Table of Content

25 February 2011, Volume 22 Issue 4

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Optimal Test Selection of Materiel Based on Bayesian Network under Test Uncertainty

CHEN Xi-Xiang, QIU Jing, LIU Guan-Jun

2011, 22(4):  379-384. 

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Synthetically considering the ubiquitous uncertainties of

the process of materiel diagnosis and testing,a model of testablitiy analysis was founded referring to the Bayesian network by introducing test probabilities. Based on the corresponding dependency matrix between faults and tests under the condition of test uncertainties, testability indices were computed via Bayesian reasoning, and then the test set

was optimized using hybrid BPSO(binary particle swarm optimization) and GA(genetic

algorithm). The experiments show that the conclusions are consistent with the actual situations because of the test uncertainties considered, consequently have higher confidence comparing with traditional methods.

Research on Efficient Cutting Technology of High Speed WEDM　

LIU Zhi-Dong, WANG Zhen-Xin, ZHANG Yan, XU An-Yang

2011, 22(4):  385-389. 

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Based on present situation of the cutting efficiency of

high speed WEDM maintaining within 200mm²/min,the interelectrode mechanism of efficient cutting with large energy was studied. Analyses suggest that cooling liquid's

selection, the injection system of cooling liquid, discharge gap and material erosion's type all have great effects on the efficient cutting. Coaxial and high-pressure injection

improve obviously the situation of interelectrode flow field with timely supplement of cooling liquid, avoiding the cutting surface burned and the cutting efficiency

reaches more than 200mm²/min stably. 

Critical Load and Optimum Design for Hydraulic Cylinders

LIN Rong-Chuan, GUO Yin-Biao, WEI Sha-Sha, LIN Hui

2011, 22(4):  389-393. 

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The gap between piston rod and cylinder is an important factor which affects the stability of a hydraulic cylinder.With the effects of gap, bending was caused in piston rod and cylinder under axial and lateral forces. Based on buckling differential equations for hydraulic

cylinder, a deflection nonlinear equation for piston rod and cylinder was proposed for calculating the critical load.Under the condition of known volume constraints and critical

load,the parametric finite element method was used to establish and analyze the mechanical model of hydraulic cylinder.A nonlinear quadratic programming method was applied

 for the optimum design of the structures. Compared with the size which calculated by

Ritz and verified by stability test, the results show the method is applicable for calculation of stability for hydraulic cylinders.

Optimal Design of Micromachined Silicon Condenser Microphone Based on Multi-objective Genetic Algorithm

DONG Jian, WANG Wei, JI Shi-Ming

2011, 22(4):  394-397. 

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A new approach to design micromachined condenser microphone based on multi-objective genetic algorithm was proposed.The parameters of the sandwich diaphragm and the backplate as well as the space among them as the design variables,and the sensitivity and the pull-in voltage and the frequency bandwidth were optimized.A Pareto-optimal set was obtained by

multi-objective genetic algorithms.The set,in accordance with demands of design mostly   was chosen as the parameters of microphone from the Pareto-optimal set.

Structure Capability Optimization Based on Sensitivity of Parameters

LI Chu-Ye, WANG Wei-Chao, MA Yan

2011, 22(4):  397-402. 

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Under the conditions of parameter optimization for

NC machine tool crossbeam, the technique of shake cycle optimization(SCO) was educed,this method permits weight changing wave, parameter changing by the control of minimizing deformation, and ultimately results in better structure with the weight balanced.Integrated with FEA tool, this optimized technique is very availability and realization facility.This sensitivity-based fast algorithm is credible and feasible in theory by some mathematical models and the practical application tests.

Global Optimization Design of V-belt Fatigue Life

ZHANG Shao-Jun, MO Zhong, LIU Guang-Lian

2011, 22(4):  403-407. 

