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The exact output regulation problem for Takagi-Sugeno (TS) fuzzy models, designed from linear local subsystems, may have a solution if input matrices are the same for every local linear subsystem. Unfortunately, such a condition is difficult to accomplish in general. Therefore, in this work, an adaptive network-based fuzzy inference system (ANFIS) is integrated into the fuzzy controller in order to obtain the optimal fuzzy membership functions yielding adequate combination of the local regulators such that the output regulation error in steady-state is reduced, avoiding in this way the aforementioned condition. In comparison with the steepest descent method employed for tuning fuzzy controllers, ANFIS approximates the mappings between local regulators with membership functions which are not necessary known functions as Gaussian bell (gbell), sigmoidal, and triangular membership functions. Due to the structure of the fuzzy controller, Levenberg-Marquardt method is employed during the training of ANFIS.

Tin sulfide doped with copper (SnS:Cu) thin films were deposited on glass substrates by the ultrasonic spray pyrolysis (USP) technique at different concentration ratios (y = [Cu]/[Sn] = 0% (undoped), 2%, 5% and 10%). The aim of this work is to analyze the effect of copper on structural, morphological, and optoelectronic properties of SnS:Cu and discuss their possible application as an absorber layer in a solar cell structure proposed which is simulated using SCAPS software. X-ray diffraction (XRD) reveals an orthorhombic structure in the undoped sample and a cubic structure in doped ones. Raman spectroscopy suggests a possible unit cell size change due to the addition of Cu. Scanning electron microscopy (SEM) shows growth in grain density with an increasing y. Image analysis based on second-order features was used to discuss grain distribution. UV-VIS spectroscopy helps to find an increase of bandgap for the doped samples when copper concentration increases, going from 1.82 eV in the doped film y = 2% to 2.2 eV in the 10% doped samples. A value of 3.51 eV was found for the undoped sample y = 0%. A rise in both carrier concentration and mobility but a decrease in resistivity when y is increased was observed through the Hall–Van der Pauw technique. Simulations by SCAPS helped conclude that considering the material thickness, the SnS:Cu compound can be an alternative for implementation in the manufacturing of solar cells as an absorber layer since it is possible to obtain the optoelectronic properties necessary using the UPS economical technique.