Table of Content

25 December 2020, Volume 42 Issue 12 Previous Issue    Next Issue

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Cloud Control System for Intelligent and Connected Vehicles and Its Application Li Keqiang, Chang Xueyang, Li Jiawen, Xu Qing, Gao Bolin, Pan Jian 2020, 42 (12):  1595-1605.  doi: 10.19562/j.chinasae.qcgc.2020.12.001 Abstract ( 1700 )   PDF (3499KB) ( 1858 )   Save In this paper, the concept of cloud control system for intelligent and connected vehicles is proposed based on the theory of cyber-physical system (CPS). The system uses the new generation of information and communication technologies to integrate the physical layer, cyber layer and application layer of human, vehicles, road infrastructures and cloud for integrated perception, decision-making and control to realize comprehensive improvement of vehicles and traffic safety and efficiency. Based on the introduction of the system architecture, working principle and key technologies, integrated perception technology on edge cloud and vehicle control technology under time-varying delay are studied. Furthermore, a cloud control system for real road is developed. Simulation and field test results verify the performance of cloud computing, integrated perception, decision-making, and connected control of the proposed system, which demonstrates its feasibility and superiority in application References | Related Articles | Metrics

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An Analysis on Challenge and Development Trend of Safety Management Technologies for Traction Battery in New Energy Vehicles Wang Zhenpo, Yuan Changgui, Li Xiaoyu 2020, 42 (12):  1606-1620.  doi: 10.19562/j.chinasae.qcgc.2020.12.002 Abstract ( 1063 )   PDF (1831KB) ( 1491 )   Save The safety management of traction battery is important means to ensure the safe operation of new energy vehicles, which directly affects the durability and reliability of vehicle. In this paper,three aspects, i.e. the safety concept, key technologies and futural development trend of traction battery are reviewed, in which the key technologies of battery safety including the mechanism and control measures of thermal runaway and protective structures are expounded respectively, with their achievements and inadequacies comparatively analyzed. Finally aiming at the challenges the current safety management of traction battery faces, the development trend of battery safety management in the future is given -- from mechanism analysis to system design optimization and from passive safety protection to active safety prediction References | Related Articles | Metrics

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Design and Energy Management of Electro-hydraulic Parallel Hybrid Power System for Battery Bus Liu Huanlong, Chen Guanpeng, Wang Jiawei 2020, 42 (12):  1621-1629.  doi: 10.19562/j.chinasae.qcgc.2020.12.003 Abstract ( 250 )   PDF (2560KB) ( 394 )   Save In order to solve the problems of large motor torque shock and short battery life when the city battery bus starts or accelerates, this paper designs a new dual-shaft parallel electro-hydraulic hybrid system for a certain type of electric bus running in Chengdu to study the improvement of the comprehensive energy utilization rate by adjusting the working state of the motor under typical working conditions. Based on the co-simulation of AMESim and MATLAB/Simulink-stateflow software, the vehicle and control model are established and the rule-based dynamic optimization energy management strategy is set up. The dynamic performance and energy utilization characteristics of Chinese City Bus Cycle(CCBC) and field investigation driving conditions of this kind of bus are analyzed. The core problems of energy coupling of electro-hydraulic hybrid system are studied experimentally, which verifies the correctness of the design thought and the simulation model. The results show that under the premise of satisfying the demand of dynamic performance, the designed electro-hydraulic hybrid system can effectively improve the distribution of the motor’s operating point and greatly reduce the peak torque shock. Under CCBC conditions, the peak torque is reduced by 33.8%, and the driving range is increased by 30.6%; while under field investigation conditions, the peak torque is reduced by 33.0%, and the driving range is increased by 20.0% References | Related Articles | Metrics

