http://dspace.univ-setif.dz:8888/jspui/handle/123456789/1419 Sat, 09 May 2026 19:52:11 GMT 2026-05-09T19:52:11Z http://dspace.univ-setif.dz:8888/jspui/handle/123456789/3084 Titre: Structural and photoluminescent properties of CuGaxIn1−xSe2thinfilms prepared by close-spaced vapor transport technique Auteur(s): Tassoult, Houda; Bouloufa, Abdesselam; Pawlowski, Marek; Igalson, Malgorzata Résumé: CuGaxIn1−xSe2(CIGS) (x = 0, x = 0.3 and x =1) absorber layers were deposited onto transparent conducting oxide (SnO2) substrates using close-spaced vapor transport technique (CSVT). The aim of this work was to assess the quality of CIGS absorber films with various gallium contents. Composition found by Energy Dispersive Spectroscopy (EDS) showed that the investigated samples were Cu-poor and CuGa0.3In0.7Se2thin film had a composition close to 0.3 as planned. The structural properties were investigated by X-ray diffraction analysis (XRD) and Raman spectroscopy, while optical properties were investigated by measuring transmittance and photoluminescence spectroscopy. It was found that all investigated samples crystallize with (112) as a pre-ferential crystallographic direction. The shift of the XRD peaks towards a higher value of 2θwith the increase of Ga composition was observed. The grain size determined from the width of 112 XRD peak was within 40–75 nm range with no clear correlation with Ga content. Raman spectra of samples with x =0 and 0.3 featured mainly a peak assigned to the A1mode at about 175 cm −1 . In CuGaSe2the secondary Cu2Se phase was detected both by XRD and Raman. The band gap as evaluated by optical transmission measurement is shifted towards lower than expected values due to substantial defect-related bands broadening. A large concentration of defects in the samples was also confirmed by low or absent PL signal in the vicinity of the bandgap, while the emission due to deep defects was prevailing in the spectrum. The optoelectronic properties as indicated by photoluminescence have to be improved if CSVT method of absorber preparation is to be used more widely in photovoltaics. Wed, 23 Jan 2019 00:00:00 GMT http://dspace.univ-setif.dz:8888/jspui/handle/123456789/3084 2019-01-23T00:00:00Z http://dspace.univ-setif.dz:8888/jspui/handle/123456789/3062 Titre: A miniaturized printed monopole antenna for 5.2-5.8 GHz WLAN applications Auteur(s): Chetouah, Farouk; Aidel, Salih; Bouzit, Nacerdine; Messaoudene, Idris Résumé: In this article, a new design of a compact printed rectangular antenna for wireless local area network (WLAN) applications in 802.11a is investigated. The defected ground structure (DGS) technique is successfully used to reduce the ground plane by cutting a large slot to achieve significant miniaturization. The ground plane structure consists of inverted‘L’ shape. The rectangular radiating element has a size of 63 5mm2 and is connected to a microstrip transmission feed line. The simulated and measured resonance frequency of the single-band antenna is approximately 5.8 GHz and may cover an impedance bandwidth of 1 GHz for the measurement and 1.65 GHz for the simulation. The simulated and the measured data are in good agree-ment. The proposed antenna is very compact (1036mm2 ) and its impedance bandwidth is suitable for the 5.2-5.8 GHz WLAN communication systems. Wed, 16 Jan 2019 00:00:00 GMT http://dspace.univ-setif.dz:8888/jspui/handle/123456789/3062 2019-01-16T00:00:00Z http://dspace.univ-setif.dz:8888/jspui/handle/123456789/2967 Titre: Emulation-based fault analysis on RFID tags for robustness and security evaluation Auteur(s): Mezzah, Ibrahim; Chemali, Hamimi; Kermiaa, Omar Résumé: This paper presents an FPGA (field-programmable gate array) based fault emulation system for analysis of fault impact on security and robustness of RFID (radio frequency identification) tags. This emulation system that deals with any RFID protocol consists of two tag-reader pairs, a fault injection module and an emulation controller all implemented in a single FPGA. The designed approach performs single event upset (SEU) and single event transient (SET) fault injection and permits with high flexibility to set communication scenarios and related parameters. Moreover, we propose a classification of produced errors to evaluate fault impacts and identify most sensitive tag flip-flops causing large number of failures and security concerns. The proposed fault injection approach provides suitable means to increase tags' security and robustness. In our experimentation campaign, an ultra-high frequency (UHF) tag architecture has been exposed to intensive SEU and SET fault injections. The duration of the campaign including results analysis is 30 min in where 6,215,316 faults are experimented. Our results have shown that the tag has tolerated 61.82% of SEUs and 67.83% of SETs. The flip-flops that constitute the tag FSM (finite state machine) have been identified as the most sensitive parts causing large number of failures. Thu, 29 Nov 2018 00:00:00 GMT http://dspace.univ-setif.dz:8888/jspui/handle/123456789/2967 2018-11-29T00:00:00Z http://dspace.univ-setif.dz:8888/jspui/handle/123456789/2962 Titre: Real-Time Genetic Algorithms-Based MPPT: Study and Comparison (Theoretical an Experimental) with Conventional Methods Auteur(s): Hadji, Slimane; Gaubert, Jean-Pau; Krim, Fateh Résumé: Maximum Power Point Tracking (MPPT) methods are used in photovoltaic (PV) systems to continually maximize the PV array output power, which strongly depends on both solar radiation and cell temperature. The PV power oscillations around the maximum power point (MPP) resulting from the conventional methods and complexity of the non-conventional ones are convincing reasons to look for novel MPPT methods. This paper deals with simple Genetic Algorithms (GAs) based MPPT method in order to improve the convergence, rapidity, and accuracy of the PV system. The proposed method can also efficiently track the global MPP, which is very useful for partial shading. At first, a review of the algorithm is given, followed with many test examples; then, a comparison by means Matlab/Simulink© (R2009b) is conducted between the proposed MPPT and, the popular Perturb and Observe (PO) and Incremental Conductance (IC) techniques. The results show clearly the superiority of the proposed controller. Indeed, with the proposed algorithm, oscillations around the MPP are dramatically minimized, a better stability is observed and increase in the output power efficiency is obtained. All these results are experimentally validated by a test bench developed at LIAS laboratory (Poitiers University, Poitiers, France) using real PV panels and a PV emulator which allows one to define a profile insolation model. In addition, the proposed method permits one to perform the test of linearity between the optimal current Imp (current at maximum power) and the short-circuit current Isc, and between the optimal voltage Vmp and open-circuit voltage Voc, so the current and voltage factors can be easily obtained with our algorithm. Tue, 27 Nov 2018 00:00:00 GMT http://dspace.univ-setif.dz:8888/jspui/handle/123456789/2962 2018-11-27T00:00:00Z