Table of Content

25 August 2018, Volume 40 Issue 8 Previous Issue    Next Issue

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A Study on Predictive Energy Management Strategy for a Plugin Hybrid Electric Bus Based on Markov Chain Xie Shaobo, Liu Tong, Li Huiling, Xin Zongke 2018, 40 (8):  871-877.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.001 Abstract ( 10 )   Save To make energy management strategy becomes more real time application oriented, a study on the predictive control strategy for a parallel plugin hybrid electric bus (PHEB) with an automatic mechanical transmission (AMT) is conducted in this paper to achieve a coordinated optimization of gear selection and power distribution. Firstly, the transfer probability of torque state is calculated based on Markov chain model. Then on this basis, a coordinated optimization of power distribution and gear selection is performed in rolling time domain, in which 2D dynamic programming (DP) algorithm with two state variables (battery SOC and gear position) is chosen for optimization in rolling time domain. Finally the effects of different prediction durations on prediction results are analyzed, and DP algorithm, rulebased energy management strategy and predictive control strategy are compared. The results show that compared with DPbased energy management strategy, the energy consumption with the predictive strategy proposed in the paper increases by 173%, but compared with rulebased energy management strategy, the energy consumption with predictive strategy lowers by 297%. Related Articles | Metrics

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Effects of the Polarity of Electric Field on Combustion Characteristics of Methaneair Mixture Fang Jianfeng, Wu Xiaomin, Zhao Haijun 2018, 40 (8):  878-883.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.002 Abstract ( 6 )   Save In order to further study the mechanism of ionic wind produced by electric field, an experiment on the influences of electric fields with different polarity on the combustion characteristics of methaneair mixture is conducted with a constant volume bomb. The results show that no matter the positive or negative electric field applied, the flame propagation pattern is changed significantly, the propagation radius and propagation rate of flame along the direction of electric field increase, while the combustion pressure rise of mixture also apparently speeds up. For different polarity of electric field, the effects of negative electric field are obviously stronger than that of positive electric field. Under the action of positive and negative electric field with a voltage of 12kV applied, the peaks of flame propagation rate of mixture (λ=16) increase by 417% and 623% respectively, pressure peaks rise by 85% and 123% respectively and the corresponding timing advance by 211% and 318% respectively. Related Articles | Metrics

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A Research on Battery Performance Assessment Based on DelphiVariation Coefficient Combination Weighting Method Zhang Rui, Zhou Yongqin & Li Ran 2018, 40 (8):  884-891.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.003 Abstract ( 2 )   Save Aiming at the problem of overall performance decline when battery cells are assembled into battery pack, an evaluation method of battery performance based on Delphivariation coefficient combination weighting method is proposed. The method adopts multilevel fuzzy comprehensive evaluation technique, selects different factors related to battery performances, gets judgment data samples through the design of experiment, emphatically studies the setting up of factor set, the determination of weighting factors and the selection of membership function under different features of indicator, and establishes the complete assessment model of battery performance. By collecting the experimental data of eight battery samples, the results of primary judgment of different batteries under different characteristics are obtained, and the final weighting factor of each indicator is determined by Delphivariation coefficient combination weighting method. The results of judgment provide a basis for making decision for the use of traction battery pack and hence raise the utilization efficiency of battery and the overall performance of electric vehicles. Related Articles | Metrics

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Energy Saving and Environmental Protection Performance Analysis of New Refrigerant R1233zde Yang Jingye, Lu Bingqing,Chen Jiangping 2018, 40 (8):  892-896.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.004 Abstract ( 13 )   Save Organic Rankine cycle gains attention from commercial vehicle field as a feasible method to recover engine waste heat. R245fa is a regular working fluid utilized in ORCs. With increasingly stringent carbon emission standards, refrigerants with GWP higher than 150 will be abandoned in the future. In this paper, a new competitor R1233zde with low GWP is proposed as an alternative to R245fa for organic Rankine cycle. Thermodynamic properties of R1233zde are extremely close to R245fa but with low GWP 7. A steady state simulation of ORC system is established to compare parameters performance including evaporating temperature, pump power consumption and cycle efficiency between the two working fluids under the same operating condition. Results show that pump power consumption of R1233zde is reduced by 1505%-1702% and the optimal cycle efficiency of R1233zde is 703% higher than R245fa. Related Articles | Metrics

