Journal of Chongqing Jiaotong University(Natural Science)

Urban Traffic State Recognition Based on Genetic Algorithm Optimized Support Vector Machine

LI Qiaoru1,2, HAO Enqiang1, CHEN Liang1,2, FAN Zhongguo1, YANG Wenwei1

2020, 39(08): 1-5. DOI: 10.3969/j.issn.1674-0696.2020.08.01

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Urban traffic state recognition is the foundation of the intelligent traffic control, induction and coordination system. In order to improve the generalization ability of support vector machine in urban traffic state recognition, Genetic Algorithm (GA) and Support Vector Machine (SVM) were combined, and the key parameters of the support vector machine — the penalty coefficient C and the kernel function parameters σ were optimized by using the global search advantages of genetic algorithm. The urban traffic state recognition model based on genetic algorithm optimized support vector machine (GA-SVM) was established and verified by an example in MATLAB platform. The research results show that: compared with the SVM model, the GA-SVM model overcomes the shortcomings of determining the parameter method by means of experience, and the recognition accuracy is improved by 3.75%, that is to mean, the proposed model can better identify the urban traffic state.

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Specific Chromatogram Construction and Similarity Identification of Individual Travel of Public Transport Commuters

LIANG Quan1, WENG Jiancheng2, ZHOU Wei3, RONG Jian2

2020, 39(08): 6-13. DOI: 10.3969/j.issn.1674-0696.2020.08.02

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It is helpful to grasp the overall travel rules of public transport more accurately and better meet the travel needs of passengers to obtain the travel behavior characteristics of public transport commuters from the perspective of individuals. Based on the public transport card swiping data and line station data, by use of the representation advantage of graph visualization of public transport commuters, the travel graph construction method of public transport commuting trip was studied, which took the horizontal axis as the time series axis, the vertical axis as the position axis, and the node size as the direction angle. On this basis, the method of structure similarity combined with the longest common subsequence was used to realize the similarity identification of graph, which selected attribute indicators such as travel mode, direction, time and route. Taking the one-week public transport travel data of individual passengers as an example, the rationality and validity of the research results were verified. The research results can intuitively reflect the individual travel process, which provides a new idea for the expression and extraction of trip characteristics.

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Automatic Extraction and Analysis of Expressway Subsidence Based on Ground 3D Laser Scanning

ZHAO Lidu1, CHEN Bo2, LIU Guoqiang2, WU Yifei2, ZHOU Yin1, YANG Yupeng3, GUO Tong4, HAN Daguang1

2020, 39(08): 14-19. DOI: 10.3969/j.issn.1674-0696.2020.08.03

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The road surface settlement is the key to influence the safety of driving during the operation and maintenance of expressways. Conventional inspections are mostly based on leveling, which have the disadvantages of heavy workload, long cycle and easy to be affected by external conditions. An algorithm and analysis method for automatically identifying pavement subsidence by ground 3D laser scanning point cloud was proposed. In the proposed method, the point cloud was registered firstly based on the combination of geometric features and iterative closest point algorithm. After the registration data was classified and identified by point cloud, the road feature line was extracted based on the sliding window method and the pavement model of the expressway was established. By analyzing the proposed model, the indexes of subsidence area, location and depth were obtained. Finally, a highway at the operation and maintenance stage was adopted to verify the feasibility and accuracy of the proposed algorithm. Through the algorithm processing and the actual pavement model analysis, it is found that there is a settlement area with a depth of 40 cm at 45 m away from the starting point of the experimental section of the expressway. The analysis results show that the proposed algorithm of laser point cloud data processing and pavement model analysis can efficiently and accurately analyze the settlement of expressway pavement. The successful application of the proposed method is of great significance for the deep application and effective promotion of 3D laser scanning technology in the traffic field.