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An optimal design model was constructed to maximize the fatigue life of V-belt drive herein. The properties of the objective function such as convexity and monotonicity were deeply studied, and it is proved that the feasible region of

the optimal design model is bounded, close and convex.Then, a global optimization method, called optimal segment algorithm,was proposed for this model.An example supported the efficiency of the proposed model and method.

Simulation of Sloshing Trajectory for Robots Based on Virtual Reality

ZHANG Ke-Min, LIANG Ti-Chang

2011, 22(4):  408-411. 

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In order to develop telepresence simulation experimental platform for robots based on virtual reality,it was proposed that a new simulation method to realize sloshing trajectory of robot's endpoints in the virtual scene by building the model of 1-DOF

and small damping free vibration.Taking 3-DOF robot for good example the model

 was analysed in detail. Finally, discrete equations for joint trajectory of the robot

were obtained to realize VS programming simulation, and the compiled program of telepresence simulation platform for 3-DOF robot was developed to carry a simulation experiment. The simulation results show that this algorithm is valid.

Research on Equidistant Curves of General Scroll Profiles for Scroll Vacuum Pump Based on Envelope Principle

WANG Li-Cun, CHEN Jin, WANG Xu-Dong, ZHANG Xian-Meng, CHEN Ban

2011, 22(4):  412-415. 

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For developing new creating ways of scroll profiles for

scroll vacuum pump of oil filter, a theoretical method of creating equidistant curves

was studied. And the abroad applications of this method were analyzed. Using the circle cluster envelope principle, the fundamental formulas of equidistant curve created by plane curve were deduced. Taking the points of the scroll profile as the centre of a circle,

and taking parameter h as the radius,circles

were made and used to construct the circle cluster in the fixed plane. The envelope curve of both sides of the envelope curves were just the two equidistant curves of the scroll profiles. And the correctness and practicability of the method of creating equidistant curves formulas were validated.

Experimental Research on Identification of Dynamic Characteristic Parameters of Rolling Guide's Joint

ZHANG Hua, YUAN Jun-Tang, HONG Zhen-Hua

2011, 22(4):  415-418. 

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In order to identify the dynamic characteristic parameters of

rolling guide's joint, a measurement model of equivalent single degree of freedom system was established. This model simplified the institution with rolling guides installed to single degree of freedom system and eliminated the influences of the base

displacements on parameter identification. Based on the measurement model,a measuring device for identifying the dynamic characteristic parameters of rolling guide was developed. The MRC45 linear rolling guide of Schneeberger was selected as an example to

measure the dynamic characteristic parameters of its joint.The dynamic stiffness with high precision in normal and tangential sides of rolling guide was obtained and the effects of load on dynamic stiffness were also analyzed.

A Method of Real-time Estimation of Contouring Errors

LI Pei-Xin, MA Ti, XU Dong, WANG Zhi-Cheng, HAN Xu

2011, 22(4):  419-423. 

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Based on the study of contour error calculation methods detailed, a novel approach for estimating the contour errors in real-time was proposed for the

requirements of real-time task in high-end CNC.This method solved the problems which, for free-form curve, the contour error calculation process is complex and needs

large computations. Experimental results for a biaxial motion system show that the proposed approach has very small amount of computation and owns very high calculation accuracy in real-time tasks and it can guide the selection of the current control parameters and observe the control effects of the contour errors.

Optimal Calculation for Thermal Errors of Machine Guide Way with Approximation Model Method

LI Hao-Lin, YING Xing-Juan, CHI Yu-Lun

2011, 22(4):  423-427. 

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In order to obtain the thermal errors of a machine guide way in whole stroke in real time,the methodology of approximation model and numerical simulation were applied to optimize the boundary conditions of finite element model in machine guide way.The objective of approximation model was to reduce errors between calculations and experiments; the calculations was obtained from finite element analysis. Finally, the optimal calculation results of the guide way thermal

errors were obtained. It can be used to thermal error compensation in machine guide way and enhances the manufacturing accuracy. The problem of thermal error measurement

of machine guide way in real time was solved.

