Table of Content

25 May 2021, Volume 49 Issue 5

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2021, 49(5):  0. 

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Traffic & Transportation Engineering

Construction of Autonomous Vehicles Test Scenarios with Typical Dangerous Accident Characteristics



CHEN Jiqing, SHU Xiaoxiong, LAN Fengchong, et al

2021, 49(5):  1-8.  doi:10.12141/j.issn.1000-565X.200371

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To meet the need of mass testing scenarios and high-risk scenarios for the autonomous vehicles safety testing and verification, and based on the accident data of 641 cases involving road section in the National Automobile Accident In-Depth Investigation System, five scene elements were selected according to traffic environment elements and test vehicle basic information elements. Then the vehicle accident data was analyzed by one-hot coding and cluster analysis methods. The dangerous accident characteristics were identified and analyzed by combining the vehicle accident data with the typical vehicle collision dangerous scenarios obtained by clustering. And 15 test scenarios of autonomous vehicles involving road section type were extracted, including 6 test scenarios involving common sections and 9 test scenarios involving intersections. Research shows that Chinese traffic environment has unique characteristics. In the test scenario, 53.3% of the target vehicles involved powered two-wheeler (including motorcycles and electric mopeds) and 40.0% involved M1 passenger vehicles. The proposed dangerous accident characteristics can better describe and clarify the test scenario.The research results can provide a test scenario with Chinese traffic environment characteristics for virtual testing of autonomous cars and a basis for the development and testing of vehicle active safety products.

Coupling Thermodynamics Analysis for Ascent Stage of Stratospheric Airship



HAN Qiang, TANG Ziqi, ZHANG Run, et al

2021, 49(5):  9-17,46.  doi:10.12141/j.issn.1000-565X.200202

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A new coupling thermodynamics analysis method based on the ADAMS and MATLAB joint simulation was proposed for ascent stage of stratospheric airship in complex external environment and multi-physical coupling conditions. An accurate thermal-mechanical coupling mathematical model for ascent of airship was built by using MATLAB in this method. Based on this method, the discrete time-domain method and Newton iterative algorithm were used to decouple the model to obtain relevant parameter curves. The model of airship was established in dynamic environment of ADAMS and a CONSUB subroutine which is available to retrieve the variable data of the airship mass in real time was developed. The visualized simulation control for the ascent stage of variable mass stratospheric airship was realized by applying the decoupled load and calling the subroutine. The coupling thermodyna-mics analysis of a certain stratospheric airship was performed using the above method to obtain the rules of trajectory, attitude and air temperature in air bag. The results show that the design minimum of the pressure difference between the inside and outside of the airbag is not significant for real-time control of airship speed, and the temperature of gas in the air bag rises during the stratosphere stage. The analysis indicates that this method can efficiently and accurately simulate the ascent of stratospheric airship with variable mass under the coupling of complex multi-physical conditions and obtain thermodynamic parameters. This method is of great reference value for the parameter control and optimization design of airship.

Bus Priority Signal Control Method Based on Variable Phase in Internet Vehicles Environment



SONG Xianmin, LENG Ning, JIANG Jingling, et al

2021, 49(5):  18-27.  doi:10.12141/j.issn.1000-565X.200141

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A bus priority signal control method based on variable phase was proposed to adapt to the operation characteristics of intersections with large traffic flow fluctuation. The method allows the phase sequence and phase combination of intersection signal to be dynamically adjusted in real time. Based on the bidirectional and real-time information transmission in Internet vehicles environment, a prediction model of bus arrival time in different situations was developed. The model considers the time and speed of the bus and the queuing status of the intersection when the bus enters the communication range. Then, the green time were determined for different candidate schemes according to bus arrival time. Aiming at the highest passenger pass rate, the optimal scheme was selected from candidate schemes as the next green phase. Finally, the COM interface of VISSIM and Python were used to achieve the proposed method in Internet vehicles environment. The intersection of Fei Yue Road and Guang Gu Street in Changchun was taken as an example. The test shows this method can effectively reduce the per person delay of intersections when the road saturation is 0.8, 0.9 and 1.0. When the road saturation is 0.9 and the bus proportion is 2%, 4% and 6%, the method can reduce the per person delay of buses by more than 40%. Therefore, this method is more suitable for unsaturated intersection with lower proportion of buses.

