Papers by Keyword: Fuzzy Variable

Abstract: Edge covering problem, dominating set problem, and independent set problem are classic problems in graph theory except for vertex covering problem. In this paper, we study the maximum independent set problem under fuzzy uncertainty environments, which aims to search for the independent set with maximum value in a graph. First, credibility theory is introduced to describe the fuzzy variable. Three decision models are performed based on the credibility theory. A hybrid intelligence algorithm which integrates genetic algorithm and fuzzy simulation is proposed due to the unavailability of traditional algorithm. Finally, numerical experiments are performed to prove the efficiency of the fuzzy decision modes and the hybrid intelligence algorithm.

Abstract: Edge covering problem, dominating set problem, and independent set problem are classic problems in graph theory except for vertex covering problem. In this paper, we study the maximum independent set problem under fuzzy uncertainty environments, which aims to search for the independent set with maximum value in a graph. First, credibility theory is introduced to describe the fuzzy variable. Three decision models are performed based on the credibility theory. A hybrid intelligence algorithm which integrates genetic algorithm and fuzzy simulation is proposed due to the unavailability of traditional algorithm. Finally, numerical experiments are performed to prove the efficiency of the fuzzy decision modes and the hybrid intelligence algorithm.

Abstract: Liu process is a special fuzzy process which plays an important role in the theory of fuzzy differential equations. This paper proposes the concept of reflected Liu process at the origin. Then some properties of this type of Liu process are deduced.

Abstract: When calculating Liu integral, it is difficult to use the definition of Liu integral directly. As we know, the mean value theorem of integral is an important tool to calculate Riemann integral, inspired by this, the mean value theorem of a new kind of fuzzy integral was obtained in this paper.

Abstract: The mechanical fuzzy reliability models based on cut-set method have been applied to many fields in engineering. The reliability analysis results are affected by the cut-set distribution. In this paper, a basic mechanical fuzzy reliability model using cut-set method was established. Based on this model, the deficiency of the three previous cut-set distributions, i.e. uniform distribution, linear distribution and truncated normal distribution, was analyzed, and a new cut-set distribution named modified truncated normal distribution was proposed. The analysis results showed that when the cut-set is long enough, the reliabilities of the fuzzy models with the three previous cut-set distributions tend to a fixed value which has nothing to do with the specific mechanical structures, which makes the models have no good convergence and unreasonable. While, the fuzzy reliability model with the new cut-set distribution proposed in this paper can converge well to the classical random reliability model. Moreover, the reliabilities of a stress-strength interference problem and a resonance problem were assessed as two examples to verify the theoretical analysis results, which indicate that with this new cut-set distribution, the fuzzy reliability models have better convergence and wider applications.

Abstract: In the paper, some properties related to the moment generating function of a fuzzy variable are discussed based on uncertainty theory. And we obtain the result that the convergence of moment generating functions to an moment generating function implies convergence of credibility distribution functions. Thats, the moment generating function characterizes a credibility distribution.

Abstract: In the paper, some properties related to characteristic function of a fuzzy variable are discussed based on uncertainty theory.

Abstract: This paper offers an assessment of flight delays rating, which deals with general concept of risk and safety. With the use of linguistic terms, subjective assessments of qualitative delays rating indexes are represented with fuzzy variable. The relative weights of rating attributes are assessed using a pairwise comparison process. Based on the concept of optimality, Fuzzy simulation approach is employed to dispose of the evaluation model and compute the expected values. Finally, an empirical study about a major domestic airline is conducted to demonstrate the effectiveness of the approach.

Abstract: An integrated supplier selection problem under fuzzy environment is studied in this paper. Firstly, the linear weight method is used to calculate the scores of suppliers according to their different attributes, such as: quality, service, warranty, delivery, reputation and position, which are assumed as fuzzy variables. Secondly, a fuzzy expected value programming model and a fuzzy chance-constrained programming model are proposed to select the best combination of the suppliers and determine the order quantities. A hybrid intelligent algorithm, based on fuzzy simulation, genetic algorithm and neural network, is used to solve the two models. Finally, a numerical example is given to illustrate the effectiveness of the proposed models.

Abstract: With the development of network technology and electronic commerce, an increasing number of people started on-line shopping. And the information of a probability distribution of the goods market demand is not easy to get due to lack of historical data. To resolve these two problems, this paper gives a system framework and model of returns policy for supply chain with electronic market in fuzzy environment. Basing on the uncertainty theory, this paper characterizes the demand of traditional and electronic market as fuzzy variables. A fuzzy expected value model is formulated for this problem, and a hybrid intelligent algorithm is designed to solve it.