• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.323-330
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• 2017

Recently Samet, Vetro and Vetro introduced the notion of ${\alpha}$-${\Psi}$-contractive type mappings and initiated some fixed point theorems in complete metric spaces. The notion of ${\alpha}_*$ - ${\Psi}$-contractive multifunctions and initiated some fixed point results by Hasanzade Asl et. al. [8]. In this paper, we introduced the notion of ${\alpha}_*$ - ${\Psi}$-contractive multifunctions in a fuzzy metric space and gave fixed point results for these multifunctions in complete fuzzy metric spaces. We also obtain a fixed point results for self-maps in complete fuzzy metric spaces satisfying contractive condition.

• Bulletin of the Korean Mathematical Society
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• v.41 no.4
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• pp.647-656
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• 2004

In this paper, by using operations, some characterizations and some properties of fuzzy lower and upper continuous multifunctions and its weaker and stronger forms including fuzzy lower and upper weakly continuous, fuzzy lower and upper ${\theta}-continuous$, fuzzy lower and upper strongly ${\theta}-continuous$, fuzzy lower and upper almost strongly ${\theta}-continuous$, fuzzy lower and upper weakly ${\theta}-continuous$, fuzzy lower and upper almost continuous, fuzzy lower and upper super continuous, fuzzy lower and upper ${\delta}-continuous$, are presented.

• East Asian mathematical journal
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• v.23 no.1
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• pp.9-22
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• 2007

New classes of multifunctions called fuzzy upper and fuzzy lower semi-irresolute (semi-continuous) multifunctions in fuzzy topological spaces are introduced in this paper. We also obtain some characterizations of this class and some basic interesting properties of such fuzzy multifunctions. We discuss mutual relationship and also relationship with other existing such multifunctions.

• Journal of Power Electronics
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• v.14 no.3
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• pp.444-457
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• 2014

This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with $k_i$ and $R_L$ as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of $R_L$ and the operating point of the PV simulator to match the controller parameters with $R_L$. The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.