Dynamic Characteristics of Planetary Gears with Elastic Ring Gear

DUAN Fu-Hai, TU Cha, LIN Ding-Xiao, CHEN Xu

2011, 22(4):  428-432. 

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A torsional dynamics model of planetary gears was developed to study the effects of elastic ring gear on its dynamics characteristics. The models were solved by using numerical methods. Some experiments were taken based on numerical results. The numerical and experimental results show that the mesh stiffness influences the dynamic loads for planetary gear systems with elastic ring gear significantly, and high dynamic loads for system will yield as the difference between external and internal mesh stiffness becomes large, substituting elastic ring gear for rigid one can increase dynamic loads on sun-planet mesh markedly, however, reduce dynamic loads on ring-planet mesh to certain extent. Sun-planet dynamic load can be reduced by decreasing their mesh stiffness. The system mesh dynamic loads may effectively be reduced by choosing system parameters properly in planetary gear systems with elastic ring gear.

Research on Classification Algorithm of Reduced Support Vector Machine for Low Limb Movement Recognition

TUN Jian-Feng, TUN Qun, SUN Shou-Qian

2011, 22(4):  433-438. 

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In order to improve precision of the multi-motion pattern recognition of lower limb movements, a recognition method based on reduced

SVM was proposed. The daily movements were decomposed into different segments to form the recognition goals, and the surface electromyography signals of low limb muscles were used as information sources. The eigenvectors were extracted using Mallat wavelet transform and statistical characteristics in time-domain. Then the simplified method of kernel clustering was used to reduce the computational complexity and improve the robustness of algorithm. Four patterns were identified herein,i.e. standing, normal speed walking, up-stairs and down-stairs. The experimental results show the effectiveness of this method.

Research on Mutual Information Registration Combined Neighborhood Intensity with Spatial Signature

WEI Yu-Lan, YA Yun-Hui, LI Bing, ZHANG Yao, LI Jun

2011, 22(4):  439-443. 

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In order to overcome the shortcomings of mutual information

registration,such as susceptible to noise and registration errors caused by ignore the spatial signature, a new similarity measure of mutual information method was proposed,

which combined intensity with geometric characteristics of the neighborhood . The method took advantage of the intensity mutual information, while fully integrating the neighborhood of

the geometric distance between pixels and the relation between intensity. In the calculation of mutual information, every pixel was determined by neighborhood pixel according to weight value by distance and intensity changing relationship.Experimental results show that compared with traditional mutual information and gradient mutual information,the new registration method is more accurate, and anti-Gaussian-noise performance is better.

Dynamic Simulation on Flat Valve of Water Hydraulic Piston Pump 

HUANG Guo-Qi, XU Jin, SHU Yu-Quan

2011, 22(4):  443-446. 

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Dynamic performance of a water hydraulic piston

pump with flat valves was analyzed.Its mathematic model was established

and the influence factors were studied by simulation. The results show that the bigger clearance volume or higher vacuum degree makes flat valve delay more serious, and reducing spring stiffness or spool quality is favorable to promote the performance of flat valve. In addition, too high rotational speed is not suitable in this kind of pump and work pressure also has influence on the opening delay to flat valve．

Research on Dose and Depth Adjustable Needle-free Injector

ZHANG Lei, WU Xi-Jie, LI Jia-Qi, ZHANG Qing-Zhi

2011, 22(4):  447-451,457. 

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Based on the comparison between the features and properties of several kinds of existing needle-free injectors, a flexible needle-free injector which was adjustable in both dose and injecting depth was proposed to overcome the disadvantages of non-adjustable needle-free injectors. The original design was optimized by the application of adjustable pre-pressure spring structure for the purpose of regulating the potential energy stored by the spring in according with the actual application situation. A serial of ampoules were also designed to match different doses. Simulation experiments and analysis conducted on Fluent verify that this new needle-free injector is adjustable in a dose range of 0.1~1mL and a depth range of 6~20mm. 