Optimization of Urban and Rural Public Transport Operation and Scheduling Considering Small Piece Express



HAN Wanli, DU Bangshen, ZHAO Jianyou, et al

2021, 49(5):  28-37.  doi:10.12141/j.issn.1000-565X.200479

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In view of the problems such as long departure interval, low occupancy rate, low profit, high cost of rural express delivery and poor delivery time that the development of urban and rural public transport in China faced, the paper put forward a solution to the urban and rural public transport operation and dispatching considering small-scale express. Firstly, the operation mode of “urban and rural public transport + small express” was put forward based on the analysis of rural small-scale express transportation demand and urban-rural public transport supply, and its influential factors were analyzed. Secondly, game theory and multi-objective programming theory were used to construct a double-objective scheduling optimization model which maximizes the income of public transport companies and minimizes the shortest travel time of passengers, considering the benefits of the new urban-rural public transport companies, passengers and small-scale express enterprises. And genetic simulated annealing algorithm was designed to provide a solution for the model. Finally, Huazhou District of Weinan City in Shaanxi Province was taken as an example to verify the solution. The comparative analysis between optimization and actual operation results shows that the scheduling optimization model constructed under the new mode has good optimization effect. It verifies the feasibility of the new model and the effectiveness of the model.

Optimization for Low Aerodynamic Drag Boat-Tail of GTS Model Based on Adaptive Approximation Model



HU Xingjun, LIU Yichen, LI Jincheng, et al

2021, 49(5):  38-46.  doi:10.12141/j.issn.1000-565X.200470

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To solve the problems of large sample size and low optimization efficiency of static approximation model, the least squares support vector regression (LSSVR) based adaptive approximation model with particle swarm optimization (PSO) algorithm was introduced to construct the optimization algorithm. The global and local adaptive approximation models were constructed to reduce the possibility of the optimization algorithm falling into the local optimal solution and to accelerate the convergence process. The Branin function was used as test function to prove the effectiveness of the proposed adaptive PSO-LSSVR approximation model for single-objective optimization problems. The adaptive PSO-LSSVR approximation model was applied to the rapid optimization of boat-tail of GTS model. The upper boat-tail angle, the lower boat-tail angle, the side boat-tail angle and the tail plate length were taken as design variables, and the optimal solution could be obtained only with 31 sample data sets.  And the error of aerodynamic drag coefficient predicted by the approximation model is only 0.18%. The aerodynamic drag of GTS model with optimized boat-tail is reduced by 9.38% after optimization, which proves that the adaptive PSO-LSSVR approximation model optimization method is feasible for fast optimization problem with small samples.

Vehicle Speed Estimation Based on UniTire Model



LI Jing WANG Chen ZHANG Jiaxu

2021, 49(5):  47-55.  doi:10.12141/j.issn.1000-565X.200469

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Accurate and real-time acquisition of vehicle speed information is a necessary prerequisite for vehicle to achieve high-precision positioning and navigation, advanced cruise control and formation cruise control. Therefore, a novel vehicle speed estimation method was proposed based on UniTire model. Firstly, a vehicle speed estimation nominal model, which includes vehicle longitudinal, lateral and yaw dynamics, was established based on UniTire model. The global accurate solution of characteristic parameters of the model was obtained based on adaptive genetic algorithm and quasi-Newton algorithm. Subsequently, the process noise and observed noise of the nominal model was taken as scheduling variables, and a cluster of vehicle speed estimators was designed based on strong tracking central difference Kalman filter. The outputs of the cluster of vehicle speed estimators were smoothly fused based on interactive multiple model algorithm. Finally, the feasibility and validity of the proposed self-driving vehicle speed estimation method were verified with hardware in the loop simulation system for full-vehicle. The results show that, compared with strong tracking central difference Kalman filter, the proposed method has stronger adaptive ability to the statistical characteristics of the system noise and higher estimation accuracy.

