Table of Content

25 March 2016, Volume 44 Issue 3

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Mechanical Engineering

Warming-Assisted Burnishing and Fretting Wear Performance of Ti-6Al-4V Alloys

QU Sheng-guan PAN Yu-xiang LI Gang LI Xiao-qiang YANG Chao

2016, 44(3):  1-7.  doi:10.3969/j.issn.1000-565X.2016.03.001

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Warming-assisted burnishing (WAB) was applied to the surface modification of Ti-6Al-4V alloys,and the characteristics of the modified surface were investigated by using scanning electron microscope,BMT.3D surface topography measurement instrument,Vickers micro-hardness tester and VHX-600E three-dimension microscope.Moreover,the tribological properties of untreated specimen，burnishing (BU)-treated specimen and WAB-treated specimen were examined by using a SRV Ⅳ tester under dry condition,respectively.The results show that (1) the surface roughness of Ti-6Al-4V alloys is significantly reduced and a thick hardening layer is generated on the alloy surface after WAB processing; (2) the friction coefficient and wear volume of WAB-treated specimen are both low- er than those of the untreated and the BU-treated specimens; (3) the wear mechanism of untreated specimen is ad- hesive wear accompanied with slight plastic deformation,while that of BU-treated and WAB-treated specimens are abrasive wear with slight fatigue spalling.It is thus concluded that WAB processing can improve the fretting wear resistance of Ti-6Al-4V alloys significantly.

Peridynamic Theory-Based Prediction of Micro Breakage of Cemented Carbide Tool

JIANG Hong-wan HE Lin FAN Lin ZHAO Xian-feng ZHAN Gang

2016, 44(3):  8-15.  doi:10.3969/j.issn.1000-565X.2016.03.002

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Breakage is one of the important forms of tool failure.The traditional tool breakage analysis is mostly car- ried out through cutting test,which not only costs a lot but also lasts a long cycle.On the basis of peridynamic (PD) theory,this paper focuses on the micro breakage in the field near the main cutting edge in cutting process of 42CrMo large-diameter oil pipeline with cemented carbide tool.Firstly,finite element simulation of the cutting process is car- ried out to extract tool load.Secondly,in Visual Studio environment,the program for PD modeling and analysis is compiled by using C language according to PD theory.Then,with the help of image processing unit in Matlab,nu- merical analysis of micro breakage in the field near the main cutting edge of the cemented carbide tool is made in terms of the crack initiation position,the displacement trend of material particle in different directions and the growth trend of crack.The results show that the PD theory-based numerical analysis of cemented carbide tool’s mi- cro breakage helps reveal the mechanism and growth of micro breakage of the tool material in the field near the main cutting edge,that is,the micro breakage under certain working conditions is mainly caused by the shock load-in- duced micro cracks which is in a certain angle with the normal of rake face,and that the breakage trends to spread to the internal material discontinuously.

Experimental Investigation into Accuracy of Narrow-Slit Electrochemical Machining with Cathodic Compound Feeding

WANG Feng ZHAO Jian-she GAN Wei-min QI Lu TIAN Zong-jun

2016, 44(3):  16-22.  doi:10.3969/j.issn.1000-565X.2016.03.003

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In order to improve the stability and localization of narrow-slit electrochemical machining,a cathodic com- pound feeding mode with continuous linear feeding and vibration was proposed,and the corresponding machining experi- ments were carried out on the basis of the improved waveform-adjustable vibration system with a vibration frequency of 0 ～50Hz and with a vibration amplitude of 0 ～2mm.The results show that,(1) in comparison with linear feeding,cathodic compound feeding is more effective in improving machining localization and reducing narrow slit’s width; (2) high vibration frequency and amplitude both help reduce the stray corrosion and improve the narrow-slit machining consistency; and (3) different shapes of narrow slits with a slit width of 0.305mm can be machined out by adopting the cathodic compound feeding mode.

Parameter Selection of CNC Real-Time Task on the Basis of Multi-Objective Optimization

ZHAI Zhen-kun LI Di

2016, 44(3):  23-28.  doi:10.3969/j.issn.1000-565X.2016.03.004

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In order to realize the parameter selection of CNC real-time task in collaborative design mode,a task pa- rameter selection method on the basis of multi-objective optimization is proposed.In this method,a multi-objective optimization model is established according to real-time task model,performance objective as well as system con- straint,and the model is solved by means of an extended non-dominated sorting genetic algorithm with co-evolution operator and elite team retention mechanism,thus the speed of searching optimal task parameters in large-scale de- cision space improves,which promotes the overall performance of CNC system to achieve the optimum.Finally,the parameter selection strategy of CNC real-time task is summarized according to simulation results and the superiority of the proposed method in practical application is proved through a comparison with the traditional task parameter selection approach.

