Iranian journal of fuzzy systems
Volume:11 Issue: 5, Oct 2014

Controller design remains an elusive and challenging problem for uncertain nonlinear dynamics. Interval type-2 fuzzy logic systems (IT2FLS) in comparison with type-1 fuzzy logic systems claim to effectively handle system uncertainties especially in the presence of disturbances and noises, but lack a formal mechanism to guarantee performance. In contrast, adaptive sliding mode control (ASMC) provides a robust mechanism to provide system stability against parameter changes and uncertainties, but suffers from chattering phenomenon.In this paper, a stable indirect adaptive interval type-2 fuzzy PI sliding mode controller (AIT2FSMC) is investigated for a class of nonlinear systems in the presence of system''s unmodeled dynamics and external disturbances. The added Proportional Integral (PI) structure is used to further attenuate the chattering problem that is common in sliding mode control systems. The interval type-2 fuzzy adaptation law adjusts the consequent parameters of the rules based on a Lyapunov synthesis approach. Mathematical analysis proves the closed loop asymptotic stability, while benefiting from human expert knowledge to improve transient response of the system. Application to two nonlinear systems verifies the robustness of the proposed AIT2FSMC approach in the presence ofuncertainties and bounded external disturbances, especially when disturbances have fast changes and large magnitudes.

All steps of a mining project generally disturb the environment''s riginal condition during construction. Therefore, it is crucial to mplement an appropriate mine reclamation plan throughout all mine planning stages from sustainable and environmental point of view.Planting the suitable plant species in each step of any reclamation plan and each area is one of the necessities in this respect. Selecting of plant species is carried out on the basis of the primary factors. After that priorities between the selected speciesare defined on account of the secondary factors by a MCDM model. In this regard, a Fuzzy AHP approach was used. This method was applied to Sungun open pit copper mine in Iran as a case study. Decision making was conducted on the basis of oral judgments and group expertise in the case study. The results achieved from the analysesshowed that the priorities of alternatives are as Maple, Ash, Oak, Barberry, Paliurus spina -Christi, Sloe, respectively.

The idea of difference sequences of real (or complex) numbers was introduced by Ki zmaz cite{Kizmaz}. In this paper, using the difference operator and a lacunary sequence, we introduce and examine the class of sequence $bv_{theta}left(Delta,mathcal{F}right). $ We study some of its properties like solidity, symmetricity, etc.

In 1997, Fang proposed the concept of boundedness of $L$-fuzzy sets in $L$-topological vector spaces. Since then, this concept has been widely accepted and adopted in the literature. In this paper, several characterizations of bounded $L$-fuzzy sets in $L$-topological vector spaces are obtained and some properties of bounded $L$-fuzzy sets are investigated.

Statistical process control ($SPC$), an internationally recognized technique for improving product quality and productivity, has been widely employed in various industries. $SPC$ relies on the use of control charts to monitor a manufacturing process for identifying causes of process variation and signaling the necessity of corrective action for the process. Fuzzy data exist ubiquitously in the modern manufacturing process, and in this paper, two alternative approaches to fuzzy control charts are developed for monitoring sample averages and range. These approaches are based on «fuzzy mode» and «fuzzy rules» methods, when the measures are expressed by non-symmetric triangular fuzzy numbers. In contrast to the existing fuzzy control charts, the proposed approach does not require the use of the defuzzification and this prevents the loss of information included in samples. A numeric example illustrates the performance of the method and interprets the results.

A new approach to define the similarity measure between interval-valued fuzzy sets is presented. The proposed approach is based on a weighted measure in which the normalized similarities between lower functions and also between upper functions arecombined by a weight parameter. The properties of this similarity measure are investigated. It is shown that, the proposed measure has some advantages in comparison with the commonly used similarity measures.

In this paper, the concept of fuzzy metric-like spaces is introduced which generalizes the notion of fuzzy metric spaces given by George and Veeramani cite{Vee1}. Some fixed point results for fuzzy contractive mappings on fuzzy metric-like spaces are derived. These results generalize several comparable results from the current literature. We also provide illustrative examples in support of our new results where result from current literature are not applicable.

Employing the notions of the strong $L$-topology introduced by Zhang and the $L$-frame introduced by Yao and the concept of $L$-enriched topological system defined in the present paper, we construct adjunctions among the categories {bf St$L$-Top} of strong $L$-topological spaces, {bf S$L$-Loc} of strict $L$-locales and {bf $L$-EnTopSys} of $L$-enriched topological systems. All of these concepts are essentially based on the theory of $L$-enriched categories, thus we obtain a unified enriched-categorical version of the classical adjunctions among the categories {bf Top} of topological spaces, {bf Loc} of locales and {bf TopSys} of topological systems, as well as a unified enriched-categoricalapproach to treating these concepts.