Journal of Chongqing Jiaotong University(Natural Science)

Evaluation Method of Bridge Technical Condition Based on Cloud Model and Anomaly Recognition

ZHOU Jianting1, ZHANG Shun1, NIE Zhixin1, HE Yahui2

2019, 38(02): 1-6. DOI: 10.3969/j.issn.1674-0696.2019.02.01

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Current evaluation process for bridge technical condition included the problem of uncertainty and the neglect of the influence of the main structural components on the overall safety of the bridge, so anomaly recognition was introduced into evaluation process. The cloud model theory specialized in uncertainties was combined with the traditional fuzzy comprehensive analysis method, and an evaluation method of bridge technical condition based on cloud model and anomaly recognition was proposed. Firstly, the weight of each component and structure was determined, then the remark set and evaluation data were transformed into cloud model, and the evaluation results before and after introducing anomaly recognition in the evaluation process were acquired. Finally, the proposed model was applied to evaluate an actual bridge. The results show that anomaly recognition is introduced in the traditional cloud model evaluation to consider the impact of main structural components on the overall safety of the bridge. The evaluation method of the proposed model is more in line with the actual engineering situation, the process is more objective and the results are more comprehensive.

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Influence of Calculation Model on Shear Lag Results of Simple-Supported Box and T Beam

ZHANG Junfeng,ZHU Bing, LI Jie, MAO Dehao, CHEN Daihai

2019, 38(02): 7-12. DOI: 10.3969/j.issn.1674-0696.2019.02.02

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Taking shear lag effect as the research object, a simple-supported box girder model and a practical simple-supported T-beam structure were calculated and compared by using MIDAS and ANSYS software respectively, combined with different load forms, element types and grid density. The influence of model parameters and load types on the obtained results was analyzed, which provided parameters for the finite element analysis of shear lag effect. The research indicates that: under the same calculation condition, the stress amplitude of ANSYS is slightly larger than that of MIDAS, the stress amplitude of solid element is slightly larger than that of plate element, and the stress amplitude of high density grid is slightly larger than that of low density grid, but the deviation is mostly within ±5%. For the situation that there is no haunch at web and top flange, under arbitrary loads, the shear lag effect of roof can be accurately obtained by 1 time grid plate element of two kinds of software. If there is haunch at web and top flange, the shear lag effect of top flange can be analyzed by plate element under point load and line load. However, for both surface and body load, the solid element analysis is needed, and 1 time grid density is applicable for the both conditions.

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Web Cracking Causes of Cantilever Box Girder

HONG Hua, JIN Sujing, YANG Yongyong

2019, 38(02): 13-18. DOI: 10.3969/j.issn.1674-0696.2019.02.03

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In the practical engineering, box girder web cracking phenomenon is common, and causes of cracking in webs are complex and diverse. The main causes of web cracking of box girder were discussed from the perspective of qualitative and quantitative analysis. It is concluded that: ①the specific causes of web cracking of box girder mainly include concrete shrinkage, temperature effect, radial force caused by bending of prestressing tendons and Poisson effect caused by compressive stress in anchorage zone; among them, the radial force caused by bending of prestressing tendons and Poisson effect caused by compressive stress in anchorage zone are the main causes of box girder web cracking; ②the web cracks caused by these two factors are analyzed by the finite element software ANSYS through engineering examples, and the results show that the web cracking of box girder is easy to occur in the bending section of web prestressing tendons, and its direction is basically perpendicular to the bending prestressing tendons.

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Dynamic Response Characteristics of Soft Clay around Tunnel under Subway Cyclic Loads

PU Shutao1, YE Bin2, WANG Haicheng1, GUO Weixiang1, CHEN Zaiqian1

2019, 38(02): 19-26. DOI: 10.3969/j.issn.1674-0696.2019.02.04

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Based on the project of Shanghai Metro Line 9 and the filed measurement, a calculation program DBLEAVES was adopted to study the dynamic response characteristics of soft clay around tunnel under subway cyclic loads. The research results show that: under subway cyclic loads, the settlement law of soft clay around tunnel is arc spreading out around tunnel and the value is getting smaller and smaller until the boundary of influence. Ground settlement develops in the form of settlement trough. The largest settlement occurs directly below the tunnel and the final settlement of soil around tunnel is 19.8mm by fitting. In terms of acceleration response, the spatial distribution rule of acceleration response is the same as that of settlement. Acceleration and the decay rate of the right-bottom soil around tunnel are slightly larger than that of top-right soil. At the beginning of cyclic loads, excess pore water pressure of soil is rising quickly with nearly linear development and gradually intends to be stabilized and dissipated to the boundary with the increase of the number of cycles. Excess pore water pressure is much smaller than the effective stress of soil, so the liquefaction phenomenon will not happen below the tunnel under subway cyclic loads.