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Study on Control Strategy of CCSCR System to Meet Ultra-low NOx　Emission Standard Liu Shiyu, Wang Guoyang, Tan Zhi, Zhang Zhaohuan, Shuai Shijin, Wang Zhiming 2020, 42 (12):  1630-1637.  doi: 10.19562/j.chinasae.qcgc.2020.12.004 Abstract ( 317 )   PDF (1462KB) ( 298 )   Save Close-coupled selective catalytic reduction (ccSCR) technology is a feasible post-processing technology to meet California’s ultra-low NOx emission standard. In this paper, the control strategy of 　ccSCR　 system is studied by numerical simulation. SCR single state model is used to predict NH3 storage, NOx emission and NH3 leakage. The NOx emission characteristics of federal test procedure (FTP) are analyzed when ccSCR catalyst is not installed. Based on the analysis, the dual-nozzle independent control strategy and dual-nozzle joint control strategy are proposed. The results show that ccSCR system can make full use of exhaust gas heat and greatly reduce the starting time of urea injection, with the starting time of urea injection reduced to 51 from 568 s on cold-start FTP. The dual-nozzle joint control strategy will jointly control the NH3 storage in the ccSCR and the downstream SCR catalyst. The NOx conversion efficiency of the ccSCR system can reach 99.56% by using this strategy, and the specific NOx emission meets the requirements of the future California ultra-low NOx emission standard References | Related Articles | Metrics

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Multi-objective Integrated Adaptive Cruise and Regenerative Braking Control of Intelligent Electric Vehicles Guo Jinghua, Li Wenchang, Wang Jingyao, Li Keqiang 2020, 42 (12):  1638-1646.  doi: 10.19562/j.chinasae.qcgc.2020.12.005 Abstract ( 289 )   PDF (1319KB) ( 447 )   Save In order to improve the safety, comfort and economy of intelligent electric vehicles (IEVs), this paper proposes an integrated control method of adaptive cruise and regenerative braking of IEVs. Firstly, a nonlinear coupling model describing the longitudinal driving dynamic behavior of IEVs is established, which consists of vehicle model, power battery, motor, single-speed transmission and hydraulic braking system. Then, in view of the features of nonlinear coupling and parameter uncertainties of IEVs, an adaptive fuzzy sliding mode upper controller is designed to calculate the desired acceleration of IEVs in the process of adaptive cruise in real time. Fuzzy theory is used to approximate the switching term of sliding mode control to reduce shake. Finally, a drive/braking control law is designed, and a regenerative braking control strategy is proposed to effectively coordinate the regenerative braking system with the hydraulic braking system to maximize the braking energy recovery of IEVs. The test results show that the proposed integrated control method of adaptive cruise and regenerative braking can effectively improve the efficiency of braking energy recovery while ensuring the safety and comfort of IEVs References | Related Articles | Metrics

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Research on Active Collision Avoidance Control of Vehicles Under DifferentEmergency Conditions Pei Xiaofei, Li Peng, Chen Zhenfu, Guo Xuexun 2020, 42 (12):  1647-1654.  doi: 10.19562/j.chinasae.qcgc.2020.12.006 Abstract ( 468 )   PDF (2329KB) ( 653 )   Save An emergency collision avoidance strategy integrating active braking and active steering is proposed for complex conditions in this paper. Firstly, according to the vehicle speed and road adhesion coefficient and combining with the braking and steering safety distance model, a steering and braking priority that considers the effect of frontal obstacles is obtained. Based on this and in view of the other traffic factors in the side lane, the collision avoidance mode under steering priority is further subdivided into three types: steering, braking and steering plus braking. For collision avoidance by steering, a fifth-degree polynomial is used for path planning. Based on the safety and smoothness cost functions, an optimal safe and smooth desired path is comprehensively selected, and then achieving path tracking by using feedforward and LQR feedback control. A driver-in-the-loop simulation is conducted to verify the effectiveness of the active collision avoidance algorithm proposed. The test results under three typical operating conditions show that the intelligent vehicle can make reasonable decision on collision avoidance mode according to different emergency operating conditions, and can successfully complete the active collision avoidance operations of steering, braking and steering plus braking. Compared with the path generated by Sigmoid function, the planned path based on the fifth-degree polynomial is more suitable for emergency collision avoidance References | Related Articles | Metrics