Towing Torque Prediction and Influence Factor Analysis of Wet Friction Clutch

LIN Teng-jiao WANG Qing XIE Yan PAN Li Lü He-sheng

2016, 44(3):  29-35.  doi:10.3969/j.issn.1000-565X.2016.03.005

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Firstly,by taking the oil flow path of wet multi-disc friction clutch in marine as research object,the flu- id dynamic simulation of disk-separating process is conducted by means of dynamic mesh technique,and the distri- bution of oil film thickness between friction and steel disks is recovered.Secondly,on the basis of hydrodynamic lu- brication theory and Newton’s inner friction law,a mathematical model describing the towing torque of wet multi- disc clutch that contains friction plates with radial and circumferential grooves is established,and the analytical so- lutions of towing torque are obtained.Then,a parametric discrete model of oil film is established and the numerical solutions of towing torque are achieved by means of finite element method.Finally,the towing torque affected by groove form,drive shaft speed and oil temperature is analyzed.Calculated results show that (1) the numerical solu- tions of towing torque accord well with the analytical ones; (2) the groove form has a great influence on the towing torque; and (3) the towing torque of clutch increases with the increase of drive shaft speed and with the decrease of oil temperature.

Design and Analysis of Double-Impeller Torque Converter with Continuously Variable Capacity

MA Wen-xing JI Long-fei XU Wen LIU Chun-bao

2016, 44(3):  36-43.  doi:10.3969/j.issn.1000-565X.2016.03.006

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Firstly,a high-performance general three-element centripetal turbine torque converter with an effective cycle round diameter of 425mm was selected as a reference prototype to design a prototype with the same perfor- mance by means of similar-design method.Secondly,the cycle round and blades of double-impeller torque converter were obtained by segmenting the impeller blades of the prototype reasonably.Then,the structure of slip clutch was designed,and the main technical parameters of slip clutch and friction plate were determined.Finally,the designed double-impeller torque converter was calculated numerically by means of CFD (Computational Fluid Dynamics) method to obtain the capacity characteristics and the original characteristics under such three conditions as double working impellers,single working impeller and slipping.It is indicated by comparative analysis that the designed double-impeller torque converter can realize the continuity and controllability of capacity through slip control,so that it can be used to the variable capacity matching between loader engine and torque converter.

Motion Planning of Robot on the Basis of Task Decomposition and Speed Distribution

ZHANG Qin FAN Chang-xiang

2016, 44(3):  44-50.  doi:10.3969/j.issn.1000-565X.2016.03.007

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In order to overcome the motion difficulties of robot near its singularities,a new motion planning algo- rithm is proposed on the basis of task decomposition and speed distribution.In this algorithm,the control task is di- vided into several sub-tasks according to their priorities,and each sub-task is controlled independently.The velocity component of each sub-task is determined according to the driving capability of joint motors and the priority of each sub-task,which helps implement the coordinated movement of robot even in the condition of low flexibility when the robot moves near the singularities or stays in the singularities,thus achieving the control objective and avoiding the vibration,excessive end-effector error and system instability caused by the sudden change of joint relative velocity.By taking a PUMA robot for example,the composition of the control system is illustrated,and the feasibility of the proposed method is proved via simulation.

Automotive Engineering

Design of Hybrid Power System for Prolonging Lifespan of Lithium-Ion Battery Applied to Electric Vehicles

LUO Yu-tao LIU Xiu-tian LIANG Wei-qiang RUAN Xu-song

2016, 44(3):  51-59.  doi:10.3969/j.issn.1000-565X.2016.03.008

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Firstly,both the limitations of lithium-ion battery as a single power of new-energy automotive and the ad- vantages of super capacitor as an auxiliary power source are analyzed,and the topology of hybrid power system com- posed by lithium-ion battery and super capacitor is designed.Secondly,the parameters of the hybrid power system are matched on the basis of NEDC driving cycle by considering the performances of both lithium-ion battery and su- per capacitor,and the load shifting rule of super capacitor is used to improve the performance and lifespan of lithium- ion battery.Then,a capacity fading model is established on the basis of vehicle driving cycle test.Finally,by means of the multi-objective optimization logic threshold control strategy with speed tracking,the reasonability of the proposed topology,capacity fading model and logic control strategy of the hybrid power system is verified through Matlab/Simulink simulation.The results show that the proposed model helps improve the battery lifespan by 50% and prevent the battery from high-current impact,and thus vehicle cost decreases.