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Finite Element Analysis on Constitutive Model of Serial Viscoelastic-Viscoplastic Asphalt Mixture

XU Jianping1, 2, ZHU Yaoting3

2019, 38(02): 27-34. DOI: 10.3969/j.issn.1674-0696.2019.02.05

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In order to simulate and calculate the structure and time-dependent mechanical behavior of asphalt pavement effectively, a serial viscoelastic-viscoplastic constitutive model was implemented into finite element calculation.The constitutive model was realized by finite element method by compiling material subroutine.The 3-D generalized Maxwell viscoelastic model was expressed in form of a hereditary integral,and the recursive formula of convolution equation was deduced by Prony series characteristics.The stiffness matrix of the iteration process was obtained by updating the strain under the condition of strain increment.The differential viscoplastic constitutive equation was based on the radial regression method to establish the variable evolution equation in the integral step.The convergence problem was solved by N-R iteration algorithm.The uniform tangent stiffness matrix of the whole iteration process was established by using the discrete derivation of the constitutive model.By comparing and analyzing the time- dependent behavior of indoor tests with typical examples, the rationality and validity of the finite element method were verified.It provides theoretical basis and practical analysis for structure calculation of asphalt pavement.

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Discrete Element Simulation of Uniaxial Static Creep Test of Porous Asphalt Mixture

WANG Rong1, 2, HU Changbin2

2019, 38(02): 35-43. DOI: 10.3969/j.issn.1674-0696.2019.02.06

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In order to reveal the meso-mechanics mechanism of uniaxial static creep test of porous asphalt mixture, image recognition technology was used to obtain the coarse aggregate and the pore mesoscopic information of rutting slab, through combining laboratory test and numerical simulation. Based on the discrete element, a uniaxial static creep test model was set up and the influence of three factors such as asphalt modulus, bond strength and mixture porosity on the high temperature performance of asphalt mixture was studied. The results show that, under the same external load and acting time, the modulus has a slightly greater effect on the decrease of permanent deformation than creep compliance. The modulus increases from 1 to 5 times, the creep compliance decreases by 3.7 times and the permanent deformation decreases by about 4.7 times. When modulus increases to 4 times, the decrease amplitude of permanent deformation and creep compliance tends to be gentle. The porosity increases from 18% to 22%, and creep compliance and permanent deformation increase by about 40%. The durability of the mixture is obviously reduced. The increase of permanent deformation and creep compliance is gentle in the stage of porosity ranging from 18% to 19%; the amplification of permanent deformation and creep compliance increases and approaches linear relationship in the stage of porosity ranging from 19% to 22%. The bearing capacity of the mixture increases with the increase of bond strength. The effect of different bond strengths (280, 300, 500 N) on the permanent deformation and creep compliance is basically the same, and the effect of low bond strength (250-300 N) on the permanent deformation and creep compliance is much greater than that of high bond strength (300-700 N). Among the three factors affecting the reliability of creep compliance and permanent deformation, bond strength, porosity and modulus are in turn.

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Forecasting of Asphalt Pavement Performance Based on GA-Gray Neural Network

CHEN Shizhou1, 2, LI Shan1, XIONG Feng2, LI Guannan1

2019, 38(02): 44-50. DOI: 10.3969/j.issn.1674-0696.2019.02.07

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In order to accurately predict the variation trend of asphalt pavement performance in our country, the unbiased GM(1,1) model and sliding GM(1,1) model were proposed on the basis of the traditional gray forecasting model GM(1,1) model.The traditional model, unbiased model and sliding GM (1, 1) model were combined with BP neural network optimized by genetic algorithm (GA), and a combined forecasting model of GA-grey neural network was obtained, which took into account the advantages of grey theory, genetic algorithm and BP neural network.Finally, the effectiveness of the proposed combination model was verified with specific examples.The results show that: the average relative error of traditional GM(1,1) model is 4.67%; the average relative error of unbiased GM(1,1) model is 4.64%; the average relative error of sliding GM(1,1) model is 4.63%; the average relative error of gray neural network combination model is 2.41%,while the average relative error of GA-gray neural network combination model is only 0.54%. Therefore, it is proved that the proposed combination model has higher prediction accuracy and smaller error, which can be used as a basis for pavement maintenance planning.

