Research On Dynamic Evaluation Method Of Ecological Environmental Vulnerability In Mining Area Based On Petri-net

At present,the destruction of ecological environment caused by exploitation of mineral resources in China is not optimistic.Excessive resources consumption in mining areas and a series of ecological environmental problems such as soil pollution,vegetation destruction,soil erosion and other environmental problems have become increasingly prominent,resulting in the decline of ecological carrying capacity in the periphery of mining and gradual increment of environment vulnerability,posing a serious threat to the ecological environment around the mining area.At the same time,with the needs of economic development,China's mining technology is constantly deepening,mining intensity continues to increase,but the ecological environment in mining area is deteriorating day by day,sustainable development is facing serious challenges.If relevant protection and control measures are not taken in time,the pollution problem will become more and more serious,which will eventually restrict the economic development and the improvement of people's living standard.Therefore,how to objectively and vividly establish the simulation model of mining ecological environment destruction,and more truly reflect the ecological environment fragile process caused by mining activities,thereby dynamically evaluating ecological environment vulnerability,effectively controlling the mining level,reasonably taking remediation measures,are not only conducive to protect the ecological environment around the mining area,reduce the ecological damage caused by mining,but also in line with the strategic objective of sustainable development.This paper is targeted to dynamically evaluate ecological environment vulnerability in mining area,starting from the basic theory of Petri net and aiming at deficiencies existing in the current research at home and abroad,and committed to put forward a set of theory,model and method about dynamic evaluation of mining ecological environment vulnerability based on Petri net,which can achieve vulnerability assessment more scientifically,objectively and reasonably.Specifically,this paper launches the research mainly from the following aspects:Firstly,in order to use Petri net to calculate actual values,the dynamic evaluation method based on state Petri-net is proposed.It adopts the definition of state Petri net,gives calculation and representation methods of state values in state Petri net,and uses net structure to describe composition framework of vulnerability in fragile mining area and running of net system to reflect the state change process in which ecological environment deteriorates.Moreover,vulnerability calculation is incorporated into running procedure of state Petri-net naturally.Therefore,the vulnerability evaluation based on state Petri net is realized.The state Petri-net model is able to visually display the process of ecological environment degenerating,as well as artificial and natural repair process.It can be used to predict the degree of frangibility in mining area and furthermore provide scientific suggestions for corresponding rehabilitation decisions.Secondly,in order to integrate random time during mining activity into the model,so as to establish more actual simulation model of vulnerable process of ecological environment in mining and evaluate vulnerability dynamically,stochastic Petri net(SPN)is adopted.The place set is divided to destruction state set,repair state set and virtual place set.Ways of representation and calculation method of these three types of places are given respectively.The state value of a place is also to record actual change quantity of this place and vulnerability calculation is integrated into network system running naturally.Then,vulnerability algorithm based on SPN is given.SPN is able to take random time during mining activity into account and to conduct further performance analysis in the help of its isomorphic relationship with Markov chain.Therefore,it can provide scientific reference for prediction of ecological environment vulnerability and analysis of ecological system performance.Finally,considering the circumstance that input and output are known during actual system modeling,but weight parameters are unknown,combining Petri net theory and the basic idea of BP algorithm in neural network,the neural Petri net model for dynamic evaluation of mining ecological environment vulnerability is proposed.Then,we give neural Petri net modeling method,deduce formula of weight error correction in neural Petri net,present the back propagation learning algorithm and give the vulnerability algorithm based on neural Petri net.The neural Petri net model effectively avoids the deficiency that weight parameters are given subjectively artificially in some research,more scientifically and objectively realizes the dynamic evaluation of ecological environment vulnerability in mining area,thus makes the evaluation result more reliable.In recent years,with the increasingly serious ecological environment destruction,the research on ecological environment vulnerability has gradually risen to a hot issue in the field of international ecological environment research.Although domestic and foreign scholars has studied vulnerability evaluation of different ecosystems and different regions,and put forward a variety of evaluation methods,but there are still rare research papers aiming at the mining ecological system vulnerability.It can be said that the study of ecological environment vulnerability in mining area is still in the exploratory stage.Based on basic Petri net model,this paper puts forward a series of models and methods about vulnerability dynamic evaluation,not only compensates some shortcomings in existing research,but also enriches Petri net theory and its application.The research results in this paper provide scientific reference for vulnerability prediction and repair plan selection,as well as new ideas and new methods for the dynamic evaluation of ecological environment vulnerability in mining area,which has important application value.