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Journal of Jiangsu University(Natural Science Eidtion)

	2022 Vol.43 Issue.3 Published 2022-05-10

	249	Coupling characteristics of driver preview time and road bend radius
		WANG Xianbin， HAN Hong， SHI Shuming
		A drivervehicleroad system dynamics model was established to investigate the impact of coupling characteristics of driver preview time and road bend radius on vehicle handling stability. Through the simulation experiment based on actual road data, the effects of driver preview time and road bend radius on vehicle dynamics characteristics and path tracking were analyzed, and the correctness of the model was verified. The effects of the coupling characteristics of driver preview time and road bend radius on vehicle handling stability were investigated based on phase trajectory, tire lateral force, vehicle track deviation, body attitude and vehicle state variables of longitudinal speed, lateral speed and yaw rate. The simulation results indicate that the relationship between driver preview time and road bend radius has significant coupling characteristics. When the vehicle longitudinal speed and road cross slope are the same, the minimum radius of the curve required for the safe operation of vehicle is increased with the shortening of driver preview time.
		2022 Vol. 43 (3): 249-255 [Abstract] ( 40 ) [HTML 1KB] [ PDF 3653KB] ( 1204 )

	256	Lane tracking control of commercial vehicle based on RMPC
		TANG Bin, YIN Yue, JIANG Haobin, LIN Ziyan, HUA Yifeng, XIE Jun
		Lane keeping system (LKS) is helpful to improve the driving safety of commercial vehicles. To ensure the robustness of LKS control system and reduce the model uncertainty caused by the simplified model process, the robust model predictive control algorithm based on the linear matrix inequality(LMI) was used to conduct the lane tracking control of commercial vehicles. Three degrees of freedom vehicle dynamics model was established, and the discretization and linearization were carried out. Based on the discrete dynamics model of vehicle, the model predictive controller was designed with path deviation and control increment as objective function. The model predictive control problem was transformed into minmax optimization problem by LMI. By the online dynamic optimization, the path deviation was eliminated, and the vehicle was returned to the centerline rapidly. The Trucksim/Simulink cosimulation was carried out to verify the algorithm. The results show that the lane keeping control system based on robust model predictive control（RMPC）algorithm can improve the lane tracking accuracy and driving stability of commercial vehicles.
		2022 Vol. 43 (3): 256-262 [Abstract] ( 55 ) [HTML 1KB] [ PDF 2435KB] ( 360 )

	263	Vibration characteristics and control of transducer under constraint of nonlinear stiffness of hydraulic cylinder
		GUO Yan, HE Ren, TAO Wei
		According to the energy collection requirements of the vibration energy recovery device of hydrostatic speed bump, a transducer based on hydraulic cylinder was proposed. The nonlinear stiffness characteristics of the hydraulic cylinder of transducer were analyzed, and the change law curve between effective stiffness and piston position of the hydraulic cylinder of transducer was obtained. To solve the vibration problem of transducer under the influence of dynamic characteristics, a vibration model of the transducer was established under the constraint of nonlinear stiffness of hydraulic cylinder, and the amplitudefrequency response of the system was obtained by the average method. The effects of nonlinear stiffness, initial displacement of rodless piston of hydraulic cylinder and external excitation amplitude of transducer system on the amplitudefrequency characteristics of transducer hydraulic cylinder system were analyzed. The feedback control of transducer system was investigated based on the Lyapunov discriminant method, and the effectiveness of the feedback controller was verified by comparing the vibration velocity and displacement curves before and after the control. The results show that the feedback control can reduce the occurrence of violent vibration and improve the system stability.
		2022 Vol. 43 (3): 263-269 [Abstract] ( 36 ) [HTML 1KB] [ PDF 1679KB] ( 364 )

	270	Driving behavior impact on emissions of light-duty gasoline vehicle based on portable emission measurement system
		YU Qian，XIAO Xiong，YANG Mingpeng，LIU Haihai
		To quantify the multidimensional characteristics of driving behavior and corresponding emission characteristics, the portable emission measurement system(PEMS) was used to collect the emissions and microscopic driving behaviors data. The relationship between driving behavior and lightduty gasoline vehicle emission was analyzed. The driving segments were divided into two categories of ecodriving and nonecodriving, and five ecodriving behavior identification models were established based on logistic regression, Naive Bayes, decision tree, support vector machine and BP neural network, respectively. The results show that when the road traffic tends to be saturated or forced, the driving behavior of drivers and the driving activities change significantly. The change of driving activities leads to the significant increasing of emission factor in saturated flow and forced flow. The driving operation intensity, the driving mode duration and the driving mode transfer frequency have impact on the pollutant emission. The model based on decision tree has high accuracy of 94.00%.
		2022 Vol. 43 (3): 270-276 [Abstract] ( 590 ) [HTML 1KB] [ PDF 7442KB] ( 377 )

