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Journal of Jiangsu University(Natural Science Eidtion)

	2022 Vol.43 Issue.4 Published 2022-07-10

	373	Identification of adhesion coefficient ahead based on image feature and HMM
		YUAN Chaochun， ZHANG Haifeng， HE Youguo， JIE Shen,CHEN Long
		To identify the road adhesion coefficient ahead, the grayscale co-occurrence matrix and HSV color space were used to extract the seven texture feature parameters of typical road images. Based on the similarity characteristics, the Burckhardt μ-s model was improved, and a realtime estimation algorithm of the current road peak adhesion coefficient was proposed. The effectiveness and realtime performance were verified by Carsim and Simulink cosimulation. A roadtire adhesion characteristic model was established based on hidden Markov model(HMM), and the correctness of the model was verified. The HMM model algorithm was verified through real vehicle experiments. The results show that the recognition rate of HMM model is more than 90% for the roadtire adhesion coefficient ahead, and the proposed model can be used in the automatic emergency braking module of smart cars. The vehicle can brake in advance under the front harsh road environment, which effectively shortens the braking distance.
		2022 Vol. 43 (4): 373-380 [Abstract] ( 25 ) [HTML 1KB] [ PDF 2405KB] ( 362 )

	381	Carfollowing model of intelligent and connected vehicle considering variable headway
		QIN Yanyan, YANG Jinying, LI Shuqing
		To solve the car-following problem of intelligent and connected vehicle (ICV), a car-following model of ICV was proposed, and the model properties were analyzed. Considering the carfollowing property of variable headway, the ICV car-following model was proposed to maintain simple model structure and clear physical meaning of model parameters. Based on the function of spacing and speed at equilibrium state, the flow-density function curve of the proposed ICV car-following model was calculated. The mechanism of improving traffic capacity by the proposed ICV car-following model was also analyzed. From the perspective of microcosmic kinematics, the stability criterion of the proposed ICV car-following model was theoretically derived. The results show that according to the proposed ICV car-following model, the maximum capacity can be obtained with the density of 66.887 2 car·km^-1 and the speed of 63.576 0 km·h^-1. The model stability criterion is related with traffic flow speed and can be stable at any speed, which shows that the model has good model stability condition.
		2022 Vol. 43 (4): 381-385 [Abstract] ( 19 ) [HTML 1KB] [ PDF 1342KB] ( 558 )

	386	Path tracking of 4WIS autonomous vehicle based on double-layer control strategy
		LI Yuhao， ZHAO Youqun
		To improve the system stability and tracking accuracy of the four-wheel independent steering(4WIS) unmanned vehicle during path tracking and improve the tire wear, the path tracking control algorithm was proposed based on double-layer control strategy. The upper layer was a model reference adaptive path tracking controller based on Popov hyperstability theory. Based on the two-degree-of-freedom model, the path tracking error state equation was derived. The linear quadratic optimal method was used to solve the problem that the positive linear link of the system was not strictly positive reality. The Popov integral inequality was solved to ensure the hyperstability of system. In the lower layer controller, based on Ackermann steering theorem, the angle allocation control algorithm was designed with considering tire sideslip. The simulation experiment was carried out on the CarSim/Simulink co-simulation platform. The results show that the designed path tracking controller based on double-layer control strategy can realize the path tracking task with high precision and ensure the driving stability of 4WIS unmanned vehicle to improve the tire wear.
		2022 Vol. 43 (4): 386-393 [Abstract] ( 31 ) [HTML 1KB] [ PDF 1547KB] ( 343 )