Control of Positive-Torque Downshifting Process of Automatic Transmission with State Variable Constraints

YE Jie HUANG Xiang-dong ZHAO Ke-gang HE Xiao-peng LIU Yan-wei

2016, 44(3):  60-67.  doi:10.3969/j.issn.1000-565X.2016.03.009

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By taking an automatic transmission that implements the power shifting only with a single friction clutch as the research objective,the dynamic process of positive-torque downshifting of automatic transmission is analyzed to establish a coordination control strategy for friction clutch and engine torque.By considering the jerk at the end of the inertia phase and the friction work as the comprehensive objective functional,the coordination control is ac- complished on the basis of minimum principle,which is used to optimize the inertia phase in downshifting process with torque constraints.Moreover,by taking the gradient of the power source torque and the friction clutch as two control variables and by applying the inequality constraints on control variables and state variables,the constrained Bolza problem is solved numerically and the optimal state variables’trajectory is obtained.Simulation and bench test results indicate that the proposed method effectively decreases the torque fluctuation of transmission output shaft,promotes the dynamic property and improves the shift quality.

Parameter Optimization of Powertrain System for Electric Vehicles Oriented to Performance Requirements

XIONG Hui-yuan WU Xiao-li ZONG Zhi-jian YU Li-min

2016, 44(3):  68-75.  doi:10.3969/j.issn.1000-565X.2016.03.010

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Proposed in this paper is an integrated design and optimization method of powertrain parameters for elec- tric vehicles on the basis of QFD (Quality Function Deployment) and orthogonal test,which promotes the compre- hensive performance of electric vehicles effectively.Firstly,a QFD-based coupling model considering both customer requirements and technical characteristics is set up,and the weighting factors of technical characteristics are deter- mined by applying rough number and grey correlation method.Secondly,an optimization model of powertrain pa- rameters is constructed through orthogonal test,with vehicle comprehensive performance being taken as the objec- tive.Then,the comprehensive performance coefficients of vehicles are obtained by means of grey correlation method,and the optimal solution to multi-objective optimization as well as the sensibility analysis of performance factors is dealt with.Finally,a design and optimization model on Matlab platform is established and is further verified with an electric vehicle.An increment of 32.3% in comprehensive performance is obtained,which verifies the effective- ness of the proposed method.

Estimation of Vehicle State Parameters Based on Unscented Kalman Filtering

2016, 44(3):  76-80,88.  doi:10.3969/j.issn.1000-565X.2016.03.011

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In order to improve the estimation accuracy of some vehicle state parameters that can not be obtained by sensors directly and thus to estimate the state variation of running vehicles accurately,a method on the basis of un- scented Kalman filtering (UKF) is proposed,which helps enhance the robustness of vehicle control system.In this method,an UKF algorithm on the basis of traditional Kalman filtering is developed to estimate such vehicle state parameters as side slip angle,yaw rate and road adhesion coefficient,and a simulation by using both Simulink and Carsim software is carried out.The results indicate that the proposed UKF is superior to the extended Kalman filte- ring for its short response time and high estimation accuracy.Thus，it can meet the requirements of advanced dy- namic control system of vehicles.

Simulation Method of Spinning Forming of Multi-Wedge Belt Wheel as Engine Accessory

WAN Li-xiang ZHENG Bang-zhi SHANGGUAN Wen-bin WU Qi-hong

2016, 44(3):  81-88.  doi:10.3969/j.issn.1000-565X.2016.03.012

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Firstly,a simulation model to describe the spinning forming process of multi-wedge belt wheel is estab- lished,with its correctness and validity being verified by means of system energy method and according to wheel force as well as equivalent plastic strain (PEEQ) of each step.Secondly,by analyzing the distribution of equiva- lent strain of each step,the laws of material forming and flow in each step are discussed.Then,aiming at the de- fects of a practical product,an analysis of forming process is made in a simulative way,and the results are finally compared with the actual forming results.It is found that the proposed simulation method is available for analyzing the spinning forming of multi-wedge belt wheel.

Effect of Driving Torque on Dynamic Characteristics of Vehicles

WANG Xian-bin SHI Shu-ming

2016, 44(3):  89-95.  doi:10.3969/j.issn.1000-565X.2016.03.013

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In order to discover the effect of driving torque on the dynamic characteristics of vehicle system,firstly,a planar-motion nonlinear dynamic model of the vehicle system with five degrees of freedom (longitudinal velocity,lateral velocity，yaw rate，front-wheel rotational velocity and rear-wheel rotational velocity) is established on the basis of Magic tyre formula.Then,by taking the rear-wheel driving system as an example,the phase space analysis of multiple initial values,the time domain analysis of single initial value as well as the corresponding tyre-force dis- tribution feature analysis is carried out,and the effect of constant driving torque on the dynamic characteristics of vehicle without front-wheel steering angle input is discussed.Finally,through a further analysis of the numerical calculation with constant driving torque，the bifurcation diagrams of system state variables are plotted.The results show that,under the condition of zero steering angle input,bifurcation phenomenon of the vehicle dynamic system with 5 degrees of freedom may occur with the increase of driving torque; and that driving torque has an obvious effect on the dynamic characteristics of vehicles.

