Browsing by Author "Alem, Said"

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    Bond graph to digraph conversion : a sensor placement optimization for fault detection and isolation by a structural approach
    (2014) Alem, Said; Benazzouz, Djamel
    In this paper, we consider the optimal sensors placement problem for faults detection and isolation using a novel structural and qualitative approach. This approach is based on the conversion of Bond Graph to Digraph representation of a structural system. When the fault detection and isolation of an existing system’s sensors are impossible or uncertain, a reconfiguration sensor placement of this system should be reconsidered. This paper proposes how this reconfiguration takes place by recovering all missing or redundant parts of the system. This novel approach is illustrated over a thermo-fluid application
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    Comparative Analysis of Stiffness in Redundant Co-axial Spherical Parallel Manipulator Using Matrix Structural Analysis and VJM Method
    (Springer, 2023) Chebili, Zakarya; Alem, Said; Djefal, Selman
    Several studies have addressed stifness analysis through diferent available methods including fnite element analysis (FEA) and the virtual joint method (VJM) among others. However, matrix structural analysis (MSA) has not been used, although previous research has shown that it provides reliable results. Therefore, this paper focuses on the kineto-static analysis of a three-degree-of-freedom symmetrical parallel kinematic manipulator (PKM) with curved links, known as a spherical parallel manipulator (SPM). First, kinematic modeling is introduced through the inverse kinematic problem and the Jacobian matrix; then a detailed study of the stifness modeling is established. Secondly, the force–defection relationship is studied in the form of a numerical calculation and a graphical representation. Moreover, the kinematic redundancy is derived. Through MATLAB simulations, the defection of the joints in both parts, translation, and rotation, is graphically represented using a numerical calculation method. Comparatively, SPM is purposefully compared to VJM in order to determine the efciency of the proposed method. Interestingly, kinematic redundancy leads to better SPM performance, in which adding extra links (legs) to the robot strengthens the SPM structure and yields less joint defection. It is worth noting that the MSA technique successfully deals with complex structures such as closed-loop chains, which is clearly apparent in the simplicity of its mathematical model toward the considered robot.
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    Design of a cost and reliability optimized framework for the techno-economic analysis of a stand-alone PV/FC Li-ion battery system
    (Springer Science and Business Media Deutschland GmbH, 2025) Berrazouane, Sofiane; Alem, Said; Mellal, Mohamed Arezki
    The multiple advantages of the Li-ion batteries and the long-term storage capacity of hydrogen are exploited in this work to obtain an optimal system configuration and achieve energy self-sufficiency. The degradation cost of the battery, based on both calendar and cyclic aging, is included to provide a more detailed and accurate techno-economic balance and estimation. Moreover, the operating cost of the battery and hydrogen system is considered in the energy management strategy (EMS) to determine the prioritized storage system to be used. Therefore, to economize the costs and increase the reliability of the standalone photovoltaic/fuel cell (PV/FC) Li-ion battery system, an EMS is developed by customizing and adapting the Improved Grey Wolf Optimizer (IGWO), referred to as the Modified Improved Grey Wolf Optimizer (M-IGWO). The proposed system achieves a Levelized Cost of Energy (LCOE) of 0.3257 $/kWh when Loss of Power Supply Probability (LPSP) is less than 1%, with 68.18% use of hydrogen system over the time and 26.11% of the battery, demonstrating high reliability. Depending on the operating mode, the battery utilization to support H2_system is decreasing from 10.71% to 1.18%, while the hydrogen system utilization to support battery is decreasing from 29.64% to 9.16%. These findings highlight the effectiveness of the M-IGWO algorithm and EMS in optimizing PV/FC Li-ion battery system for various scenarios
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    Genetic algorithm for multiobjective optimization : applied in high speed machining milling operation
    (2012) Mokhtari, Hicham; Ouziala, Mahdi; Mellal, Mohamed Arezki; Belaidi, Idir; Alem, Said; Berrazouane, Sofiane
    Genetic Algorithms (GAs) are general-purpose heuristic search algorithms that mimic the evolutionary process in order to find the fittest solutions. The algorithms were introduced by Holland in 1975. Since then, they have received growing interest due to their ability to discover good solutions quickly for complex searching and optimization problems. Simple genetic algorithms have been developed to solve the problems of multi objective optimization, such as NSGA II. The objective of this research is to apply the elitist non-dominated sorting GA (NSGA-II) for multi-objective optimization problems in case of high speed machining for the milling operation. The implemented model under Matlab, allows, from a considered space research. We have optimized the values of Vc and f, for an imposed Depth, while the production cost and time are minimized, under technical constrains of the production system
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    International conference on advanced mechanics and renewable energies abstracts book
    (Belaidi Idir, 2018) Belaidi, Idir; Mechakra, Hamza; Alem, Said; Lounici, Mohand Said
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    New hot isostatic pressing (HIP) simulation method with taking into account of the operating cycle ramp
    (Springer, 2019) Locif, REDOUANI; BOUDRAHEM, Smail; Alem, Said
    Hot isostatic pressing (HIP) is a process that allows producing full dense materials with high mechanical properties. The simulation work undertaken on this subject does not take into account the densification which operating during the rise in pressure and temperature. In this paper, we propose a new method for HIP simulations by considering the powder densification, which operating during the rise in pressure and in temperature. Experiments were performed using tungsten powders by varying the parameters of the used HIP cycles. The obtained results are in good agreement with the simulations predictions, especially when pressures exceed 200 MPa. They clearly show that an important part of the powders densification can reach in some cases 88% during the cycles rise. This approach is very interesting for the number of tuning tests reduction and for the implementation prices improvement.