	394	Longitudinal following control of intelligent vehicle fleet based on fuzzy MPC
		LEI Lili， ZHANG Tong
		To solve the problems of low efficiency and unstable system in the traditional control, a longitudinal following model of the intelligent vehicle fleet was proposed based on the fuzzy model predictive control (MPC) method. According to the longitudinal following model of the fleet, the objective function of MPC including following performance and riding comfort was derived, and the fuzzy strategy was introduced based on the MPC controller. The followability weight coefficient in the MPC objective function was adjusted in real time, and the ideal acceleration was outputted to meet the needs of the driving scene. The lower-level controller was established by combining the longitudinal inverse dynamics model and PID control to convert the expected acceleration into throttle opening or brake pressure. The joint simulation platform of Carsim and Simulink was established to simulate the high-speed driving conditions of the intelligent vehicle fleet, and the simulation result was compared with those of PID method and traditional MPC method, respectively. The results show that the dynamic parameters of the fuzzy MPC controller under highspeed conditions can meet the constraints with the distance error less than 8 m. Compared with PID control and traditional MPC control, the maximum speed error is reduced by 6.6 and 2.5 m·s^-1， respectively. In the emergency braking scenario, the speed change is more stable, and the riding comfort of the vehicle fleet is improved.
		2022 Vol. 43 (4): 394-399 [Abstract] ( 39 ) [HTML 1KB] [ PDF 3477KB] ( 453 )

	400	Pedestrian trajectory and intention estimation under low brightness based on human key points
		WANG Wei， LUO Shi， GENG Guoqing， LIU Jun
		The driving environment at night is more complex than that during the day, so the perception of the driving environment at night by the assistant driving system is very important. For pedestrian recognition, the traditional pedestrian trajectory and intention estimation algorithm is not suitable at night. To estimate pedestrian intention and trajectory at night, a method was proposed for estimating pedestrian intention and trajectory in short distance under low brightness environment. The new image enhancement algorithm was used to improve the face recognition rate. For the enhanced image, the matching algorithm was proposed based on YOLOv3 and Openpose. The Kalman filter was used to correct the YOLOv3 recognition error, and a pedestrian face orientation estimation algorithm was proposed based on the matching results to obtain a new method for estimating pedestrian intention. The results show that the proposed pedestrian trajectory and intention estimation method is suitable for low luminance environment after image enhancement.
		2022 Vol. 43 (4): 400-406 [Abstract] ( 23 ) [HTML 1KB] [ PDF 16023KB] ( 423 )

	407	Ride comfort and road friendliness analysis of ISD suspension for heavy vehicles under variable vehicle mass
		YAN Long, YANG Xiaofeng, SHEN Yujie, HE Tao, LIU Yanling
		To solve the problems of heavy vehicle with load variation and road damage, the heavy vehicle passive suspension halfcar model and the heavy vehicle inerter-spring-damper (ISD) suspension halfcar model were established respectively. The heavy vehicle ISD suspension component parameters were optimized by the improved ant colony algorithm. According to time domain and frequency domain, the action mechanism of heavy vehicle ride comfort and road friendliness under the condition of variable vehicle mass was simulated and analyzed. The results show that compared with the traditional passive suspension, ISD suspension of heavy vehicle can greatly reduce the body acceleration, suspension working space and dynamic tire load. The root mean square value of centroid acceleration is improved by 15.08%, and the road damage coefficient is decreased uniformly and significantly in the range of full spring load rate with the root mean square value improved by 14.21%. ISD suspension of heavy vehicle has certain advantages for the comprehensive and coordinated improvement of ride comfort and road friendliness.
		2022 Vol. 43 (4): 407-415 [Abstract] ( 44 ) [HTML 1KB] [ PDF 5442KB] ( 550 )