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Performance Evaluation of Construction Project Cost Management Based on Entropy Weight Extension Theory

DONG Na1, ZHANG Ning1, XIONG Feng1, LUO Linglong2, LIU Yu3

2019, 38(02): 51-58. DOI: 10.3969/j.issn.1674-0696.2019.02.08

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As an important part of cost management, cost management performance evaluation plays an important role in guiding the forward development of project cost management. Based on the current construction project management system and combined with relevant specifications, an evaluation index system was established on the basis of collecting construction project cost management data from five aspects: the overall performance of cost management, process performance, direct cost management performance, indirect cost management performance and other cost management performance. The index weight was determined by the method of entropy weight and the results were analyzed. The improved extension theory was used to establish the performance evaluation model, which was verified by a road project. The results show that the proposed performance evaluation model not only quantitatively evaluates the level of construction cost management, but also combines with time limit, quality and safety to help improve the level of project management. In the later application, with the accumulation of enterprise project data, the model can be optimized by ifself.

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Slope Safety Evaluation Model of TOPSIS Based on Penalty-Incentive Variable Weight Method

YANG Chunfeng1, REN Yanfei1, WANG Keyi2

2019, 38(02): 59-64. DOI: 10.3969/j.issn.1674-0696.2019.02.09

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At present, multi-factor stability evaluation models of the highway slope stability often adopt a fixed weight system, which weakens the essential characteristics such as the nonlinearity and emergence of evaluation index complex systems, resulting in evaluation results with deviation. To solve the above problem, a TOPSIS evaluation model of slope stability based on penalty-incentive variable weight method was proposed, which was constructed on the basis of accident-causing theory, from four aspects: construction scale, geological conditions, inducing factors and construction environment. Combined with the application analysis of the construction of Zhangjiakou section of Beijing-Xinjiang Expressway, the feasibility of the proposed model was proved. Research shows that the variable weight theory can highlight the negative effects of the degradation index and make the evaluation result more accurate; the TOPSIS evaluation model based on penalty-incentive variable weight can provide more scientific decision-making for slope stability analysis.

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Spatial Conflict Type Identification and its Driving Mechanism of Land Use in the Three Gorges Reservoir Area (Chongqing Section)

GUAN Dongjie1, 2, CHEN Ting1, HE Xiujuan1, LUO Xue1, LUO Li1, DENG Huiting1

2019, 38(02): 65-71. DOI: 10.3969/j.issn.1674-0696.2019.02.10

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Based on the remote sensing interpretation data of the Three Gorges Reservoir area (Chongqing section), the study area was divided into 3 175 4×4 km evaluation units, and a spatial conflict measurement model for land use was constructed on the basis of the characteristics of landscape ecology and land use system. Four types of land use spatial conflicts were classified on the basis of the spatial conflict measurement value of the evaluation unit. Finally, the principal component analysis was carried out on the driving factors of the land use space conflict of the study area. The results show that: 1)the spatial conflict in the study area is in a rather severe state during the study period, and the proportion of the severe conflict type and the moderate conflict type is over 55%. 2) From the point of view of spatial distribution, the high value area of land use spatial conflict is concentrated in the northeast and southwest regions and it shifts from the northeast to the southwest, with the passage of time. Finally, it expands outward with the main urban area in southwest China as the center, while the types of general and minor conflicts are distributed in the northernmost and southeastern fringes. 3) The change trend from 1990 to 2010 shows that some moderate conflict types have been transformed into severe conflict types, indicating that the land use space conflicts in the study area are continuously strengthening, and the conflict areas are converted from woodland and grassland to wetland, cultivated land and construction land. 4) The driving factors of space conflict in the Three Gorges Reservoir area (Chongqing section) can be summarized as economic development, population growth pressure and the construction of the Three Gorges Project.

