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Search Results: 1 - 10 of 461935 matches for " A. Ouali "
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Sensorless Control Strategy for Wind Energy Conversion System Based on Cascaded Doubly Fed Induction Generator Using Artificial Neuronal Network
S. Nouali,A. Ouali
International Journal of Electrical and Power Engineering , 2012, DOI: 10.3923/ijepe.2011.42.48
Abstract: In this study, we present a new sensorless control for Wind Energy Conversion System (WECS) based on Cascaded Doubly Fed Induction Generator (CDFIG). The aim of this control is to extract the maximum wind power and to control the power generation only by measuring phase voltages and currents. The proposed control scheme is ensured without the need of using any rotor speed or wind sensors from the aspect of reliability and increase in cost. For that a neuronal observer is introduced to estimate the rotor speed. To impose the Maximum Power Point (MPPT) an extended luenberger observer was introduced in cascade with the neuronal observer to estimate the optimal aerodynamic torque. After an approximation with an another artificial neuronal network, observer makes it possible to estimate the wind velocity. This later will be injected in the algorithm control to impose the MPPT. Simulation results demonstrate the sensorless control device excellent performances.
Finite Element Formulation of a Beam with Piezoelectric Patch
A. Mahieddine,M. Ouali
Journal of Engineering and Applied Sciences , 2012,
Abstract: A finite element model is used to analyze beams with piezoelectric sensors and actuators. The formulation is based on first order Kirchoff theory and accounts for lateral strains. Various parametric studies are conducted to demonstrate the effectiveness of piezoelectrics in actively controlling the vibration of beams.
High energy description of dark energy in an approximate 3-brane Brans-Dicke cosmology
A. Errahmani,T. Ouali
Physics , 2006, DOI: 10.1016/j.physletb.2006.08.063
Abstract: We consider a Brans-Dicke cosmology in five-dimensional space-time. Neglecting the quadratic and the mixed Brans-Dicke terms in the Einstein equation, we derive a modified wave equation of the Brans-Dicke field. We show that, at high energy limit, the 3-brane Brans-Dicke cosmology could be described as the standard one by changing the equation of state. Finally as an illustration of the purpose, we show that the dark energy component of the universe agrees with the observations data.
Late time acceleration in 3-brane Brans-Dicke cosmology
A. Errahmani,T. Ouali
Physics , 2007, DOI: 10.1142/S0217732308026881
Abstract: In order to investigate more features of the Brans-Dicke cosmology in the five-dimensional space-time, we explore the solutions of its dynamiacal systems. A behavior of the universe in its early and late time by means of the scale factor is considered. As a results, we show that it is possible to avoid the big rip singularity and to cross the phantom divide line. Furthermore, we review the dark energy component of the universe and its agreement with the observation data for this 3-brane Brans Dicke cosmology by means of the cosmological parameters.
Genetic Algorithms for Optimal Reactive Power Compensation of a Power System with Wind Generators based on Artificial Neural Networks
L. Krichen,H. Hadj Abdallah,A. Ouali
Journal of Electrical Systems , 2007,
Abstract: In this paper, we develop a method to maintain an acceptable voltages profile and minimization of active losses of a power system including wind generators in real time. These tasks are ensured by acting on capacitor and inductance benches implemented in the consuming nodes. To solve this problem, we minimize an objective function associated to active losses under constraints imposed on the voltages and the reactive productions of the various benches. The minimization procedure was realised by the use of genetic algorithms (GA). The major disadvantage of this technique is that it requires a significant computing time thus not making it possible to deal with the problem in real time. After a training phase, a neural model has the capacity to provide a good estimation of the voltages, the reactive productions and the losses for forecast curves of the load and the wind speed, in real time.
Optimal cost and allocation for UPFC using HRGAPSO to improve power system security and loadability
Marouani I., Guesmi T., Hadj Abdallah H., Ouali A.
International Journal of Energy and Environment , 2011,
Abstract: With the electricity market deregulation, the number of unplanned power exchanges increases. Some lines located on particular paths may become overload. It is advisable for the transmission system operator to have another way of controlling power flows in order to permit a more efficient and secure use of transmission lines. The FACTS devices (Flexible AC Transmission Systems) could be a mean to carry out this function. In this paper, unified power flow controller (UPFC) is located in order to maximize the system loadability and index security. The optimization problem is solved using a new evolutionary learning algorithm based on a hybrid of real genetic algorithm (RGA) and particle swarm optimization (PSO) called HRGAPSO. The Newton-Raphson load flow algorithm is modified to consider the insertion of the UPFC devices in the network. Simulations results validate the efficiency of this approach to improvement in security, reduction in losses of power system, minimizing the installation cost of UPFC and increasing power transfer capability of the existing power transmission lines. The optimization results was performed on 14-bus test system and implemented using MATLAB.
