Le champ du traitement des images et des vidéos attire l'attention depuis les deux dernières décennies. Ce champ couvre maintenant un spectre énorme d'applications comme la TV 3D, la télé-surveillance, la vision par ordinateur, l'imagerie médicale, la compression, la transmission, etc. En ce début de vingt et unième siècle nous sommes témoins d'une révolution importante. Les largeurs de bande des réseaux, les capacités de mémoire et les capacités de calcul ont été fortement augmentés durant cette période. Un client peut avoir un débit de plus de 100~mbps tandis qu'un autre peut utiliser une ligne à 56~kbps. Simultanément, un client peut avoir un poste de travail puissant, tandis que d'autres peuvent avoir juste un téléphone mobile. Au milieu de ces extrêmes, il y a des milliers de clients avec des capacités et des besoins très variables. De plus, les préférences d'un client doivent s'adapter à sa capacité, par exemple un client handicapé par sa largeur de bande peut être plus intéressé par une visualisation en temps réel sans interruption que d'avoir une haute résolution. Pour y faire face, des architectures hiérarchiques de codeurs vidéo ont été intoduites afin de comprimer une seule fois, et de décomprimer de différentes manières. Comme la DCT n'a pas la fonctionnalité de multi-résolution, une architecture vidéo hiérarchique est conçue pour faire face aux défis des largeurs de bande et des puissances de traitement hétérogènes. Avec l'inondation des contenus numériques, qui peuvent être facilement copiés et modifiés, le besoin de la protection des contenus vidéo a pris plus d'importance. La protection de vidéos peut être réalisée avec l'aide de trois technologies : le tatouage de méta-données et l'insertion de droits d'auteur, le cryptage pour limiter l'accès aux personnes autorisées et la prise des empreintes digitales active pour le traçage de traître. L'idée principale dans notre travail est de développer des technologies de protection transparentes à l'utilisateur. Cela doit aboutir ainsi à un codeur vidéo modifié qui sera capable de coder et d'avoir un flux de données protégé. Puisque le contenu multimédia hiérarchique a déjà commencé à voir le jour, algorithmes pour la protection indépendante de couches d'amélioration sont également proposées.

This thesis presents a comprehensive procedure to study sub-synchronous interactions in wind integrated power systems effectively and efficiently. The proposed procedure involves a screening phase and a detailed analysis phase. The screening is performed using a frequency scan and the detailed analysis is performed using small signal stability analysis. To facilitate the small signal analysis, a detailed linearized model of a Type 3 wind power plant is presented in this thesis. The model presented includes the generator, a three-mass drive train model, rotor and grid side converter controller models, converter transformer model and the pitch controller model. To accurately capture the effects of sub-synchronous interactions, the ac network is modelled using dynamic phasors. It is shown that using the proposed procedure, the sub-synchronous interaction between a Type 3 wind power plant and a series compensated line is due to an electrical resonance between the wind power plant generator and the series capacitor. It is also shown that this interaction is highly controllable through the rotor side converter current controllers. This fact will be proven by studying the sub-synchronous interactions in a single machine power system as well as in multi machine power systems. This thesis also presents a sub-synchronous interaction mitigation method using network devices. The performance of an SVC and a STATCOM is evaluated in this thesis. A small signal stability analysis based method will be used to design a sub-synchronous damping controller. A method will be presented to estimate the damping controller parameters systematically to obtain the desired performance using small signal stability analysis results. Furthermore, it will be shown that by strongly controlling the voltage of the point of common coupling, the damping of the oscillations produced by the sub-synchronous interaction between the wind power plant and the series compensated line can be improved. Based on the findings of this research, the thesis proposes a number of recommendations to be adopted when studying the sub-synchronous interactions in wind integrated power systems. These recommendations will facilitate to do such studies effectively and pinpoint the root cause of the sub-synchronous interactions.

