فهرست مطالب
 Volume:12 Issue:2, 2015
 تاریخ انتشار: 1394/03/10
 تعداد عناوین: 11


Pages 121In this paper, we introduce a TakagiSugeno (TS) fuzzy model which is derived from a typical MultiLayer Perceptron Neural Network (MLP NN). At first, it is shown that the considered MLP NN can be interpreted as a variety of TS fuzzy model. It is discussed that the utilized Membership Function (MF) in such TS fuzzy model, despite its flexible structure, has some major restrictions. After modifying the MF, we introduce a TS fuzzy model whose MFs are tunable near and far from focal points, separately. To identify such TS fuzzy model, an incremental learning algorithm, based on an efficient space partitioning technique, is proposed. Through an illustrative example, the methodology of the learning algorithm is explained. Next, through two case studies: approximation of a nonlinear function for a sun sensor and identification of a pH neutralization process, the superiority of the introduced TS fuzzy model in comparison to some other TS fuzzy models and MLP NN is shown.Keywords: Takagi, Sugeno fuzzy model, Multi layer perceptron, Tunable membership functions, Nonlinear function approximation, pH neutralization process

Pages 2340In this paper the fuzzy structural reliability index was determined through modeling epistemic uncertainty arising from ambiguity in statistical parameters of random variables. The First Order Reliability Method (FORM) has been used and a robust genetic algorithm in the alpha level optimization method has been proposed for the determination of the fuzzy reliability index. The sensitivity level of fuzzy response due to the introduced epistemic uncertainty was also measured using the modified criterion of Shannon entropy. By introducing bounds of uncertainty, the fuzzy response obtained from the proposed method presented more realistic estimation of the structure reliability compared to classic methods. This uncertainty interval is of special importance in concrete structures since the quality of production and implementation of concrete varies in different cross sections in reality. The proposed method is implementable in reliability problems in which most of random variables are fuzzy sets and in problems containing nonlinear limit state functions and provides a precise acceptable response. The capabilities of the proposed method were demonstrated using different examples. The results indicated the accuracy of the proposed method and showed that classical methods like FORM cover only special case of the proposed method.Keywords: Fuzzy reliability index, Alpha level optimization method, Genetic algorithm, First order reliability method

Pages 4161In this paper we continue development of formal theory of a special class of fuzzy logics, called EQlogics. Unlike fuzzy logics being extensions of the MTLlogic in which the basic connective is implication, the basic connective in EQlogics is equivalence. Therefore, a new algebra of truth values called EQalgebra was developed. This is a lower semilattice with top element endowed with two binary operations of fuzzy equality and multiplication. EQalgebra generalizes residuated lattices, namely, every residuated lattice is an EQalgebra but not viceversa. In this paper, we introduce additional connective $logdelta$ in EQlogics (analogous to Baaz delta connective in MTLalgebra based fuzzy logics) and demonstrate that the resulting logic has again reasonable properties including completeness. Introducing $Delta$ in EQlogic makes it possible to prove also generalized deduction theorem which otherwise does not hold in EQlogics weaker than MTLlogic.Keywords: EQ, algebra, EQ, logic, Equational logic, Delta connective, Generalized deduction theorem

Pages 6367The purpose of the present work is to introduce the concept of bifuzzy core of a fuzzy automaton, which induces a bifuzzy topology on the stateset of this fuzzy automaton. This is shown that this bifuzzy topology can be used to characterize the concepts such as bifuzzy family of submachines, bifuzzy separable family and bifuzzy retrievable family of a fuzzy automaton.Keywords: Fuzzy automata, Bifuzzy source, Bifuzzy successor, Bifuzzy core, Bifuzzy topology

Pages 7586In this paper the fixed point theorem of Schauder is used to prove the existence of a continuous solution of the nonlinear fuzzy Volterra integral equations. Then using some conditions the uniqueness of the solution is investigated.Keywords: Fuzzy numbers, Fuzzy Volterra integral equations, Existence, uniqueness

Pages 8794In this paper, existence theorems for the fuzzy VolterraFredholm integral equations of mixed type (FVFIEMT) involving fuzzy number valued mappings have been investigated. Then, by using Banach's contraction principle, sufficient conditions for the existence of a unique solution of FVFIEMT are given. Finally, illustrative examples are presented to validate the obtained results.Keywords: Fuzzy Volterra, Fredholm integral equation, Two, dimensional integral equation, Fuzzy integral equations of mixed type, Fuzzy valued function

Pages 95106In this paper, we introduce and study fuzzy variationallike inclusion, fuzzy resolvent equation and $H(cdot,cdot)$$phi$$eta$accretive operator in real uniformly smooth Banach spaces. It is established that fuzzy variationallike inclusion is equivalent to a fixed point problem as well as to a fuzzy resolvent equation. This equivalence is used to define an iterative algorithm for solving fuzzy resolvent equation. Some examples are given.Keywords: Fuzzy variational, like inclusion, Fuzzy resolvent equation, $H(cdot, cdot)$, $phi$, $eta$, accretive operator, Algorithm, Fixed point

Pages 107115In this paper a first step in classifying the fuzzy normal subgroups of a finite group is made. Explicit formulas for the number of distinct fuzzy normal subgroups are obtained in the particular cases of symmetric groups and dihedral groups.Keywords: Fuzzy normal subgroups, Chains of normal subgroups, Maximal chains of normal subgroups, Symmetric groups, Dihedral groups

Pages 117127In this paper, we use parametric form of fuzzy number, then an iterative approach for obtaining approximate solution for a class of nonlinear fuzzy Fredholm integrodifferential equation of the second kind is proposed. This paper presents a method based on NewtonCotes methods with positive coefficient. Then we obtain approximate solution of the nonlinear fuzzy integrodifferential equations by an iterative approach.Keywords: Nonlinear fuzzy integro, differential equations, Newton, Cotes methods

Pages 129136In this paper, we extend the construction of a fuzzy subgroup generated by a fuzzy subset to $L$setting. This construction is illustrated by an example. We also prove that for an $L$subset of a group, the subgroup generated by its level subset is the level subset of the subgroup generated by that $L$subset provided the given $L$subset possesses supproperty.Keywords: $L$, algebra, $L$, subgroup, Normal $L$, subgroup, Generated $L$, subgroup

Pages 137143In the present paper, we give a new approach to Caristi's fixed point theorem on nonArchimedean fuzzy metric spaces. For this we define an ordinary metric $d$ using the nonArchimedean fuzzy metric $M$ on a nonempty set $X$ and we establish some relationship between $(X,d)$ and $(X,M,ast)$%. Hence, we prove our result by considering the original Caristi's fixed point theorem.Keywords: Fixed point, Caristi map, Fuzzy metric space