Study on Stiffness and Deformation Behavior of Slewing Bearing in Shield Machines

TU Hai-Dong, DING Cheng, ZHANG Kai-Zhi, WANG Hao

2011, 22(4):  452-457. 

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A finite element analysis model on a three-row roller slewing bearing was established based on the algorithm of Hertz contact theory and load equivalent model of the bearing. The stiffness behaviors subjected by the radial, axial and capsizing moment loads were investigated by using the explicit calculation. The behavior of stiffness and the load subjected on the bear was analyzed. The relationship among stiffness characteristics and load as well as dynamic stiffness under impact load was studied. The results show that the radial stiffness increases nonlinearly with load when the contact nonlinearity is considered. However, the axial stiffness decreases nonlinearly with load. The load in the axial direction has little influence on capsizing stiffness. The stress and deformation distribution of various rollers can not be described with a simple cosine function. The results can provide the guidance on the redundant actuating design of motors and synchronization control of redundant driving motors of shield during excavation in the complex geological formations. 

Effects of Process Parameters on Vibration Signals in Dry Milling of Aeronautic Aluminum Alloy 7050-T7451

ZHONG Wei-Wu, DIAO Dong-Biao, WANG Xi, XU Hui

2011, 22(4):  458-461,503. 

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In order to study the influences of process parameters on dry cutting process, a signal acquisition system was set up to sample vibration signals in dry milling process. The sampled data were analyzed in time domain and frequency domain.The

results show that:vibration in dry milling is mainly caused by forced vibration, which is inherent in milling process because of the intermittent cutting;RMS value of vibration signals has complex non-linear relationship with cutting speed, feed per tooth and radial depth of cut;frequency components of vibration signals mainly concentrate in three bands in

0~20kHz,and changes of processing parameters result in change in energy ratios of the three bands.

Research on Active Control System of Imitative Vibration Isolative Platform for Precise Instruments

LI Guo-Beng, HAN Tong-Feng, WEI Yan-Ding

2011, 22(4):  462-467. 

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An active vibration isolative technique based on the giant magnetostrictive actuator was proposed, and a two-stage imitative vibration isolative platform for precise instruments was developed. Based on the imitative vibration isolative platform, the mathematical models of the system were established. According to the immune theory, an immune PID controller was designed to match the vibration active isolation system. Finally, this active control system of imitative vibration isolative platform was simulated using Simulink software and tested in the laboratory. The research results demonstrate that it can effectively suppress environmental vibration and satisfy vibration isolative requests of general precision instrument.

Optimized Contour-parallel Offset Tool-path Linking Method Based on Free Region

ZHANG Ming, LIU Wei-Jun, BIAN Hong-You

2011, 22(4):  468-473. 

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To solve the CPO tool-path linking problem,A simple and effective CPO tool-path linking method was presented.In order to effectively manage tool-path loops (TPLs), a tree-liked data structure called TRT was constructed. To obtain subpaths, TRT was split into several grouped TPLs, and then grouped TPLs were linked by using TPL-connector．After subpaths were constructed,subpaths linking problem was optimized by the way of searching slotting point in free region(FR)．Finally, the simulation was conducted to verify the validity, and the simulation shows that the method can significantly reduce the retraction number and sometimes can even avoid retraction on the basis of improving computational efficiency.

Study on Drag Characteristics for Flow Field of Underhood Based on Numerical Model of Cooling System

YUAN Zhi-Qun, GU Zheng-Qi, FANG Qiu, YUAN Xia-Xi

2011, 22(4):  474-478,483. 

