The Application Of Fuzzy Set Theory In The Water Environment Systems - Water Quality Assessment

This paper systematically studies the application of engineering fuzzy sets system theory and method to the evaluation of water quality pollution problems existed in environmental systems, which includes six chapters briefly introduced as follows.First, fuzzy concepts are to be recognized as objective and pervasive natural attributes in water environmental systems, and the significance and necessity of the application of engineering fuzzy sets theory to this field are also discussed. Then, combining with reference review, the research tendency of fuzzy sets theory in water quality evaluation is summarized. Finally, the framework and key points of this paper are generalized.Chapter 2 mainly reviews fuzzy recognition., fuzzy partition and fuzzy decision making theory proposed by Prof. Chen Shouyu, which are the theoretical foundation of this paper. In Chapter 3, the study-worthy problems of applying engineering fuzzy sets theory to (lie recognition of water quality are first discussed, then the mathematical and physical features of fuzzy iteration method, with a goal function of least quadratic sum of weighted general Euclidean weighted distances, are profoundly demonstrated. The scientific evaluation of water quality is an important research field in basic theory study of modern environmental science, and the rationality of the selected evaluation methods has a direct influence on the reliability of the evaluation results. Due to the existed fuzzy concepts, engineering fuzzy sets theory is introduced into environmental evaluation in Chapter 4, and then fuzzy synthetic evaluation model is used to carry out water quality evaluation, which is based on precise mathematical model, and is more consistent with the fact of water quality compared with the result from traditional evaluating methods. In Chapter 5, based on the characteristics of water environmental evaluation and fuzzy pattern recognition model proposed by Prof. Chen Shouyu, a new formula to transform decision-making index matrix into the relative membership degree matrix is introduced, then under dynamic ranking conditions, the fuzzy recognition model presented by Prof. Chen is used to implement evaluation, which has reasonable structure, and can fully integrate the information from real data, and consequently leads to more reliable evaluating results.Chapter 6 generalizes the above work, and presents research tasks to be studied further.This paper aims to study the application of engineering fuzzy sets theory to water environmental systems, especially to water quality evaluation. Compared with the traditional methods used in environmental protection sectors, the applicability of engineering fuzzy sets theory and method to water environmental systems is further validated, which offers more reasonable reference to polluted status of city water resources.