Journal of Intelligent & Fuzzy Systems - Volume 25, issue 2

Authors: Yu, Dejian

Article Type: Research Article

Abstract: An interval-valued intuitionistic fuzzy set (Atanassov and Gargov, 1989) is one of the generalizations of fuzzy set theory. Since it is characterized by a membership range and a non-membership range, it is very useful in modeling real life problems. This study develops an approach to deal with the decision making problems in the context of interval-valued intuitionistic fuzzy sets. First, the generalized interval-valued intuitionistic fuzzy weighted geometric (GIIFWG) and generalized interval-valued intuitionistic fuzzy ordered weighted geometric (GIIFOWG) operators are proposed to aggregate the interval-valued intuitionistic fuzzy values. Then, the properties and special cases of these operators are studied in detail. …Furthermore, an example is provided to illustrate the developed methods. The results reveal that different parameters of the aggregation operators may bring out different ranks of alternatives. Show more

Keywords: Interval-valued intuitionistic fuzzy set, generalized geometric aggregation operator, OWA operator

DOI: 10.3233/IFS-120652

Citation: Journal of Intelligent & Fuzzy Systems, vol. 25, no. 2, pp. 471-480, 2013

Authors: da Silva, Wilson Ricardo Leal | Štemberk, Petr

Article Type: Research Article

Abstract: With a goal of reducing the overall production process variability of Ready-mixed concrete (RMC) and decreasing production costs, a fuzzy logic-based expert system was developed. Inspired by shooting sports, the system guides the plant chief technician by recommending the actions to be taken to reduce variability. Such guidance is based on the evaluation of the compressive strength and coefficient of variation results from the samples molded by those responsible for testing concrete. The system was tested in a RMC plant with monthly production of ≈ 3300 m3 . The results indicate that no major interventions are necessary for the investigated …plant; however, training is likely recommended for some of the staff so as to attain a lower overall variability. These conclusions are in agreement with the technician's interpretation, proving that the system is satisfactory for application in the process. Additionally, a cost analysis was performed, and the results show that a potential reduction of 5.6 % in the monthly production cost can be reached. This represents an attractive reduction since the RMC profit margin is about 8.0 %. Show more

Keywords: Expert system, fuzzy logic, Ready-mixed concrete, compressive strength

DOI: 10.3233/IFS-120655

Citation: Journal of Intelligent & Fuzzy Systems, vol. 25, no. 2, pp. 481-491, 2013

Authors: Di Nuovo, Alessandro | Ascia, Giuseppe

Article Type: Research Article

Abstract: Following the successful applications of the fuzzy models in various application domains, the issue of automatic generation of Fuzzy Rule Based Systems (FRBSs) from observational data was widely studied in the literature and several approaches have been proposed. Most approaches were designed to search for the best accuracy of the generated model, neglecting the interpretability of FRBSs, which is commonly recognized as one of main reasons of the success of fuzzy linguistic models. To fill this gap, a current hot issue in linguistic fuzzy modelling area is the search for a good accuracy-interpretability trade-off. At present, despite the work done, …the definition of interpretability is rather problematic. In fact there is still not an universal index widely accepted. This is mainly because the understanding of fuzzy systems is a subjective task that strongly depends on the background of the person who makes the assessment. In consequence an effective way consists of proposing a fuzzy system index instead of numerical ones. In this paper, we give our contribution proposing a fuzzy system as index to measure both fuzzy rule and set levels complexity of the system. At best of our knowledge there are not indexes to preserve interpretability of a FRBS when it is deep tuned, to this end a new fuzzy system index is formulated and an implementation is presented. To show how our fuzzy system index could be used for interpretability preservation, it is integrated in a classical Multi-Objective Evolutionary Algorithm (MOEA) and its results are presented through six comparative examples based on well-known data sets in the pattern classification field. Show more

Keywords: Interpretable fuzzy systems, fuzzy rule based classifier systems design, Fuzzy linguistic modifiers, genetic fuzzy systems

DOI: 10.3233/IFS-120660

Citation: Journal of Intelligent & Fuzzy Systems, vol. 25, no. 2, pp. 493-504, 2013

Authors: Zhang, Qinghua | Xiao, Yu | Wang, Guoyin

Article Type: Research Article

Abstract: Vague set, as well as intuitionistic fuzzy set, is a further generalization of fuzzy set. Instead of using point-based membership in fuzzy set, interval-based membership is used in vague set. As a result, vague set has more powerful ability to process fuzzy information than fuzzy set in some degree. By exploring the uncertainty of vague set, the disadvantages of existing methods for measuring fuzziness of vague set are analyzed. In order to overcome these disadvantages in existing measuring methods and better characterize uncertainty of vague set, the concept of fuzziness interval of vague set is defined and a new measuring …method, average fuzziness is proposed based on integral calculus method. Accordingly, the proposed method is compared with the existing methods in property, which shows the accuracy of measuring fuzziness of vague set is better than the other methods. Whereas the advantages of the average fuzziness of a vague set, the method of transforming vague set into fuzzy set is proposed and discussed. Show more

Keywords: Vague set, intuitionistic fuzzy set, fuzzy set, fuzziness, uncertainty

DOI: 10.3233/IFS-2012-0571

Citation: Journal of Intelligent & Fuzzy Systems, vol. 25, no. 2, pp. 505-515, 2013