L’article décrit la conception et la mise en øeuvre en temps réel d’une commande non linéaire appliquée à un système de conversion de l’énergie éolienne (SCEE). La commande backstepping a été mise en øeuvre pour améliorer les performances du système de conversion éolienne basé sur un générateur synchrone à aimants permanents (PMSG) connecté au réseau. Deux convertisseurs statiques assurent la connexion au réseau et sont contrôlés par la modulation de largeur d’impulsion (MLI). L’algorithme de contrôle proposé assure un contrôle de vitesse adéquat pour extraire la puissance maximale. Une description détaillée des lois de contrôle du backstepping basées sur la technique de stabilité de Lyapunov a été exposée. Les résultats obtenus par l’application de cette approche ont clairement répondu aux exigences de robustesse et de suivi des références même dans des conditions de vent fluctuants, et ont confirmé l’efficacité d’un tel contrôle dans les modes de fonctionnement statique et dynamique.

To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting sliding mode control (STSMC) is adopted. STSMC is used to replace the conventional proportional-integral-Fuzzy Logic Controller (PI-FLC) of the inner current control loops. The combination of the proposed control strategy with space vector modulation (SVM) applied to a PWM rectifier brings many advantages such as reduction in harmonics, and precise and rapid tracking of the references. The performance of the proposed control technique (STSMC-VFOC-SVM) is verified through simulations and compared with the traditional technique (PI-FLC-VFOC-SVM). It shows that the proposed method improves the dynamics of the system with reduced current harmonics. In addition, the use of a virtual flux estimator instead of a phase-locked loop (PLL) eliminates the line voltage sensors and thus increases the reliability of the system.

Considering three sites under different climate conditions (arid, semi-arid, and subhumid), this study aims to use the vadose-zone water stable isotope profiles to estimate the groundwater recharge rate. High-resolution vertical subsurface soil sampling along the vadose zone of the investigated sites was conducted. The collected samples were analysed to determine their stable isotope ratios (δ²H and δ¹⁸O) that were used along with the piston displacement method to estimate recharge. Annual recharge rates of 0.2% (± 0.1%), 2.5%, and 18% of the total annual precipitation were obtained for the arid, semi-arid, and subhumid sites, respectively. Recharge rates at the semi-arid and subhumid sites are comparable to those previously estimated using water balance-based methods. The recharge rate at the arid site is lower than that previously estimated for that site using the water budget-based method, revealing difficulties in applying the piston displacement method under an arid regime.

The present study aimed to investigate the potential protective effects of zinc (Zn) against hexavalent chromium-induced hepatotoxicity in pregnant Wistar rats. Female rats were treated subcutaneously (s.c) on the 3 rd day of pregnancy, with NaCl 0.9 % and served as control, K₂Cr₂O7 (10 mg/kg bw) alone, or K₂Cr₂O7 in association with ZnCl2 (20 mg/kg bw). Hepatic biochemical parameters, oxidative stress biomarkers and DNA damage were monitored. Results revealed that K₂Cr₂O7 disturbed plasma ALT, AST, ALP and GGT, induced hepatic oxidative stress and DNA fragmentation. The co-treatment with Zn has alleviated K2Cr2O7-induced hepatotoxicity by exhibiting antioxidant and genoprotective effects in pregnant Wistar rats.

Some epidemiological situations, because of their magnitude and their propagation dynamics, can escape local or national control. For example, the world is currently experiencing an uncontrollable cross-border spread of the corona virus (Covid-19). The Wilaya of Batna is among the most affected in Algeria by many epidemiological diseases, including tuberculosis, which raises questions about possible causal links between this contagious and often fatal disease and the environmental and socio-economic reality of this territory. We based our study on a number of factors, covering economic, societal and health aspects, which constitute indicators of the standard of living in each of the 61 communes of the Wilaya of Batna. The relationship between the epidemiological status of tuberculosis in these communes and these indicators showed significant correlations and thus confirmed the reliability of the choice of parameters of vulnerability to tuberculosis. To understand their interaction and impact on the disease and its spatial distribution, we used the hierarchical multicriteria analysis (AHP) method, the results of which were implemented in a GIS database. The aim was to provide health and territorial decision makers with a decision support tool. The results show that the spatial distribution of tuberculosis cases which reappeared in the Wilaya of Batna after its eradication since years is in good correlation with the socio-economic situation of each commune of the territory and confirm that this scourge of tuberculosis is closely linked to the degradation of the living conditions of the inhabitants.

