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Table of Content

    25 October 2022, Volume 44 Issue 10 Previous Issue    Next Issue
    Trajectory Tracking Control Method Based on Vehicle Dynamics Hybrid Model for Intelligent Vehicle
    Peijun Fang,Yingfeng Cai,Long Chen,Yubo Lian,Hai Wang,Yilin Zhong,Xiaoqiang Sun
    2022, 44 (10):  1469-1483.  doi: 10.19562/j.chinasae.qcgc.2022.10.001
    Abstract ( 612 )   HTML ( 62 )   PDF (7582KB) ( 542 )   Save

    The vehicle dynamics modeling process based on mechanism analysis is usually simplified with assumptions,which can't accurately calculate the dynamic changes of actual vehicles under different road conditions, thus causing problems such as low trajectory tracking control accuracy and instability of intelligent automotive. To tackle the above-mentioned problems, this paper proposes a non-linear modeling and control method based on hybrid modeling technology. By constructing mechanism analysis - data-driven vehicle dynamics series hybrid model, the vehicle state and control data are calculated and processed by the mechanism model, and then used as the input of the data-driven module after a level combination. Besides, long-short-term memory network used as the backbone realizes the nonlinear correlation feature extraction of time-series data and the final model output calculation. The test results show that the model can supplement some unmodeled dynamics in the mechanism model, improve the model calculation accuracy and has the ability to implicitly understand different road adhesion conditions. In addition, the Euler integration is used to complete the discretization of the prediction model and design the model predictive control track tracking algorithm. The feedforward feedback control algorithm is designed to provide external input required by the prediction model in the horizontal control while realizing the longitudinal control of the vehicle, finally achieving more accurate trajectory tracking control effect that is more in line with the actual driving environment. The co-simulation results of Carsim / Simulink show that the method achieves accurate output of different road attachment coefficients, synchronously enhances the intelligent automotive trajectory tracking control accuracy and stability, and has good horizontal and longitudinal coordination control.

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    Human-Vehicle Cooperative Game Collision Avoidance Based on Asymmetric Potential Fields
    Shaobo Lu,Feifei Xie,Bohan Zhang,Jiafeng Lu,Caixia Li
    2022, 44 (10):  1484-1493.  doi: 10.19562/j.chinasae.qcgc.2022.10.002
    Abstract ( 205 )   HTML ( 21 )   PDF (4188KB) ( 380 )   Save

    In order to ensure the safety of pedestrians and the stability of vehicle in the emergency pedestrian avoidance of human-machine co-driven vehicle, a human (driver)-vehicle cooperative game collision avoidance strategy based on pedestrian asymmetric potential field is proposed. Firstly, with full consideration of the street-crossing characteristics of pedestrian and his relative motion with vehicle, an asymmetric double elliptical pedestrian potential field is established for better characterize pedestrian risk, based on which the path planning for collision avoidance is performed. Then, for enhancing vehicle stability during collision avoidance and ensuring trajectory tracking performance, a non-cooperative game-based driver-AFS-ARS three-way synergy controller is constructed with a simulation on the condition of pedestrian avoidance is conducted for verification. The results show that with the ARS control added, not only the trajectory tracking performance in collision avoidance is ensured, the stability of vehicle is also apparently enhanced, with its average absolute value of error in lateral speed being 46.43% less than driver-AFS cooperative control.

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    Research on Trajectory Tracking Control of Unmanned Vehicle Based on Efficient NMPC Algorithm
    Hongwei Wang,Chenyu Liu,Lei Li,Haotian Zhang
    2022, 44 (10):  1494-1502.  doi: 10.19562/j.chinasae.qcgc.2022.10.003
    Abstract ( 420 )   HTML ( 21 )   PDF (2205KB) ( 487 )   Save