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Shape Optimization of CrossSections in Vehicle Frame with Constraints of Stamping Process Gui Chunyang, Ju Wei, Zuo Wenjie 2018, 40 (8):  897-903.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.005 Abstract ( 5 )   Save In order to rapidly evaluate the performance of vehicle body at conceptual design stage, vehicle body is often simplified to a frame structure consisting of thin walled beams with complex crosssections. Its key technique, i.e. the shape design of complex crosssections in thinwalled beams will be studied in this paper. Firstly, the calculation formulas for the mechanical properties of complex cross sections, including open, singlecell, doublecell, threecell and fourcell sections are derived. Next, the constraints of stamping process, covering the shortest length of line segments, draft angle, chamfer radius and assembly constraints are described by mathematical expressions. Then the shape and thickness of crosssections are optimized with the constraints of inertia moments in bending and torsion and stamping conditions, to achieve the minimization of crosssection area. Finally, the effectiveness of the scheme adopted is verified by a calculation example. Related Articles | Metrics

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Size Optimization on Main Crosssections of Bodyinwhite Based on Conceptual Model for Car Body Wang Zhenhu, Wang Wanlin, Zhang Songbo, Yin Shuang, Li Luoxing 2018, 40 (8):  904-911.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.006 Abstract ( 9 )   Save In order to realize the optimization on the main crosssection size of new car body at concept design stage, a precise bodyinwhite concept model with real joints is established based on earlystage styling and hard point data in general layout and using the detailed data of related joints and main crosssections in the database of car makes with same platform. Then according to the sensibilities of bending and torsional stiffness to the inertial moments Iy，Iz, torsion constants J and areas A of main crosssections, obtained by sensibility analysis, 19 key crosssections are selected. Finally a size optimization is conducted on key crosssections by using sequential quadratic programming algorithm with minimizing body mass as objective, bending and torsional stiffness and 1storder bending and torsional modal frequencies as constraints. As a result of optimization, car body mass reduces by 833kg with a mass reduction rate of 27%, bending and torsional stiffness increases by 47% and 40% respectively, and the 1storder bending and torsional modal frequencies rises by 2% and 12% respectively. Related Articles | Metrics

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Multiobjective Lightweight Optimization on Closed BIW Based on Analysisdriven Design Lü Tiantong, Wang Dengfeng, Wang Chuanqing 2018, 40 (8):  912-917.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.007 Abstract ( 13 )   Save This paper aims to perform a multiobjective lightweight optimization for a closed BIW based on the concept of “analysisdriven design”. Firstly, a parametric model for the closed BIW is constructed to achieve the rapid change and updating of finite element model, on which the modularization is defined, and by combining the parametric model with the modularization defined, the function of full automatic arithmetic for the closed BIW is realized on backstage. With minimizing the mass of closed BIW and maximizing its torsional stiffness as objectives, first order bending mode, bending stiffness and the strengths in bending and torsion as constraints and fifty four parameters including the thickness of panels and the location and shape of main sections as design variables, a multiobjective lightweight optimization of closed BIW is carried out by using NSGAII algorithm, which realizes the concept of analysisdriven design based on the change of performance gradient and corresponding search function. The results of optimization show that the mass of closed BIW reduces by 3241kg, attaining a weight reduction rate of 763%, and all performances enhance with a highest improvement rate of 269% except the static bending stiffness of BIW being lowered by 074%. Related Articles | Metrics

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Simulation Analysis and Experimental Study on a Lightweight Structure for Vehicle AntiCollision Beam Hu Hongzhou & Zhong Zhihua 2018, 40 (8):  918-925.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.008 Abstract ( 19 )   Save In order to concurrently take into consideration the both requirements on lightweight structure and impact safety, a design scheme of aluminum alloy corrugated plate is proposed to strengthen the rectangular anticollision beams of vehicles. Models are built and simulations are conducted to study the effects of the different structural features and parameters of corrugated plate on the strengthening results of anticollision beams, which are then verified by tests under the conditions of both concentrated and uniformly distributed loadings. The results of both simulations and tests show that the strengthening structure of aluminum alloy corrugated plate is an effective way for the lightweight design of vehicle anticollision beams, having significant value in engineering application. Related Articles | Metrics

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Modeling and Analysis of Creep Groan in Vehicle Disc Brake Based on Finite Element Method Zhang Lijun, Xu Jie, Meng Dejian & Yu Zhuoping 2018, 40 (8):  926-934.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.009 Abstract ( 8 )   Save Finite element method is used to study the nonlinear dynamic characteristics of vehicle disk brake when creep groan occurs. The simulation and test results of time domain, frequency domain and phase diagram characteristics of brake caliper vibration are very similar, verifying the correctness of simulation model. Analyses reveal that the diskpad friction pair is alternatively in adhesive and sliding states, energy conversion relations in each period are also consistent with the typical stickslip vibration characteristics, and there is a complex state transition process in all nodes in contact surface when contact state changes. When creep groan occurs, the tangential frictional force between disc and pad fluctuates between the maximum static friction force and sliding friction force. The amplitude of vibration acceleration is the maximum along the tangential direction of brake caliper and shows obvious order relation. The frequency of the stickslip vibration is very close to the natural frequency of the system with their vibration mode also similar to each other, demonstrating the stickslip vibration is closely correlated to the inherent attributes of system. Related Articles | Metrics