Research on Behavior Characteristics of Flame Ejected from Broken Glass in Tunnel Train Fire Accident



XI Yanhong, QU Shuqiang, MAO Jun, et al

2021, 49(5):  56-64.  doi:10.12141/j.issn.1000-565X.200421

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When the passenger compartment caught fire in the long high-speed railway tunnel, the window glasses may be deformed and break off to form new vents, which can accelerate the fire combustion. The flame will eject to tunnel from the opening and lead to catastrophic loss of casualties and properties. This paper studied the behavior characteristics of the ejected flame and the longitudinal distribution law of smoke temperature in the high-speed train compartment. Based on the energy balance equation, methods for calculating the heat release rate (HRR) in and out of the on-fire train were put forward, and the coupling relationship between the flame tilted angle and HRR was established. Moreover, the coupling relationship between the maximum dimensionless temperature near the tunnel wall and the dimensionless flame ejecting HRR was obtained. The results show that the HRR in and out of the on-fire train compartment increases in the parabolic rule. The HRR in and out of the on-fire train compartment are equal when the whole HRR is 17.85MW; the HRR in the on-fire train compartment is larger than that flame ejecting HRR when the total HRR is within the range of 1MW to 15MW. But HRR in the on-fire train compartment is smaller than that out of the on-fire train compartment when the total HRR is within the range of 20MW to 30MW. With the increase of the total HRR and hot-gas, the temperature near the tunnel wall increased, and the highest temperature appears in position of 3 meters high. The flame will eject when the HRR is above 20MW. 

Architecture & Civil Engineering

Multi-Scale Simulation on the Wind Field for Complex Terrain Based on Coupled WRF and CFD Techniques



YANG Yi, TAN Jiancheng, JIN Bochong, et al

2021, 49(5):  65-73,83.  doi:10.12141/j.issn.1000-565X.200560

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The accurate simulation on the wind field is an important prerequisite for the wind resistance research for the super high-rise buildings. In this research, the mesoscale WRF (Weather Research and Forecast) model, which can simulate high atmospheric circulations, and the CFD simulation, which possesses high spatial and temporal resolutions, were combined together to simulate a typical hilly area around the Shenzhen meteorological tower. Based on the WRF simulation loaded with the Four-Dimensional Data Assimilation (FDDA) technique and the CFD simulation for an equilibrium atmospheric boundary layer flow, the multi-scale wind field simulation analyses for this complex terrain were performed. The simulation result verified the applicability of the Analysis Nudging (AN) scheme and the Surface Analysis Nudging (SAN) scheme in WRF simulation, and it shows the accuracy of AN scheme is relatively higher. Compared with the separate mesoscale WRF simulation, the coupling multi-scale mo-deling results are much closer to the meteorological measurement data. The mesoscale WRF model can provide more accurate inlet boundary conditions for the small-scale CFD models and the downscale refined simulation can be rea-lized through the nesting operation in the mesh interface. Thus the simulation accuracy of the wind field can be improved by employing current multi-scale WRF-CFD simulation technique. This study indicates that the multi-scale simulation on the wind field in boundary layer based on the coupled WRF-CFD technique will be an effective way to improve the accuracy of the wind effect analysis for high-rise buildings.

Artificial Seismic Wave Simulation and Structural Seismic Resistance Random Simulation Analysis Based on Unit Impulse Response



LI Xueping ZHANG Leiyuan WEI Peng

2021, 49(5):  74-83.  doi:10.12141/j.issn.1000-565X.200692

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An explicit time-domain method(ETDM) based on analytical response of unit impulse was proposed  to simulate the random seismic analysis of artificial seismic waves and building structures with response spectrum consistent with “Code for Seismic Design of Buildings” (GB 50011—2010). Firstly, explicit time domain expressions based on analytical response of unit impulse for single and multiple degree of freedom dynamical systems were derived. Then, the explicit time domain expression for single degree of freedom system was applied to solve the stochastic dynamic equation of the ground motion. Through iteration, the artificial seismic wave of the specified intensity and the artificial seismic wave that is consistent with the standard response spectrum can be simulated efficiently by taking the advantage of equation in quickly solving the dynamic response. Then, the explicit time-domain expressions of the simulated seismic wave and the multi-degree-of-freedom dynamic system were applied to the random seismic simulation analysis of structures and verified by a numerical example. The study shows that, based on the existing ground motion model and the explicit time domain representation of the unit pulse, the seismic wave which is consistent with the standard response spectrum can be simulated efficiently, and ETDM based on unit pulse combined with mode superposition method has sufficient accuracy and high efficiency in seismic random simulation analysis of structures, thus can be used for seismic time-history analysis of building structures.

