first ten nature frequencies and modes of vibration of the boom system were acquired. The impacts of the boom parameters on nature frequencies of the boom system were also analyzed. In addition, vibration experiments on a real boom system were implemented to verify the theoretical nature frequency. The research results can provide basis for the improvement of the boom structure and the further research of vibration control.