基于状态Petri网的矿区生态环境脆弱度动态评价方法

Dynamic evaluation method for the ecological environment vulnerability in the mining area based on the state Petri-net

采用状态Petri网模型对矿区生态环境脆弱度进行动态评价,给出了状态Petri网中累积值、加权值、不变值和虚拟值4种不同状态值的计算及表示方法,提出了基于状态Petri网的矿区生态环境脆弱度计算方法。库所的累积值用于计算采矿过程中环境指标的总变化量。加权值主要用于脆弱度的计算。具有不变值的库所在相应的变迁被激发前后状态值均保持不变。没有实际意义的虚拟值在状态Petri网中仅起到逻辑或过渡作用。网结构描述了矿区生态环境脆弱度的组成结构,网系统的运行反映了生态环境脆弱化的状态变化过程,并且将脆弱度的计算融入了状态Petri网的运行中。在案例研究中,绘制了4种修复方案下脆弱度的变化情况曲线,表明该评价方法可以对矿区生态环境脆弱度进行动态评价。状态Petri网模型能将矿区生态环境脆弱化过程,以及人工修复和自然修复过程直观形象地展现出来,为预测矿区生态环境脆弱度的变化情况及制定相应的修复方案提供参考。该模型适用于矿山长期开采对生态环境造成破坏过程的建模及计算,而且对矿山的开采过程也不需要作特别的假设限制。

The paper is intended to propose a method for calculating the ecological environmental vulnerability confronted by the mining area based on the state Petri-net. For the said purpose,we have proposed the calculation and representation method for the four kinds of status values,that is,the Petri-net accumulated value,the weighted value,the constant value,as well as the virtual value. As to the accumulated value of a place,the method is intended to be used for calculating the total changing value of environment indicators during the mining process,whereas the weighing value is mainly to be applied in the calculation of vulnerability. The state value of a place has to be taken as the constant value,which keeps unchanged pre-and-post the corresponding transition. The so-called virtual value is used to refer to the logical or transitional one without any practical meaning,which merely indicates some nominal role or function in the Petri-net. The socalled composition framework of the vulnerability has to be described by the net structure in the fragile mining area,whereas the net system running is intended to reflect the state changing process of the deterioration of the ecological environment. What is more,the vulnerability calculation has to be incorporated into the naturally running procedure of the state Petri-net. Furthermore,we have laid out a case study curve graph to indicate the vulnerability variation in the four different repair schemes,which proves that the proposed evaluation method is feasible to evaluate dynamically the ecological environmental vulnerability in the mining area. It also shows that the state Petri-net model can visually display the process of ecological environment degeneration,and the corresponding artificial and natural repair or restoration process. Thus,what is stated above can prove that the model we have developed can be used to predict the degree of frangibility of the mining area and present corresponding scientific suggestions for rehabilitation decisions. Therefore,it can be predicted that it is available and suitable for modeling and evaluating the deteriorating evolutional processes of the ecological environments caused by the long-term mining exploitation,though no particular assumptions or limitations are imposed to the mining process in this model. Hence,the paper is entitled to offer a novel approach to the dynamic evaluation of ecological environmental vulnerability for the mining area.