Institutional repository of university M'Hamed Bougara Boumerdes
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Exploring tensile properties of bio composites reinforced date palm fibers using experimental and Modelling Approaches
No full textThe objective of this study was to assess the tensile strength of epoxy bio-composites reinforced with palm fibers, both untreated and treated with sodium carbonate NaHCO3 at a concentration of 10 % (w/v) for 24 and 96 h, with varying weight percentages of fibers (15 %, 20 %, 25 %, and 30 %). To predict the mechanical performance of the composites, two methods were employed: artificial neural network (ANN) and response surface methodology (RSM). A Box-Behnken RSM design was used to conduct experiments and establish a mathematical model of the bio-composite behavior as a function of the fiber percentage in the samples, specimen cross-section, and treatment time. The ANN forecasts showed consistent expected values for the bio-composite sample behavior, with a correlation coefficient (R2) greater than 0.98 for Young's modulus and 0.97 for stress. Similarly, the correlation coefficients obtained by RSM for the mechanical properties were also highly satisfactory, with an R2 of 0.89 for Young's modulus and 0.87 for stress. Finally, the errors generated by each method (Box-Behnken and ANN) were compared to the experimental results
Robust fault estimation for wind turbine pitch and drive train systems
No full textThe reliability and accuracy of the wind conversion system largely depend on the early detection and diagnosis of faults. In this paper, a novel fault estimator for wind turbine pitch and drive train systems is developed. The main objective is to estimate actuator and sensor faults along with the system states while mitigating the impact of process disturbances and noises. To accomplish this, an augmented state is created by combining the states of the system and different faults. Subsequently, an Unknown Input Observer (UIO) is developed to estimate them simultaneously. The UIO matrices are obtained by optimizing a multi-objective function formed by transforming states and faults estimation errors into the frequency domain using a genetic algorithm. Compared with other approaches, particularly H∞, the proposed technique shows great superiority in accurately estimating various actuators and sensors faults
Comparative Assessment of Non-newtonian Single-Phase and Two-Phase Approaches for Numerical Studies of Centrifugal Pumps Handling Emulsion
No full textComputational Fluid Dynamics is commonly employed to assess the effect of oil-water emulsions on pump performance, usually using two-phase models. However, these models often neglect the emulsion’s non-Newtonian behavior, despite its known experimental significance in enhancing pump performance. This study attempts to evaluate both single-phase non-Newtonian and two-phase approaches to model emulsion flow within centrifugal pumps. The non-Newtonian single-phase and several two-phase models are evaluated by comparing the predicted pump heads with experimental data of a multistage pump from the literature. The findings show that the non-Newtonian single-phase model generally provides better agreement with experimental measurements, particularly for emulsions with low dispersed phase fractions. Nevertheless, for emulsions with a high dispersed phase fraction (≈ 50%), the difference between the two approaches is insignificant. Thus, due to the lack of a universal multiphase model for emulsion simulation, the non-Newtonian single-phase model can serve as a viable alternative, overcoming the limitations of two-phase approaches in simulating complex multiphase fluid systems
السّياسات العامة لإصلاح وتطوير الجماعات المحلية في الجزائر ( 2010- 2022 )
No full text525 ص. ، 30 سمإن تغيير أسس العلاقة بين الدولة والجماعات المحلية يجد مبرّره في الواقع الذي تشهده هذه المؤسّسات، وعدم قدرة مختلف السّياسات العامة المتعلقة بإصلاحها وتطويرها خلال الفترة الممتدة ما بين(2010/2022) على تحقيق النّتائج المنتظرة منها، وذلك لسمة التّكيف التي ميّزتها، وهو ما لم يسمح بتكوين هوية لهذه الكيانات القانونية، تتحدّد بموجبها التّسمية التي تستمد من خلالها أسس استقلاليتها، هذه الأخيرة التي تظلّ محدودة النّتائج ما لم تدعمها الدولة من خلال الإطار المعياري كمنطلق لتعديل الواقع العملي، على اعتبار أن أي إصلاح يكون محدود النّتائج ما لم تدعمه الدولة معياريا ومؤسساتيا من خلال الانتقال من نموذج أحادي للإصلاح تصمّمه السّلطة المركزية إلى نموذج تشاركي يضمن المساحة الكافية لمشاركة الجماعات المحلية في هذا التّصميم، إلى جانب الفواعل المحلية الأخرى ذات الشّأن، ما سيجعل عمليات تنفيذ السّياسات العامة تحقّق أمننة نظام الجماعات المحلية قانونيا، تنظيميا، وظيفيا، ماليا ومؤسساتيا، وكل هذا في إطار إرادة سياسية حقيقية لإصلاح وتطوير الجماعات المحلية في الجزائر، وهو ما سيمكّن لاحقا من تصميم"مقياس أداء للجماعات المحلية"، يتم الاعتماد عليه في التّحفيز والمساءلة الموضوعية ودعم التنافسية ما بين الجماعات المحلي