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A Remote Sensing Image Fusion Method Based on KPCA and Brovey Transform

KE Hongxia, GAO Jianping

2019, 38(02): 72-78. DOI: 10.3969/j.issn.1674-0696.2019.02.11

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Aiming at the problem that the spatial details and spectral features of PCA-Brovey algorithm could not be improved simultaneously in fusing multi-spectral remote sensing images (MS) and panchromatic images (PAN), a remote sensing image fusion method based on KPCA-Brovey was proposed. Firstly, by utilizing the characteristics of non-linear spectral data mining based on Kernel Principal Component Transform (KPCA) algorithm, three principal components including KPC1, KPC2 and KPC3 with the largest amount of information in multispectral images were extracted. Then, three principal components and panchromatic bands were normalized by Brovey algorithm to enrich the spatial and spectral information in the fusion results. Finally, the experimental results with two satellites data, from Landsat5-TM (Wuhan District) and QuickBird (Foshan District), indicated that the proposed method obviously outperformed the PCA-Brovey method in spectral and spatial information extracting. The spectral information extracting rates were increased to 96.6 % (Wuhan District) and 96.1% (Foshan District) respectively. The spectral correlation coefficients were increased to 0.9079（Wuhan District）and 0.8979(Foshan District) respectively.

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PWARX Driving Behavior Identification Model Based on Twice Clustering

YING Haining1, TANG Zhenmin2, HAN Xu2

2019, 38(02): 79-85. DOI: 10.3969/j.issn.1674-0696.2019.02.12

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According to the draw backs of traditional clustering-based PWARX model such as the dependence of prior knowledge and the low accuracy of subspace segmentation, an improved algorithm for PWARX identification model based on twice clustering was proposed, which was applied to driving behavior modeling. Firstly, clustering in the sample space was carried out by affinity propagation (AP) algorithm.Then the linear models were used to fit the obtained clusters, and K-means algorithm was used to cluster in the parameter space of the linear model to obtain the region partition of the PWA sub-model. Finally, the PWA sub-models were solved in each subspace. The proposed algorith mrationally took advantage of the characteristics of the AP algorithm and the K-means algorithm, and obtained a good sub-model region segmentation effect by twice clustering in the sample and parameter space.The proposed algorithm was used to model the driving behavior of 10 drivers.The results show that the average accuracy of model identification of the proposed algorithm is 91.5%.

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Influence of Advance Guide Signs on Drivers in Interchange Area of Highway

HUANG Lihua1, 2, ZHAO Xiaohua1, 2, LI Yang1, 3, RONG Jian1, 2

2019, 38(02): 86-93. DOI: 10.3969/j.issn.1674-0696.2019.02.13

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In order to study the utility of multi-level advance guide signs in the overpass area, a driving simulation experiment was carried out to obtain vehicle driving status data, taking the type of ramp and the setting of three-level advance guide signs as control factors. Seven indicators were analyzed by repeated measurement variance analysis and LSD pairwise comparison analysis method. The results show that: there are significant differences only in the number of lane changes among the seven indicators. From the in- depth analysis of lane change behavior characteristics, it is indicated that the influence of advance guide signs on lane-changing behavior has nothing to do with the installation of overpass type guide signs. Under directional, semi-directional and circular ramp conditions, setting advance guide signs will increase the number of lane changes in influence range. Moreover, the key increase area is located in the range from 100m before to 300m behind of the third level advance guide sign. Setting advance guide signs will increase the proportion of people who change lanes for the second and third time by 14.61% and 2.37% respectively, which will effectively improve drivers lane change behavior.