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Influence Analysis of Public Transport Controls against Novel Coronavirus Pneumonia(COVID-19) during Outbreak Period

JI-YANG Beibei, MO Shijie, CHENG Feng

2020, 39(08): 20-28. DOI: 10.3969/j.issn.1674-0696.2020.08.04

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Since January 2020, with Wuhan as the center, COVID-19 has shown explosive growth. Control measures have been quickly imposed, such as traffic control and home quarantine, in order to block the rapid spread of the epidemic, which has significant results. Based on the data collected from 56 cities in the early stage of the outbreak of the epidemic, including economic level, traffic control intensity, timeliness of traffic control and distance from the epidemic center, the relationship between different influencing factors and the largest cumulative number of confirmed cases was explored based on the canonical correlation analysis and mediation effect analysis.The results show that the most influential factor on the cumulative number of confirmed cases is economic level, followed by the relative distance, the timeliness of traffic control and the intensity of traffic control; among them, 35.21% of the impact of economic level on the cumulative number of confirmed cases is caused by the intermediary role of timeliness of traffic control;in addition,the intensity of traffic control has a significant moderating effect on the impact of the timeliness of control on the cumulative number of confirmed cases.

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Dynamic Traffic Flow Based on Bibliometrics

LIU Wei, LIU Chuan

2020, 39(08): 29-35. DOI: 10.3969/j.issn.1674-0696.2020.08.05

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Research on dynamic traffic flow is related to the development of intelligent transportation. In order to more systematically understand the status of dynamic traffic flow research in China, the relevant technology of bibliometrics and the literature analysis visualization software CiteSpace were used to analyze 146 core source journals, EI source journals and SCI source journals about dynamic traffic flow research collected by CNKI from 1990 to October 2018, respectively from the general trend of journal publication, journal source distribution, research institutions distribution, fund distribution and keyword co-occurrence network. The study finds that the research related to dynamic traffic flow has been increasing year by year since the 1990s, and has stabilized in recent years. The sources of journals are widely distributed, but the distribution is uneven. The research institutions are single, almost all of them are well-known universities in China, lacking other types of research units. There are many fund projects, but the coverage is not wide, most of them are national-level fund projects. The research models and application fields of dynamic traffic flow are mainly based on cell transmission model and intersection signal control. Generally speaking, the research on dynamic traffic flow in China has not formed a core research institution, and the research depth is not deep enough. Finally, it is suggested that researchers should study the deep learning algorithm more deeply and study the problems related to dynamic traffic flow from the aspect of intelligent model algorithm, so as to form a core research group and lay a solid foundation for ITS.

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Intersection Signal Control Based on Bus Priority and Comprehensive Approach Area

DENG Mingjun,CHEN Jia, YAO Yu

2020, 39(08): 36-44. DOI: 10.3969/j.issn.1674-0696.2020.08.06

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The priority development of urban public transport and innovative optimization of traffic organization and management are effective ways to solve the urban traffic problem. It is effective to improve the traffic capacity of the intersection without changing the original road facility conditions of the intersection by setting comprehensive approach area. Based on the methods of setting the comprehensive approach area and bus priority at intersections, the layout method and setting conditions of comprehensive approach area and bus priority at the entrance of intersection were discussed. And a traffic organization and signal control method at intersections based on bus priority and comprehensive approach area was proposed. And VISSIM micro-simulation software was used to verify an intersection in Nanchang. The research results show that: compared with the condition before optimization, setting the comprehensive approach area based on bus priority at the entrance of intersection reduces the average delay of social vehicles and significantly reduces the average delay of public transport at the same time.

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Reroute Planning for Parallel Route

WANG Lili, LIU Ziang

2020, 39(08): 45-50. DOI: 10.3969/j.issn.1674-0696.2020.08.07

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The current research on reroute planning is short of the analysis of spatial structure according to local conditions. In view of this, the corresponding reroute planning method was designed for parallel routes. Firstly, a new reroute planning method for single aircraft was designed by combining grid environment with dynamic programming method. Then, based on this method, in view of the problems that may be faced by the parallel route rerouting, after fully considering the flight safety and economy, the corresponding rerouting priority allocation mechanism was designed to solve these problems. Finally, taking the newly opened Chengdu-Lasa double line in Southwest China as an example, the simulation was carried out. The simulation results show that: compared with the reroute planning method based on geometric algorithm, the proposed method can reduce 5% flight mileage and 8% fuel consumption on the basis of ensuring flight safety. Therefore, the proposed method is a safe and economical reroute planning method for parallel routes.