Traitement des effluents liquides industriels de Naftal chargée en métaux lourds et en hydrocarbures par adsorption sur le Charbon actif
No full text74 p. : ill. ; 30 cmLa Wilaya d’Alger représente le pôle industriel le plus important de l’Algérie, mais cette forte concentration industrielle n’est pas sans conséquences. D’énormes quantités d’effluents liquides sont rejetés dans le milieu récepteur et sans traitements appliqués, ces polluants détériorent l’environnement, et entraînent de graves risques sanitaires. Le rendement d’une station d’épuration, représente ainsi le facteur principal pour l’évaluation de la qualité des eaux rejetées dans les milieux naturels. Dans le cadre de l’étude des performances opératoires de la station d’épuration des eaux usées industrielles de Naftal, basée sur le procédé physique de décantation dans des séparateurs Eau/Hydrocarbure. Nous avons procédé à l’estimation des variations des différents paramètres physico-chimiques et biologiques les plus significatifs (Température, Ph, DBO5, DCO, MES, Azote total, Hydrocarbures totaux, Indice de phénols, Plomb et chrome). Cependant, Nous avons trouvé que la station de traitement ne peut pas traiter les substances difficilement biodégradables. Durant les dernières décennies, beaucoup de recherche se sont intéressé aux nouvelles méthodes de décontamination notamment l’adsorption sur charbon actif. Ce travail a pour le but de tester l’efficacité de cette méthode de dépollution
Innovative Approaches to Camembert Cheese: Optimizing Prebiotics and Coagulation Conditions for Enhanced Quality and Nutrition
No full textThe objective of this study is to investigate how different factors, such as lactic acid bacteria, prebiotics (flaxseed powder, watercress seed powder, okra mucilage), and coagulation temperature influence the final quality of curd by conducting three optimization experiments and implementing a structured experimental plan. In the first phase, milk coagulation was assessed at 45 °C with various combinations of lactic acid bacteria (probiotics) and prebiotics (powdered flaxseed and watercress). In the second investigation phase, the effects of lowered probiotic and prebiotic (powdered flaxseed and watercress) concentrations were examined at the coagulation temperature of 38 °C. We investigated the concentration of lactic acid bacteria at 3 mg/mL of milk and the effects of temperature and prebiotics (okra mucilage and flaxseed powder). We observed short milk clotting time (2 s) using the optimized mixture (0.18 mg of probiotics, 1.5 mg of flaxseed powder, and 1.147 mg of watercress powder) per 10 mL of milk. It contrasts with the classical coagulation way optimized at (5.9 and 9.5 s), which were generated at optimal temperatures of 45 and 45.7 °C, respectively. Our new mixture improves the fermentation process of camembert cheese at 38 °C. This cheese had a high flavonoid content, fewer lactic bacteria and molds, a homogeneous texture, and no outer crust, and exceptional sensory attributes such as a creamy and fluid paste. These attributes suggest its potential benefits as a dairy product for individuals with cardiovascular and gastrointestinal conditions
دور الإدارة الإلكترونیة في تحسین الخدمات التأمینیة : دراسة حالة الشركة الوطنية للتأمين خلاا الفترة 2022-2023-وكالة الرويبة SAA 1273-
No full text71p.:ill.;30cm
Application of Remote Sensing and GIS for the Quantification of Spatiotemporal Changes—Land Use/Land Cover in Steppe Landscapes: Case of the Djelfa Region (Algeria)