    In view of the lowering of the trajectory tracking accuracy and the solution efficiency caused by the increase of nonlinear degree and dynamic constraints of unmanned vehicles under complex working conditions, an efficient algorithm based on nonlinear model predictive control (NMPC) is proposed in this paper. Firstly, in consideration of the nonlinear factors of the vehicle model, the dynamic model and the magic formula tire model are established. A terminal state is integrated to the performance index. The multi-constraint conditions within the stability range are added, and barrier function method is used to solve nonlinear inequality constraints to ensure the smoothness of the solution process. Then in order to reduce the computational burden caused by solving nonlinear optimization problems, an improved continuous/generalized minimum residual (improved-C/GMRES) algorithm is proposed. Compared with the traditional C/GMRES algorithm, the continuously increasing penalty factor is introduced to speed up the numerical calculation efficiency and reduce the computational burden of the algorithm. Finally, based on the joint simulation platform of Simulink and Carsim, the trajectory tracking accuracy and solution efficiency are verified in double-shift line motion and serpentine motion. Simulation results show that compared with the traditional C/GMRES algorithm, the proposed algorithm can significantly improve the tracking accuracy and driving stability of trajectory tracking, and greatly accelerates the solution efficiency.

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    Vehicle Visual SLAM in Dynamic Scenes Based on Semantic Segmentation and Motion Consistency Constraints
    Shengjie Huang,Manjiang Hu,Yunshui Zhou,Zhouping Yin,Xiaohui Qin,Yougang Bian,Qianqian Jia
    2022, 44 (10):  1503-1510.  doi: 10.19562/j.chinasae.qcgc.2022.10.004
    Abstract ( 234 )   HTML ( 12 )   PDF (3204KB) ( 322 )   Save

    Traditional simultaneous localization and mapping (SLAM) methods for vehicles generally rely on the assumption of static environment, so the positional estimation accuracy may be decreased and the front-end visual odometer may even fail to track in dynamic scenes. This paper proposes a SLAM method for dynamic scenes by combining Fast-SCNN real-time semantic segmentation network and motion consistency constraints. Firstly, FAST-SCNN is used to obtain a segmentation mask of potential dynamic targets and remove the feature points to obtain a preliminary estimation of the camera position. Subsequently, based on the motion constraints and the chi-square test, the static points in the potential dynamic target are added again to further optimize the camera pose. The validation set test results show that the average pixel accuracy and mean intersection over union (mIOU) of the proposed semantic segmentation network is greater than 90%, with the processing time for 1 frame of picture is about 14.5 milliseconds, which meets the segmentation accuracy and real-time requirements of the SLAM system. Based on the public data set of TUM and real vehicle data set, the average performance improvement by using the proposed method exceeds by 80% over ORB-SLAM3 in various indicators, which significantly enhances the operating accuracy and robustness of SLAM in dynamic scenes and hence guarantees driving safety of intelligent vehicles.

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    Small Target Detection Method for Dual-Modal Autonomous Driving with Yolo v5 and Lite-HRNet Fusion
    Zilong Liu,Xiangfei Shen
    2022, 44 (10):  1511-1520.  doi: 10.19562/j.chinasae.qcgc.2022.10.005
    Abstract ( 721 )   HTML ( 25 )   PDF (2181KB) ( 535 )   Save

    This paper proposes a Yolo v5 network fused with Lite-HRNet to solve the problem of missed detection in the current target detection algorithm for autonomous driving field when detecting small and dense targets. Firstly, in order to obtain high-resolution feature detection maps, Lite-HRNet is used as the backbone network of Yolo v5 to enhance the detection of small and dense objects. In order to improve the detection performance in dark scenes, the infrared image and the visible light image are dynamically weighted to give full play to the complementary advantages of the visible light image and the infrared image. Because of the sufficient feature fusion of the backbone network, in order to speed up the detection speed, the feature fusion structure in the detection layer is cancelled. Secondly, α-EIoU is used as the bounding box loss function in order to speed up the convergence and improve the regression accuracy. At the same time, the bisecting K-means algorithm is used for clustering to select more appropriate anchor boxes for the data set, and the small target data augmentation algorithm is used for sample expansion of the dataset. Finally, a comparative test with Yolo v5 on the flir dataset is conducted. According to the experimental results, the average detection accuracy of this algorithm is 7.64% higher than Yolo v5, and the missed detection rate of small targets and dense targets is significantly reduced.