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Deterioration of the Flexural Behavior of RC Beams Based on Accelerated Corrosion Experiments

SUN Ma, ZHOU Jianting, XU Lueqin, GAO Peng, YANG Shanqing

2020, 39(08): 51-58. DOI: 10.3969/j.issn.1674-0696.2020.08.08

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In order to effectively predict the deterioration rule of the flexural behavior of the corroded reinforced concrete beams (RC beams), the flexural behavior study on three groups of RC beams was conducted based on accelerated corrosion method. The influence of different longitudinal reinforcement corrosion rates on the failure mode, strain distribution and load deflection curve of RC beams was discussed. Based on the applicability evaluation of the existing theoretical models, combined with the time-varying material analysis model, an analysis method for the degradation rule of flexural bearing capacity of RC beams was proposed. The results show that with the increase of corrosion degree of longitudinal bars, the plastic deformation characteristics of RC beams continuously decrease, and the failure mode changes from pure plastic bending to brittle shear bending. As the neutral axis of the mid-span section moves upward, the assumption of plane section cannot be satisfied gradually. Moreover, the flexural bearing capacity of the beam decreases continuously, and the bearing platform of load-deflection curve gradually becomes shorter until it disappears. According to the applicability analysis of the existing bending capacity models, it is found that the calculation accuracy of Sun Bin model is the highest and the discreteness is the least. The deterioration analytical method of flexural behavior of RC beams based on the Sun Bin model can obtain the deterioration curves which are in good agreement with the experimental results.

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Settlement Characteristics of Anchor Static Pressure Piles in Prefabricated Bridge Piers

QIU Hongsheng1，ZHU Wanxin1，LI Junhui2，FU Zhanglong1

2020, 39(08): 59-65. DOI: 10.3969/j.issn.1674-0696.2020.08.09

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In the construction of urban viaducts, in order to reduce the impact of bridge piers and foundation construction on road traffic, the quick-installed bridge piers and anchor static pressure pile construction technology can be used. Taking the anchor static pressure pile foundation of a quick-installed bridge pier as the background, the settlement characteristics of the static pressure pile of the anchor rod were studied according to the characteristics of post-pressing piles. The finite element models of pile-free pile cap and pile-group foundation after pile-pressing were established respectively. The influence of the elastic modulus of the upper soil layer (E1), the elastic modulus of the lower soil layer (E2) and the friction coefficient of the pile side (f) on the maximum settlement of the foundation (smax) and the load sharing ratio (η) were compared and analyzed. The results show that: under the two working conditions with pile-free pile cap and pile-group foundation after pile pressing, with the increase of E1 and E2, the maximum settlement of the foundation smax continues to decrease; E1 has a greater influence on the smax of the pile-free foundation, and E2 has a greater influence on the smax of the pile-group foundation; as f increases, the smax of the pile group foundation and the soil load sharing ratio ηsoil gradually decrease, but the influence of f is limited.

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Temperature Effect Separation Method of Deflection Monitoring of Prestressed Concrete Girder Bridge

WU Haijun1,2, HE Li1, WEI Yue3

2020, 39(08): 66-71. DOI: 10.3969/j.issn.1674-0696.2020.08.10

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In large span girder bridge, the deflection value caused by temperature accounts for a large proportion in the measured total deflection value of the structure, which has an impact on the safety evaluation of the real bridge. Aiming at this phenomenon, a practical separation method of temperature effect in bridge deflection monitoring was proposed by using the idea of linear regression. Taking Jiangjin Yangtze River Bridge as the engineering background, a linear regression model was established to fit the regression linear equation to achieve the purpose of separating temperature effect, with the temperature monitoring value as independent variable and deflection monitoring value as response variable. The results show that the relationship between the mid-span deflection change and the temperature change is positive. There is a significant linear relationship between the temperature change inside the box girder and the mid-span deflection change. The temperature effect can be separated by deducting the temperature effect fitting value calculated by the fitting linear equation from the measured value.The daily operation of the bridge can be effectively monitored by using the residual value and setting the corresponding threshold.

