Université de Sétif

About: Université de Sétif is a education organization based out in Sétif, Algeria. It is known for research contribution in the topics: Thin film & Control theory. The organization has 1003 authors who have published 1074 publications receiving 10730 citations.

A new variable step size neural networks MPPT controller: Review, simulation and hardware implementation

Abstract: In this paper, two new Artificial Neural Network MPPT controllers based on fixed and variable step size have been proposed and investigated. The data required to generate the ANN model are generated using the classical Perturbation and Observation algorithm. The neural network MPPT controller is developed in two steps: the offline step required for training of different neural networks parameters in order to find the optimal neural network MPPT controller (structure, activation function and training algorithm) and the Online step where the optimal neural network MPPT controller is used in PV system. The performance of the proposed variable step size and fixed step size ANN-MPPT methods are analyzed under different operating conditions using Matlab/Simulink. To validate the simulated system hardware implementation of the proposed algorithms was carried out using experimental prototype MPPT based on Flyback converter connected to Solarex MSX-60 (4 panels) and dsPIC30F4011 control circuit. Analysis and comparative study between the proposed fixed and variable step size ANN-MPPT controllers have been presented, showing a real contributions in term of tracking accuracy, response time, overshoot and steady state ripple. In addition, this paper can be considered as a review study on ANN-MPPT methods for PV systems.

Control of the γ-alumina to α-alumina phase transformation for an optimized alumina densification

Abstract: In this work, we studied the aptitude to sintering green bodies using γ-Al 2 O 3 transition alumina as raw powder. We focused on the influence of the heating rate on densification and microstructural evolution. Phase transformations from transition alumina γ → δ → θ → α-Al 2 O 3 were studied by in situ X-rays diffraction from the ambient to 1200 °C. XRD patterns revealed coexistence of various phase transformations during the heating cycle. DTA and dilatometry results showed that low heating rate leads to a significant reduction of the temperature of the α-Al 2 O 3 alumina formation. Around 1190, 1217 and 1240 °C were found when using 5, 10 and 20 °C/min of heating rate, respectively. The activation energy for θ-Al 2 O 3 → α-Al 2 O 3 transformation calculated by Kissinger and JMA equations using dilatometry method were 464.29 and 488.79 kJ/mol, respectively and by DTA method were 450.72 and 475.49 kJ/mol, respectively. In addition, the sintering of the green bodies with low heating rate promotes the rearrangement of the grains during θ-Al 2 O 3 → α-Al 2 O 3 transformation, enhancing the relative density to 95% and preventing the development of a vermicular structure.