Background. This research centers on tackling the serious global problem of trafficaccidents. With more than a million deaths each year and numerous injuries, it’svital to predict and prevent these accidents. By combining satellite images and dataon accidents, this study uses a mix of advanced learning methods to build a modelthat can foresee accidents. This model aims to improve how accurately we predictaccidents and understand what causes them. Ultimately, this could lead to betterroad safety, smoother maintenance, and even benefits for self-driving cars and insurance. Objective.The objective of this thesis is to create a predictive model that improvesthe accuracy of traffic accident severity forecasts by integrating satellite imagery andhistorical accident data and comparing this model with stand-alone data models.Through this hybrid approach, the aim is to enhance prediction precision and gaindeeper insights into the underlying factors contributing to accidents, thereby potentially aiding in the reduction of accidents and their resulting impact. Method.The proposed method involves doing a literature review to find currentimage recognition models and then experimentation by training a Logistic Regression, Random Forest, SVM classifier, VGG19, and the hybrid model using the CNNand VGG19 and then comparing their performance using metrics mentioned in thethesis work. Results.The performance of the proposed method is evaluated using various metrics, including precision, recall, F1 score, and confusion matrix, on a large datasetof labeled images. The results indicate that a high accuracy of 81.7% is achieved indetecting traffic accident severity through our proposed approach where the modelbuilt on individual structural data and image data got an accuracy of 58.4% and72.5%. The potential utilization of our proposed method can detect safe and dangerous locations for accidents. Conclusion.The predictive modeling of Traffic accidents are performed using thethree different types of datasets which are structural data, satellite images, and acombination of both. The finalized architectures are an SVM classifier, VGG19, anda hybrid input model using CNN and VGG19. These models are compared in orderto find the best-performing approach. The results indicate that our hybrid modelhas the best accuracy with 81.7% indicating a strong performance by the model.

This thesis discusses the modeling of a micro-grid with photovoltaic (PV)-wind-fuel cell (FC) hybrid energy system and its operations. The system consists of the PV power, wind power, FC power, static var compensator (SVC) and an intelligent power controller. Wind and PV are primary power sources of the system, and an FC-electrolyzer combination is used as a backup and a long-term storage system. A simulation model for the micro-grid control of hybrid energy system has been developed using MATLAB/Simulink. A SVC was used to supply reactive power and regulate the voltage of the hybrid system. To achieve a fast and stable response for the real power control, the intelligent controller consists of a Radial Basis Function Network-Sliding Mode Control (RBFNSM) and a General Regression Neural Network (GRNN) for maximum power point tracking (MPPT). The pitch angle of wind turbine is controlled by RBFNSM, and the PV system uses GRNN, where the output signal is used to control the DC/DC boost converters to achieve the MPPT.

Les travaux de cette thèse ont pour but de développer des stratégies de régulation de débit pour le codage vidéo scalable MPEG-4 SVC. Plusieurs approches sont proposées, en fonction des besoins en termes de précision et de la complexité désirée. La qualité du flux vidéo décodé est également prise en compte afin d'améliorer l'impression visuelle. La multiplication des moyens de transmission et la diversification des appareils capables de lire du contenu vidéo contraignent les diffuseurs à dépenser beaucoup de temps et de moyens pour être en mesure de fournir une qualité de vidéo optimale quel que soit le contexte. La vidéo scalable a été développée en réponse à ce besoin d'adaptation des contenus vidéo aux différents contextes de diffusion. Le standard H.264/MPEG-4 SVC (Scalable Video Coding) propose trois types de scalabilité (spatiale, temporelle et en qualité), qui permettent d'adapter la résolution, le nombre d'images par seconde et la qualité du flux en fonction des besoins. Un flux vidéo unique est encodé, contentant plusieurs couches de résolution différentes codées les unes par rapport aux autres, de façon à rendre le codage de l'ensemble plus efficace. La régulation de débit permet d'adapter le débit en sortie de l'encodeur pour respecter des contraintes liées à la transmission ou au décodage du flux vidéo. À partir d'une consigne donnée, le budget à respecter est réparti entre les différents éléments du flux. Un modèle de débit est ensuite utilisé pour anticiper le comportement du débit en fonction des paramètres d'encodage afin de respecter les contraintes imposées au flux. À partir de cette problématique, deux approches sont proposées. La première se base sur un pré-encodage de chaque image pour fournir une base de calcul au modèle de débit. Elle permet d'obtenir une régulation très précise, avec une erreur entre le budget alloué et le débit effectif inférieure à 7\% sur les trois types de scalabilité. La seconde approche utilise les informations rassemblées dans les images précédentes comme base pour le modèle de débit de l'image à encoder. Elle ne requiert pas de pré-encodage, et ne pénalise pas la complexité du processus d'encodage. En outre, la perte de performances par rapport à l'approche en deux passes est minime et la consigne de débit par seconde est respectée de manière précise. Enfin, une méthode permettant de réduire les variations de la qualité est proposée pour améliorer l'impression visuelle ressentie par l'utilisateur. Les résultats montrent que la méthode présentée est capable de réguler le débit avec une grande précision sur les trois types de scalabilité, tout en réduisant les variations de la qualité et en conservant une complexité de calculs très faible. Ces atouts la rendent non seulement intéressante du point de vue des performances, mais également applicable dans des contextes pratiques où les ressources en temps sont limitées.