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Analytical Calculation of Loaded Magnetic Field in Hub Motor for Electric Vehicle Zhang Heshan, Deng Zhaoxiang, Yang Minglei, Luo Jie, Xu Jin 2020, 42 (12):  1655-1664.  doi: 10.19562/j.chinasae.qcgc.2020.12.007 Abstract ( 202 )   PDF (3572KB) ( 452 )   Save To overcome the shortcomings of finite element analysis (FEA), i.e., tedious iterative modeling and time-and resource-consuming etc., a magnetic field analytical modeling method is proposed, concurrently considering both accuracy and efficiency.Taking a 48-slot/16-pole pair hub motor with surface-inset external rotor as study object, the loaded magnetic field analytical model of hub motor is established under a 2D polar coordinate system by using subdomain technique.The entire solution domain of the motor is divided into four types of subdomains, i.e., stator winding slots, slot openings, air gap and permanent magnet rotor slots, and the Laplace’s or Poisson’s equation of magnetic vector potential is solved in different subdomain according to different excitation source. Then, the boundary conditions between adjacent subdomains are used to solve the general solution of the magnetic vector potential in subdomain, and the electromagnetic performance such as magnetic field distribution, back electromotive force, inductance and torque are further calculated,and which with different slot opening structures are compared. FEA and prototype tests are conducted to validate the correctness of analytical models, and on this basis, the effects of polar arc coefficient and slot opening width on torque are further studied.The results show that with a polar arc coefficient of 0.825 and a slot opening angular width of 2.169°, the average output torque increases from original 160.75 N·m to 165.08 N·m, and the torque pulsation rate reduces from original 8.8% to 3.025% References | Related Articles | Metrics

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Real Time Algorithm for Blade Arm Suspension Kinematics and Its Verification and Application Tan Kanlun, Deng Jiaqing, Tang Zhuo, Yuan Dengmu 2020, 42 (12):  1665-1670.  doi: 10.19562/j.chinasae.qcgc.2020.12.008 Abstract ( 232 )   PDF (1791KB) ( 327 )   Save Chassis development requires fast algorithms of suspension kinematics to improve the development efficiency and autonomous driving needs stable and real time algorithms of suspension kinematics to improve the accuracy of model predictive control under unsteady conditions. In this paper, the linear equations for the instantaneous velocity of the wheel center of the blade arm suspension are firstly established using vector and matrix tools and they are combined with the dynamic explicit integration to solve the trajectory of the suspension in real time. Then, the five typical characteristic curves obtained from the algorithm are compared with those acquired from ADAMS simulations and vehicle tests. The results show that the three methods have high consistency, while the real-time algorithm have higher accuracy compared to ADAMS simulation. Finally, the suspension CAD software is established based on the real-time algorithm, with a speed dozens of times faster than ADAMS simulation References | Related Articles | Metrics

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Road Identification Algorithm of Intelligent Tire Based on Support Vector Machine Wang Yan, Liang Guanqun, Wei Yintao 2020, 42 (12):  1671-1678.  doi: 10.19562/j.chinasae.qcgc.2020.12.009 Abstract ( 307 )   PDF (1985KB) ( 405 )   Save In this paper, an intelligent tire algorithm based on support vector machine (SVM) is proposed to predict and classify tire-road friction coefficient. Firstly, the intelligent tire hardware system is developed based on MEMS three-dimensional accelerometer and field test is carried out on three types of road with different adhesion conditions. The radial and lateral acceleration signals are obtained and statistical features in time and frequency domain are extracted. Then, the feature dimension is reduced by principal component analysis (PCA). Based on the feature parameters after dimension reduction, support vector machine is applied for classification training. Finally, the SVM classifier with optimized parameters is used to identify the peak adhesion coefficient. Vehicle field test results show that the proposed algorithm can realize quick estimation of road state, thus providing the key information of road for vehicle control system. Compared with the traditional identification algorithm of adhesion coefficient, the proposed method in this paper is more direct, stable and reliable which does not need acceleration, braking or steering conditions. The method has strong generalization ability, wide application range which is of great potential engineering value References | Related Articles | Metrics