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    Effect of Driving Experience on Take-Over Performance of L3 Automatic Driving
    Linyan Wang,Huijun Zhang,Hongyu Hu
    2022, 44 (10):  1521-1526.  doi: 10.19562/j.chinasae.qcgc.2022.10.006
    Abstract ( 196 )   HTML ( 13 )   PDF (1499KB) ( 181 )   Save

    L3 level automatic driving system allows the driver to leave from driving tasks temporarily within its Operational Design Domain (ODD). When the system reaches its boundary, it issues a Take-over Request (TOR), alerting the driver to take over the vehicle in time. In order to explore the take-over performance of drivers with different driving experience in L3 automatic driving, emergency obstacle avoidance driving scenarios with non-driving tasks and visual assistance are designed for 24 participants of different ages with significantly different driving experience to carry out the take-over experiment on the driving simulator platform. The results show that different driving experience has no significant effect on reaction time, but there is significant difference in take-over performance. Experienced drivers have a significant improvement in the metrics like maximum steering wheel Angle and standard deviation of steering wheel Angle; i.e., experienced drivers can resume the control of the vehicle more steadily and safely. In addition, the difference between experienced and inexperienced is more significant without visual assistance.

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    Estimation of Vehicle Motion State Based on Hybrid Neural Network
    Zhenhai Gao,Wenhao Wen,Minghong Tang,Jian Zhang,Guoying Chen
    2022, 44 (10):  1527-1536.  doi: 10.19562/j.chinasae.qcgc.2022.10.007
    Abstract ( 287 )   HTML ( 16 )   PDF (5103KB) ( 448 )   Save

    For the problem that the existing vehicle motion state estimation algorithm relies heavily on the accuracy of the dynamic model and the accuracy is difficult to guarantee under large slip angle, the paper proposes a vehicle motion state estimation algorithm based on the hybrid neural network (HNN). By analyzing the basic dynamic characteristics of the vehicle itself, an hybrid neural network architecture suitable for vehicle motion state estimation is designed, and the deep learning estimation of vehicle motion state is realized. Based on the dataset composed of multi standard operating conditions and typical real vehicle test conditions, network training and test verification are carried out. The results show that compared with the traditional algorithm, the proposed HNN algorithm realizes estimation of vehicle motion state without dynamic vehicle model, improves estimation accuracy, and is robust to road adhesion coefficient change.

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    Research on Semi-active Suspension Preview Control Based on VSL-MPC
    Xiaokai Chen,Mingkai Zeng,Xiang Liu,An Jiang
    2022, 44 (10):  1537-1546.  doi: 10.19562/j.chinasae.qcgc.2022.10.008
    Abstract ( 287 )   HTML ( 34 )   PDF (4083KB) ( 346 )   Save

    On board sensors provide rich environment information for intelligent vehicles. However, in the electronically controlled suspension control algorithm, the road information perceived by vehicles has not been fully utilized, resulting in poor vehicle dynamics control effect. In this paper, a variable step length model predictive control (VSL-MPC) algorithm is proposed based on the high-performance preview control of semi-active suspension. The VSL-MPC algorithm determines the step length of preview control by real-time vehicle velocity and the road information collected by the binocular camera, so that the road perception information included in the control algorithm can reflect the road features more accurately, which is helpful for the semi-active suspension to adjust the damping characteristics of the suspension at a more appropriate time to realize a more ideal suspension decision-making control. The road profile information is collected by the binocular camera first. Then the optimal performance limit of semi-active suspension system is introduced as the performance evaluation benchmark, and four different semi-active suspension simulation models based on model predictive control are established. The results of simulation show that under the typical urban road conditions such as continuous deceleration belts and manhole cover impact, the performance gap between the VSL-MPC algorithm and the benchmark is only 0.72 and 2.33 dB, which are much smaller than 4.31 and 4.46 dB of traditional preview MPC algorithm, and 4.04 and 4.74 dB of non-preview MPC algorithm, when taking the vertical acceleration of sprung mass as the indicator. The VSL-MPC algorithm can enhance the dynamic performance of semi-active suspension effectively.

