Search results for "Fuzzy set"
showing 10 items of 197 documents
A Stochastic Soft Constraints Fuzzy Model for a Portfolio Selection Problem
2006
The financial market behavior is affected by several non-probabilistic factors such as vagueness and ambiguity. In this paper we develop a multistage stochastic soft constraints fuzzy program with recourse in order to capture both uncertainty and imprecision as well as to solve a portfolio management problem. The results we obtained confirm the studies carried out in literature addressed to integrate stochastic and possibilistic programming.
Fuzzy green vehicle routing problem for designing a three echelons supply chain
2020
Abstract In this study, a three-echelon fuzzy green vehicle routing problem (3E-FGVRP) is considered for designing a regional agri-food supply chain on a time horizon. To account for the variability associated with the quantities requested by customers, it is assumed that the demands are fuzzy numbers simulated by a time-dependent algorithm. Moreover, the vehicle fleet and distribution centres are considered with a defined capacity. The credibility theory of fuzzy sets is used to implement a multi-objective fuzzy chance-constrained programming model, where the total costs and carbon emissions are minimised. The resolution of the 3E-FGVRP is conducted by using a non-dominated sorting genetic…
A methodology for the reduction of imprecision in the engineering process
1997
Abstract Engineering design is characterized by a high level of imprecision, vague parameters, and ill-defined relationships. In design, imprecision reduction must occur to arrive at a final product specification. Few design systems exist for adequately representing design imprecision, and formally reducing it to precise values. Fuzzy set theory has considerable potential for addressing the imprecision in design. However, it lacks a formal methodology for system development and operation. One repercussion of this is that imprecision reduction is, at present, implemented in a relatively ad-hoc manner. The main contribution of this paper is to introduce a methodology called precision converge…
A fuzzy approach to the evaluation of image complexity
2009
The inherently multidimensional problem of evaluating the complexity of an image is of a certain relevance in both computer science and cognitive psychology. Computer scientists usually analyze spatial dimensions in order to deal with automatic vision problems, such as feature extraction. Psychologists seem more interested in the temporal dimension of complexity, as a means to explore attentional models. Is it possible to define, by merging both approaches, a more general index of visual complexity? The aim of this paper is the definition of objective measures of image complexity that fits with the so named perceived time. Towards the end we have defined a fuzzy mathematical model of visual…
Are There Essentially Incomplete Knowledge Representation Systems?
2001
A mathematical model of a knowledge representation system (KR-system) is proposed. Its prototype is the concept of an information system in the sense of Z. Pawlak; however, the model is, in fact, a substantial extension of the latter. In our model, attributes may form an arbitrary category, where morphisms represent built-in functional dependencies, and uncertainty of knowledge is treated in terms of category theory via monads. Several notions of simulation are also considered for such KR-systems. In this general setting, the semiphilosophical problem mentioned in the title, still open, is given a precise meaning.
Mathematics and Soft Computing in Music
2011
Mathematics is the fundamental tool for dealing with the physical processes that explain music but it is also in the very essence of this art. Musical notes, the first elements which music works with, are defined for each tuning system as very specific frequencies; however, instrumentalists know that small changes in these values do not have serious consequences. In fact, sometimes consensus is only reached if the entire orchestra alters the theoretical pitches. The explanation for this contradiction is that musicians implicitly handle very complex mathematical processes involving some uncertainty in the concepts and this is better explained in terms of fuzzy logic. Modelling the notes as f…
Compatibility of the Different Tuning Systems in an Orchestra
2009
Focusing on the daily practice of musicians, we give flexibility to the mathematical treatment of musical notes, tuning systems and the relations between them. This allows us to connect the theory and the practice of music. Using the techniques of fuzzy logic, we describe the concepts with fuzzy sets and introduce the α-compatibility as a degree of interchangeability between tuning systems. To show how our proposal works, we use a fragment of Haydn and analyze the compatibility of the notes taken from 48 recordings for the tuning systems of Pythagoras, Zarlino and Equal Temperament of 12 notes.
Fuzzy logic helps to integrate music theory and practice
2010
Among the many practices of composers, instrumentalists and singers which clearly correspond with fuzzy logic our focus here is on tuning. Different criteria have been used to select the sounds that music uses. A set containing these sounds (musical notes) is called a tuning system. Several tuning systems coexist in a classical orchestra. The pitches of the notes are different and very precisely defined for each system; however the consequences of small deviations from these theoretical frequencies are not serious. Actually, the orchestra members are aware of the necessity of reaching a consensus and adjust their instruments to tune well. Because of this, many musicians feel that the mathem…
A fuzzy-set analysis of conditions influencing mutual fund performance
2019
Abstract This paper presents an application of fuzzy-set qualitative comparative analysis (fsQCA) to frame the conditions that lead to over- or under-performance of mutual funds. Building upon a considerable library of research on fund returns, the study uses fsQCA to affirm and extend earlier discoveries. Considered here is fund performance relative to Morningstar ratings, features of the funds themselves, as well as characteristics of the fund managers. Results suggest that positive Morningstar and analyst ratings are necessary conditions, on average, for funds to generate value according to the Jensen's alpha ratio. Just over seven percent of the cases imply that funds have attractive Sh…
Non-fragile fuzzy control design for nonlinear time-delay systems
2013
In this paper, a non-fragile fuzzy control design is proposed for a class of nonlinear systems with mixed discrete and distributed time delays. The Takagi and Sugeno (T-S) fuzzy set approach is applied to the modelling of the nonlinear dynamics, and a T-S fuzzy model is constructed, which can represent the nonlinear system. Then, based on the fuzzy linear model, a fuzzy linear controller is developed to stabilize the nonlinear system. The control law is obtained to ensure stochastically exponentially stability in the mean square. The sufficient conditions for the existence of such a control are proposed in terms of certain linear matrix inequalities.