Research On Structural Evolution Based On Double-layer Standard Network Model

Air is the necessity of people's life.With the improvement of people's living standards,the air quality has an increasing impact on people's health.In recent years,with the rapid development of the economy,air quality has continued to deteriorate,constantly threatening the health of the people.In order to fundamentally change the air quality environment,it is necessary to increase the formulation of air quality standards.Air quality standards are an effective way to measure air quality and improve air quality.In order to develop a sound air quality standard system,we need to study the current air quality standard network,and find the shortcomings of the standard system from the network to make corresponding suggestions.This thesis combined social network method and TOPSIS method to study air quality standard citation network and drafting unit cooperative network,and for the first time apply TOPSIS method to evaluate and analyze standards and drafting unit.The air quality standards and drafting units at different time points were analyzed from the three aspects of network node index,network overall index and comprehensive evaluation.Firstly,the evolution of the citation network of air quality standards is analyzed through the degree,betweenness centrality,eccentricity and clustering coefficient.The citation network is comprehensively analyzed through the average distance and density.The TOPSIS method is used to evaluate the standards,and the change process of the core standards in the network is obtained.Then,the cooperation network of the drafting unit is analyzed through the degree of participation,cooperation and contribution,the overall analysis of the cooperation network is conducted through the average distance and density,and the drafting unit is comprehensively evaluated by the TOPSIS method,and the more important drafting unit is obtained at different time points.It is found that the scale of air quality standard citation network and the cooperation network of drafting unit are increasing with time,and the connection is increasing,but the density is small.The core standard in the network is aging.The importance of air quality standards will also change when the national policy focuses on migration;the drafting units are single,and most of them are research institutes;the drafting units in the cooperation network have low knowledge dissemination efficiency.Based on the research on the structural evolution of the double-layer network model of air quality standard,this thesis finds that the air quality standard has the following problems: the nodes in the double-layer network are not closely connected,the core air quality standard is aging,the drafting unit has a single type,and the drafting unit index has obvious differentiation.Therefore,we put forward the following four suggestions: first,strengthen the connection between network nodes;second,attach importance to the establishment of the core standard system;third,enhance the diversity of drafting units;fourth,strengthen the support of drafting units,and hope to provide guidance for the formulation of air quality standards.