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    Road Slope Estimation Based on Unscented Kalman Filtering and Gated Recurrent Unit
    Datong Qin,Kang Wang,Jihao Feng,Yonggang Liu,Kun Cheng,Yu Xia
    2022, 44 (10):  1547-1555.  doi: 10.19562/j.chinasae.qcgc.2022.10.009
    Abstract ( 152 )   HTML ( 13 )   PDF (4634KB) ( 351 )   Save

    In view of the poor universality of external lidar and other sensors, and the large error of traditional road slope estimation method based on onboard CAN bus data in four special conditions of vehicle, including starting, gear shifting, braking, and stopping, a road slope estimation approach based on unscented Kalman filter (UKF) and gated recurrent unit (GRU) is proposed. The working condition is determined according to vehicle speed and other data. Under non-special conditions, the vehicle dynamic model is established and UKF is used to estimate the slope. Under special working conditions, the time series slope with unstable-regularity is converted to the distance series slope, and GRU is used to estimate the short-range slope. The results of simulation and real vehicle tests show that under non-special conditions, the method proposed can accurately estimate the road slope using UKF, and under special conditions, the method can effectively track the changing trend of distance series slope through GRU, significantly enhancing the estimation accuracy of road slope.

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    Research on High-Accuracy Finite Element Modeling Method for Tire Mechanics Characteristics Simulation
    Dang Lu,Wenhao Yang,Haidong Wu,Nanshi Chen,Jian Cheng,Zhenwei Zhang
    2022, 44 (10):  1556-1562.  doi: 10.19562/j.chinasae.qcgc.2022.10.010
    Abstract ( 139 )   HTML ( 11 )   PDF (3155KB) ( 239 )   Save

    In order to enhance the tire finite element simulation accuracy and better meet the requirements of high-precision virtual sample delivery, a tire reverse analysis method is proposed. First, the section profile is acquired by 3D scanning of a real tire, which is then cut along radial direction to obtain a piece of tire section with certain thickness. Next, the thin tire section is put onto the print paper of tire section profile obtained by 3D scanning and make both section profile well coincide, which is then scanned to get a section picture of tire material layout as real profile, with which and designed profile acquired from tire manufacturer, two 3D tire model is generated by rotating section profile around tire center. Then both real tire test and finite element simulation on both tire models with real and designed profiles respectively are carried out under static condition. Finally, a comparative simulation on the static mechanics characteristics of tires with real and designed profiles under different tire pressures is conducted. The results show that the simulation accuracies of radial, lateral and longitudinal stiffness of tire with real profile reach 99.2%, 97.9% and 98.2%, i.e. 4.3, 4.6 and 7.4 percentage points higher than that of designed profile respectively, but the torsional stiffness of tires with two different profiles has little difference. Under all different tire pressures, the stiffness of tire with designed profile in all different directions always higher than that of real profile and they all increase with the rise of tire pressure.

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    Research on Heat Pump PTC Coupling Heating Strategy for Electric Vehicle
    Hongzeng Ji,Jingyang Cai,Jinchen Pei,Xinglei He,Fen Guo,Yichun Wang
    2022, 44 (10):  1563-1570.  doi: 10.19562/j.chinasae.qcgc.2022.10.011
    Abstract ( 194 )   HTML ( 10 )   PDF (2087KB) ( 511 )   Save

