Institutional repository of university M'Hamed Bougara Boumerdes
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Dynamic characteristics analysis of functionally graded cracked beams resting on viscoelastic medium using a new quasi-3D HSDT
No full textIn this study, a new four-unknown quasi-3D shear deformation theory is proposed for studying the vibration responses of functionally graded (FG) beams containing open-edge cracks resting on three-parameter viscoelastic foundations (VEFs). The number of unknowns and governing equations in the current theory has been reduced, making it easier to use. Even less than conventional theories, this theory includes indeterminate integral variables and contains only four unknowns where no shear correction factor is used. The study is conducted with an eye toward a three-parameter foundation that takes into account the effects of the elastic medium’s damping coefficient, the Pasternak coefficient, and the Winkler coefficient. The material characteristics of the FG beams are considered to vary in the thickness direction via a power law distribution as a function of the volume fractions of the constituents. The system of differential equations governing the free vibration behavior of FG beams is derived by Hamilton’s principle. To satisfy the foundation conditions, the Navier method is used to obtain the analytical solutions of the dynamic response of cracked FG beams resting on viscoelastic foundations. Comparison of the results of the current theory with other results and with data available in the literature demonstrates its accuracy. A detailed parametric study is presented to show the impact of material properties, slenderness ratio, foundation type and foundation damping coefficient, crack depth, and location on the natural frequencies of cracked FG beams resting on VEFs
Analyse de l’efficacité thermique des fours de la raffinerie «RA2/K» avec l’implémentation d’un préchauffeur d’air de combustion
No full text111 p. : ill. ; 30 cmLe Transfert de chaleur joue un rôle essentiel dans l'industrie du raffinage de pétrole afin d'améliorer l'efficacité énergétique des procédés industriels. Il est crucial d'assurer une gestion optimale de la chaleur afin de diminuer les dépenses d'exploitation et de réduire au minimum l'empreinte écologique. L'installation d'un préchauffeur d'air est l'une des technologies les plus avancées utilisées pour exploiter l'énergie des fumées provenant des fours pétroliers. Ce système capte la chaleur des fumées produites par les fours afin de préchauffer l'air de combustion. Le préchauffeur d'air, en diminuant la quantité de combustible requise pour atteindre les températures de fonctionnement requises, permet d'améliorer considérablement le rendement thermique des fours. Une analyse approfondie de l'efficacité thermique de trois fours tubulaires avec deux configurations différentes avant et après la mise en marche du préchauffeur d'air est présentée dans cette étude. Elle évalue les économies de combustible, les bénéfices financiers et les conséquences environnementales. Les résultats montrent qu’il est possible d'obtenir une amélioration significative de la performance énergétique et la durabilité industrielle en utilisant des préchauffeurs d'air
Discretization Order Influences on Extended Kalman Filter Estimation for Doubly-Fed Induction Generator
No full textThe main objective of this paper is to analyze the influence of the discretization step on the estimated states of the Doubly-Fed Induction Generator (DFIG). Although the Extended Kalman Filter (EKF) has been widely used for such systems, the discretization process is conventionally ensured by the first-order Forward Euler method. Therefore, the effects of the discretization order of the discrete state-space representation on the Extended Kalman Filter estimation have not been studied before. In this paper, we combine the Extended Kalman Filter with two second-order discretization methods: Central Difference and Adams-Bashforth methods, to estimate the states of a Doubly-Fed Induction Generator and improve the estimation precision of the rotor speed and the Flux of the generator. A comparative study has been conducted to analyze the qualitative and quantitative responses of the estimator for different cases. The obtained results have demonstrated the significance of the discretization order on the estimation process of the two states of the DFIG
An Enhanced white shark optimization algorithm for unmanned aerial vehicles placement
No full textIn this chapter, we propose an Elite Opposition-Based White Shark Optimization (ELWSO) Algorithm, for tackling the Unmanned Aerial Vehicles (UAVs) Placement problem in smart cities. The proposed EWSO scheme is based on the incorporation of the Elite opposition-based strategy to ameliorate the optimization efficiency of the original WSO. EWSO was assessed in terms of fitness, coverage, and connectivity metrics under 23 cases with different numbers of UAVs and users. The results of simulated experiments, conducted using MATLAB 2021b version, revealed that the EWSO algorithm outperforms the basic WSO, Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Bat Algorithm (BA)
Covid 19 Implications on credit loss provisioning rules under ifrs 9: Pro-cyclicality concerns