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Influence Factors of Car-Hailing Service Quality Based on Grounded Theory

REN Qiliang, ZHAO Ziyu

2019, 38(02): 94-101. DOI: 10.3969/j.issn.1674-0696.2019.02.14

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Using qualitative research method to explore the influencing factors of network car-hailing service quality can provide the foundation and basis for the proposal of network car-hailing service quality regulation. Through interviewing traffic authorities, operators, drivers and passengers and collecting relevant information, a grounded analysis was carried out, and basic information were conceptualized and categorized by open coding. The spindle coding formed five main categories: supervision mechanism of supervision department, management mode of operator, driver service efficiency, vehicle environmental benefit and performance guarantee of car- hailing platform. And the influence factor model of network car-hailing service quality was established. The results show that the supervision of traffic authorities and operators is the basis and guarantee of network car-hailing service quality; the overall quality of the driver and the passengers driving environment directly affect the passengers service quality; as a vehicle-booking medium, network car-hailing platform is also an important aspect that affects the passengers service quality.

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Dispatching Method of Expressway Emergency Resources under Construction Environment

WANG Wei1, 2, WU Yi1, ZHAO Yang1, QU Weidong1

2019, 38(02): 102-108. DOI: 10.3969/j.issn.1674-0696.2019.02.15

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In the course of researching highway emergency rescue system, the emergency resource scheduling method is the core of the emergency rescue system of the whole expressway. Aiming at the shortest end time of emergency rescue and the least cost related to emergency rescue, an emergency resource scheduling model based on the road capacity of construction area was established by using mathematical programming method, with the full consideration of the influence of expressway construction area on road section capacity, combining with the nature and characteristics of expressway construction area. The greedy algorithm was used to optimize the proposed model, and then to determine whether the emergency rescue points were involved in the rescue and the specific time and ability of participating in the rescue through the construction area. The cost-capability ratio of each rescue point was compared, so that the appropriate emergency rescue point could be selected for effective rescue. Taking the construction area of Jinan-Qinghai section of Shandong expressway as an example, the proposed model was empirically analyzed. The analysis results show that the application of the proposed model can reduce the rescue fee by 16.036 thousand yuan, which is 13.6% lower than the initial plan and reduces the rescue cost.

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Internal Feeder Ship Allocation and Ship Dispatching Optimization

ZHENG Hongxing1, LI Shanshan1, SI Yu2

2019, 38(02): 109-116. DOI: 10.3969/j.issn.1674-0696.2019.02.16

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In order to balance the operation cost and customer service level of internal feeder in shipping enterprises, the problem of feeder line tramp ship configuration and scheduling was studied. Considering the actual constraints such as the limited time of vessels in hub port and the capacity of branch ships, as well as considering the freight requirements of feeder ports at different time during the planning period, an optimization model of internal branch ship allocation and dispatching was established, which aimed at minimizing the sum of operation cost and cargo rejection cost of internal branch. Combined with the characteristics of the problem, a harmony annealing hybrid algorithm was designed to solve the proposed model. Case study not only validates the effectiveness of the proposed model and the algorithm, but also gives sensitivity analysis of the limited time and unit dumping cost of ships in hub port.

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Cause of Crash Injury Severity in Single-Motorcycle Crash on Roadway Segments

WEN Huiying, TANG Zuogan

2019, 38(02): 117-125. DOI: 10.3969/j.issn.1674-0696.2019.02.17

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1526 motorcycle crashes in Indiana in America from 2013 to 2015 were used to study the factors influencing the severity of motorcycle crash accidents on roadway segments. Considering 21 independent variables from 5 aspects such as drivers characteristics, vehicle attributes, road conditions, environment and accident characteristics, a nested logit model was constructed to account for the correlation between severity categories (fatality, incapacitating injury, non-incapacitating injury, property damage only). The model parameters were estimated by Full Information Maximum Likelihood (FIML). The estimation results show that the overall fitness of the proposed model is good. The results show that gender of motorcyclist, age of motorcyclist, helmet usage, alcohol use, ejection or not, speeding or not, running off the road or not, passenger on motorcycle, age of vehicle, wet pavement or not, horizontal curve, speed limit, months, light conditions, rural areas or not, motorcycle collisions (pole, curb, culvert, guardrail, tree) are associated with the crash injury severity at 0.1 significance level. Factors associated with a substantially higher probability of fatality include ejection, speeding, motorcycle age over 10, running off the road, accidents occurred in April, July, night, accidents occurred in rural areas and motorcycle collisions with poles. These findings can help transportation agencies develop appropriate strategies to reduce injury severity resulting from single-motorcycle accidents on roadway segments, and can also provide reference for further analysis of motorcycle accidents in China in the later period.