Effect of Gaussian doping profile on the performance of a thin film polycrystalline solar cell
Kolsi S.,Ben Amar M.,Samet H.,Ouali A.
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20122900025
Abstract: A two-dimensional (2D) analytical model based on the Green’s function method is applied to an n+-p thin film polycrystalline solar cell that allows us to calculate the conversion efficiency. This model considers the effective Gaussian doping profile in the p region in order to improve cell efficiency. The dependence of mobility and lifetime on grain doping is also investigated. This model is implemented through a simulation program in order to optimize conversion efficiency while varying thickness and doping profile in the base region of the cell. Compared with n+-p standard structure, our proposed structure shows a 43% improvement in conversion efficiency for a polycrystalline solar cell.
FFS et RCD : partis nationaux ou partis kabyles ? SFF and RCD: National Party or Kabylia regional party?
Ouali Ilikoud
Revue des Mondes Musulmans et de la Méditerranée , 2011, DOI: 10.4000/remmm.2870
Abstract: Après octobre 1988 et la mise en place d’une nouvelle formule politique qui consacre le pluripartisme, l’identité berbère devient en Algérie, un enjeu majeur des stratégies partisanes de deux partis : le Front des forces socialistes et le Rassemblement pour la culture et la démocratie. Le premier est ancien et a participé à l’émergence dans les années 1980 du Mouvement culturel berbère. Le second est issu de ce mouvement et s’institutionnalise en parti à la faveur de l’instauration du multipartisme en 1989. L’analyse porte donc sur les stra-tégies identitaires déployées par ces deux formations rivales. Concurrentes auprès des autorités publiques et en termes d’ancrage territorial, elles déploient un discours culturaliste et localiste bien qu’elles se situent dans le champ politique national. Réalisée à la fin des années 1990, elle questionne en dernier ressort les diverses attitudes adoptées par ces entrepreneurs politiques berbéristes aux buttes aux pièges de l’enfermement régional et ethnique : dans quelle mesure peuvent-elles dépasser ce cadre régional et constituer une alternative démocratique viable en Algérie ? After October 1988 and the establishment of a "new political formula" sanctioning a multi-party system, the Berber identity became a major issue for the partisan strategies of two Algerian parties: the Socialist Forces Front and the Rally for Culture and Democracy. The former is older and played a role in the emergence of the Berber cultural movement of the 1980’s. The latter is an offspring of the SFF movement and institutionalised with the introduction of the multi-party system in 1989. The article examines the identification strategies deployed by these two rival groups. They compete with public authorities and position themselves in the national political arena all the while appealing to community and ethnic roots and employing indigenous arguments. Completed in the late 1990’s, the study ultimately questions the diverse attitudes of Berber political actors who face increasing risks of regional and ethnic isolation : How can such parties rise above the regional context to represent a viable democratic alternative for Algeria ?
Renal Pleomorphic Sarcoma in Polycystic Kidney Disease: Case Report  [PDF]
N. Cherif Idrissi El Ganouni, M. Ouali Idrissi, Karima Jiddi, Z. Dahami, F. Barjani, I. Sarf, B. Belaabidia, O. Essadki, A. Ousehal
Open Journal of Radiology (OJRad) , 2012, DOI: 10.4236/ojrad.2012.23012
Abstract: We report a case of pleomorphic sarcoma in a 42-year-old man with adult polycystic kidney disease [APKD]. Abdominal ultrasonography, computed tomography and MRI scans have revealed heterogenous bilateral renal cysts with a voluminous mass in the upper pole left kidney. Radical left nephrectomy with histopathologic and immunohistologic examination have confirmed the diagnosis of pleomorphic sarcoma. Sarcoma associated with adult polycystic kidney disease is extremely rare and does not have particular radiological or biological features when compared to primary renal sarcoma.
Case Report: L\'uretère rétro-cave. A propos de deux cas
M Ouali, H Tazi, K Tazi, K El Khader, A Koutani, A Ibn Attya, M Hachimi, A Lakrissa
African Journal of Urology , 2005,
Abstract: No abstract available African Journal of Urology Vol.11(1) 2005: 69-73
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