	277	Layout method and optimization of averaging Pitot tube in VAV terminal unit
		WANG Yinghui， SONG Chunguang， CHEN Shunlong， WANG Yong
		To improve the effectiveness of air volume control, the airflow field from the inlet to the rear duct in VAV terminal unit was numerically simulated. Combined with the velocity distribution at different cross section in the air duct, the reasonable method for the layout of the averaging Pitot tube was proposed by minimizing the mean relative error of air volume between the measured value and the theoretical value. Comparing the number and position of intersection points of the velocity distribution curves and the theoretical values on the cross section of the air duct under the conditions of air volume of 100300 m3·h-1 with different opening degrees of damper, the installation position of the averaging Pitot tube and the location of the measuring holes were determined. The results show that the optimal averaging Pitot tube is located on the section with X of 306 mm along the flow direction and with Y of 210 mm along the height direction of air duct, and the measuring hole coordinates are at Z of 116 mm, 188 mm, 264 mm and 330 mm, respectively. The measured value of the air velocity is well consistent with the theoretical value. The minimum relative error is only 2.25% at the opening degree of damper with 50%, and the maximum relative error is 9.04% at that with 30%.
		2022 Vol. 43 (3): 277-281 [Abstract] ( 45 ) [HTML 1KB] [ PDF 3572KB] ( 352 )

	282	Design and analysis of threshing device of corn harvester based on virtual prototype
		LI Yanying, LIU Mengnan, XU Liyou, ZHOU Xiaoliang
		To better evaluate the dynamic characteristics of threshing device of corn harvester and reduce the R & D cost, a design method was proposed based on virtual prototyping technology. A new scheme was designed for threshing device, and the relevant parameters of the threshing drum， transmission element and other key components were determined. Based on SolidWorks and ADAMS, the virtual prototype model of threshing device was established. According to the actual working conditions, the driving and load functions were added to carry out the simulation analysis. The simulation results show that the impact of load force and torque has little influence on the speed of input pulley. The speed response of output threshing roller is fast with stable system and high transmission efficiency， and the dynamic balance is fully meet the requirements of the standard. The simulation model is verified with high accuracy and reliability through the real vehicle test, which provides a reference for the digital design and optimization of the threshing drum of corn harvester.
		2022 Vol. 43 (3): 282-288 [Abstract] ( 36 ) [HTML 1KB] [ PDF 3243KB] ( 337 )

	289	Center line extraction of paddy seedling row based on segmented vertical projection
		CHEN Yusong， GENG Changxing， WANG Yong， ZHU Guofeng
		To extract the center line of paddy seedling row, an algorithm was proposed based on segmented vertical projection. The binary color image after preprocessing was divided into three sections of lower， middle and upper in the longitudinal direction. From the lower section， the vertical projection method was used to determine the edge around the crop row.The feature points between the left and right edges were extracted to fit a temporary line, and the intersection position of the line and the top of the section was used to determine the edge points belonging to the same crop row in the middle section.The same method was used in the upper section of the image, and all of the feature points were extracted into different sets of points according to different crop rows. The least square method was used to fit each point in the point set representing the crop row. The experimental results show that in the 1 280×1 024 pixel scolor image,the accuracy of the proposed method is 9450%， and the average time of each frame is 208 ms.
		2022 Vol. 43 (3): 289-295 [Abstract] ( 48 ) [HTML 1KB] [ PDF 49180KB] ( 319 )

	296	Extraction method of small agricultural AGV navigation baseline based on crop row characteristics
		LIU Hao, GONG Jinliang, ZHANG Yanfei
		To solve the problem that agricultural robots based on visual navigation were easily disturbed by weeds and lack of seedlings during the navigation baseline extraction process， a method was proposed to quickly and accurately extract the center line of corn row as navigation baseline of the small agricultural AGV under the field environment of corn in 35 leaf stage. The ultragreen gray method and Otsu method were used to achieve realtime acquisition of crop information. The characteristics of crop row length, pixels and direction were simulated by parallelograms to achieve preliminary positioning of crop row positions. The shape feature of crop row in the image was simulated by trapezoid, which was narrow and wide at the bottom to achieve the final positioning of the crop row position. According to the statistical characteristics of Hough transform， the crop line detection was realized. The angle deviation comparison between the current frame navigation baseline and the previous frame navigation baseline was conducted without comparing the first frame image, and the deviation beyond a certain range should inherit the previous frame navigation baseline line. The test data shows that it takes average time of 78 ms to process a frame of 640×480 pixels, and the accuracy of the navigation baseline extraction is about 94%.
		2022 Vol. 43 (3): 296-301 [Abstract] ( 51 ) [HTML 1KB] [ PDF 11707KB] ( 326 )