	416	Development and test of high-speed aerosol disinfection machine by deep rotary tillage method
		GAO Jianmin, AI Anjun, LIU Xingda, ZHANG Bozhao
		To overcome the influence of soil bacteria on crop growth, the combined operation method of deep rotary tillage and soil disinfection was put forward, and the prototype was developed and manufactured. The transmission system of the machine was designed. Bevel gears were used for reversing transmission, and seven cylindrical spur gears were arranged in herringbone shape with included angle of 15° to the horizontal. For the design of disinfection structure, the medicine tube was connected from the top of hollow knife shaft, and the medicine night was diffused to the deep soil layer by the rotation of knife shaft. The surface spraying rod was provided for applying medicine on the soil surface. To solve the problems of high power consumption and traction resistance of deep rotary tillage, the mixed factors and mixed horizontal uniform design table of U8(82×42) and LS-DYNA were selected to carry out virtual simulation test on the soil cutting process of vertical rotary tillage with single cutter. The rotating speed of cutter was taken with 8 values at intervals of 100 r·min^-1 from 100 r·min^-1, and the moving speed was taken with 8 values at intervals of 0.1 m·s^-1 from 0.1 m·s^-1. The blades were curved, rectangular, triangular and twisted shapes, respectively. The arrangement of rotary tillage blades was four pairs of adjacent blades with helical angles of 90° and 60°, and three pairs of adjacent blades with helical angles of 90° and 60°, which were four levels in total. According to the results of virtual simulation test, the data of cutter roller running resistance and cutter roller cutting torque are obtained. When the curved rotary blades are selected for the arrangement of three pairs of rotary blades with the helix angle of two adjacent blades on the same helix of 90°, the cutting torque of the cutter roller is the smallest, and the movement speed of the cutter roller has little influence on the torque. The field test results show that the maximum tillage depth of the prototype is 320 mm with the stability coefficient of tillage depth of 94.484% and the uniformity of disinfection of 92.554%, while the uniformity of traditional artificial surface application is only 72.546%. The proposed prototype can meet the requirements of deep tillage and disinfection of soil.
		2022 Vol. 43 (4): 416-423 [Abstract] ( 38 ) [HTML 1KB] [ PDF 5160KB] ( 330 )

	424	Effect of AC electric field on separation of biodiesel and glycerin
		WANG Junfeng， LU Shuaiquan， FAN Zhiheng, WANG Dongbao
		The high-voltage AC electric field was used to promote the separation of soybean oil-methanol transesterification product biodiesel and glycerin. The effects of electric field strength, alcohol-to-oil molar ratio and catalyst on the sedimentation rate of glycerin droplets were explored, and the physical properties of biodiesel and byproduct glycerin prepared under different transesterification conditions were measured. The results show that the high-voltage AC electric field can effectively improve the separation efficiency of biodiesel and glycerin. GC-MS test results show that high-strength electric fields has no effect on the quality of biodiesel. In the electric field formed by spiral electrode, the coalescence efficiency of glycerin reaches the maximum when the electric field strength of E′ is 175 V·mm^-1. Different molar ratios of alcohol and oil can cause differences in the physical properties of the by-product glycerin and have little effect on the sedimentation rate of glycerin droplets. The increase of alkaline catalyst content can promote the sedimentation of glycerin, and the sedimentation efficiency of glycerin under the action of potassium hydroxide is increased.
		2022 Vol. 43 (4): 424-430 [Abstract] ( 31 ) [HTML 1KB] [ PDF 2371KB] ( 389 )

	431	Simulation on NO_x emission of SCR system with PODE/methanol blend fuel
		JI Qian, ZHAO Lian, TAN Bingqian, LIU Junheng, WEI Mingliang
		To control the NO_x emission of polyoxymethylene dimethyl ethers (PODE)/methanol blend fuel, the simulation model of selective catalytic reduction (SCR) system was established based on Converge software, and the influence of SCR system on the NO_x emission of PODE/methanol blend fuel was investigated by numerical simulation. The results show that with the increasing of n(NH₃)/n(NO_x), NH₃ distribution uniformity, velocity distribution uniformity and NO_x conversion efficiency of SCR system are increased firstly with latter decreasing, while the leakage of NH₃ is increased gradually. When the n(NH₃)/n(NO_x) is 1.3, the γ_NH3reaches the highest value of 0.988 with the maximum μ_ν value of 0.983 and the NO_xconversion efficiency of 81.4%. Mixers can effectively improve the performance of SCR system. According to the optimization of SCR mixer by orthogonal experiment, the optimal scheme is obtained with the mixer blade number of 16, the blade inclination of 30° and the blade width of 16 mm, and the optimization scheme is verified by bench test. The NO_x conversion efficiency of the optimized SCR system is 75.4% ，and the leakage of NH₃ is reduced by 9.6×10^-7 for the diesel engine at 1 800 r·min^-1 and 100% load.
		2022 Vol. 43 (4): 431-438 [Abstract] ( 28 ) [HTML 1KB] [ PDF 3624KB] ( 457 )