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Braking Intention Identification Method for Electric Vehicles Based on EEMD and Entropy Theory Wang Bo, Tang Xianzhi, Wang Liandong, Yang Shujun & Ma Lei 2018, 40 (8):  935-941.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.010 Abstract ( 5 )   Save For suppressing the mode mixing phenomena in the process of signal decomposition caused by intermittent or pulse compositions in brake pedal signals and further enhancing the correctness and realtime performance of braking intention identification, a cluster identification method for driver braking intention based on ensemble empirical mode decomposition (EEMD) and entropy theory is proposed for electric vehicles in this paper. Firstly brake pedal signals are decomposed into IMF components by EEMD to suppress mode mixing and more accurately extract brake pedal signal features. Then IMF components are selected by using Shannon entropy to reduce the computation efforts for feature extraction, and the features of IMF components of brake pedal signals selected are extracted by sample entropy to get the eigenvectors of brake pedal signals for different braking intentions. Finally clustering algorithm is adopted to perform braking intention identification. The results of offline test and realtime test show that the clustering identification method for braking intention based on EEMD and entropy theory has higher accuracy rate and better realtime performance compared with that based on HilbertHuang transform. Related Articles | Metrics

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A Highaccuracy Vehicle Tracking Algorithm Based on Digital Image Correlation Cheng Teng, Jiang Yaxi, Wu Bofu, Wang Jingjing, Zhu Xihan & Du Qingyu 2018, 40 (8):  942-946.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.011 Abstract ( 6 )   Save In order to solve the problem of inaccurate tracking of the vehicle ahead and the inadequate timeliness of collision prewarning in a visionbased prewarning system for reducing traffic safety accidents, a highaccuracy vehicle tracking algorithm based on digital image correlation (DIC) is proposed. With the detected vehicle area as a reference subarea, the algorithm adopts DIC method to perform subpixel level search and matching around reference sub area, and then implements vehicle tracking. The scaling value of resulting tracked frame can be used to calculate highaccuracy relative speed for enhancing safety assurance. The results of experiments verify that the algorithm proposed can effectively improve tracking accuracy and realtime performance and reduce the dependence on highresolution lenses. Related Articles | Metrics

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Vehicle Cooperative Positioning Enhancement Method Based on V2X Communication Networks Duan Xuting, Tian Daxin & Wang Yunpeng 2018, 40 (8):  947-951.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.012 Abstract ( 10 )   Save In view of the importance of vehicle positioning accuracy to the application of Internet of Vehicles and the problems of inadequate positioning accuracy and failure of traditional satellite positioning system in weak signal coverage areas like urban canyons and tunnels, a vehicle positioning method based on V2X communication network is investigated in this paper. The positioning terminals of dedicated short range communications and multimode communications network are developed with their performance testing and application deployment completed, and the vehicle cooperative positioning enhancement method based on multiplemodel filtering algorithm is designed. The results show that the method proposed can increase positioning accuracy by nearly 40%, compared with traditional GPSbased method. Related Articles | Metrics

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Obstacle Detection and Tracking for Unmanned Vehicles Based on 3D Laser Radar Xie Desheng, Xu Youchun, Wang Rendong & Su Zhiyuan 2018, 40 (8):  952-959.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.013 Abstract ( 12 )   Save Aiming at the problem of detection and tracking of obstacles in real traffic scenarios, a method of detecting and tracking unmanned vehicles based on 3D laser radar HDL64E is proposed. Firstly, the point cloud data generated by 3D laser radar is rasterized after road segmentation, with the raster supplemented. After obstacle clustering, the detection of static obstacles is conducted with multiframe fusion based on realtime kinematic GPS data and the azimuth angle data in inertial navigation system. Furthermore, dynamic obstacle detection is performed by using dynamic obstacle template matching algorithm on travelable areas determined by static obstacle detection. Finally, the standard Kalman filter is adopted to track dynamic obstacles. The results of a large number of experiments in applying the method to a selfdeveloped unmanned vehicle show that the method proposed has a high reliability, meeting the environmental perception requirements for unmanned vehicles. Related Articles | Metrics

