| With the continuous development of the industrial economy and the speedy construction of smart cities,the number of urban population and motor vehicles continues to increase,resulting in high intensity and compound air pollution that far exceeds the self-cleaning capacity of the environment cannot be underestimated.Since the implementation of China’s13th and 14 th Five-Year Plans,volatile organic compounds(VOCs),a key factor in the formation of air pollution,have gradually been fine-tuned and controlled.However,existing studies have mainly focused on the analysis of VOCs emissions and pollution potential from anthropogenic sources,and there is a lack of detailed assessment of VOCs emission concentrations from road mobile sources in urban areas,as well as a lack of research on their early warning.In view of this,this study takes VOCs from road mobile sources in Xi’an as the research object.On the basis of exploring the distribution characteristics of related emission concentrations,the construction of a comprehensive emission situation assessment index system and early warning of excessive emission concentrations were taken as the research focus.At the same time,the early warning for exceeding the emission concentration and provides suggestions for the fine control of VOCs from road mobile sources in the city based on the characteristic analysis and early warning analysis.Firstly,in order to construct a reasonable comprehensive assessment index system for emission trends,the distribution of VOCs emission concentrations from road mobile sources in Xi’an was analyzed.Through literature comparison,according to the research classification,inventory construction principle and calculation method of VOCs emission from road mobile sources,based on the collection,observation and integration of relevant data such as regional geography,road network traffic and road mobile sources in Xi’an.the emission of VOCs from road mobile sources in Xi’an in 2014,2017 and 2020 was calculated by using the localized emission factors in the MOVES model,and the emission sources and regional concentrations were compared and analyzed according to the calculation results.It lays a foundation for the construction of a comprehensive evaluation index system for VOCs emissions from road mobile sources in Xi’an.Secondly,in order to build a good early warning model for excessive emission concentration,a comprehensive assessment index system for VOCs emission from road mobile sources in Xi’an was constructed.Based on the preliminary characteristic indicators of VOCs emission concentration distribution of road mobile sources in Xi’an,the theory of situation assessment and disaster early warning is introduced,and the specific assessment index layer is formed by summarizing and analyzing the factors of the pregnant environment and the disaster-causing factors.At the same time,considering the characteristics of crossover and redundancy of information among many specific evaluation indicators of road mobile source VOCs,the specific assessment indicators of emission situation are calculated and compressed based on the principal component method(PCA),and the comprehensive evaluation index system of VOCs emission situation of road mobile source in Xi’an is obtained,which provides guarantee for the subsequent early warning research of excessive emission concentration.Finally,an early warning analysis of VOCs emission concentrations from road mobile sources in Xi’an was carried out.On the basis of the traditional RBF neural network model,the whale algorithm(WOA)is used to optimize the parameter settings such as learning rate and fitness in the model,and an optimized RBF neural network prediction model is formed.Through the experimental and simulation tests of the early warning of excessive VOCs emission concentration of road mobile sources in Xi’an,an optimized WOA-RBF early warning model with high accuracy is obtained.Finally,combined with the optimization of the emission concentration situation output Y value and the real concentration exceeding the standard in the RBF model,the early warning analysis is carried out,and countermeasures and suggestions for normalized control are proposed. |
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