| Many cities are facing more and more serious problems of air pollution.Motor vehicle pollutants,as the main source of urban air pollution,not only cause the decline of urban air quality,but also affect the health of residents and the economic development of the city.Studying the emission characteristics of motor vehicle pollutants in urban areas is of great significance to the formulation of motor vehicle pollution control strategies and improvement of urban atmospheric environmental quality.The data of traditional algorithms for estimating motor vehicle pollutant emissions in urban areas usually comes from yearbook data,questionnaires,etc.The accuracy and timeliness of the data are poor,and the accuracy of pollutant emission estimation is low.With the development of intelligent traffic collection technology,technologies such as Global Positioning System(GPS)and video recognition can collect real traffic data.These real traffic data are used to improve the accuracy of the estimation results.However,they usually only include some motor vehicles such as taxis or floating cars,which is difficult to reflect the overall level of urban motor vehicle pollutant emissions.In recent years,Radio Frequency Identification(RFID)has been used in the field of intelligent transportation.It can not only quickly obtain the traffic information of vehicles in urban road network,but also cover all the motor vehicles in the city.It is economical,efficient,and safe.This study established an urban vehicle emission model based on RFID data and improved the existing approach.Taking Chongqing as an example,we analyzed macroscopically the emission characteristics of motor vehicle pollutants.The main achievements are obtained as followings.(1)Briefly introducing the acquisition principle of the RFID electronic license plate recognition system.And aiming at the problem of data redundancy existing in the raw RFID data,a method was designed to calculate the redundancy rate of duplicate data and similar data.The validity of collected information from RFID electronic license plate recognition system was verified,which laid the foundation for the establishment of urban vehicle emission model based on RFID data.(2)Proposing an urban emission inventory model based on RFID data.Taking Chongqing as an example,the parameters in the model were determined and the emissions of four motor vehicle pollutants(CO,HC,NOx,and PM)in the main urban area of Chongqing were estimated.The model divides pollutant emissions from motor vehicles into operating emissions,start-up emissions and evaporative emissions.The parameters are mainly divided into two categories: traffic flow parameters and emission factors.Traffic flow parameters include fleet composition,mileage,driving time,average speed,and number of start-up.Taking Chongqing RFID data as an example,algorithms are proposed to calculate each traffic flow parameter.And the driving characteristics of each type of motor vehicle are briefly analyzed.Emission factors are also divided into operating emission factors,start-up emission factors,and evaporative emission factors.Operating emission factors must be corrected in light of the actual conditions of the city.Other emission factors can be found in relevant literature.Combined with the actual situation in the main urban area of Chongqing,the operating emission factors were determined,and the emissions of CO,HC,NOx,and PM in the main urban area of Chongqing were estimated based on the proposed model.Besides,the uncertainty of the results was analyzed.(3)Analyzing the characteristics of motor vehicle emission pollutants in the main urban area of Chongqing on a macro scale,in terms of emission types,vehicle models,fuel types,and emission standards.The variation of pollutant emission contribution of different type motor vehicle over a week was also analyzed.This thesis provides not only basic data for the treatment and prevention of motor vehicle pollution,but also scientific basis for motor vehicle management in the urban areas of Chongqing. |
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