	439	Detection method and analysis of trajectory of horizontal pulled gate head based on point laser
		WANG Huaming, ZHOU Kaiqiang, QIANG Bin, MA Dongming, ZHANG Henghong
		To analyze the trajectory change of the gate head caused by the running wear of trolley at the bottom of horizontal pulled gate, a method for detecting the trajectory of gate head of the horizontal pulled gate was proposed based on the point laser. The laser spot area in the preprocessed image was segmented by threshold segmentation and hole filling method. The Canny edge detection and sub-pixel edge extraction algorithm based on Zernike moment were used to calculate the sub-pixel edge of spot area, and the spot center coordinate was obtained by calculating the spot centroid. The mean value of the data in the same time interval was calculated, and the trend of the trajectory was analyzed by linear regression analysis. The results show that the proposed method can truthfully obtain and record the track coordinate data of the horizontal pulled gate head, and the linear regression model of the gate head trajectory can be calculated to analyze the wear condition and wear law of the key components of the bottom trolley for the horizontal pulled gate.
		2022 Vol. 43 (4): 439-445 [Abstract] ( 16 ) [HTML 1KB] [ PDF 3353KB] ( 353 )

	446	Named entity recognition of LSTM based on hierarchical residual connection
		WANG Jin, LI Ying, JIANG Xiaocui, LYU Xiaoxu, XIAO Huangqing
		To solve the problem of the existing LSTM extracted feature vectors in named entity recognition tasks with insufficient ability for expressing shortterm information features, the LSTM network was proposed based on hierarchical residual connections. The nonlinear fitting capability of shortterm information features was improved by adding residual blocks to stack the LSTM network depth. The activation function was dynamically selected by global information encoding to reduce the number of parameters during enhancing the computational power of network. The model fitting capability was improved by dynamically adjusting the number of layers of residual connections to the input through attention mechanism. The residual network and Dynamic ReLU activation function were given, and the overall framework of LSTM named entity recognition was established based on hierarchical residual connections. The residual connection module, the Dynamic ReLU module and the attention mechanism module were defined. The proposed method was compared with related algorithms of FLAT and Lattice LSTM, and the experiments were conducted on Weibo and Resume dataset. The results show that the LSTM based on hierarchical residual connectivity achieves the best effect on the Weibo corpus and is second only to FLAT on the Resume corpus with F₁ of 0.700 1 and 0.958 6, respectively.
		2022 Vol. 43 (4): 446-452 [Abstract] ( 29 ) [HTML 1KB] [ PDF 1451KB] ( 477 )

	453	Application of fuzzy clustering analysis in classification and selection of coarse aggregate
		YUE Guanghua, TENG Li, ZHOU Wenbo, LIU Ning, HAO Jiaping
		To overcome the problem of paying attention to a certain index and neglecting the overall performance during selecting aggregates for a new highway, and to avoid the lack of scientificity due to too subjective classification evaluation of aggregates, the fuzzy cluster analysis was applied in the classification and selection of coarse aggregates. The basic principle and calculation steps of fuzzy clustering analysis method were given. Nine coarse aggregates produced by nine crushing plants along a new highway in Gansu were selected. The physical and mechanical properties of the course aggregate were tested. The fuzzy clustering analysis method was used to standardize with 9 technical properties of the course aggregates as original data, and the fuzzy similarity matrix was established to calculate the transitive closure for clustering. The effectiveness and reliability of the classification results were tested by F-statistic and experience method. The results show that the fuzzy clustering analysis method is applicable to the classification of coarse aggregate, and the method can provide reference for the selection of coarse aggregate before the highway road construction.
		2022 Vol. 43 (4): 453-457 [Abstract] ( 27 ) [HTML 1KB] [ PDF 1098KB] ( 340 )