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Safety Analysis of Wind-Induced Driving of High Pier Bridges in High-Altitude Regions

MA Peixin1, ZHANG Yongshui2, LIU Lin3, HU Weifeng3, CHEN Ning4

2020, 39(08): 72-76. DOI: 10.3969/j.issn.1674-0696.2020.08.11

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Aiming at the anti-wind performance of driving on the high pier bridge in the canyon area of high altitude in Qinghai Province, the aerodynamic characteristics of vehicle-bridge combination of the typical van type truck were analyzed by using the professional CFD software Fluent, and the aerodynamic parameter curves of the vehicle and the bridge under different wind attack angles were obtained respectively. On this basis, the response analysis and evaluation of wind-vehicle-bridge system under different road conditions, pavement conditions and cross wind speeds were carried out, and the corresponding speed limit operation standards were obtained. The research results show that: in the speed range of 100 km/h, the critical wind speed of the vehicle is greater than 35m/s when the vehicle is driving along the “dry” road surface with different road conditions, in the speed range of 100km/h, when the vehicle is driving along the road with the “very good” and “good” wet road conditions, the critical wind speed of the vehicle is 30 m/s; when the road conditions are “normal”, the critical wind speed and vehicle speed are 30m/s and 90km/h respectively, which indicates that the critical wind speed of vehicle driving safety and vehicle speed will both decrease with the deterioration of road grade; when the road condition level is “very good” and “good”, in the range of the given wind speed (15~35 m/s) and vehicle speed (60~100 km/h), the vehicle will not have driving comfort problems; when the road condition level is “normal” and the vehicles driving speed exceeds 80km/h, the total root mean square acceleration of vehicle weight is greater than 0.8, and the behavior of driving on the bridge will produce uncomfortable feelings for the drivers and passengers.

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Effect of Humidity on Viscoelastic Properties of Asphalt Mixture

LUO Rong1,2, HOU Qiang1,2, LIU Hanqi1,2

2020, 39(08): 77-83. DOI: 10.3969/j.issn.1674-0696.2020.08.12

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In order to study the effect of humidity on the viscoelastic properties of asphalt mixture, the uniaxial tensile dynamic modulus tests were carried out on the two types of asphalt mixture specimens at 0%, 50%, 80% and 100% relative humidity. The master curves of dynamic modulus and phase angle at different humidity levels were plotted with reference temperature of 20°C. The changes of viscoelastic properties of asphalt mixture were analyzed by dynamic modulus ratio, loss modulus ratio and storage modulus ratio. The research results show that when the humidity is increased from 0% to 100%, the dynamic modulus of the asphalt mixture decreases, the storage modulus increases firstly and then decreases, and the loss modulus decreases gradually. When the vehicle speed is 60~120km/h, the modulus of the type 1 mixture decreases by 21%, the modulus of the type 2 mixture decreases by 35%, indicating that the load carrying capacity decreases. The storage modulus of the type 1 mixture increases by 11% and then decreases by 20%, and the loss modulus decreases by 21%. The storage modulus of the type 2 mixture increases by 21% and then decreases by 30%, and the loss modulus decreases by 37%. When the humidity increases slightly (less than 50%), the viscosity properties of the asphalt mixture are enhanced and the elastic properties are weakened. However, when the humidity is too high (more than 80%), the whole viscoelasticity of asphalt mixture is weakened due to the weakening of adhesion between asphalt and aggregate.