    In order to decrease the power consumption for EV heating, it is proposed that there are heating performance zones for heat pump system heating within the ambient temperature range of -20 to 5℃ based on the heating performance test of the heat pump system. The PTC coupling heating strategy of the heat pump with PTC involving in the low efficiency zone in advance is developed. The system model built by AMESim is used for simulation and the comparison study is conducted with the traditional strategy. Compared with the heat pump with 6 000 r/min rotary speed coupling 278.95 W PTC heating power, the heat pump with 4 700 r/min rotary speed coupling 462.11 W PTC heating power consumes 6.4% less energy to maintain the car temperature at 24 ℃。Compared with single heat pump heating, the heat pump coupling PTC heating strategy with PTC intervention in advance has the advantages of faster heating, lower energy consumption and lower rotary speed. When the ambient temperature is -10 ℃ and the target temperature in the vehicle is 20 ℃,the energy consumption in the regulation process can be reduced by 9.4% at most and by 2.8% after stabilization. When the strategy with PTC intervention in advance is adopted, the compressor speed should be maintained as close to the critical speed in the high efficiency zone as possible. The strategy can significantly improve the heating efficiency and comfort without changing the system structure.

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    Study on Shift Schedule of 2DCT for Pure Electric Vehicle Based on NSGA-Ⅱ Algorithm and Fuzzy Control
    Xuebing Yin,Yong Chen,Qinglin Dai,Hai Liu,Naili Tian,Bolin He
    2022, 44 (10):  1571-1580.  doi: 10.19562/j.chinasae.qcgc.2022.10.012
    Abstract ( 109 )   HTML ( 14 )   PDF (3827KB) ( 285 )   Save

    Shift schedule is a key factor affecting the economy and power performance of vehicle.For the independently developed two gear dry dual clutch transmission (2DCT) of pure electric vehicle, taking the shifting speed under different pedal opening as the optimization variable, the Pareto front of the shifting speed is obtained by NSGA-Ⅱ algorithm,and the shift schedule considering both economy and power performance of pedal opening and speed is obtained by linear weighting method. A three-parameter fuzzy controller is constructed by introducing in acceleration to dynamically adjust the shifting speed, and the comprehensive shifting schedule is obtained. The results show that the comprehensive shift schedule can take into account the economy and power performance of the vehicle simultaneously, and reduce the shift frequency greatly compared with the economic shift schedule.

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    Analysis of Influencing Factors of Carbon Emission Reduction in the Driving Stage of Electric Vehicles Based on Big Data
    Weipeng Zhan,Zhenpo Wang,Junjun Deng,Peng Liu,Dingsong Cui,Haitao Li
    2022, 44 (10):  1581-1590.  doi: 10.19562/j.chinasae.qcgc.2022.10.013
    Abstract ( 235 )   HTML ( 33 )   PDF (6504KB) ( 391 )   Save

    Based on a large number of real vehicle data in China, this paper analyzes the impact of energy structure changes, battery capacity degradation, operating conditions, temperature, purpose, battery charging efficiency, vehicle transmission efficiency and other factors on carbon emission reduction of electric vehicles (EVs), and establishes a carbon emission model of EV driving stage. According to the national and provincial dimensions, this paper analyzes the reasons for the regional differences in carbon emission reduction of EVs, and studies the emission reduction benefits of different types of EVs. Sensitivity analysis is carried out on the influence of electricity carbon emission factor, climate and temperature on carbon emission reduction of EVs. Finally, based on the analysis results, suggestions are put forward for the low-carbon development path in the field of road transportation.

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    Study on the Slid Mode in Vehicle Small-Overlap Frontal Crash
    Xiaojie Chen,Song Li
    2022, 44 (10):  1591-1599.  doi: 10.19562/j.chinasae.qcgc.2022.10.014
    Abstract ( 133 )   HTML ( 11 )   PDF (5001KB) ( 274 )   Save

    Based on the plane motion theory, a theoretical analysis method for the slide mode of the vehicle in small-overlap frontal crash is proposed, and the relationship between the slide value and the impact forces is revealed and verified by experiments and tests. The impact area is divided into six parts and the sixth-order impact force characteristic curves are put forward. Based on the characteristic curves and the uniform design method, the sample space of vehicle slide value and different characteristic curves is obtained by using the theoretical method proposed. Furthermore, the BP neural network is established to conduct a sensitivity analysis of the impact forces and the vehicle slide value in the six regions of characteristic curves, with the critical impact region under that working condition identified. The theoretical method proposed and the sensitivity analysis conducted provide a theoretical support for the structural design for small-overlap frontal crash.