Traffic & Transportation Engineering

A Probe into Travel Spacing of Vehicles on Highway Bridges

WANG Qiang SU Cheng

2016, 44(3):  96-102.  doi:10.3969/j.issn.1000-565X.2016.03.014

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By means of one-dimension renewal random counting field,the vehicles on highway bridges were de- scribed,and an exponential distribution was derived theoretically to describe the statistic characteristic of travel spacing of vehicles in normal traffic state,which was then verified by the statistic results obtained by weigh-in-mo- tion in situ of the vehicles running naturally on highway bridges,finding that the exponential distribution property can be used to appraise the adaptability of bridges to traffic flow.Then,by taking 3 seconds as a time interval de- marcation,the actually-surveyed vehicles were divided into two running states,namely normal traffic state and dense traffic state,and the difference in time interval and travel spacing of vehicles in these two running states be- tween the statistic results obtained when revising the current bridge design code and the actual results was analyzed comparatively,finding that 3 seconds is not a suitable demarcation of vehicle running state and that travel spacing is more objective and reasonable for the demarcation.By comparing the probability distribution of the travel spacing between actual naturally vehicles on highway bridges and the theoretically-derived vehicles in normal traffic state，it is found that 44.35m is a suitable travel spacing for the demarcation of running state.When the travel spacing is less than 44.35m,vehicles run in dense traffic state and their probability distribution can be regressed as a polyno- mial function,while when the travel spacing is more than 44.35m,vehicles run in normal traffic state and the probability distribution function can be regressed as an exponential one.Such achievements help further establish a multi-parameter load model of random vehicles running on highway bridges.

Risk-Based Probe into Appropriate Scour Depth of Bridge Under Multiple Hazards

YANG Yan-kai MA Ｒu-jin CHEN Ai-rong

2016, 44(3):  103-109,127.  doi:10.3969/j.issn.1000-565X.2016.03.015

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In order to guide the future design of new bridges or the assessment of existing ones,a multi-hazard de- sign framework is proposed on the basis of risk-consistent design for bridges under earthquake and scour hazards,and the appropriate scour depth considering the earthquake is investigated.Firstly,a fragility analysis considering scour is carried out for the bridge under earthquake to obtain the fragility surface and fragility curve of the bridge.Secondly,two probabilistic risk models respectively corresponding to earthquake and scour hazards are proposed and are used to reveal the relationship between the failure probability under seismic hazard and the scour depth and to obtain the joint failure probability of the bridge.Then,the scour depth corresponding to joint failure probability is taken as the appropriate scour depth to make a comparison with the designed value,from which load combination factors for bridge design are determined.Finally,a case study on a suspend bridge is carried out.The results show that the proposed method effectively considers both bridge risk and economy，so that it lays a foundation for explo- ring the combined action of earthquake and scour hazards for bridges with different types and scales.

Emergency Vehicle Scheduling and Reallocation on the Basis of Non-Cooperative Game

ZHAO Jian-dong DUAN Xiao-hong SONG Shou-xin

2016, 44(3):  110-117.  doi:10.3969/j.issn.1000-565X.2016.03.016

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When an emergency vehicle scheduling problem involving multiple accidents and multiple rescue sites occurs,the response time of potential accidents can be shortened by redistributing idle emergency vehicles on res- cue sites,in addition to optimizing the scheduling of vehicles for current accidents.This paper presents an improved model of emergency vehicle scheduling and reallocation on the basis of bi-level programming and non-cooperative game.The upper level of the model is established under the constraints of accident requirements and accident rescue window to minimize the response time for current accidents,while in the lower level of the model,each rescue site is treated as a participant in a non-cooperative game,the payoff function of each participant is determined after tak- ing into account the reallocation time of the vehicle and the potential risks within the coverage area of each rescue site,so that the optimal reallocation strategy is transferred into Nash equilibrium in a non-cooperative game.After- wards,an integrated bi-level shuffled frog-leaping algorithm is proposed,which contains an upper-layer algorithm for single-objective programming and a lower-layer algorithm for solving the non-cooperative game.Several illustra- tive examples verify the rationality of the proposed model and the effectiveness of the integrated bi-level shuffled frog-leaping algorithm.