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Microwave Self-healing Properties of Macro-facture in SBS Modified Asphalt Mixture

ZHU Hongzhou1,2, YUAN Hai2, LIU Yufeng2, FAN Shiping3, DING Yongjie2

2020, 39(08): 84-89. DOI: 10.3969/j.issn.1674-0696.2020.08.13

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To research the effect of microwave heating on the self-healing performance of macro-fracture of SBS modified asphalt mixture, semi-circular specimens of AC-13 asphalt mixture were prepared. The fracture-healing-fracture test was carried out by means of semicircular bending test and microwave heating. Taking the tensile strength ratio of loading test before and after healing as healing index HI (healing index), the effect of healing time and microwave intensity on the surface temperature of specimen and the self-healing performance of asphalt mixture was analyzed. The research results indicate that the process of microwave heating is mainly that the polar particles in the aggregate absorb the microwave, generate heat and transfer to the weak polarity asphalt, so as to realize the overall temperature rise of the mixture. The surface temperature of the specimens shows a good binary linear regression relationship with heating time and microwave intensity. In a certain range, the increase of heating time and microwave intensity can promote the self-healing behavior of mixture, which is mainly related to the temperature of mixture under the microwave condition. The optimum strength recovery rate of AC-13 SBS modified asphalt mixture is 83%~85% after heating for 100 s under microwave intensity of 700 W or heating for 120 s under microwave intensity of 560 W, and the surface temperature of the specimens is between 90 ℃~96 ℃.

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High and Low Temperature Performance of High-Content Rubber Powder Modified Asphalt Mortar

WANG Guoqing1, SONG Shukang1, QIN Lusheng2, WANG Qingkai3, WANG Xinqiang1

2020, 39(08): 90-94. DOI: 10.3969/j.issn.1674-0696.2020.08.14

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In view of the performance of asphalt mortar, based on the theory of mortar, three different modified asphalts (20% rubber modified asphalt, 30% high-content rubber powder modified asphalt and SBS modified asphalt) mortar specimens were tested by high temperature cone penetration test and low temperature beam bending test. The research results show that the shear strength of the asphalt mortar specimens decreases with the increase of temperature. The shear strength at 50 ℃ and the maximum bending strain at -10 ℃ of high-content rubber powder modified asphalt mortar are 1.4 and 1.8 times more than those of SBS modified asphalt mortar respectively, which indicates the high-content rubber powder modified asphalt mortar has better high and low temperature than SBS modified asphalt mortar does. The shear strength at 50 ℃ and the maximum bending strain at -10 ℃ of high-content rubber powder modified asphalt mortar are 1.5 and 2.2 times more than those of 20% rubber modified asphalt mortar respectively. With the increase of rubber powder content, the high and low temperature properties of asphalt mortar can be effectively improved.

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Influence Analysis of the Damage of the Cement Concrete Pit Pavement on Dynamic Load of Heavy-Load Vehicles

CAO Yuanwen, WANG Dong, WANG Jianwen, ZHOU Hua

2020, 39(08): 95-100. DOI: 10.3969/j.issn.1674-0696.2020.08.15

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The damage of cement concrete pavement will be accelerated due to the overload of vehicles. In order to analyze the influence of pavement damage on the dynamic load of heavy-load vehicles, taking Foton Omar S5 two-axle vehicle as the research object,the dynamic load effect of damaged cement pavement on heavy-load vehicles under the joint action of different pit road damage conditions, different loads and different speeds was analyzed by use of ADAMS software, which was based on the “1+2” four-degree-of-freedom vehicle vibration model. The research shows that: under the same pit depth,with the increase of vehicle speed, the dynamic load of the vehicle increases, and the maximum dynamic load is 1.93 times of the static load. Under the same pit depth,with the increase of load, the vehicle dynamic load increases and the dynamic load coefficient decreases.When the pit depth is within 50~60 mm, the maximum dynamic load of the vehicle is 1.49 times of the static load. Relative to wheels, the damage degree of the pit road surface has a serious interference on the ride comfort of heavy-load vehicles.