Influence of Grout on the Mechanical Performance of Prefabricated Assembled Socket Bridge Pier



XU Yan, TONG Ziliang, ZENG Zeng, et al

2021, 49(5):  84-91.  doi:10.12141/j.issn.1000-565X.200260

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In the socket connection, the bridge piers adopt prefabricated piers. After the bridge piers are inserted into the reserved holes of the cap, high-strength fast-setting grouting is poured into the periphery of the bridge pier insertion end to compact the reserved holes. The structural reliability of the socket connection mainly depends on the grouting and socket depth. Pseudo static tests and ANSYS numerical simulations were performed on the socket specimens and cast-in-place specimens. The effects of the grouts adhesive properties, the elastic modulus of the grout and the filling thickness on the overall mechanical properties were studied. The results show that,when the grout is bonded well, the socket specimen has the same level of thrust stiffness and ultimate bearing capacity as the cast-in-place specimen; after the cement grout fails, a new force transmission path occurs between the bridge pier and the cap. The socket specimen still has good thrust rigidity and horizontal bearing capacity, but the reinforcement of the socket test piece on the base plate of the socket needs to be strengthened accordingly to improve the bearing performance of the cap; the elastic modulus of the grout and the filling thickness have little effect on the ultimate bearing capacity of socket specimens,and the horizontal stiffness of the socket specimen is not influenced by the thickness of the grout, but it increases with the increases of the elastic modulus of the grout.

Natural Frequencies Computation of Composite Laminates with Multiple Delaminations



XUE Jianghong, YAO Sishi, JIN Fusong, et al

2021, 49(5):  92-101.  doi:10.12141/j.issn.1000-565X.200495

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In order to investigate the influence of the contact mechanism on the composite laminates with multiple delaminations, free vibration of composite laminates containing a through-the-width delamination was analyzed with a four-region exact model in which the contact mechanism at the interfaces of the delamination is considered. By examining the solutions from the exact model and adopting equivalent model based on equivalent stiffness, the delaminated region was translated into a perfect, delamination free laminate which has the same geometric size and the stacking sequence but a reduced stiffness. Numerical calculations were carried out to justify the accuracy and effectiveness of the equivalent model by comparing the natural frequencies given by the equivalent model with those given by the exact model and the finite element model. On this basis, the free vibration of composite laminates with multiple through-the-widths delamination was analyzed using the established equivalent model and the finite element model. It is found from the analysis that for laminates with multiple horizontal delamination, the larger the total length of delamination is, the smaller the natural frequency is; for composite laminates with multiple vertical dela-mination, the natural frequency of laminates with uniform distribution of delamination along the thickness is the smallest. Generally, the natural frequency decrease with the increasing number of delamination, but the natural frequency is affected by the relative depth between layers simultaneously. The results show that the natural frequencies of the delaminated laminates from the equivalent model are in good agreement with the ABAQUS finite element solutions, and the correctness of the equivalent theory is verified. It provides strong technical support for the correct evaluation of the residual bearing capacity of the delaminated composite structures in engineering fields.

Mechanical Engineering

Research on Clonal Selection Algorithm for Multi-Robot Task Allocation and Scheduling



QUAN Yanming HE Yiming

2021, 49(5):  102-110.  doi:10.12141/j.issn.1000-565X.200300

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A clonal selection algorithm (CSA) for multi-robot collaborative scheduling was proposed to solve  the difficulties in controlling and optimizing the task assignment and scheduling of multi-robot in the same period in intelligent manufacturing system. Firstly, the initial conditions of multi-robot task were analyzed. Then taking the task completion as the constraint condition and taking task flow time, single robot maximum cost and multi-robot total cost as the objective function, a mathematical model of multi-robot task allocation and scheduling optimization was constructed. The affinity function was introduced to dynamically change the parameters of clone, mutation and selection, so as to improve the computational efficiency. Finally, the scheduling method was verified by Gantt chart analysis. The results show that the proposed method is stable and feasible. Meanwhile, the experiments show that the clonal selection algorithm has the superiority of fast convergence speed and high calculation accuracy, and can optimize various indicators under complex multi-task conditions.

