Search results for "Fuzzy set"
showing 10 items of 197 documents
Sobriety and spatiality in varieties of algebras
2008
The paper considers a generalization of the classical Papert-Papert-Isbell adjunction between the categories of topological spaces and locales to an arbitrary variety of algebras and illustrates the obtained results by the category of algebras over a given unital commutative quantale.
"Fixed Point Theorems for '?, ?'Contractive maps in Weak nonArchimedean Fuzzy Metric Spaces and Application"
2011
The present study introduce the notion of (ψ, ϕ)-Contractive maps in weak non-Archimedean fuzzy metric spaces to derive a common fixed point theorem which complements and extends the main theorems of [C.Vetro, Fixed points in weak non-Archimedean fuzzy metric spaces, Fuzzy Sets and System, 162 (2011), 84-90] and [D.Mihet, Fuzzy ψ-contractive mappings in non-Archimedean fuzzy metric spaces, Fuzzy Sets and System, 159 (2008) 739-744]. We support our result by establishing an application to product spaces.
THERP and HEART integrated methodology for human error assessment
2015
Abstract THERP and HEART integrated methodology is proposed to investigate accident scenarios that involve operator errors during high-dose-rate (HDR) treatments. The new approach has been modified on the basis of fuzzy set concept with the aim of prioritizing an exhaustive list of erroneous tasks that can lead to patient radiological overexposures. The results allow for the identification of human errors that are necessary to achieve a better understanding of health hazards in the radiotherapy treatment process, so that it can be properly monitored and appropriately managed.
Towards a Modelization of the elusive Concept of Wisdom using Fuzzy Techniques
2012
After having been a term of reflection in philosophy as well as psychology for ages, the fascination with human wisdom finally reaches the realms of computer science. In comparison to the first philosophical definition attempts, that date back to Aristotle (384 BC – 322BC), the efforts in information science during the late 1980s seem quite recent. Nevertheless have there been astonishing new insights provided by cognitive science since those first formal modelizations were designed – findings that strongly suggest a reconsideration of our current formalization of wisdom in the computer science domain. We suggest to establish a new, integrated view on the concept of wisdom, using the insigh…
Risk analysis using fuzzy set theory of accidental exposure of medical staff during brachytherapy procedures
2010
Using fuzzy set theory, this paper presents results from risk analyses that explore potential exposure of medical operators working in a high dose rate brachytherapy irradiation plant. In these analyses, the HEART methodology, a first generation method for human reliability analysis, has been employed to evaluate the probability of human error. This technique has been modified on the basis of fuzzy set concepts to take into account, more directly, the uncertainties of the so-called error-promoting factors on which the method is based. Moreover, with regard to some identified accident scenarios, fuzzy potential dose was also evaluated to estimate the relevant risk. The results also provide s…
Fuzzy Metric Approach to Aggregation of Risk Levels
2019
In this paper we propose a special construction of a general aggregation operator. The construction allows to aggregate fuzzy sets taking into account the distance between elements of the universe. We consider the case when fuzzy sets to be aggregated represent the risk level evaluation by several experts. We describe how the proposed construction could be applied for risk level assessment in the case when a strong fuzzy metric is used to characterize the similarity of objects under evaluation.
On the robust design of unknown inputs Takagi-Sugeno observer
2012
This paper deals with the observer design for Takagi-Sugeno (T-S) fuzzy models subject to unknown inputs and disturbance affecting both states and outputs of the system. Sufficient conditions to design an unknown input T-S observer are given in Linear Matrix Inequalities (LMIs) terms. Relaxations are introduced by using intermediate variables. Numerical example is given to illustrate the effectiveness of the given result.
Fuzziness, Cognition and Cybernetics: a historical perspective
2015
In the present paper, we connect some old reflections about the relationships existing between the theory of fuzzy sets and cybernetics with modern, contemporary analyses of the crucial (better: unavoidable) role that fuzziness plays in the attempts at scientifically describing aspects of information sciences. The connection, which has a basic conceptual origin, has been triggered also by the recent 50th anniversary of Norbert Wiener’s death which has been instrumental in looking again at some crucial aspects of the birth of information sciences in the midst of the last century. Fuzzy sets are an essential part of this revolution and share all the innovations as well as the difficulties of …
A new approach to fuzzy sets: Application to the design of nonlinear time series, symmetry-breaking patterns, and non-sinusoidal limit-cycle oscillat…
2019
Abstract It is shown that characteristic functions of sets can be made fuzzy by means of the B κ -function, recently introduced by the author, where the fuzziness parameter κ ∈ R controls how much a fuzzy set deviates from the crisp set obtained in the limit κ → 0. As applications, we present first a general expression for a switching function that may be of interest in electrical engineering and in the design of nonlinear time series. We then introduce another general expression that allows wallpaper and frieze patterns for every possible planar symmetry group (besides patterns typical of quasicrystals) to be designed. We show how the fuzziness parameter κ plays an analogous role to temper…
Handling stakeholder uncertain judgments in strategic transport service analyses
2013
Abstract The quality level of services has to be constantly controlled, especially under conditions of competition increasing and limited resources. However, considering that service performance analyses are based on stakeholders' judgments, they can be characterized by possible uncertainties related to incompleteness for partial ignorance, imprecision for subjectivity and even vagueness. Therefore, under these conditions, unreliable results can be obtained by widely used service analysis methodologies. In the present paper, a methodology based on a recent extension of the SERVQUAL model, and that uses in combined manner the fuzzy set theory and the analytic hierarchy process method is prop…