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Experimental Study on Critical Characteristics of Shale Tension Compression Failure Based on Acoustic Emission Counting Information Entropy

REN Song1,WANG Le1, XIE Kainan1,2, JIANG Deyi1, JIANG Xiang1

2020, 39(08): 101-107. DOI: 10.3969/j.issn.1674-0696.2020.08.16

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In order to clearly understand the self-organized critical phenomenon of shale in the process of tension and compression fracture, uniaxial compression and Brazilian splitting tests were carried out for shale with brittle characteristics at different rates. The number of acoustic emission (AE) events in the whole process was collected synchronously. The information entropy H of AE event number was defined by combining information entropy theory with AE event number, and the evolution law of AE event number in the process of loading was obtained. The research results show that under the tension and pressure conditions, the information entropy of AE events increases with time, and the law is similar. When the information entropy of AE events keeps stable (r≈0.95), the rock enters the critical state. According to the acoustic emission localization map, the entropy value is maximum when the critical point is reached, and the penetrating crack begins to form. After entering the critical state, the entropy value is in steady a state, and the location signals gather towards the fracture area until the failure. Through the acoustic emission localization changes of four states, the evolution process of defects in shale from the disordered state of slow random development to the orderly state of instantaneous development according to certain laws is revealed, which is well corresponding to the entropy change. The energy probability density function satisfies the power law distribution (P≈X-r) in the process of tension and compression, which has a similar critical index.

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Influence of Design Parameters of Drip Irrigation System in Highway Central Green Belt on the Outflow Uniformity

FU Xuhui1, 2, WANG Wenguang3, TAN Hua3, TU Guangsheng3, TENG Gang3, TAN Jiangyong1

2020, 39(08): 108-112. DOI: 10.3969/j.issn.1674-0696.2020.08.17

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In view of the complex conditions of large drop ratio and long pipeline of Chongqing Zhong-Wan highway green belt drip irrigation project, an iterative solution mathematical model was established based on Darcy-Weisbach formula, and the indoor hydraulic experiment was arranged to obtain the measured parameters to verify. In view of the influence of the design parameters of the drip pipe network, including the length of the pipe, the distance between the drippers and the slope ratio on the outflow uniformity, it is pointed out that the appropriate combination of the initial water head and the distance between the drippers can meet the requirements of the outflow uniformity of the drip irrigation system under certain slope ratio, pipe length and other boundary conditions.

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Determination Method and Application of Metal Elements in Steel Slag Based on Inductively Coupled Plasma Atomic Emission Spectrometry

ZHAO Yi1, CHEN Chao2, XIANG Yangkai1, LI Xiao3, LI Tongbin1

2020, 39(08): 113-118. DOI: 10.3969/j.issn.1674-0696.2020.08.18

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In order to study the heavy metals pollution characteristics of steel slag as road building material, relying on Qianan-Caofeidian highway construction project, steel slags from Tangshan Iron & Steel Group Co., Ltd. and Donghai Steel Group as the subgrade materials were selected as test samples, a method for simultaneous determination of various metal elements in steel slag based on inductively coupled plasma atomic emission spectrometry (ICP-AES) was established, in which the concentrated nitric acid and hydrochloric acid were used as extractants. The results show that the proposed determination method of metal elements in steel slag based on ICP-AES has the advantages of convenient operation, rapid analysis, few interference factors and reliable conclusions. The standard solution concentration is in linear relationship with emission spectrum intensity of inductively coupled plasma atomicemission spectrometer. The standard curve equations of 12 metal elements are fitted, and the correlation coefficients R2 are all above 0.97, whose linear relationship is good. The leaching contents of Ca, Fe, Mg and Mn in steel slag samples are relatively high. Both the leaching content of the metal elements in steel slag samples of Tangshan Iron & Steel Group Co., Ltd.and Donghai Steel Group meets the requirements of the identification standard of solid hazardous waste. Steel slag can be used as subgrade and pavement materials in road engineering construction, but the release characteristics of metal elements still need to be observed on site to ensure the ecological safety around the road engineering.