	302	An improved interframe differential target detection and tracking algorithm based on multi-region information fusion constraints
		GONG Jinliang, CHEN Tao, ZHANG Yanfei, LAN Yubin
		To solve the problem of frame difference method with rough target detail recognition, an improved target detection and tracking algorithm was proposed, and a detection method combining twotime region restriction algorithm and Kalman filtering algorithm was constructed. The dynamic region of interest (ROI) was obtained by the proposed grid partitioning algorithm, and the lane line region was identified only within the salience range of the road. According to the lane line area information and with the established road area mask as evaluation index of the frame difference method, the processing accuracy of the algorithm was improved. An extended Otsu algorithm was adopted to solve the problem of effectiveness of target extraction performance with frame difference method by adaptive dynamic threshold. With the detected centroid coordinates of target as observation quantity, the target trajectory was tracked and predicted through Kalman filter. Halcon vision software platform was used to verify the performance of the proposed algorithm. The results show that the average processing time of the proposed algorithm is 32.132 ms, which can meet the realtime requirements. The average accuracy of lane line detection is more than 95%. The proposed algorithm can quickly and accurately extract the lane area and identify the target position in the environment.
		2022 Vol. 43 (3): 302-309 [Abstract] ( 47 ) [HTML 1KB] [ PDF 2933KB] ( 381 )

	310	Multi-label text classification based on graph embedding and region attention
		WANG Jin, XU Wei, DING Yi, SUN Kaiwei, WANG Lilei
		The traditional multilabel text classification method tends to ignore the correlations between labels and the correlations between labels and texts, and low frequency labels are not predicted well. To solve the problems, graph embedding technique and region attention mechanism were used to mine the correlation between labels. The encodergraph embedding and the region attentiondecoder were proposed to tackle the multilabel text classification. BiLSTM was used as encoder, and the label embedding matrix was generated by the graph embedding technique. The tokenlevel and regionlevel information were combined by the regional attention mechanism to consider the information of different parts of the text during generating each label, which could potentially extract the association between text and label. Recurrent neural network (RNN) and multilayer perception (MLP) were used as decoders and combined with stochastic gradient method to improve multilabel classification. The experiments were carried out on AAPD dataset and RCV1V2 dataset, and the relevant parameters were set according to the characteristics of the datasets. The microF1 and Hamming Loss were used as evaluation indexes to compare the proposed method with some classic ones, such as LP and CNN. The results show that the proposed method can predict the low frequency labels according to the higher ones, and it has higher microF1 and lower Hamming Loss than those by classical methods.
		2022 Vol. 43 (3): 310-318 [Abstract] ( 49 ) [HTML 1KB] [ PDF 1324KB] ( 451 )

	319	Short-term load forecasting method based on cuckoo search algorithm and support vector machine considering demand price elasticity
		SU Juan, FANG Shu, XING Guangjin, DU Songhuai, SHAN Baoguo
		To solve the problems that electricity demand was affected by multiple disturbance factors in the electricity market, and the price elasticity of demand was increased, for obtaining more accurate and comprehensive power load forecast value, the cuckoo search algorithm and support vector machine (CSSVM) shortterm load forecasting method was proposed with considering demand price elasticity. The Pearson correlation coefficient method was used to analyze the load autocorrelation and the correlation among load and historical load temperature, humidity, electricity price, load difference and electricity price difference. Based on the definition of demand price elasticity, a demand price elasticity model was established to reflect the impact of electricity market transactions on load. The cuckoo search algorithm was used to optimize the parameters of support vector machine, and the CSSVM shortterm load forecasting model was established with considering the price elasticity of demand. The actual data of a certain state in the PJM power market in the United States was taken as example to conduct the prediction, and the prediction error was compared with that of comparison model. The results show that the average relative percentage error of the proposed model is 13.43%, and the prediction accuracy is improved by 5.31% compared with that of the model without introduction of demand price elasticity.
		2022 Vol. 43 (3): 319-324 [Abstract] ( 41 ) [HTML 1KB] [ PDF 1578KB] ( 392 )