A Probe into Air Pressure Pulse Amplitude of High-Speed Trains Crossing in Open Air

XI Yan-hong MAO Jun LIU Run-dong YANG Guo-wei

2016, 44(3):  118-127.  doi:10.3969/j.issn.1000-565X.2016.03.017

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The aerodynamic characteristics of high-speed trains passing by in open air are numerically analyzed on the basis of moving mesh.Then,the Steinheur empirical formula for calculating air pressure pulse amplitude is mo- dified,and a new formula is presented.The results show that (1) the pressure pulse amplitude of low-speed trains passing by in open air is less than that of high-speed trains; (2) the amplitude is related to crossing speed,track- ing distance as well as monitoring point height,and is basically proportional to the traveling speed square of trains; (3) smaller tracking distance results in higher amplitude; and (4) tracking distance has a greater effect on the am- plitude in comparison with monitoring point height when other conditions keep constant.

Biological Engineering

Exposition of Phosphotyrosine Site on ITAM-like Motif of ERM Proteins Mediated by Force Through PSGL-1

WU Jian-hua KUANG Xiao-min LIU Wen-ping FANG Ying

2016, 44(3):  128-135.  doi:10.3969/j.issn.1000-565X.2016.03.018

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P-selectin glycoprotein ligand 1 (PSGL-1) engaged by ezrin-radixin-moesin (ERM) proteins plays an important role in recruiting spleen tyrosine kinase (Syk) and activating leukocyte in the process of inflammatory re- sponse.Firstly,the crystal structure of radixin FERM domain indicates that the steric effect on ITAM-like motif and phosphorylation sites (Y191 and Y205) can hamper their phosphorylation by Src family tyrosine kinase and their combination with Syk.Then,steered molecular dynamics (SMD) simulation is carried out to explore the interaction between the complex of PSGL-1 juxtamembrane peptide and radixin FERM domain under force load.Both conforma- tion analysis and solvent accessible surface variant show that the mechanical signal transmitting through PSGL-1 cy- toplasmic region can mediate the exposition of phosphotyrosine site Y205 on ITAM-like motif of radixin.The results of this study present a mechanical signal pathway from PSGL-1 cytoplasmic region to Syk and expound the interac- tion mechanism of PSGL-1/ERM/Syk at atomic level.

Construction of RNA Interference Expression Vector Containing Key Aging Enzyme Zmlox-2 in Zea Mays

HAN Ying ZHAO Shou-jing YANG Yu SUN Yao WANG Le

2016, 44(3):  136-141.  doi:10.3969/j.issn.1000-565X.2016.03.019

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The peroxidation of unsaturated fatty acid caused by lipoxygenase (LOX) is known to be responsible for the deterioration of storage quality in maize(Zea mays L.) seed.In order to inhibit the expression of key aging en- zyme Zmlox-2 gene in maize,Zmlox-2 gene in maize seed was cloned according to the principle of RNA interfer- ence (RNAi),and the RNAi plant expression vector containing Zmlox-2 was constructed by means of recombinant PCR and enzyme connection technology.Then,the recombinant vector pRI101-on-Zmlox-2-RNAi was transformed into Agrobacterium tumefaciens via heat shock method.Experimental results show that the RNAi expression vector containing Zmlox-2 gene has been successfully constructed.This research lays a theoretical and experimental foun- dation for the induction of genetic transformation and the exploration of interference expression effect of aging en- zyme gene.

Investigation into Biofilm Colonization on a New-Type Biofilm Reactor for Domestic Wastewater Treatment in Traditional Villages

PU Yue-wu XU Xiao-ma WANG Si-yao WU Jie-jie WEI Cheng

2016, 44(3):  142-148.  doi:10.3969/j.issn.1000-565X.2016.03.020

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A new-type biofilm reactor started up by adding activated sludge manually was designed to treat the do- mestic wastewater in traditional villages,and the influences of COD load,C/N ratio and the reflux ratio on system operation were investigated.Experimental results show that (1) the addition of activated sludge helps successfully colony biofilm with good appearance and obvious microbial morphology variation in a short time; (2) both COD and NH₊⁴ -N removal efficiencies achieve more than 85% after the biofilm colonization; (3) the operating efficiency of biofilm reactor is greatly affected by COD load,C/N ratio and reflux ratio; and (4) the COD and NH₊⁴ -N removal efficiencies respectively achieve 91.46% and 88.65% at a COD load of 0.25kg/(m 2 ·d),a C/N ratio of 10.2 and a reflux ratio of 9.17.