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For the purpose of increasing the efficiency of cooling system and reducing the aerodynamic drag, a method of numerical model of cooling system instead of experimental model was proposed, which was applied to study the airflow characteristics of underhood coupling internal and external flow fields. The influence on internal drag of the underhood was studied fully. The results show that the influence of internal drag is notable on aerodynamic drag, which for the whole is about 10%. It will become bigger with the increase of speed of fan. The diversification is clear when speed of car is low, but the diversification is not clear when speed of car is high. The drag of cooling system will become bigger with the increase of speed of fan when the speed of car is constant and the drag of radiator is sensitive to speed of fan. The drag of cooling system will become bigger with the increase of speed of car when the speed of fan is constant and the drag of condenser is sensitive to speed of car. The simulation results agree well with the test data in the wind tunnel, which indicates numerical simulation for automotive aerodynamics characteristics is feasible. 

Nonholonomic Constraint Control System Analyses and Applications Based on Hamiltonian

Equations

LIU Yun-Beng

2011, 22(4):  479-483. 

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For the dynamic differential equations of spacecraft multibody system is strongly nonlinear with nonholonomic constraint, it is difficult to find the analytical solution and analyse its stability and control problem. The two point boundary value problem of nonlinear dynamic differential equations can be avoided by the Hamiltonian control system with nonholonomic constraints application to the analysis of attitude stability.This is a compact method for the attitude control of the spacecraft multibody system. Furthermore, the control action has a clear physical interpretation that the system stability of control can be understood as the energy balance between system and controller. The last is the simulation example. 

Application of Global Optimization Methods in Developing a Plug-in Hybrid Vehicle

GU Ji-Chao, ZHOU Yu-Liang, LI Guang-Yao, DONG Zuo-Min, AN Nian-Fei

2011, 22(4):  484-488. 

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Multi-objective Design Optimization on Crashworthiness of Full Vehicle Based on Adaptive Radial Basis Function

CHEN Guo-Dong, HAN Xu, LIU Gui-Ping, DIAO Zi-Heng

2011, 22(4):  488-493. 

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An ARBF model method was suggested and combined with

micro multi-objective genetic algorithm(μMOGA) to solve vehicle crashworthiness. In each iterative,sampling points were obtained by the optimal Latin hypercube design, while testing points were obtained by the inherit optimal Latin hypercube design, this method

regarded the errors of testing points as fitness of intergeneration projection genetic algorithm (IP-GA), assessed the model systematically and got the optimal smooth parameters to maximize model accuracy, testing points added to sample space until reaching errors

 allowable of each crashworthiness objective. Then greed algorithm was adopted to filter the testing points from the last iterative to sampling space to increase accuracy. At last, μMOGA was applied to optimize the ARBF,and got Pareto and balanced each objective to get different best compromise solutions according to engineer experiments or

engineerring requirements.

Advances of Hydrothermal Property Study of Carbon Fiber Reinforced Epoxy Laminates

ZHANG A-Ying, ZHANG Dong-Xin, LI De-Gong, XIAO Hai-Yang, GU Jin

2011, 22(4):  494-498. 

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A study of moisture absorption process, aging mechanism and mechanical properties of hydrothermal aging and finite element numerical simulation were summarized from theoretical research and experimental methods. Composite materials are sensitive to the impact, and the static strength and fatigue strength reduce as porosity

increases, which results in more vulnerable in the hygrothermal environment. Some recommendations for future work of the influence of porosity on mechanical properties after impact composites in the hydrothermal environment were also proposed.

Summary on Research of Differential for a Electric Vehicle

XU Yin, CHEN Dong

2011, 22(4):  498-503. 

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A simple summary was carried out for the powertrain's structure of the electric vehicle. Based on this, another detailed summary was carried out for two ways of the differential research. One way was designing the special motor with self adaptive differential system, and another way was designing the electronic differential which was based on kinds of control theories. An exposition was made upon the structure and the principle of the self adaptive differential. And another detailed exposition was made upon the structure, model, object and the control strategy of electronic differential. The advantages and disadvantages of the motor's rotational speed and torque which were chosen for the control objects were discussed. In the end, the developing prospects of the electric vehicle's differential were discussed.