	325	Power distribution strategy and PI parameter regulation of hybrid microgrid
		REN Peng, LI Chunlan, WANG Changyun, WANG Xiaoxuan, WANG Jing
		To solve the problems of complex power allocation strategy and difficult parameter setting of PI controller in hybrid microgrid, the power coordinated distribution strategy and the PI parameter setting method were proposed based on hybrid energy storage state of charge. The state of charge of super capacitor and the reference power of storage battery were regarded as control objectives, and the fluctuating power in the network was coordinated and distributed. The corresponding current reference value was obtained according to the distributed power. According to the ideal phase angle margin of industrial control, the PI controller was automatically optimized by Siso feedback technology to adjust the deviation between the actual value and the reference value. According to the topology of hybrid microgrid, the power coordinated distribution strategy was determined based on the state of charge of super capacitor. The relevant hybrid microgrid power distribution and the charge discharge control block diagram were constructed, and the parameters of PI controller was adjusted by Siso feedback technology. The windsolarstorage hybrid microgrid model was built on the MATLAB/Simulink simulation platform for simulation. The dynamic response of each module of the system was analyzed, and the power distribution strategies were compared. The results show that the proposed control strategy can effectively distribute the fluctuating power, smooth the instantaneous output of the battery and reduce the switching times of charge and discharge, and the dynamic recovery time is shortened with ensuring the voltage fluctuation of DC bus less than or equal to 5%.
		2022 Vol. 43 (3): 325-331 [Abstract] ( 53 ) [HTML 1KB] [ PDF 2896KB] ( 451 )

	332	Tribology and corrosion properties of HVOF-sprayed WC coatings on surface of screw pump rotor
		GUO Huafeng, ZHU Congcong, ZHAO Enlan， YU Ping， LIU Lei， LI Longhai, YANG Haifeng
		The WC-12Co and WC10Co4Cr coatings were deposited on the surface of screw pump rotor substrate (45 steel) by high velocity oxygen fuel (HVOF) technology. The micromorphology, porosity, phase structure and Vickers hardness of the coatings were characterized by SEM, EDS, XRD and microhardness tester. The wear and corrosion mechanisms of the coating were discussed based on friction and wear test and electrochemical test. The results show that the microstructure of WC12Co coating and WC10Co4Cr coating is compact, and the porosity values are 0.58% and 0.48%,respectively. The average Vickers hardness values are respective 1 38587 HV03 and 1 26862 HV03, and the wear mass loss are 19.5% and 21.8% of the substrate, respectively. The wear resistance of WC12Co coating is better. The wear mechanisms of the two coatings are mild abrasive wear, while the substrate is dominated by abrasive wear and supplemented by adhesive wear. The corrosion current densities of WC12Co coating and WC10Co4Cr coating are 21.1% and 128% of that of the substrate, respectively. The passivation film formed by Cr oxide makes the WC10Co4Cr coating have good corrosion resistance. Microgalvanic corrosion occurs between WC and metal bonded phase in both coatings, leading to the dissolution of bonded phase and shedding of some WC particles, and the corrosion products can protect the coating.
		2022 Vol. 43 (3): 332-340 [Abstract] ( 32 ) [HTML 1KB] [ PDF 33126KB] ( 361 )

	341	Preparation and electrochemical performance of Ni3S4 nanorods by thermal injection method
		MA Jun, SYED Junaid Ali, SU Dongyun, CHU Yan, MENG Xiangkang
		To solve the problem that the specific capacitance of the electrode was decreased rapidly after running for a period of time, the Ni3S4 nanorods with excellent electrochemical performance and with size of about 100 nm were synthesized by thermal injection method. The results show that the preparation of small nanomaterials as electrode material of supercapacitor is conducive to the rapid infiltration of electrolyte during the reaction process, and the electrochemical performance can be further improved. The prepared Ni3S4 nanorods can work stably in the voltage range from 0 to 055 V. When the current density is 1 A·g-1, the specific capacity reaches 1 097 F·g-1. When the current density is 20 A·g-1, the specific capacity still remains about 740 F·g-1. The retention rate of the material can reach 91% when it is tested for 10 000 cycles at 10 A·g-1.
		2022 Vol. 43 (3): 341-345 [Abstract] ( 32 ) [HTML 1KB] [ PDF 6583KB] ( 439 )