No full textThe detection of changes in landscape dynamics relies heavily on the effective integration of modern technologies and conventional ecological monitoring techniques, especially remote sensing and GIS, which are currently considered very important techniques for the study of LULC. This study illustrates the spatiotemporal dynamics of LULC in an Algerian steppe region affected by desertification. For this study, we relied on field data, as well as satellite images from Landsat 5 TM and Landsat 8 OLI, to perform a diachronic analysis of this steppe landscape, which is mainly composed of seven thematic classes: forest, agriculture, rangeland, wetland, built-up land, sandy land, and bare soil/rocky soil. Visual interpretation was employed as a starting point, followed by an unsupervised classification methodology using the ISODATA algorithm supported by seven different spectral indices calculated algebraically and the best composites for the identification of the characteristics of the terrain at different dates to find clusters and determine land use types. The Principal Component Analysis was also used to extract the most useful spectral information by compressing the redundant data contained in each spectral channel. Based on the results, we were able to identify the landscape units for both dates with very satisfactory results. Overall classification accuracy of 95% with a kappa coefficient of 0.94 for 1987 and 91% with a kappa coefficient of 0.90 was obtained for 2020. The analysis of the results showed that the Region of Djelfa has undergone a significant change. The results obtained revealed that the areas of forest, sandy land, and wetland have strongly decreased with rates of change of − 28.55%, − 84.65%, and − 27.27%, respectively, while that of the class of agriculture, rangeland, built-up land, and bare–rocky soil have experienced an increase with positive rates equal to 290.06%, 1.25%, 377.13, and 161.75%, respectively. These changes have been caused by the combined anthropogenic pressure as well as the extreme drought with very low PDSI equal to − 3.16 in 2020 which will help on the spread of diseases and put in difficulty the process of spontaneous regeneration of the old trees and the shrinking of the surface covered by water. Increase in population (urban and rural) and evolution of many agricultural practices in the region are also among the causes of change in LULC in the study area
Understanding pedagogical models of learning
No full textThe competency-based approach is the major educational objective of teaching in the License Master
Doctorate (LMD) system. However, this approach by competence is very difficult to understand, to the
extent that the notion of competence, in itself, is already an abstract notion which has multiple
definitions. This approach is the result of an evolution of educational models, which over the past century
has developed by moving from a transmissive pedagogy (also called encyclopedist), which had been in
force for several centuries, to a behaviorist pedagogy, to arrive to a social constructivist pedagogy.
But what do these different educational models represent, and above all mean? This is the purpose of
this brochure which will allow us to better understand the evolution of these models, and especially how
to adapt our teaching to the new teaching needs, imposed by the introduction of the LMD system.
One of the main characteristics in higher education for the recruitment of teachers is the possession of a
diploma in the specialty to be taught. However, the study of the teaching or communication skills of the
future teacher is not given due consideration during their recruitment. Although in recent years a few
popularization sessions have been offered to new teachers, most other teachers have only learned the
teaching profession through experience, without any prior training in pedagogy. In the classic teaching
system (classical compared to the LMD system), the main teaching model was, and still is, the
transmissive model, while it adapts very poorly to new needs, dictated by the socio-economic evolution
of our country, and also by the new teaching approach (LMD system). This 21st century is characterized
by what some are already calling ‘the digital revolution’. At the level of the Ministry of Higher Education
and Scientific Research, significant investments have been made to avoid a significant digital divide,
which could have negative consequences for the future of our universities. However, in addition to these
significant material resources, training should be added in order to make these investments profitabl
Étude de rentabilité d’un projet gazier régie par la loi « 19.13 » - contrat participation -
No full text140 p. : ill. ; 30 cmL'Objet de notre mémoire est e faire une modélisation avec « EXCEL » pour étudier la rentabilité d'un projet gazier régulé par la loi 19-13 et de calculer les principaux éléments de cette loi qui impactent la rentabilité du projet. En utilisant les données fournies par le département d'évaluation économique d'ALNAFT, nous avons analysé la fiscalité appliquée à un projet réel anonymisé "XXXX" et sa rentabilité