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Study On Optimization And Decision-making Theory And Method For Water Resources Systems Under Fuzzy Environment

Posted on:2004-04-26Degree:DoctorType:Dissertation
Country:ChinaCandidate:G T FuFull Text:PDF
GTID:1102360092480325Subject:Hydrology and water resources
Abstract/Summary:PDF Full Text Request
The exploitation, utilization, restoration, protection and management of water resources are all the activities to natural water systems, by which human beings can obtain the resources or reduce the loss from disasters. The above activities must involve decision makings. The factors effecting optimization of water resources systems arise from nature, society, economy, techniques, which are classified into two types: complex paradigm and uncertainty paradigm. Fuzzy sets theory is a powerful tool to deal with the two paradigms. Based on theories, models and approaches of optimization and decision makings in the context of fuzzy hydrology and water resources, this paper concentrates on the theories of optimization and decision making for water resources systems under fuzzy environment. The conclusions are as follows.By analyzing the types of the formulas of relative membership degrees, a pair of formulas of relative membership degree is proposed. The effects on the optimization results from non-linearization and different types are analyzed through the case study of optimum operation of flood control. The formulas proposed in this paper are with good results because of the integration of the influence from the scope of objective values and objective weights. Furthermore, the sensitivity of relative membership degrees is analyzed and a sufficient condition is derived for keeping the optimal decision ranking unchanged.Fuzzy optimization, fuzzy pattern recognition and fuzzy clustering are the mathematical basis for optimization and decision of water resources systems, and they have received a variety of applications. However there is a little study on how to apply the models to fuzzy environment. This paper first introduces the distance measure between triangular fuzzy numbers and between trapezoid fuzzy numbers. Then it applies the fuzzy numbers to the models proposed by Prof. Chen Shouyu, including fuzzy optimization, fuzzy pattern recognition and fuzzy clustering. In this way, the models are extended to optimization and decision makings under fuzzy environment. The proposed models can efficiently deal with uncertainty and capture the judgment, knowledge and preference, so they provide a new approach to complex optimization and decision making for water resources under fuzzy environment. The case study demonstrates the efficiency and feasibility of the proposed models.The proposed fuzzy pattern recognition model under fuzzy environment is applied to theIVevaluation of groundwater vulnerability. According to the experiential data of the DRASTIC index, the standard values of 10 classes for 7 indexes are proposed in the form of triangular fuzzy numbers, and similarly the weights of indexes are expressed in the form of triangular fuzzy numbers. A fuzzy recognition approach thereby is applied to evaluate the groundwater vulnerability under fuzzy environment. The case study of Dalian shows that the approach is robust and practical.Decision makings of water resources systems are of the characteristics of multi-objective and multistage. The fuzzy pattern recognition model, fuzzy cross iteration model and fuzzy pattern recognition model under fuzzy environment are regarded as a class of aggregation operators. The operators can not only integrate the influence of quantitative and qualitative objectives but also obtain the judgment, knowledge and preference of decision makers through nonstructural decision analysis method in the dynamic decision making process. Further, the operators are incorporated into fuzzy optimization dynamic programming, which are in this way extended to multiobjective and multistage decision making problems of water resources systems under fuzzy environment.Genetic algorithms are combined with fuzzy pattern recognition model to establish a multiobjective genetic algorithm. Then it is applied to solve the problem of flood control, where a multiobjective flood control model is established and the fuzzy pattern recognition is used to evaluate the individual fitness. Flood control of Feng...
Keywords/Search Tags:water resources systems, optimization, decision analysis, complexity, uncertainty, fuzzy environment, fuzzy sets, genetic algorithms
PDF Full Text Request
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