	346	Effect of temperature on compression and permeability of RAP fills
		ZHU Desheng, LIU Kaixuan, YIN Jie, ZHANG Jingyu, TANG Yong
		Recycled asphalt pavement (RAP) material formed by regeneration of waste asphalt pavement can be used as embankment fill with temperature sensitivity and viscosity because of the asphalt composition. The effects of temperature on compression and permeability characteristics and the mechanism were investigated by compression tests and permeability tests of RAP samples at different temperatures. The test results show that under the same compaction effort, the compression curve of sample with higher test temperature is below that with lower temperature, which indicates that the sample is easy to be compressed at higher temperature. The compression modulus of RAP sample is decreased gradually with the increasing of temperature, and the compressibility is increased gradually. At the same temperature, the variations of compressibility and the compression modulus for RAP samples under higher compaction effort are relatively small. The permeability coefficient of RAP sample is increased with the increasing of test temperature, and the permeability is comparable to that of gravel as fill. Considering that the compressibility and permeability of RAP materials are increased with the increasing of test temperature, the construction of embankment with RAP fill in the summertime is recommended to obtain better compression and permeability.
		2022 Vol. 43 (3): 346-350 [Abstract] ( 45 ) [HTML 1KB] [ PDF 1811KB] ( 413 )

	351	Micro-mechanical simulation of shear properties of rubber-sand mixtures
		ZHOU Enquan, ZHANG Jianghao, LU Jianfei
		To investigate the micromechanical of shear properties of rubbersand mixtures, the direct shear test of rubbersand mixtures was numerically simulated by PFC3D discrete element program. The effects of vertical normal stress and rubber content on the macro and micro mechanical behaviors of rubbersand mixtures were analyzed. The results show that the shear strength characteristics of pure sand are significantly improved by adding rubber particles. The shear stressshear displacement curve of rubbersand mixtures shows strainhardening characteristic, and the shear strength is increased with the increasing of vertical normal stress. The addition of rubber particles leads to the increasing of coordination number, strong force chain number and total force chain number, which leads to the formation of more stable force chain system. When the vertical normal stress is 200 kPa, the coordination number, the strong force chain number and the total force chain number of rubber sand mixed with 15% rubber particles are respectively increased by 361%, 253% and 277% compared with those of pure sand. Compared with pure sand, the addition of rubber particles inhibits particle rotation, while that has slight effect on the normal contact force and tangential contact force between particles.
		2022 Vol. 43 (3): 351-358 [Abstract] ( 38 ) [HTML 1KB] [ PDF 4276KB] ( 332 )

	359	Monitoring of crack depth and location of concrete beam based on piezoelectric wave method
		XIONG Fei, SU Bo, WANG Gang
		To investigate the influence of crack depth and position of concrete beams on the driving and receiving effect of piezoelectric ceramics, ABAQUS software was used to simulate the output signals of healthy concrete beam model under different excitation sources. To determine the optimal excitation frequency and optimize the characteristics of piezoelectric sheet of shape, size and thickness, the output signals of healthy concrete beam model and damaged concrete beam models with cracks in different depths and positions were simulated and analyzed. The piezoelectric wave test was carried out to monitor the damaged and healthy concrete beam models. The results show that the output signal strength and wavelet packet energy are decreased with the increasing of crack depth. The closer the distance between penetrating crack and transmitting sensor is, the stronger the signal displayed by the sensor at the receiving end is. On the contrary, the farther the distance is, the larger the signal attenuation becomes.
		2022 Vol. 43 (3): 359-365 [Abstract] ( 26 ) [HTML 1KB] [ PDF 7660KB] ( 350 )

	366	Stability and reinforcement measures of fine-grained soil tailings pond under seepage condition
		LUO Changtai, LI Dongwei, WU Xia
		Dam failure is easy to occur in the finegrained soil tailings under seepage conditions. On the basis of Lengkengchong tailings reservoir in Xingan County, the equivalent elastic modulus and the lateral pressure coefficient of dam slope were obtained by BMP90 displacement back analysis program. The Midas GTS NX numerical simulation software was used to calculate the stability of dam slope and the influence of saturation line on dam stability under flood conditions. Through onsite monitoring and measuring, the various seepage drainage and reinforcement effects were compared and analyzed. The results show that under the existing geological conditions, the minimum safety factor of dam slope is 1125 0, which is less than the code value of 1315 and needs reinforcement treatment. Under seepage condition, the safety factor in flood period is decreased from 1012 5 under normal head to 0938 2, which indicates that the increasing of saturation line leads to the instability of dam body. Radiation well is suitable for drainage and reinforcement of finegrained soil tailings pond. After reinforcement, the infiltration line is effectively reduced, and the safety factor is increased to 1323 4, which meets the safety requirements.
		2022 Vol. 43 (3): 366-372 [Abstract] ( 35 ) [HTML 1KB] [ PDF 4643KB] ( 390 )

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