	458	Grid-connected control strategy of virtual synchronous generator based on virtual power
		WU Dandan， GE Qiang， XU Jin， XU Xiaofan， QIU Baoyun
		To improve the connection efficiency to grid of distributed power sources, and solve the problems of insufficient damping and inertia in inverter grid connection, an inverter control method was investigated to realize traditional synchronous generator′s function, which was named as virtual synchronous generator (VSG) technology. Based on the role of phase locked loop (PLL) in virtual synchronous generator, the pre-synchronization control method was proposed based on virtual power. The secondary frequency modulation and the secondary voltage regulation functions were simulated in the power loop. The output value compensated the loss of active power and reactive power through inertia link, and the control parameters were flexibly adjusted according to power levels. Regarding the voltage and current on the VSG generator side, the PR control method was used to increase the constraint on the electrical value for preventing grid connection failure. The topology structure and the mathematical model of VSG were analyzed, and the improved control method of VSG was given. A corresponding simulation model was established to verify VSG control effect from two aspects of presynchronous grid-connection and grid connection stability under mutation load. The results show that the improved VSG control can reduce the complexity of grid-connected inverter and the oscillation frequency of output power and suppress the current impact on the grid side, which makes the inverter follow the dynamic change process of power grid at all time.
		2022 Vol. 43 (4): 458-463 [Abstract] ( 33 ) [HTML 1KB] [ PDF 2260KB] ( 462 )

	464	Flow characteristics of viscous oil in rotor cavity of cam pump
		LI Yibin, BAI Changxiu, QIAO Huili, YANG Yuemin
		To investigate the effects of viscosity, differential pressure and speed on the performance of cam pump, and analyze the change law of flow rate and excitation force, under different viscosity, differential pressure and speed, the three-dimensional transient numerical calculation of the flow field of cam pump was carried out and verified by experiments. The results show that with the increasing of viscosity from 1.8×10^-5 m²·s^-1to 2.2×10^-4 m²·s^-1, the outlet flow rate is increased from 16.856 m³·h^-1 to 20.736 m³·h^-1, and the outlet flow pulsation becomes stable with increased volume efficiency and widened high-speed zone of inlet and outlet. When the differential pressure is increased from 0.1 MPa to 0.6 MPa, the outlet flow rate and volume efficiency are decreased, while the outlet flow pulsation is basically consistent. The maximum absolute value of the force in x direction is increased from 514.04 N to 1 893.37 N, and the maximum value of the force in y direction is increased from 1 709.17 N to 8 855.57 N. When the speed is increased from 100 r·min^-1to 300 r·min^-1, the flow rate and volume efficiency at the outlet are increased, and the average pressure at the outlet is increased from 400.552 kPa to 405.117 kPa, while the outlet flow pulsation and pressure pulsation are increased. The maximum absolute value of the force in x direction is increased from 1 211.17 N to 1 513.11 N, and the maximum value of the force in y direction is increased from 5 810.77 N to 6 276.51 N.
		2022 Vol. 43 (4): 464-471 [Abstract] ( 20 ) [HTML 1KB] [ PDF 5322KB] ( 320 )