No full textThe objective of this paper is to analyse the procyclicality behavior of Expected Credit Loss (ECL) model introduced by IFRS 9, during the economic downturn due to the Covid 19 pandemic. A regression analysis was conducted on a dataset gathered from euro era in order to investigate the hypothesis suggesting that the new model does not exhibit a procyclical behavior. Our findings indicate that, despite the IASB's expectation that the ECL model would have a countercyclical impact, it still demonstrates procyclical behavior
Enhancing Echo Processing Through the Integration of Support Vector Machine and Weber’s Law Descriptors
No full textRemoving ground echoes from weather radar images is a topic of great importance due to their significant impact on the accuracy of processed data. To address this challenge, we aim to develop methods that effectively eliminate ground echoes while preserving the precipitation, which is a crucial meteorological parameter. To accomplish this, we propose to test Local Descriptors based on Weber’s law (WLD), as well as descriptors that combine Weber’s law with Local Binary Pattern (WLBP), using Support Vector Machine (SVM) classifiers to automate the recognition of both types of echoes. The proposed methods are rigorously tested at the sites of Setif and Bordeaux to evaluate their effectiveness in accurately identifying the ground echoes and precipitation. The results of our experiments demonstrate that the proposed techniques are highly effective in eliminating ground echoes while preserving the precipitation, and can be considered satisfactory for practical applications in meteorological data processing.Institute for Systems and Technologies of Information, Control and Communication (INSTICC
Contribution to the study of nanofluid thermophysical properties with the objective of enhancing the heat transfer
No full text123 p. : ill. ; 30 cmIn this thesis we provided an overview of fundamental heat transfer principles, including conduction and convection, emphasizing the utilization of nanofluids to improve heat transfer across diverse engineering applications. Essential applications, principles, and physical characteristics of nanoparticles were explored, alongside strategies and methodologies for preparing nanofluids and assessing nanoparticle stability. The experimental setup, featuring a square-shaped spiral heat exchanger, and associated measurement equipment was detailed. Mathematical equations relevant to heat transfer with nanofluids were examined, and modeling equations were formulated incorporating mass, momentum, and energy conservation principles. The numerical methodology used to solve these equations under specific boundary conditions was explained, along with a comprehensive overview of the steps for conducting CFD simulations with ANSYS Fluent, including mesh generation, boundary conditions, solution selection, and convergence criteria. The results of experimental work on the square-shaped spiral heat exchanger and numerical simulations were presented, demonstrating significant improvements in heat transfer flux and Nusselt numbers with nanofluids compared to pure water. Notably, a 13.46% increase in heat transfer flux was observed with a 5% nanofluid concentration and a 4.3 L/m flow rate. Additionally, there were significant increases in Nusselt numbers and heat transfer coefficients for nanofluids, indicating enhanced heat exchange performance with higher nanofluid concentration or flow Reynolds number
Cyanide removal from aqueous solution by oxidation with hydrogen peroxide in the presence of activated alumina-supported copper catalyst
No full textCyanide compounds are widely used in some electroplating, chemical, and metallurgical industries. They are often found in their liquid discharges. This work highlights the performance of an activated alumina-supported copper catalyst in the removal of cyanide by oxidation with hydrogen peroxide in aqueous solution. The influence of catalyst dose, initial molar ratio of hydrogen peroxide/cyanides, temperature, and catalyst reuse was studied. The activated alumina-supported copper significantly enhanced the reaction rate showing a good catalytic activity. The efficiency of cyanide elimination was increased after 30 minutes of oxidation from 48% to 98% by increasing the catalyst dose from 1 to 10 g/L. Rising the temperature from 30°C to 40°C promoted cyanide removal. The catalyst can be recycled four times and show good stability. The kinetics of cyanide oxidation was revealed to be pseudo-first-order regarding cyanides. The rate constants as well as the activation energy were determined
دور نظام الإدارة المتكامل في تعزيز تنافسية منظمات الأعمال: دراسة حالة مؤسسة الإسمنت للمتيجة —SCMI الفرتة الممتدة مابين 2015-2023
No full text140p.:ill.;30cm
Évaluation déterministe et probabiliste de l’intégrité des pipelines corrodés : application à l’oléoduc «OB1» (HEH-Bejaia)
No full text101 p. : ill. ; 30 cmNous proposons dans ce travail, d'apporter une analyse qualitative sur l'état de corrosion au niveau du pipeline OB1 en se basant sur les normes ANSI/ASME B31G modifiée afin d'envisager des opérations de réhabilitation si cela est nécessaire, pour éviter les risques de ruptures provoquant des pertes considérables. Le second volet de notre travail portera sur l'évaluation de la probabilité de défaillance sur un pipeline corrodé de manière quantitative, par une approche fiabilité structurale en se basant sur un modèle de charge de type Normale