2,979 publications from this institution
In this study, we propose a hybrid identification algorithm for a class of fuzzy rule-based systems. The rule-based fuzzy modeling concerns structure optimization and parameter identification using the fuzzy inference methods and hybrid structure combined with two methods of optimization theories for nonlinear systems. Two types of inference methods of a fuzzy model concern a simplified and linear type of inference. The proposed hybrid optimal identification algorithm is carried out using a combination of genetic algorithms and an improved complex method. The genetic algorithms determine initial parameters of the membership function of the premise part of the fuzzy rules. In the sequel, the improved complex method (being in essence a powerful auto-tuning algorithm) leads to fine-tuning of the parameters of the respective membership functions. An aggregate performance index with a weighting factor is proposed in order to achieve a balance between performance of the fuzzy model obtained for the training and testing data. Numerical examples are included to evaluate the performance of the proposed model. They are also contrasted with the performance of the fuzzy models existing in the literature. © 2002 John Wiley & Sons, Inc.
Mining through vast arrays of heterogeneous data (no matter where they come from) is a challenging and rewarding pursuit. To make the findings meaningful, the methods of data mining need to be presented to the end-user in a highly intelligible manner. The role of information granules is to cast data mining in the setting of some meaningful nonnumeric entities exhibiting a well-defined semantics. We propose a concept of a linguistic selector and view it as a focal element of data mining. The linguistic selectors are weighted and-combinations of the individual linguistic terms: fuzzy sets or fuzzy relations defined over features (variables) existing in the problem. When operating on a database, they are matched with the individual records and return a certain level of compatibility (matching). The fundamental aspect of such linguistic selectors deals with their relevance in terms of their semantics and statistical relevance. We quantify these two features and propose an optimization problem leading to the design of the meaningful linguistic selectors.