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Evaluation Method of Tire Rolling Resistance and Ground-grip Performance Based on Ground Contact Characteristics Liang Chen, Wang Guolin, Yu Kangying, Mei Ye 2020, 42 (12):  1679-1687.  doi: 10.19562/j.chinasae.qcgc.2020.12.010 Abstract ( 216 )   PDF (10957KB) ( 247 )   Save The deformation distribution of ten 205/55R16 PCR radial tires with different tread patterns in ground contact area after vertical loading are obtained by using digital image correlation technology, and a parameterized evaluation system is constructed to express the geometric and mechanical information in ground contact area. Based on ground contact parameters, the tire rolling resistance coefficient and braking distance are predicted by using partial least square regression method. Bootstrap resampling method is adopted to conduct significance check on regression coefficient, and the ground contact parameters with significant effects on tire performance are selected. The results show that when tire-ground contact parameters are used to evaluate the rolling resistance and ground grip performance of tire, the regression equation fitting result is rather good. The outcome of this study provides a certain guiding role in high-performance tire design References | Related Articles | Metrics

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An Experimental Study on Influence of Laser Quenching on the Frictional Vibration and Noise of Brake Disc Wang Shuwen, Zhao Deyu, Yan Shengkai, Zhang Huan 2020, 42 (12):  1688-1694.  doi: 10.19562/j.chinasae.qcgc.2020.12.011 Abstract ( 179 )   PDF (1528KB) ( 279 )   Save The generation mechanism and control technology of braking vibration and noise is a worldwide problem that the academia circle and engineers have been trying to solve for many years. In this study, laser surface quenching technique is employed to modify the frictional surfaces of four cast iron brake discs. The effects of laser quenching power on residual stress, damping coefficient, friction coefficient and braking vibrations and noise of brak discs are experimentally studied. The experiemntal results show that after laser quenching, the surface residual stress of the brake discs changes from tensile stress to compressive stress; the damping coefficient of brake discs increases with the increase of laser quenching power; the friction coefficient decreases with the increase of laser quenching power but becomes more stable, which effectively reduces braking fritional vibrations and noise. Particularly, the braking vibration of caliper reduces significantly, with a maximum reduction of RMS of the braking caliper to 30% of the original disc within the experimental range. This study is of great significance to the control of braking frictional vibrations and noise, reduction of brake wear, and improvement of the environment References | Related Articles | Metrics

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Application of Scaling Law Analysis to　Vehicle Aerodynamic Noise Yuan Haidong, Liu Xuelong, Xu Chen, Hao Jianhong 2020, 42 (12):  1695-1700.  doi: 10.19562/j.chinasae.qcgc.2020.12.012 Abstract ( 195 )   PDF (1060KB) ( 264 )   Save When vehicles are driving at high speed, aerodynamic noise is an important noise source affecting in-car comfort, while unsteady flow around vehicle body is an important factor, generating aerodynamic noise. On the one hand, hydrodynamic pressure generated by unsteady flow directly acts on the outer surfaces of vehicle body, which excites the vibrations of window glasses and radiates noise into the interior of vehicle. On the other hand, the unsteady flow itself generates aerodynamic noise, and acoustic pressure directly transmits noise into the interior of vehicle through window glasses and body panels. In this paper, a concept of scaling law is put forward to describe and distinguish the changing law of hydrodynamic pressure and acoustic pressure around vehicle body with vehicle speed and a scaling law analysis on wind tunnel test results is performed. The results show that under given conditions, aerodynamic noise is dominated by dipole source, the amplitude of acoustic pressure in the car and far field is proportional to the 3rd power of velocity, and frequency is independent of velocity; The magnitude of hydrodynamic pressure on front side window is proportional to the 1.5th power of velocity and frequency is proportional to velocity. References | Related Articles | Metrics

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Precise Adjustment Strategy of Autonomous Parking for Automatic Charging Wang Yongsheng, Luo Yugong, Gu Yanchen, Chen Rui, Qi Yunlong, Jiang Fachao 2020, 42 (12):  1701-1709.  doi: 10.19562/j.chinasae.qcgc.2020.12.013 Abstract ( 216 )   PDF (2486KB) ( 300 )   Save Automatic charging devices are difficult to connect accurately when autonomous parking system is combined with automatic charging system. To solve this problem, a precise adjustment strategy of autonomous parking is proposed. Under the framework of “forward-backward-parking” motion adjustment, combining heading angle deviation control on forward motion, lateral position deviation control on backward motion, and accurate parking control, precise adjustment of connecting position deviations can be realized by this strategy. Simultaneously, two points matching method based on preview angle and the bidirectional retrieval strategy based on preview front viewpoint matching are proposed to improve the single-point preview method. The experimental results on a real vehicle show that the proposed precise adjustment strategy of autonomous parking can decrease the longitudinal and lateral deviations of the parking stop position, and improve connecting accuracy and connecting success rate of automatic charging devices. References | Related Articles | Metrics