	472	Design and jet impingement characteristics of downhole self-excited pulsed jet energyenhancing device
		AIBAIBU·Abulimiti, PANG Dexin, LIU Yonghong, MAIERYEMUGULI·Anwaier, SUN Changyou, GUO Xinwei, CHEN Bo
		Combined with the principle of eddy current energy steering impact and feedback channel forced steering, the wall attachment effect was used to develop a new type of downhole selfexcited pulsed jet energyenhancing device. The structure parameters of the device were numerically simulated by the control variable method, and the pulsation characteristics of the pulsed jet for different structures and operating parameters were analyzed. A prototype was fabricated and tested in the laboratory. The research results show that when the ratio of inlet to outlet diameter is 0.71-1.18, the pulse effect is good. With the increasing of ratio of inlet to outlet diameter, the pulse frequency shows increasing trend, and the pulsating pressure amplitude shows downward trend with the maximum pressure amplitude of 10.20 MPa. With the increasing of spray distance of manifold, the pulse frequency is increased firstly with latter decreasing, while the pulsating pressure amplitude is decreased firstly with latter increasing. With the increasing of feedback channel crosssection ratio, the pulse frequency is gradually increased, while the pressure amplitude remains basically unchanged. The diameter change of the eddy current commutation circle has little effect on pulse frequency and pulsating pressure amplitude. The pulse frequency is increased with the increasing of Reynolds number of incoming flow. When Reynolds number is greater than 3.56×10⁵, the frequency basically no longer increases. The amplitude of pulsating pressure is increased with the increasing of Reynolds number of incoming flow.
		2022 Vol. 43 (4): 472-480 [Abstract] ( 36 ) [HTML 1KB] [ PDF 4763KB] ( 330 )

	481	Periodic emission of droplets in electrostatic atomization
		JIANG Yimin, WANG Zhentao, XIA Lei
		The visual study of the electrostatic atomization modes of anhydrous ethanol and deionized water passing through metal single capillary was carried out by the highspeed camera with micro zoom lens. The typical electrostatic atomization modes of the single capillary and the law of droplet generation were explored. Changing the applied voltage and liquid flow rate, the release frequency characteristics of droplets under different atomization modes were discussed, and the variation law of droplet release frequency under different flow rates was investigated to obtain the relationship of release period characteristics with applied voltage and flow rates of droplets in discontinuous jet mode. The results indicate that the release frequency of droplets from the end of the capillary is increased with the increasing of applied voltage. There is a sudden increase in the droplet release frequency, and the induced voltage threshold values of anhydrous ethanol and deionized water are 3.0 kV and 5.0 kV, respectively. The sudden increase in release frequency varies from a few Hz to hundreds of Hz rapidly. By comparing the periodic characteristics of anhydrous ethanol and deionized water, it is found that the surface tension and conductivity of the liquids significantly affect the release frequency. The prediction formula for the maximum release frequency by theoretical analysis is proposed, and the prediction results are basically consistent with the experiment results.
		2022 Vol. 43 (4): 481-487 [Abstract] ( 19 ) [HTML 1KB] [ PDF 2257KB] ( 331 )

	488	Measurement of soot spectral emission and error analysis based on counterflow flame
		LI Lei， WEN Daxin， WANG Yu
		The distribution of temperature and soot volume fraction in the ethylene counterflow diffusion flame was measured accurately based on soot spectral emission (SSE) method. To effectively reduce the measurement error of SSE method and improve the accuracy of experiment, the numerical simulation was used to quantitatively investigate the influence of multiple factors on the measurement of temperature and soot volume fraction in the counterflow flame. The research results show that the readout noise of the spectrometer causes serious distortion in the measurement of temperature and soot volume fraction in the low temperature zone. Ignoring the self-absorption effect, the soot volume fraction is overestimated, and the temperature is underestimated, while the use of longer wavelength radiation data can reduce the influence of ignoring the self-absorption to a certain extent. The radiant intensity calibration error caused by the calibration source temperature error only affects the temperature measurement accuracy, and the diaphragm aperture error only affects the measurement accuracy of the soot volume fraction. The uncertainty of soot absorption function is the main source of error in the measurement of temperature and soot volume fraction.
		2022 Vol. 43 (4): 488-496 [Abstract] ( 19 ) [HTML 1KB] [ PDF 3362KB] ( 347 )

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