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Magnetic Field Analysis of a Permanent Magnet Limited Angle Motor

JIANG Baojun, ZHOU Pengfei

2020, 39(08): 119-124. DOI: 10.3969/j.issn.1674-0696.2020.08.19

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It is difficult to use the traditional magnetic circuit method to design and analyze the limited angle motor for the valve switch of the limited angle machine.Based on electromagnetic field theory,the working principle of a statin permanent magnet limited angle motor was analyzed and the magnetic field was simulated by using the finite element analysis software Ansoft.When the air gap magnetic density of permanent magnet is the same as that of stator winding, the relationship of the electromagnetic torque of the motor changing with current and rotor position angle was analyzed. The simulation results show that the proposed motor stator winding current is linearly with the starting torque, the torque change and the rotor position angle in the linear zone of magnetic circuit.The starting torque increases with the increase of winding current, while the electromagnetic torque value decreases with the increase of the rotor position angle.

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Influence Factor Analysis of Electronic Differential on Four-Wheel Wheel-Driven Electric Bus

LIU Ping1, 2, CHEN Xiaofei1, 2, YANG Mingliang1, 2, YAO Yu1, 2

2020, 39(08): 125-133. DOI: 10.3969/j.issn.1674-0696.2020.08.20

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Taking the four-wheel wheel-driven electric bus as the research object, the slip rate was proposed as the evaluation index of the electronic differential, according to the working principle of the mechanical differential. The steering simulation experiment was carried out on the joint electric vehicle simulation platform established by trucksim and MATLAB/simulink, and the steering simulation experiment on the vehicle was carried out from the level of vehicle dynamics. The influence of the working conditions and the vehicle structure parameters on the electronic differential was studied. Through the simulation, the change rules of the inside and outside slip rate of the driven wheel changing with the vehicle speed, the steering wheel angle, the centroid height, the distance from centroid to the front axle and the change of the sprung mass were obtained. The research results show that: as the vehicle speed and steering wheel angle continue to increase, the slip rate of the four wheels increases; with the increase of the centroid height, the slip rate of left steering wheel increases and that of right steering wheel decreases; with the increase of the distance from centroid to the front axle, the slip rate of front axle wheel increases and that of rear axle wheel decreases; with the increase of the sprung mass, the slip rates of the four wheels all increase. Moreover, with the increase of vehicle speed and steering wheel angle, the increase of wheel slip rate is greater. The influence analysis of the obtained electronic differential changing with the working conditions and structure parameters is of guiding significance for the further study of the electronic differential control strategy.

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Vibration Study Based on the Band Gap Characteristics of Two-Dimensional Three-Component Phononic Crystal

PENG Zhongbo, LI Cheng, GAO Yang

2020, 39(08): 134-138. DOI: 10.3969/j.issn.1674-0696.2020.08.21

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A two-dimensional three-component phononic crystal structure was designed, and the energy band structure and transmission characteristics of the designed structure were calculated in combination with the finite element software COMSOL. The effect of the filling ratio of the scatterers and the thickness of the cladding layer on the first band gap of the proposed structure was discussed. On this basis, the transmission characteristics of the proposed structure were calculated by using different scattering bodies. And the effects of the same kind of scatterers at the different periods and different scatterers at the same period on the vibration of finite period phononic crystal structure were analyzed. The results show that the attenuation frequency range in the transmission characteristics was basically consistent with the energy band structure, and the calculation method of the energy band structure is correct and effective. With the increase of the number of periods in the case of the same scatterers, the vibration attenuation effect in the band gap frequency range will also be enhanced; with the same period number, the higher the density of scatterers, the better the vibration of low frequency band can be reduced. The range of low frequency band gap realized by the proposed structure has a potential application prospect for vibration and noise reduction of ships.

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