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    Prediction on Seat’s Anti-whiplash-injury Performance Based on Deep Learning
    Shaowei Zhang,Dawei Zhu,Guangzhao Zhai
    2022, 44 (10):  1600-1608.  doi: 10.19562/j.chinasae.qcgc.2022.10.015
    Abstract ( 131 )   HTML ( 11 )   PDF (3547KB) ( 267 )   Save

    On the base of traditional simulation and combined with deep learning, a rapid prediction method of seat’s anti-whiplash injury performance is proposed. Firstly, a series material level, component level, subassembly level and seat level static and dynamic physical experiments are carried out on a Shanghai VW’s vehicle seat. Then using the results of experiments to calibrate the existing simulation model, resulting in the effectiveness of the simulation model verified. Next, a simulation on all factors affecting the seat’s whiplash performance is conducted by using full-factor method, and based on simulation results and using deep learning method, a long- and short-term memory (LSTM) neural network model is established to rapidly predict the whiplash injury response of dummy. The results show that the dummy response curve obtained from prediction by LSTM neural network model agrees well with simulated curve, so can be used in subsequent seat’s whiplash performance optimization.

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    Research on Particle Emission Characteristics of Direct In-jection Gasoline Vehicles Based on the Particle Size Distribution
    Xiaohan Jiang,Jianwei Tan,Changjian Xu,Yunshan Ge,Lijun Hao,Xin Wang,Jiachen Li
    2022, 44 (10):  1609-1618.  doi: 10.19562/j.chinasae.qcgc.2022.10.016
    Abstract ( 100 )   HTML ( 5 )   PDF (2684KB) ( 491 )   Save

    Taking a national VI standard gasoline direct injection vehicle (GDIV) equipped with an exhaust particulate filter as the research object, the particle number (PN) emission concentration of different particle size ranges in the exhaust gas is measured by two instruments, namely, condensation particle counters (CPC) and electrostatic low voltatge impactor (ELPI+). The worldwide harmonized light vehicle test cycle (WLTC) cold-start test is carried out on a chassis dynamometer, and the test results show that in the ultra-high-speed section of the WLTC cycle test, the measurement results of ELPI+_29~2 500 nm is 1 order of magnitude higher than that of CPC_23~2 500 nm, with ELPI+_6~29 nm ultrafine particulate matter as the main body of PN emission accounting for up to 97.5%. Under hot start conditions, the high-speed section and ultra-high-speed section of the WLTC cycle show that the poor original exhaust of the engine and the continuous regeneration reaction of the gasoline engine particulate trap lead to large amount of ultra-fine particulate matter emission. To reduce the impact of vehicle particulate matter emissions on the environment and human health, it is necessary to conduct in-depth research on the particle size distribution of vehicle exhaust particles, and pay more attention to ultra-fine particles below 23 nm.

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    Automotive Aerodynamics Development Based on Shape Optimization Method
    Yubo Lian,Qiuli Luo,Fengli Zhang,Rongrong Zhang,Yadong Zhang
    2022, 44 (10):  1619-1626.  doi: 10.19562/j.chinasae.qcgc.2022.10.017
    Abstract ( 277 )   HTML ( 26 )   PDF (5482KB) ( 308 )   Save

    Based on the Isight optimization platform and by integrating the Sculptor mesh deformation algorithm and the computational fluid dynamics simulation technique, a vehicle aerodynamic shape optimization method with multi-parameter and multi-objectives is developed. Under the given vehicle size constraints and based on the low drag shape of BYD’s Han EV, the effects of seven outer contour parameters on aerodynamic drag are investigated, leading to a drag reduction of 4.2 counts. Furthermore, an aerodynamic optimization on the electric tail spoiler is carried out by using the shape optimization method with the optimal shape combination of multi-objective aerodynamic parameters studied, an electric tail spoiler with optimum shape and posture is obtained, resulting in a total drag reduction of 6 counts and a real-axle lift force reduction of 52 counts in the end. Finally, the effectiveness and reliability of the shape optimization method adopted are verified by wind tunnel test.

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