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Self-learning Lane-change Trajectory Planning System with Driver Characteristics Gao Zhenhai, Zhu Naixuan, Gao Fei, Mei Xingtai, Zhang Jin, He Lei 2020, 42 (12):  1710-1717.  doi: 10.19562/j.chinasae.qcgc.2020.12.014 Abstract ( 273 )   PDF (1617KB) ( 415 )   Save In order to better realize personalized driving, this paper proposes a self-learning lane-change trajectory planning system integrating driver characteristics identification. Firstly, this paper introduces the driver characteristic coefficient Jc and the driver response and operation time td into the Gaussian distribution to establish a personalized lane-change trajectory planning model, and matches the actual trajectory with the fitting trajectory through the DTW algorithm. After that, AP clustering is carried out based on the collected driver lane-change trajectories and the general values of Jc and td are calibrated offline. At the same time, the labels of 30 drivers are obtained, and their driving characteristics are divided into comfort, normal and sport type. Then, the free driving data are extracted for characteristic working conditions, and an online identification model of driver characteristics is built based on long-term and short-term memory network (LSTM). Finally, 15 drivers are selected for real-car verification. The system extracts characteristic conditions in real time and then adjusted Jc and td online based on the recognition results, and continuously updates the fitting trajectory. After the experiment, the squared Euclidean distance between the actual trajectory and the fitting trajectory of the 14 drivers is less than 1, with the fitting accuracy reaching 93.3%. Therefore, the system can reproduce the trajectory of real lane-change well. References | Related Articles | Metrics

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Research on the Driving Style Identification Method Considering the Influence of Traffic Density Zhao Han, Liu Hao, Qiu Mingming, Cao Longkai, Zhang Yilei, Yu Wei 2020, 42 (12):  1718-1727.  doi: 10.19562/j.chinasae.qcgc.2020.12.015 Abstract ( 237 )   PDF (1875KB) ( 342 )   Save In view of the correlation between the traffic density and the driver’s pedaling behavior, this paper proposes a multi-level driving style identification method that considers the influence of traffic density based on the coupling relationship between traffic density and driving style identification. Firstly, based on the simulation driving experiment platform, the data of pedal signals and speed signals of drivers under different traffic densities are collected and the characteristic parameters of different driving styles are extracted. Then, principal component analysis is used to obtain the comprehensive characteristic parameters of driving styles under the influence of different traffic densities, and the hybrid algorithm of subtractive clustering and K-means clustering is applied to classify the driving styles and modify the characteristic parameters of different driving styles on this basis. Finally, random forest algorithm is used to identify and verify the driving styles. The results show that under the influence of different traffic densities, the method proposed in this paper has high accuracy for driving styles identification, which lays a foundation for further optimization of energy management strategy for hybrid electric vehicles. References | Related Articles | Metrics

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Study on Optimization Method of Thickness Distribution of　Variable-thickness Rolled Blank Thin-Walled Structures Under Rolling Constraints Chen Yousong, Shen Guomin, Duan Libin 2020, 42 (12):  1728-1736.  doi: 10.19562/j.chinasae.qcgc.2020.12.016 Abstract ( 171 )   PDF (2330KB) ( 178 )   Save Variable-thickness rolled blanks(VRBs)is an advanced lightweight manufacturing process, the VRB thin-walled structure by which has the advantages of light weight and good energy-absorption effect. Taking the transverse impact process of thin-walled structures with top-hat section as the research object, the high-precision finite element model of VRB thin-walled structures with top-hat section is established. A comprehensive learning particle swarm optimizer (CLPSO) is proposed to handle the optimal thickness distribution problem of VRB thin-walled structures with rolling constraints based on the particle swarm optimizer (PSO). The algorithm can handle the optimal thickness distribution problem of VRB thin-walled section with large-scale design variables under rolling constraints and performance constraints. The effectiveness of CLPSO is verified by carrying out the optimal thickness design of VRB thin-walled structures with or without manufacturing constraints respectively. The optimization results show that the CLPSO algorithm with manufacturing constraints is easier to obtain design results that can be used in manufacturing than the CLPSO algorithm without manufacturing constraints; and under the conditions of meeting the performance constraints and VRB rolling constraints, the weight of thin-walled structures with VRB top-hat structure is reduced by 21.7% compared with the structure with uniform-thickness. References | Related Articles | Metrics

