https://dspace.univ-guelma.dz/jspui/handle/123456789/15823 2026-04-14T19:22:46Z https://dspace.univ-guelma.dz/jspui/handle/123456789/18720 Titre: Transmission Media Auteur(s): GRAINI, Leila 2025-10-13T00:00:00Z https://dspace.univ-guelma.dz/jspui/handle/123456789/17654 Titre: Contribution à l’étude de composants non réciproques hyperfréquences à base de matériau magnétique pour des applications en télécommunications Auteur(s): BAHLOUL, AFAF Résumé: Les systèmes de communication futurs sont confrontés à deux défis majeurs : réduire la taille des circuits et augmenter les fréquences, ce qui nécessite des niveaux d’intégration élevés et des performances supérieurs à moindre cout. Il est crucial de souligner l’importance de la catégorie des dispositifs passifs non réciproques, comme les circulateurs et les isolateurs. Lorsqu’ on travaille dans les bandes de résonance gyromagnétique en appliquant un champ magnétique continu, le matériau devient anisotrope (ferrite), permettant d’obtenir l’effet non réciproque souhaite qui permet la création des composant susmentionnés.Le YIG est un excellent choix pour ces appareils en raison de sa capacite à propager les ondes électromagnétiques de manière asymétrique. L’objectif du projet est des concevoir un circulateur entièrement passif autour des fréquences de 10 GHz. Fin de réaliser cette tâche nous allons tout d’abord représenter ce composant en utilisant le logiciel HFSS. La difficulté réside dans la conception du circulateur, car plus la fréquence de travail augmente, plus la fonction de circulation devient complexe à accomplir, plusieurs structures ont été analysées et numérisées afin de mieux représenter le matériau magnétique. La modélisation évaluera la possibilité d’utilisation du composant. 2025-06-26T00:00:00Z https://dspace.univ-guelma.dz/jspui/handle/123456789/16796 Titre: STUDY AND IMPROVEMENT OF THE QUALITY OF SERVICE OF A VIDEO STREAMING BY THE HEVC CODEC IN AD-HOC NETWORKS. Auteur(s): ELHACHI, Hana Résumé: Video transmission over all types of networks is a field that has been growing steadily in recent years. Today, improvements in network properties with greater efficiency of video codecs and increased processing and storage capacity of all types of devices contribute to making video streaming possible. Uncompressed digital videos contain large amounts of data. This is why video codecs play an important role, as they can compress video sequences and instantly transmit the video, through the transmission channels, especially in mobile networks, wireless networks, and vehicular networks or Vehicular ad-hoc Networks (VANET) in English, which are in the short term the most viable application example of ad-hoc networks. However, this solution also presents limitations mainly related to the band and problems related to the transmission, namely packet losses, noise, etc. The objective of this thesis is to study and evaluate the performance of the new and emerging HEVC (High-Efficiency Video Coding) video coding standard in the context of ad-hoc networks. This contribution aims to study the impact of delay, jitter, packet loss, and bandwidth on the Quality of Service (QoS). The focus will be on the analysis of the impact of video content on the Quality of Experience (QoE) as well as the proposal and evaluation of cryptography and coding techniques allowing better security of the information and the physical layer. The candidate is called upon to propose adequate transmission techniques that ensure an acceptable quality of perception with an optimization of the resources available through the network in question. Tests, and if necessary practical implementations, will also be possible 2025-01-08T00:00:00Z https://dspace.univ-guelma.dz/jspui/handle/123456789/16341 Titre: Design of a New Antenna for Biomedical Applications Auteur(s): GUETAF, Bilal Résumé: In the current era, antennas play a significant role in advancing biomedical engineering to enhance both health and quality of life. Various healthcare instruments, such as microwave imaging devices, magnetic resonance imaging machines, pacemakers, deep neural implants, endoscopy tools, and clinical instruments for thermal ablation, leverage the advantages of antennas. Antennas can be implanted, placed on the body, or ingested to transmit diagnostic information from the human body to external monitors and, subsequently, to healthcare professionals through the Internet. Additionally, analyzing variations in the electrical and radiation characteristics of antennas, such as near-field electromagnetic radiation, current density, electric field distribution, magnetic field distribution, specific absorption rate and reflection coefficient, enables non-ionizing and non-invasive disease detection. Important applications of antennas include the detection of brain and breast tumors, and brain strokes. Circularly polarized (CP) antennas significantly enhance the efficiency of radar systems in medical microwave imaging by mitigating indoor multi-path effects and accommodating various body postures. They also minimize polarization mismatch losses, penetrate lossy dielectric materials in human body tissues, and ensure reliable detection of pathological tissue without being constrained by antenna orientation. While numerous antennas have been documented for biomedical applications, existing ones typically utilize linear polarization and serve a singular purpose, whether for tumor screening, stroke detection, or health-monitoring. Hence, there is a need for innovative high-performance antennas capable of addressing a variety of biomedical applications. This thesis introduces a mono-static circularly polarized printed monopole antenna (CPPMA) with dimensions of 34 × 28 × 1.5 mm3, designed for applications in the Industrial, Scientific, and Medical (ISM) band. The proposed CPPMA is intended for use in medical microwave imaging and wearable health monitoring applications. Its capabilities include the detection of brain strokes and breast tumors at different positions with various sizes. Additionally, the CPPMA holds potential for deployment in remote health-monitoring systems due to its operation in the ISM band and CP properties. 2024-09-03T00:00:00Z