Influence of Pre-Stage Asymmetry on Jet-Pipe Servo Valve Zero Deviation



YIN Yaobao LI Cong

2021, 49(5):  111-119.  doi:10.12141/j.issn.1000-565X.200515

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The pre-stage asymmetry is the main factor causing the zero deviation of the jet-pipe servo valve. In view of the uneven size of two receiving holes, the misalignment of jet-pipe and the receiver and the asymmetry of the receiving hole center, a mathematical model of the jet-pipe pre-stage was established. A modified model based on definite integral was designed to deal with the asymmetry of the receiving hole center. Considering the asymmetry of the receiving area of the pre-stage, the quantitative analysis method and model of the pressure characteristics and the zero deviation value were established. The results show that the pre-stage processing, assembly and environmental effects will cause the asymmetry of the geometric structure and directly cause the zero deviation of the servo valve. The initial assembly error between the jet-pipe and the receiver, the initial error of the radius of the recei-ving hole will seriously cause the servo valve to produce a zero deviation. The servo valve produces a positive zero deviation, when the right receiving hole is smaller than the left receiving hole, the jet-pipe has an offset error to the right, and the angle between the axis of the right receiving hole and the vertical is smaller than the angle between the left receiving hole and the vertical. The experimental results are in accordance with the theoretical results. In the processing and assembly process of the servo valve, the symmetry of the pre-stage structure should be guaranteed as much as possible.

A Directly Robust Adaptive Neural Network Controller for an Underacuated Crane



CHENG Wenming, ZHANG Daoyu, CHEN Qingrong, et al

2021, 49(5):  120-128,144.  doi:10.12141/j.issn.1000-565X.200438

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A directly robust adaptive controller based on the radial basis function (RBF) neural network was proposed to solve the problem of the trajectory tracking for anti-sway control of an underacuated overhead and gantry crane with the parameter uncertainties and external disturbances. Firstly, the dynamic model of a double-pendulum crane was established by Lagrange equation of the second kind, and an ideal controller was designed for undisturbed conditions. Secondly, the RBF neural network was introduced to fit the ideal control output and its weight update rate was designed considering the effects of disturbances, after that the Lyapunov stability of the system was proved. Finally, a simulation test was carried out to verify the controller performance. The controller only takes the real-time position and speed information of the trolley as the control input, and no system parameter information is needed. The control accuracy depends on the fitting accuracy of the RBF neural network. The simulation results show that the controller proposed in this paper has excellent trajectory tracking and anti-sway performance and strong robustness.

Aperture Measurement Method Based on Conic Invariant



ZHANG Longfei, LI Jing, KOU Ying, et al

2021, 49(5):  129-134.  doi:10.12141/j.issn.1000-565X.200550

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A model of aperture measurement based on quadratic curve invariants was proposed to deal with the low detection efficiency and the problem that detection accuracy was greatly affected by the environment. The conic invariant aperture of the hole was obtained by ellipse geometry fitting on the surface of the hole. Firstly, the world coordinate system was established and the transformation relationship between the world coordinate system and the camera coordinate system was determined by calibration. The improved candy algorithm was used to extract the sub-pixel coordinates of the hole edge, and the sub-pixel coordinates of the hole edge were projected onto the hole surface according to the coordinate transformation relationship. Then, the ellipse geometric fitting of the hole edge curve on the hole surface was performed to obtain the quadratic curve invariant. Finally, the conic invariant was used to measure the aperture on the test bench, and the results were compared with those of the inner micrometer to verify the accuracy of the conic invariant model. 

Research on Coupling Effect Experiment and Decoupling Method of 3-D Force Measuring Platform



ZHANG Yirui SU Jian XU Guan

2021, 49(5):  135-144.  doi:10.12141/j.issn.1000-565X.200461

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In order to measure the force loaded on bogie test bench and improve the measurement accuracy, a three-dimensional (3-D) force measuring platform with multiple force sensors connected in parallel was designed. Its measurement principle was analyzed theoretically and a Wheatstone bridge measurement circuit was built. 3-D force measuring platform is a kind of shear stress sensor, and the analysis shows that the output voltage of its mea-surement circuit has a definite linear relationship with the force loaded. The static calibration test of 3-D force measuring platform under uniaxial load was carried out and the output characteristics under uniaxial load and the interdimensional coupling effect of load measurement were analyzed. It finds that under uniaxial load, the voltage output of the measurement circuit corresponding to the loaded axis has good linearity, but the voltage output of the non-loaded axis measuring circuit is small. In this paper, the coupling degree evaluating coupling effect between dimensions and the numerical decoupling method based on least square method and BP neural network were also proposed, and their effectiveness was verified by experiments. At the same time, the orthogonal method was used to carry out the multi-axis loading test of the three-dimensional force measuring platform. The results show that the single-axis measurement error and the overall measurement error are not more than 1.5%, thus the measurement accuracy meets the test requirements.