Search results for "fuzzy"
showing 10 items of 747 documents
Risk assessment of component failure modes and human errors using a new FMECA approach: application in the safety analysis of HDR brachytherapy
2014
Failure mode, effects and criticality analysis (FMECA) is a safety technique extensively used in many different industrial fields to identify and prevent potential failures. In the application of traditional FMECA, the risk priority number (RPN) is determined to rank the failure modes; however, the method has been criticised for having several weaknesses. Moreover, it is unable to adequately deal with human errors or negligence. In this paper, a new versatile fuzzy rule-based assessment model is proposed to evaluate the RPN index to rank both component failure and human error. The proposed methodology is applied to potential radiological over-exposure of patients during high-dose-rate brach…
Handover management in heterogenous mobile and wireless networks
2015
Since 1990, networking and mobile technologies have made a phenomenal unprecedented progress. This progress has been experienced on multiple fronts in parallel; especially on the application level and the user's needs one. This rapid evolution of the technology imposed a need for the existence of heterogeneous environments where the coverage is ensured throughout the different available networks. The challenge with such architecture would be to provide the user with the ability to navigate through the different available networks in a transparent and seamless fashion. However, the navigation among different types of networks is commonly referred to as vertical Handover. The IEEE 802.21 stan…
A Few Remarks on the Roots of Fuzziness Measures
2012
In the forty years from the introduction of Fuzzy Entropy, fuzziness measures has been employed in many different fields pertaining both hard and soft sciences, from medicine to art, from engineering to linguistics. If we look back at the road traveled, we can safely state that on of the main reasons for this enduring presence, and maybe the most underrated, is the truly uniqueness of the concept of fuzziness. Far from a reminiscence, this consideration is more of a projection on the future of fuzziness: we strongly believe that the innovation implicit in the concept, while having sometime hindered in the past its perception as a powerful paradigm and tool for the hard science community, wi…
Do Uncertainty and Fuzziness Present Themselves (and Behave) in the Same Way in Hard and Human Sciences?
2010
In the present paper the question whether uncertainty and fuzziness present themselves and behave in the same way (or not) in hard and human sciences will be briefly discussed. This problem came out from the attempt to answer the question asked by Lotfi Zadeh on the (apparent) strangeness of a very limited use of fuzzy sets in human sciences.
Implementation of a new adaptive algorithm using fuzzy cost function and robust to impulsive noise
2012
Adaptive filters are used in a wide range of applications such as noise cancellation, system identification, and prediction. One of the main problems for theses filters is the impulsive noise as it generates algorithm unstability. This work shows the development, simulation and hardware implementation of a new algorithm robust to impulsive noise. Hardware implementation becomes essential in many cases where a real time execution, reduced size, or low power system is needed. An efficient hardware architecture is proposed and different optimizations for size and speed are developed: no need for control state machine, reduced computation requirements due to simplifications, etc. Furthermore, t…
Towards the theory of M-approximate systems: Fundamentals and examples
2010
The concept of an M-approximate system is introduced. Basic properties of the category of M-approximate systems and in a natural way defined morphisms between them are studied. It is shown that categories related to fuzzy topology as well as categories related to rough sets can be described as special subcategories of the category of M-approximate systems.
Fuzzy Set Theory as a Methodological Bridge between Hard Sciences and Humanities
2013
In this paper, we will investigate the possible role of fuzzy set theory (FST), and more generally the ensemble of technologies and theoretical approaches known as soft computing, as a methodological bridge between hard sciences and humanities. We will try, building on previous works, to investigate the “family links” between these disciplines and show how FST may be of help in promoting a connection between the “two cultures”. We will discuss Carnap and his paradox of explication, the dilemma between imagination and rigor according to Bateson, the problem of interdisciplinarity, and the consequences of precision and exactness. C
Uncertainty and Equifinality in Calibrating Distributed Roughness Coefficients in a Flood Propagation Model with Limited Data
1998
Monte-Carlo simulations of a two-dimensional finite element model of a flood in the southern part of Sicily were used to explore the parameter space of distributed bed-roughness coefficients. For many real-world events specific data are extremely limited so that there is not only fuzziness in the information available to calibrate the model, but fuzziness in the degree of acceptability of model predictions based upon the different parameter values, owing to model structural errors. Here the GLUE procedure is used to compare model predictions and observations for a certain event, coupled with both a fuzzy-rule-based calibration, and a calibration technique based upon normal and heteroscedast…
Fuzzy Non-fragile H∞ Tracking Control for Flexible Air-breathing Hypersonic Vehicles
2012
Abstract This paper proposed a fuzzy non-fragile tracking control design method for flexible air-breathing hypersonic vehicles (FAHVs). The T-S fuzzy set approach is applied to the modeling of the complex nonlinear dynamics of FAHVs, and a T-S fuzzy model is constructed, which can represent the nonlinear hypersonic vehicle system. Then, by considering the actuator controller coefficients uncertainties and disturbances, the fuzzy non-fragile H ∞ tracking problem for FAHVs is proposed. A state-feedback controller design method is proposed to guarantee the tracking performance in the presence of actuator controller coefficients uncertainties. By a Lyapunov approach, the existence conditions fo…
Fuzzy Concepts in Small Worlds and the Identification of Leaders in Social Networks
2014
In the study of the Social Networks, the Small World phenomenon appears frequently. We apply some techniques of graph theory and fuzzy sets to characterize the Small World features as well as the existence of the figure of leader in Social Networks. These techniques help to the conceptual formalization in relational networks analysis, by transforming linguistic and human-focused manner concepts related to social networks in some formal representation. These techniques are also applied when the similarity among nodes wants to be measured in order to study the current homophily present in a Network.