Thèses de Doctorat et Mémoires de Magister
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Item Power system protection improvement using wide area synchro-phasor measurements(2015) Ouadi, AbderrahmaneDuring the last three decades, digital relays have been widely used in power grid due to their flexibility and enhanced security and dependability properties. The decision of the digital protective device highly depends on the digital signal filtering computing the fundamental phasors of line voltages and currents. Several digital algorithms have been proposed in the literature for estimating the fundamental phasors, however, during a transient condition, line current and voltage may include unwanted components such as dc exponentially decaying associated with the harmonics and sub-harmonics. These digital algorithms always need few cycles for obtaining the accurate fundamental phasors which are undesirable in the protection field.The approach proposed in this work for reliable phasor estimation algorithm is first to remove disturbance signals using designed digital filter, then use conventional HCDFT or FCDFT algorithm to compute phasors with required accuracy and convergence speed. Besides, the combined optimized digital filter (ODF) and DFT algorithm are therefore used to quickly and accurately calculate the phasors. The obtained phasor algorithm has the required characteristics to remove the dc component and dump the sub-harmonic as well as harmonic components. The performance of the obtained phasor measurement algorithm is tested using estimated disturbance test signals and data obtained from series-compensated power system network simulation. Simulation results corroborate performance improvement of the proposed phasor estimation algorithm as compared with those obtained using classical cosine and Fourier phasor algorithmsItem Surveillance et diagnostic d’une ligne de production par les réseaux de neurones artificiels(2010) Amrani, MohamedCe travail de recherche présente une modélisation et une simulation de diagnostic et de surveillance en temps réel des équipements stratégiques d’une ligne de production. Le modèle est basé sur les réseaux de neurones artificiels RNA. L’objectif est de détecter et localiser toute anomalie qui peut survenir dans une machine. L’équipement considéré dans cette étude est une ligne de production pharmaceutique BEKER laboratoire Dar El Beida- Algérie la machine qui nous intéresse est un équipement stratégique dans la production. Nous avons défini les zones de bon et de mauvais fonctionnement. A partir de là, la simulation des pannes est possibleItem Evaluation des risques industriels majeurs dans les installations ATEX(2010) Benmessaoud, TaharNous traitons dans ce mémoire l'évaluation des risques industriels majeurs dans les installations atmosphères explosives. Cette étude se compose de quatre parties intéressantes: La première partie comporte l’analyse des différentes méthodes et approches utilisées dans la fiabilité pour évaluer les risques industriels, et l’importance de chaque approche et méthode ainsi leurs avantages et inconvénients. La deuxième partie est consacrée à la théorie de dynamique des stimuli TSD, et ses avantages par rapport aux autres approches et méthodes classiques. Elle utilise une approche de type spécifique de chemins et séquences pour résoudre les équations de la théorie de dynamique probabiliste basée sur les stimuli SDTPD. En deuxième lieu, on présente l’algorithme de recherche adaptatif pour l’échantillonnage par maillage des chemins de dommage dans les séquences, nous précisons son avantage par rapport à la méthode de Monte Carlo. La troisième partie est réservée pour la thermodynamique du réservoir E610 de l’usine de Bhopal, dans la quelle on étudie l’évolution des différentes variables physiques dans le temps telles que la pression, la température et les concentrations molaires du mélange gazeux formé dans le réservoir de stockage de MIC sans prendre en considération le changement de phase entre le mélange gazeux et le liquide La quatrième partie est consacrée à la simulation de la dynamique multi‐variable des réactions exothermiques de mélange gazeux, on prend le scénario de l’accident de Bhopal en se limitant à étudier la région du mélange gazeux. Par l’application de l’algorithme de recherche adaptatif, on a pu simuler les séquences accidentelles avec le calcul des fréquences d’excès du domaine de dommageItem Task partition based parallel design and implementation of the MSSM algorithm on network of transputers(1995) Cheref, MohamedThe present work is concerned with the parallel design and implementation of the multiple scale signal matching (MSSM) [26,38] algorithm on a transporter [7,10,25,40] network. The MSSM algorithm is based on a multichannel vision model [35], to establish the correspondence between two images with the allowance that one of them can be deformed elastically. The MSSM algorithm uses a process consisting of two stages: the filtering and the matching stages. This process is iterated following a coarse-to-fine regime of the vision channels [35] at which the matching process is performed…Item On the irreducible realization of rational transfer function matrices(1995) Yaici, MalikaThe problem of finding the minimal realization of a given transfer function matrix has been studied by several authors. it is to determine state variable realizations with the minimum possible number of states. the irreducible realization is useful in analog and digital computer simulation or operational amplifier circuit synthesis of the transfer function. irreducible realizations are desirable for reasons of economy and sensitivity…Item Multivariable design via the solution of the lyapunov equation(1999) Amroune, HouriaRelocating poles theory has been the subject of an important number of research studies. Using state feedback for this purpose is a widely used technique because of its simplicity and the quality of control achieved. the control signal is designed to be a function of the state and the reference signal. Controllability of an open-loop system is equivalent to the possibility of assigning anarbitrary set of eigenvalues to the closed-loop system's matrix by means of suitable linear feedback of the state…Item Maximum power point tracking (MPPT) for photovoltaic system(2011) Malki, SihemThis thesis presents a theoretical study of maximum power point tracking (MPPT) for photovoltaic (PV) system. The study includes discussion of various MPPT algorithms and perform comparative tests of the two popular MPPT algorithms (the Perturbation and Observation algorithm and the Incremental and Conductance algorithm) using actual irradiance data. Some important applications of the MPPT for different loads are described; first the PV system with resistive load is discussed, the modeling and the simulation of the PV generator and the DC/DC converter is carried out using MATLAB software. After that a .study of PV water pumping system has been undertaken using DC motor and AC motor. A comparison between the performance of those systems with and without MPPT in terms of PV total energy produced and total volume of water pumped per day is carried out. Results show that MPPT can very significantly improve the performance of PV pumping systemItem Implementation of IP cores dedicated to cryptography(2012) Alouani, BrahimThis work consists to implement IP cores dedicated to cryptography, using an FPGA as a hardware working platform and VHDL as a hardware description language. The cryptography can be classified into two main parts. Secret key and public key encryption. The last one is more complicated because it uses hard arithmetic; the RSA (Rivest, Shamir, and Adleman), DH (Diffie-Hellman Key Agreement) and the elliptic curve algorithm (ECC) are the most used public key protocols in cryptography. The modular exponentiation is the core operation in these protocols. The security of these systems depends directly on the key bit lenght, in practice (between 160 and 1024 bits or more in some applications). A high bit length and complicated operations as the modular arithmetic make the hardware solution better in different applications. The modular exponentiation can be done by successive operations of modular multiplication, that is why we chose modular multiplication as a problematic in this report. Montgomery and the interleaved are the most modular product algorithms appropriate to hardware design. In our case; we chose an optimized version of MontgomeryItem Design and implementation of a parallel wavelet transform algorithm using unity model and systolic arrays(1997) Yahiaoui, AichaIn the past two decades, there has been a tremendous progress in the development and analysis of parallel programs for different applications. Since the time required to solve a problem by a traditional computer is significantly reduced when using a parallel computer, we worked on the design and analysis of a parallel algorithm to solve the wavelet transform because the analysis and synthesis using wavelets has became a very useful tool for analyzing non-stationary signals in completion of the windowed Fourier transform which is the most known time-frequency representation…