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A Simulation of Steeringbywire Assistant System Based on Driving Scene Model Gao Zhenhai, Sun Tianjun & He Lei 2018, 40 (8):  960-966.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.014 Abstract ( 7 )   Save Steeringbywire system eliminates the mechanical connection between steering wheel and front wheel, and its control algorithm calculates the driving torque of steering motor to realize the change of transmission ratio through electric control. Aiming at the problem of oversteer or understeer in real steering process, under the feedback control framework of dynamic output and based on the theories of kinematics and kinetics and the 2DOF model of vehicle, an angular gear ratio dynamic coordinated control mechanism based on driving scene model is proposed in this paper with a rotation angle control algorithm for steeringbywire assistant system established. Finally a simulation on the velocity, acceleration, yaw rate and trajectory in steering process is conducted and its results are compared with other steering control algorithms and mechanical steering, which verify the effectiveness and realtime performance of the system in     active control, compensation and correction of steering process. Related Articles | Metrics

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A Research on Theoretical Prediction Method of Energy Absorption in Bending and Axial Collapses of Thinwalled Beams with Closedhat Section Hu Zhaohui, Du Zhanpeng, Duan Libin, Zhang Guangya & Wu Jingwei 2018, 40 (8):  967-973.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.015 Abstract ( 4 )   Save Based on Kecmans bending collapse theory on thinwalled beams and Wierzbickis superfolding element theory, an improved theoretical model for quasistatic bending collapse and axial collapse of thinwalled beams with closedhat section is proposed, with corresponding energy absorption formulae derived. The model can solve the energy absorption problems of bending collapse and axial collapse of thinwalled beams with same material and thickness, same material and different thickness, different material and same thickness, and different material and thickness. The results of test and numerical simulation show that compared with traditional theories and models, the improved theoretical model has higher accuracy in predicting the energy absorption in bending collapse and axial collapse, with better universality in application scope. Related Articles | Metrics

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A Rapid Calculation Method for Nonlinear Stress of Bus Skeleton Joints Na Jingxin, Ji Jundong, Mu Wenlong, Tao Shizhen & Qu Dan 2018, 40 (8):  974-980.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.016 Abstract ( 1 )   Save To quickly and accurately estimate the postyield structural stress of bus skeleton, a rapid calculation method for the nonlinear stress of bus skeleton joints based on correction function is proposed in this paper. Simulation and test verify the effectiveness of nonlinear analysis method in simulating material failure. Both linear and nonlinear methods are used respectively to analyze a typical bus structure with three typical conditions, three typical joint structures are simulated by shell elements with adequate sample points selected, and the approximate function relationship between linear stress value and stress ratio is established with the correction function of nonlinear stress obtained. Finally the structures of another typical bus are analyzed, verifying the effectiveness of the method proposed. Related Articles | Metrics

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An Investigation into Characteristics Discrepancy of Vehicle Sidewindow Buffeting Noise Yang Zhendong, Gu Zhengqi, Xie Chao, Zhong Yiqi, Jiang Caimao & Zhang Qidong 2018, 40 (8):  981-988.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.017 Abstract ( 9 )   Save Aiming at the increasingly prominent problem of vehicle sidewindow buffeting noise, the characteristics of vehicle sidewindow buffeting noise are investigated in this paper. Firstly the generation mechanism of vehicle buffeting noise is analyzed, and then road tests on the buffeting noise of a sedan caused by different sidewindow opening patterns are conducted. The characteristics of sound pressure and sound pressure level spectrum of monitoring points are analyzed and the results show that there exist discrepancies in the characteristics of wind buffeting noise under different sidewindow opening patterns: when a single rear window opens or two rear windows open at the same time, window buffeting noise exhibits a feature of multiharmonic oscillation, while in other cases only a single peak appears in sound pressure level spectrum. When resonance happens, two rear windows simultaneously opening induce the strongest buffeting noise. From the point of view of flowfield CFD simulation and window styling, the investigation reveals the reasons of discrepancy in the characteristics of buffeting noise with different sidewindow openings, laying a foundation for controlling sidewindow buffeting noise. Related Articles | Metrics

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A Research on Automobile Airconditioning Evaporator Defrosting Determination Method Based on Evaporating Temperature Yu Binbin, Zhu Jianmin, Wang Dandong, Chen Liang, Hu Jichao & Chen Jiangping 2018, 40 (8):  989-996.  doi: doi:10.19562/j.chinasae.qcgc.2018.08.018 Abstract ( 12 )   Save A new defrosting determination method for automobile airconditioning based on evaporating temperature is proposed and the effective coefficient of mass flow is defined as the judgment criterion of this method. By contrast experiments, its validation on predicting frosting degree is verified. Results show that the average relative error between defrosting start time determined by this method and appropriate defrosting start time defined is only 72%, with a relative error range of 0～-15%. On the premise of allowing frosting on part of the evaporator surface, the new defrosting determination method can control the frosting range effectively; hence extend the cooling time while ensuring the stable operation of the airconditioning system. Related Articles | Metrics