In the last decade, the number of diabetic persons has considerably increased and the scientific community approach to understand this complex pathology has become very difficult due to the fact that diabetes is linked to other illnesses which can generate serious complications like glaucoma, nerve damage. Plants are considered new alternative resources to treat various pathologies including type 2 diabetes, and several research works showed that it is significantly more accurate to use Oral Glucose Tolerance Test (OGTT) when diagnosing diabetes which prompted us to adopt this model to evaluate the possible anti-hyperglycemic effect of n-BuOH extract of Centaurea tougourensis. More than 500 Centaurea species are distributed in Mediterranean and West Asia zones. These species demonstrated over the years their pharmacological potential like antioxidant, anti-microbial, anti-diabetic, cytotoxic, activities due to their richness in secondary metabolites. A Preliminary phytoscreening was first done to identify the most important secondary metabolites in the plant and revealed the presence of key classes like; tannins, flavonoids, triterpenes… The pre-treatment of mice group by the dose of (400 ml/kg, p.o) of plant extract resulted in a significant (P<0.01) decrease of hyperglycemia (1.32 ± 0.06 g/l) 60 min after the induction of a temporary diabetes with a maximum percentage inhibition of (37%) while the reference group treated by Glibenclamide (10 mg/kg, i.p.) was only (31%) the same time. This concluded that C. tougourensis stabilized the blood glucose level and may have the potential to treat other pathologies.

Cet article est consacré à l’étude des performances de la génératrice asynchrone à cage double étoile (GASDE) en site isolé. Le système de commande est composé d’une GASDE raccordé à un bus continu et une charge en sortie de deux redresseurs à commande MLI. Une étude comparative entre la technique de commande conventionnelle et la commande adaptée basée sur l’introduction de la SVM-PI-flou et un nouvel estimateur de flux (flux virtuel statorique) afin d’améliorer la qualité d’énergie et d’atténuer les harmoniques du courant

This study aims to assess the diversity and distribution of fungal mycoflora developing on Cedrus atlantica (Endl) G. Manetti ex Carrière needles in three sites in the Belezma National Park (Biosphere Reserve, Northeast - Algeria). Three sites were sampled according to a cedar decline gradient, these are the massifs of: Telmet (healthy site), Boumerzoug (moderately depressed) and Tougurt (decayed site). Polymerase chain reaction (PCR) molecular analysis, allows identifying 19 endophytic mycotaxa. All the identified species have a weak occurrence frequency (less than 25%). In terms of specific richness, the moderately depressed site (Boumerzoug) homes the largest number of taxa (S = 17), followed by healthy site of Telmet (12 taxa), while the depressed site of Tougurt was the least populated (8 taxa). The hierarchical classification analysis (HCA) showed that the taxonomic composition of endophyte associations differs clearly from one site to another according to the cedar decline. The clustering representing healthy massif brings 2 species which are demanding phytoparasitic endophytes (Fusarium sp. and Xylaria sp.). The group associated to moderately depressed site hosts 7 taxa with a wide ecological valence, such as: Canariomyces notabilis, Canariomyces vonarxii, Chaetomium aegilopis, Coniolariella hispanica and Penicillium kubanicum. Then, mycoflora group noted in the decayed cedar includes 10 taxa, in particular, saprophytic mycotaxa relatively less demanding with a high ecological valence like: Biscogniauxia mediterranea, Alternaria arborescens, A. tenuissima and three species of Chaetomium genus. The mycotaxa distribution is related to the specific conditions of colonized trees. Taxa specific to healthy and decayed massifs would represent bio indicators of the phytosanitary and ecological conditions of colonized cedars.