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    Optimal sensor placement for fault detection and isolation by the structural adjacency matrix
    (Academic journals, 2013) Alem, Said; BENAZZOUZ, Djamel
    In this paper, we consider the optimal sensors plac ement problem for faults detection and isolation. When the detection and isolation of faults of an ex isting system’s sensors is impossible or uncertain, a reconfiguration sensor placement of this system sho uld be reconsidered. The propagation of faults (Observability/Detectability) was studied in a stru ctured linear system on a directed graph (digraph). An optimisation of sensor placement is necessary to is olate detectable faults and obtain an optimal structural isolability. To have a maximal structura l isolability, we must find all the vertex-disjoint paths knowing that this property depends upon additional sensors. This novel approach is illustrated over a two tanks application applying on a directed graph to obtain the maximal and optimal structural detectability and isolability of the system.
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    Optimisation des performances d'un système de pompage photovoltaïque par neuro floue et le contrôle direct du couple = Optimization of the performance of a photovoltaic pumping system by neuro fuzzy and direct torque control
    (Editura Academiei Romane, 2014) Amrani Mohamed, Nader; Dib, Abderrahmane; Alem, Said
    L’énergie solaire est une source d’énergie par excellence, non polluante et prometteuse, elle s’acclimate à merveille avec plusieurs systèmes. Dans le cadre de l’exploitation de l’énergie solaire, les systèmes de pompage photovoltaïque sont les plus appliqués. Dans ce papier, nous exposons une stratégie d’optimisation des performances d’un système de pompage photovoltaïque. Dans ce contexte, nous avons opté pour une méthode de commande MPPT basée sur la neuro-flou. Afin d’améliorer les performances du moteur asynchrone, nous utilisons la notion de contrôle direct du couple (DTC) et régulateur PID. Le modèle du système proposé est réalisé par MATLAB / Simulink. (Solar energy is an energy source par excellence, clean and promising, she acclimated well with multiple systems. In the context of the use of solar energy, the most applied systems are photovoltaic pumping systems. In this paper, we present a strategy for optimizing the performance of a photovoltaic pumping system. In this context, we opted for a MPPT control method based on neuro-fuzzy known for its stability and robustness. To improve asynchronous motor performance, we use the concept of direct torque control (DTC) and PID controller. The model of the proposed system is realized by MATLAB / Simulink. )
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    Performance comparison of face recognition algorithms based on face image retrieval
    (2013) Mokhtari, Hicham; Belaidi, Idir; Alem, Said
    Biometric systems are complex systems of safety measures based on physical, biological and the humans behavioral. The automatic face recognition has become a highly active research area, mainly due to numbers published papers in recent years. In this paper, we present a comparative study for evaluation of face recognition system based on face restoration. Our study is performed in two consecutive steps, In the first step, we use two methods of image restoration called Centralized sparse representation (CSR) and adaptive sparse domain selection with adaptive regularization (ASDS-AR) while in the second step the set of methods that have been used are principal component analysis (PCA), linear discriminant analysis (LDA) kernel principal component analysis (KPCA) and Kernel Fisher Analysis (KFA) for face recognition and we associated the Gabor Wavelets and Phase Congruency in order to achieve the evaluation of our proposed model. In addition, the comparative analysis on the ORL database is also employed in the experiments to evaluate the susceptibility of the appearance based methods on various image degradations which can occur in ”real-life” operating conditions. Our experimental results suggest that Gabor linear discriminant analysis (GLDA) ensures the most consistent verification rates across the tested ORL databases for both methods CSR and ASDS-AR
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    Placement optimal des capteurs pour la détection et la localisation des défauts
    (2014) Alem, Said
    Les capteurs jouent un rôle très important dans la commande d'un système automatisé. Ils sont souvent indispensables pour garantir les propriétés du système, par exemple l'observabilité ou la détection des défauts. Les capteurs sont souvent coûteux, leur emplacement sur un système parfois très limité, leur maintenance difficile,... il est donc important de savoir utiliser de manière optimale les capteurs d'un système. Pour des raisons de fiabilité et de sûreté, on cherche à garantir le fonctionnement du système en cas de panne de certains capteurs. On considère ici le problème de placement optimal des capteurs pour la détection et localisation des défauts. Quand la détection et la localisation des défauts avec les capteurs de système déjà existants est impossible ou pas certains alors une reconfiguration de ce système est nécessaire. On s'intéresse aux problèmes de positionnement, sélection et problèmes de coût de placement des capteurs, le placement optimal et la classification des capteurs pour vérifier une propriété donnée
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    Vieillissement et Obsolescence des équipements industriels : Traitement Fiabiliste et Management de la Maintenance
    (IEEE, 2021) Chabane, Ali; Adjerid, Smail; Alem, Said; Aggad, maya
    Cet article considère le problème du vieillissement et de l’obsolescence dans le management de la maintenance. La stratégie de maintenance a des répercussions directes sur l’exploitation d’un système, la production et les charges financières. L’objectif de ce travail est d’apporter une contribution à l’analyse de l’obsolescence et du vieillissement des composants d’un véhicule industriel utilisés par la Société COSIDER. Les résultats de ce travail montrent les vieillissements rapides qui apparaissent pendant le cycle de vie du véhicule, et montrent l’importance du choix des équipements et des pièces de rechange pour réduire le taux de défiance. Mots-clés : maintenance industrielle, Stratégie de la maintenance, Sûreté de fonctionnement, vieillissement des équipements industriels, Obsolescence des équipements industriels.