http://repository.enp.edu.dz/jspui/handle/123456789/62 2026-04-14T11:46:16Z http://repository.enp.edu.dz/jspui/handle/123456789/11372 Conception d’antennes pour vêtements communicants Bouaza, Abdelmaoula Le développement des systèmes de communication corporelle individuels constitue un enjeu majeur pour la nouvelle génération de réseaux sans fil et représente l’un des défis actuels dans le domaine des sciences et technologies de la communication. Les antennes, éléments essentiels de la transmission électromagnétique, doivent être capables de fonctionner aussi bien à l’intérieur qu’à l’extérieur du corps, selon les applications visées. Dans ce travail de thèse, nous proposons la conception d’une famille d’antennes intégrables dans un vêtement de type gilet, prenant la forme d’un logo ou d’un sigle discret, et opérant dans les bandes de fréquences dédiées aux applications ISM, WBAN et WLAN, couvrant notamment 2,45 GHz, 5 GHz et 5,8 GHz. Ces antennes offrent un fonctionnement en accès ouvert, pleinement compatible avec les technologies sans fil courantes telles que Wi-Fi, Bluetooth ou LoRa. La topologie retenue garantit une intégration « visuellement discrète », conférant à l’antenne l’apparence d’un élément graphique esthétique tout en répondant aux exigences électromagnétiques. Cette solution bi-bande ouvre de nouvelles perspectives pour les dispositifs de communication portables, permettant une transmission de données fluide au sein d’un composant unique intégré dans le vêtement. Thèse de Doctorat : Electronique : Alger, Ecole Nationale Polytechnique : 2025 2025-01-01T00:00:00Z http://repository.enp.edu.dz/jspui/handle/123456789/11371 Behavioral biometrics for continuous authentication of smartphone users Ouadjer, Youcef Smartphone devices have become essential for managing sensitive operations such as on-line banking, accessing medical records, making digital payments, and using government services. As a result, consumers have raised the demand for robust and user-friendly authentication systems. However, traditional smartphone authentication methods such as knowledge-based (e.g., PIN codes, passwords) and static biometric systems (e.g., finger-print, facial recognition) suffer from significant limitations. These methods are vulnerable to smudge and spoofing attacks, and fails to provide ongoing security once a device is un-locked. To address these challenges, we propose the design and evaluation of efficient, multi-modal continuous authentication systems leveraging behavioral biometrics. As a starting point, the research presents a comprehensive review of state-of-the-art meth ods for continuous authentication, highlighting recent progress in behavioral biometric modalities such as hand movement and touch gestures, and identifying limitations in existing datasets. Particularly the lack of synchronized multi-modal behavioral biometric modalities, combined with static biometric characteristics such as facial features. Following, an efficient continuous authentication system is designed, by investigating advanced feature selection to identify most relevant features, showing consistent improvement with the subset of selected features. Further a new continuous authentication system is introduced using self-supervised contrastive learning. The system employs a lightweight convolutional neural network architecture based on depthwise separable convolutions, achieving high accuracy verification and identification tasks while maintaining computational efficiency. By extending the original self-supervised contrastive learning framework introduced in the previous contribution, a multi-modal fusion framework is designed, by combining hand movement and touch gesture data. Fusion is performed at the feature-level, demonstrating robust performance even on small annotated datasets where labeled biometric data is scarce. Lastly, a novel multi-modal dataset, MM-BioSync, is introduced to address the lack of synchronized behavioral biometric public datasets. The dataset integrates data from frontfacing cameras, motion sensors, and touchscreen interactions. Experiments conducted on the dataset reveal that integrating all modalities captured during reading and writing tasks yields the best performance in user verification, underscoring the value of multimodal approaches for continuous authentication. The findings of this thesis highlight the potential of behavioral biometrics and multimodal fusion in enabling continuous user authentication. By addressing key challenges related to model performance, computational efficiency, and dataset availability, this work advances the state-of-the-art and provides a foundation for developing secure and user-friendly authentication solutions on smartphones. Thèse de Doctorat : Électronique. Instrumentation : Alger, Ecole Nationale Polytechnique : 2026. - Thèse confidentielle 2 ans jusqu'à Janvier 2028 2026-01-01T00:00:00Z http://repository.enp.edu.dz/jspui/handle/123456789/11370 Micronisation et amélioration de l'indice de blancheur des carbonates de calcium du gisement de Djebel El Madjène -COSIDER carrières Bendiff, Selma; Boughani, Kamilia Le présent travail de fin d'études porte sur la micronisation et l'amélioration de l'indice de blancheur du carbonate de calcium (CaCO3) extrait du gisement de Djebel El Madjène (Constantine). L'objectif principal est d'optimiser les conditions de broyage afin d'obtenir une taille de particules micrométriques tout en améliorant les propriétés optiques du produit. Une série d'essais de broyage à différentes vitesses et durées a été réalisée, suivie d'analyses granulométriques et colorimétriques. L'ajout contrôlé d'acide stéarique comme agent de surface (0,1-0,3%) s'est révélé efficace pour limiter le colmatage, améliorer la dispersion et accroître la blancheur, atteignant des valeurs supérieures à 98%. En revanche, à des teneurs élevées (> 2%), le produit devient hydrophobe et présente une baisse de blancheur. Les résultats obtenus confirment que la combinaison d'une micronisation optimisée et d'un traitement de surface adapté constitue une voie efficace pour valoriser le carbonate de calcium local à des fins industrielles à haute valeur ajoutée. Mémoire de Projet de Fin d’Études : Génie Minier: Alger, École Nationale Polytechnique : 2025 2025-01-01T00:00:00Z http://repository.enp.edu.dz/jspui/handle/123456789/11369 Investigations on modern control techniques for multi-source energy conversion systems connected to microgrids Hadjaidji, Fatma Zohra Microgrids are small-scale electrical networks integrating renewable energy sources, distributed generators, and local loads. They are designed to provide reliable and high-quality power supply in various operating modes, whether islanded or connected to the main grid, ensuring a seamless transition between these two modes. Thistype of system faces numerous technical challenges related to the nature of the loads, interruptions in energy sources, and the interconnection of components with different characteristics, which can impact the quality of the supplied power and the overall stability of the microgrid. With the emergence of modern power electronics converters and advanced control devices, a large part of these challenges can be solved. The work conducted as part of this thesis aligns with this context. Based on the robust performance of modern control systems, including fractional-order control, sliding mode control, and fuzzy logic control, we have developed new strategies and control tools for microgrids. Modern types of voltage source inverters, called Z-source and quasi-Z-source inverters, have been integrated. Through their design and adopted control strategies, an input voltage boosting function is enabled. Thanks to modifications in universal droop control, an improved hierarchical structure and a new decentralized structure were designed for managing multiple voltage-source inverters connected in parallel. The decentralized control strategy was proposed as a solution to manage the various operating modes of the microgrid without the need for communication lines. This approach avoids the drawbacks of centralized secondary control in hierarchical structures, such as delays or data loss, which could lead to a complete system failure. Furthermore, modern metaheuristic algorithms were employed to determine the optimal values for control parameters. Thèse de Doctorat : Automatique : Alger, Ecole Nationale Polytechnique : 2025 2025-01-01T00:00:00Z