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Lightweight Design of Aluminum Rear Subframein Conceptual Design Stage Liao Ying, Li Feng, Li Zhi 2020, 42 (12):  1737-1743.  doi: 10.19562/j.chinasae.qcgc.2020.12.017 Abstract ( 237 )   PDF (1263KB) ( 363 )   Save The formulation of performance targets and the lightweight design method of aluminum alloy rear subframe are emphatically investigated in this paper. Firstly, a method combining forward design and competitive product analysis is adopted to determine the performance targets of aluminum alloy rear subframe, including mass,modal frequencies, static stiffness and strength etc. Then the ICM hybrid modeling method is introduced to obtain the skeleton of rear subframe and reduce its weight. Based on identifying the force transmission path of rear subframe, topology optimization is performed, redundant material is removed and the mathematical model is obtained.Twelve shape variables of parameterized subframe are selected as the lightweight design variables for multidisciplinary optimization to obtain the optimal shape meeting target requirements.After lightweighting,the mass reduces by 1.84 kg with a mass reduction rate of 7.4%, and the 1st-order bending frequency increases by 10.2 Hz, meaning a 4.5% of enhancement. The results of hard point static stiffness and strength analysis also show that the method is fast and reliable,with a good prospect of engineering application References | Related Articles | Metrics

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Research on Low Temperature Heat Pump Air Conditioning System in New Energy Electric Vehicle Wang Linlin, Jiao Pengfei, Wang Wei, Yi Hucheng, Mu Liansong, Liu Shuangxi, Xu Xiang 2020, 42 (12):  1744-1750.  doi: 10.19562/j.chinasae.qcgc.2020.12.018 Abstract ( 321 )   PDF (1626KB) ( 619 )   Save In order to enhance the energy economy of electric vehicles and reduce the degradation of low-temperature heating performance, three solutions of heat pump air conditioning system in low temperature environment are proposed and comparatively analyzed: (1) waste heat recovery and utilization: the waste heat of battery, motor and electric control system is recovered and utilized, optimizing the energy consumption of vehicle while improving the performance of heat pump air conditioning system; (2) vapor-injection heat pump air conditioning system: experimental study is conducted on heat pump air conditioning system using R1234yf refrigerant, and the results show that the heat generating COP with vapor injection is about 10%~30% higher than that without vapor injection. The lower the ambient temperature, the more obvious the improvement of COP;(3) heat pump air conditioning system with CO2 refrigerant: researches indicate that due to the characteristics of CO2 refrigerant, heat pump system can provide stable and effective heating at an ambient temperature of - 20　℃. So a conclusion is drawn that at present, vapor injection heat pump air conditioning system is an effective mean for the low temperature heating in electric vehicles, while in the future, the use of natural refrigerant CO2 will be the inevitable trend References | Related Articles | Metrics

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Research on the Analysis Method of Welding Spot Layout Robustness Based on Sensitivity Ranking Song Haisheng, Chen Zhiyong, Yang Na, Yang Changhai, Shi Wenku 2020, 42 (12):  1751-1757.  doi: 10.19562/j.chinasae.qcgc.2020.12.019 Abstract ( 177 )   PDF (2179KB) ( 283 )   Save In view of the defects of Monte-Calo robustness analysis method commonly used at present for robustness analysis for welding spot layout, i.e. high cost, low efficiency and the heavy dependance of accuracy on sample number, a novel robustness analysis method based on welding spot sensitivity ranking is proposed with Monte-Calo important sampling theory as reference. Taking a domestic light bus as example, two methods are comparatively verified. The results show that the method proposed in this paper has higher efficiency, lower cost and higher accuracy with fewer samples needed compared with Monte-Calo one References | Related Articles | Metrics