Journal of Intelligent & Fuzzy Systems - Volume 22, issue 5-6

Authors: Amirfakhrian, Majid

Article Type: Research Article

Abstract: In this research an algebraic fuzzy equation of degree n with crisp coefficients and fuzzy variable has been introduced and presented an iterative method to find the fuzzy roots of it, numerically. An algorithm also has been presented to generate a sequence that can be converged to the root of an algebraic fuzzy equation.

Keywords: Nearest approximation, fuzzy numbers, fuzzy polynomial, algebraic fuzzy equation

DOI: 10.3233/IFS-2011-0483

Citation: Journal of Intelligent & Fuzzy Systems, vol. 22, no. 5-6, pp. 207-216, 2011

Authors: Ghadiri, Nasser | Baraani-Dastjerdi, Ahmad | Ghasem-Aghaee, Nasser | Nematbakhsh, Mohammad A.

Article Type: Research Article

Abstract: Collaborative and group-based queries aim to find one or more points in a search space which have the minimum aggregate distance to all members of a group, situated at a set of query points. Current approaches like Group Nearest-Neighbor (GNN) queries are based on single-measure models of distance, like Euclidean distance. In reality, human has a multi-measure perception of distance so that spatial, temporal and economical aspects are important to people with possibly different individual preferences. Current approaches to GNN are unable to handle such distance measures, since it depends on the perceptions and preferences of the users. In this …study, we focus on the role of users, as members of a group, situated at GNN query points. An enriched model of distance is introduced which takes the advantage of interval type-2 fuzzy sets to cope with high-order distance uncertainties, emerged from different perceptions of distance by users, and their different preferences. The flexibility of this aggregate model in handling uncertainty enables every member of the group to use a set of group-defined words to express his/her perception of multiple distance types, and to use words instead of numeric values to set the weights for each distance type according to his/her preferences. Our experimental evaluations show that the query results are closer to group preferences by providing higher quality of consensus, while keeping the spatial dispersion of the top-k results at a small level, and improved performance with reasonable response time. The proposed distance model also provides more robustness to changes of mobile member locations, eliminating unnecessary repeated computations. Show more

Keywords: Distance perception, community consensus, spatio-temporal query, type-2 fuzzy sets, computing with words

DOI: 10.3233/IFS-2011-0484

Citation: Journal of Intelligent & Fuzzy Systems, vol. 22, no. 5-6, pp. 217-236, 2011

Authors: Baykasoglu, Adil | Gocken, Tolunay

Article Type: Research Article

Abstract: Inventory management is critical for many industries. A proper control of inventory can considerably enhance a company's profit margins. Determination of the Economic Order Quantities (EOQ) is important in order to achieve optimal operating conditions. There are various EOQ models which originate from the classical EOQ model in the literature. In reality, it is not easy to determine parameters of an EOQ model precisely. Fuzzy set theory gives an opportunity to represent the linguistic terms and vagueness in EOQ models. In the literature, various researchers solved different fuzzy versions of EOQ problem. In this study, a fully fuzzy constrained multi-item …EOQ model is considered. The parameters of the problem are defined as triangular fuzzy numbers. The fuzzy constrained multi-item EOQ problem is tried to be solved directly by employing four different fuzzy ranking functions and Particle Swarm Optimization (PSO) algorithm. One of the primary objectives of this study is to show that fuzzy mathematical programming models can also be solved directly by employing fuzzy ranking functions and meta-heuristic algorithms. Results obtained from both approaches (direct approach and transformation approach) are also reported in the paper. Show more

Keywords: Fuzzy mathematical programming, economic order quantity, fuzzy ranking, particle swarm optimization

DOI: 10.3233/IFS-2011-0486

Citation: Journal of Intelligent & Fuzzy Systems, vol. 22, no. 5-6, pp. 237-251, 2011

Authors: Alizadeh, H. Moheb | Ghomi, S.M.T. Fatemi

Article Type: Research Article

Abstract: This paper develops Mean and Range control charts in fuzzy environment using different transformation methods. It is assumed that the observations of each sample are fuzzy random variables, which have triangular membership functions. After calculating fuzzy mean and fuzzy range of each sample using fuzzy arithmetic, their representative values are calculated exploiting the transformation methods. Then, using statistical properties of the obtained representative values and basic structure of Shewhart control charts, new Mean and Range control charts are constructed to monitor the process mean and variation. After that, the power of control charts constructed based on different transformation methods are …examined applying average run length (ARL) criterion. According to this criterion, it is concluded that, contrary to the previous claim, these different transformation methods lead to mean and rang control charts with various performances. Moreover, it is represented that the value of α – level has significant influence on the performance of obtained control charts. Finally, it is derived that incorporating fuzziness into observations results in less powerful control charts. Show more

Keywords: Mean and Range control charts, fuzzy sets, transformation methods, fuzzy random variable, ARL criterion

DOI: 10.3233/IFS-2011-0487

Citation: Journal of Intelligent & Fuzzy Systems, vol. 22, no. 5-6, pp. 253-265, 2011

Authors: Coza, C. | Nicol, C. | Macnab, C.J.B. | Ramirez-Serrano, A.

Article Type: Research Article

Abstract: The nonlinear and open-loop unstable dynamics of a quadrotor helicopter makes a control system design non-trivial. However, even more difficulty lies in adapting to an uncertain dynamic model and unknown payloads while remaining robust to significant buffeting wind disturbances. Fuzzy-adaptive or neural-adaptive control offer possible solutions, exhibiting computational efficiency and adaptation to arbitrary nonlinearities. A common method for making these adaptive controls robust to disturbances, e-modification, is found to be unsuitable when applied to the quadrotor in simulation. The adaptive parameters tend to drift to large values in the presence of a sinusoidal disturbance. In this work, we propose a …method that uses alternate adaptive parameters in the adaptation scheme. The proposed method successfully controls the quadrotor in simulation, with realistic control signals and computational effort. The adaptive parameter drift and control chatter present with e-modification both vanish. Moreover, performance improves dramatically in the presence of disturbances. Show more

Keywords: Adaptive fuzzy control, neural adaptive control, cerebellar model articulation controller (CMAC), quadrotor helicopter, helicopter control

DOI: 10.3233/IFS-2011-0488

Citation: Journal of Intelligent & Fuzzy Systems, vol. 22, no. 5-6, pp. 267-283, 2011

Article Type: Correction

DOI: 10.3233/IFS-2011-0485

Citation: Journal of Intelligent & Fuzzy Systems, vol. 22, no. 5-6, pp. 285-285, 2011

Article Type: Other

Citation: Journal of Intelligent & Fuzzy Systems, vol. 22, no. 5-6, pp. 287-288, 2011