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Load Model of Vehicles Idling Congestion on Urban Bridge Based on Measured Traffic Data

LI Tianhua1, ZHAO Xin2, ZHANG Kejia1, TIAN Zhenou2,BAI Wenying1

2019, 38(02): 126-132. DOI: 10.3969/j.issn.1674-0696.2019.02.18

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An economical and feasible observation method and data reading means of traffic congestion were proposed for more accurate acquisition of load spectrum and load model of vehicles idling congestion on urban bridges. In 3-month field vehicle congestion load database collected from a viaduct in Urumqi,80 specific types of vehicles were identified and classified into three major types(cars, medium bus and large bus) by the proposed method. The recorded vehiclecongestion load parameters involved vehicle type (length, width, wheelbase and axle load), vehicle-bridge distances and vehicle wheelbase.The statistical eigenvalues of these parameters were obtained by statistical analysis of the above parameter samples.On this basis, 3 kinds of typical vehicle load spectra of urban bridges in Urumqi and 7 kinds of typical load models of vehicles idling congestion on urban bridges were established, which laid a foundation for future research on the effect of vehicles idling congestion on urban bridges.

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SOC Estimation of Lithium Battery Based on Equivalent Model of Extended Kalman Filter

AN Zhiguo1, SUN Zhikun1, ZHANG Dongsheng1, GUO Jingyi2

2019, 38(02): 133-138. DOI: 10.3969/j.issn.1674-0696.2019.02.19

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The main task of the battery management system (BMS) is to diagnose the battery state of charge (SOC), endurance mileage and prevent overcharge and discharge of batteries in real time. The rapid and accurate estimation of SOC is the core technology of BMS. Based on the dynamic nonlinear system of lithium battery, a more realistic and improved equivalent model of PNGV battery was proposed. Based on the improved PNGV battery equivalent model, the experimental results of battery SOC diagnosis of Kalman filter (KF) and extended Kalman filter (EKF) were compared. The experimental error of EKF was analyzed. The results show that EKF is more accurate in diagnosing battery SOC, and the error can be kept within 5%.

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Driving Cycle Development of Light Vehicles Based on Short Trip Method

WANG Guolin1, GUO Xin1, ZHANG Shupei1, ZHANG Wei1, XU Yueyun2

2019, 38(02): 139-143. DOI: 10.3969/j.issn.1674-0696.2019.02.20

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In the process of analyzing the correlation between the driving characteristics and the energy consumption of light vehicles, the direct data comparison of a large amount of the measured data resulted in time multiplying of data analysis and distortion of comparison results. Vehicle driving condition was the concentrated reflection of the actual road driving characteristics of vehicles, and an important means to analyze vehicle fuel consumption and emissions.Taking private cars and taxis as the research objects of light vehicles,the driving conditions of private cars and taxis were established by short-distance method based on collecting a large amount of actual driving data of vehicles. Finally, the validity of the driving cycle construction was verified, and the probability distribution of the speed and acceleration of the private cars and taxis driving cycle and the actual driving cycle were compared respectively.The results show good consistency, which indicates that the established driving conditions of light vehicles are effective in representing the actual road driving characteristics of vehicles.

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Numerical Analysis on the Structure Falling in Water Flow Based on k-ε Viscous Model

WANG Yonghu1, LIN Tianlong2

2019, 38(02): 144-150. DOI: 10.3969/j.issn.1674-0696.2019.02.21

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To research the trajectory and underwater dispersion of the structure falling in water flow, the 3D cylinder falling model was established for the phenomenon of the structure falling in water flow. The realizable k-εviscous model, the volume of fluid (VOF) method, open channel model, dynamic mesh and 6 degrees of freedom (6DOF) model were used to simulate the cylinder falling in water flow. Then vertical and horizontal velocity of the structure falling was analyzed quantitatively in all the process. The analysis results indicate that when the cylinder is separated from the cavity, the force of water flow is the greatest. The dropping phenomena and trajectories of structures were compared with the dropping experiments, and the error analysis further confirmed that the simulation data were basically consistent with the experimental results. The fitting equation of the trajectory of a cylinder falling in water was given. The numerical analysis provides a certain reference for the analysis of structure falling kinematics and underwater dispersal salvage.

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