Publications Scientifiques
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Item Synthesis and characterization of MoO3: application to the photo production of oxygen under visible light(Springer, 2024) Koriche, Nesrine; Abbas, Moussa; Trari, MohamedOne of the most striking features of molybdenum oxide is the versatility of its catalytic properties, which are determined by the valence states of molybdenum and its coordination. It may be anticipated that MoO3 surface must contain catalytic sites which are active in different types of elementary steps. MoO3 was successfully synthesized by hydrothermal route at 400 °C, acquiring n-type conduction, due to oxygen deficiency. The single phase, elucidated by X-ray diffraction, crystallizes in an orthorhombic unit cell (Space Group (SG) Pbnm, N° 62) with a crystallite size of 12 nm. MoO3 is a direct band gap semiconductor with a forbidden band value of 2.93 eV where the electrical conduction occurs by low polaron hopping between mixed valences Mo+6/+5 with an activation energy of 0.14 eV. The thermo-power indicates n-type conduction, and confirmed by the capacitance-potential measurement; the latter gives an electrons density of 1.87 × 1020/cm3and a mobility of 1.77 × 10−6 m2/V.s. The flat band potential Vfb (0.11 VSCE) is determined from the capacitance measurement. The physical and chemical characterizations are correlated for the construction of the potential diagram in order to assess the photo electrochemical properties of MoO3 for the oxygen evolution. The valence band, is located above the O2/H2O potential ( ~ 1.3 VSCE), allowing O2 evolution upon visible light and the oxide is photocathodically protected against corrosion. An evolution rate of 0.13 mL/(mg. h) is obtained within 20 min. at optimal conditions (100 mg of catalyst and 50 °C).Item An Analytical Approach for Evaluating Turn-On Switching Losses in SiC MOSFET With Kelvin Pin: Concept and Implementation(Institute of Electrical and Electronics Engineers Inc, 2024) Mohammed Cherif, okba; Nadji, Bouchra; Tadjer, Sid Ahmed; Bencherif, HichemWith the progressive adoption of silicon carbide (SiC) power devices in modern power converters, exploiting their superior efficiency, faster switching speed, and higher power density, an understanding of the factors influencing these properties becomes vital. One such critical factor is switching losses, which can drastically affect overall system performance. This study develops and presents a new analytical model for predicting the turn-on switching losses in SiC MOSFETs with Kelvin pin. The proposed model, derived from a carefully constructed set of nonlinear differential equations, accounts for the nonlinearity of the transconductance by incorporating a novel transfer characteristic model. The model also incorporates the nonlinear junction capacitances effects. The developed analytical model allows for the prediction and optimization of turn-on switching losses in SiC MOSFETs, thus enabling improved energy efficiency and reliability. The accuracy of the proposed model is verified through comparison with experimental results obtained using the double pulse test board that was designed and constructed, demonstrating its applicability for the investigation of SiC MOSFET power lossesItem An Analytical Approach for Evaluating Turn-On Switching Losses in SiC MOSFET With Kelvin Pin: Concept and Implementation(IEEE, 2024) Okba, Mohammed Cherif; bouchra, Nadji; Tadjar, S A; Bencherif, HichemWith the progressive adoption of silicon carbide (SiC) power devices in modern power converters, exploiting their superior efficiency, faster switching speed, and higher power density, an understanding of the factors influencing these properties becomes vital. One such critical factor is switching losses, which can drastically affect overall system performance. This study develops and presents a new analytical model for predicting the turn-on switching losses in SiC MOSFETs with Kelvin pin. The proposed model, derived from a carefully constructed set of nonlinear differential equations, accounts for the nonlinearity of the transconductance by incorporating a novel transfer characteristic model. The model also incorporates the nonlinear junction capacitances effects. The developed analytical model allows for the prediction and optimization of turn-on switching losses in SiC MOSFETs, thus enabling improved energy efficiency and reliability. The accuracy of the proposed model is verified through comparison with experimental results obtained using the double pulse test board that was designed and constructed, demonstrating its applicability for the investigation of SiC MOSFET power losses.Item Experimental research of diagnostic measurement tests for power transformers(2013) Aibeche, Abderrazak; Grouni, S.; Akroum, Hamza; Boualegue, K.This paper deals with experimental research of practical diagnostics measurement tests in industrial power transformers. In practical research we analyze the quality insulation diagnostic. The transformers system insulation is evaluated by using diagnostics of the dissipation factor in data industrial transformer (250 MVA, 15.75/220 kV) application. The insulation quality of power transformer is determined by multiple measurement tests of the insulation resistance winding, capacitance and dielectric dissipation factor. The measurement tests of dissipation factor given at the end of the production cycle not only assures that the quality of the transformer meets the specified levels but also provides insight into the subtleties of the manufacturing process. This paper gives an experimental research of measurement tests setup of dielectric dissipation factor that used GST and Guard mode techniques of earthling systems transformers insulationItem Electrical characterization of ethanol sensing device based on vanadium oxide/Porous Si/Si structure(Elsevier, 2013) Chebout, K.; Iratni, A.; Bouremana, A.; Sam, S.; Keffous, A.; Gabouze, N.