Multimedia services and applications became the driving force in the development and widespread deployment of wireless broadband access technologies and high speed local area networks. Mobile phone service providers are offering wide range of multimedia applications over high speed wireless data networks. People can watch live TV, stream on-demand video clips and place videotelephony calls using multimedia capable mobile devices. Mobile devices will soon support capturing and displaying high definition video. Similar evolution is also occurring in the local area domain. The video receiver or storage devices were conventionally connected to display devices using cables. By using wireless local area networking (WLAN) technologies, convenient and cable-free connectivity can be achieved. Media over wireless home networks prevents the cable mess and provides mobility to portable TVs. However, there still exit challenges for improving the quality-of-service (QoS) of multimedia applications. Conventional service architectures, network structures and protocols lack to provide a robust distribution medium since most of them are not designed considering the high data rate and real-time transmission requirements of digital video. In this thesis the challenges of wireless video streaming are addressed in two main categories. Streaming protocol level issues constitute the first category. We will refer to the collection of network protocols that enable transmitting digital compressed video from a source to a receiver as the streaming protocol. The objective of streaming protocol solutions is the high quality video transfer between two networked devices. Novel application-layer video bit-rate adaptation methods are designed for handling short- and long-term bandwidth variations of the wireless local area network (WLAN) links. Both transrating and scalable video coding techniques are used to generate video bit-rate flexibility. Another contribution of this thesis study is an error control method that dynamically adjusts the forward error correction (FEC) rate based on channel bit-error rate (BER) estimation and video coding structure. The second category is the streaming service level issues, which generally surface in large scale systems. Service system solutions target to achieve system scalability and provide low cost / high quality service to consumers. Peer-to-peer assisted video streaming technologies are developed to reduce the load of video servers. Novel video file segment caching strategies are proposed for more efficient peer-to-peer collaboration.

Modern interconnected power systems are becoming highly complex and sophisticated, while increasing energy penetrations through congested inter-tie lines causing the operating point approaching stability margins. This as a result, exposes the overall system to potential low frequency power oscillation phenomena following disturbances. This in turn can lead to cascading events and blackouts. Recent approaches to counteract this phenomenon are based on utilization of wide area monitoring systems (WAMS) and power electronics based devices, such as flexible AC transmission systems (FACTS) and HVDC links for advanced power oscillation damping provision. The rise of hybrid AC-DC power systems is therefore sought as a viable solution in overcoming this challenge and securing wide-area stability. If multiple FACTS devices and HVDC links are integrated in a scheme with no supervising control actions considered amongst them, the overall system response might not be optimal. Each device might attempt to individually damp power oscillations ignoring the control status of the rest. This introduces an increasing chance of destabilizing interactions taking place between them, leading to under-utilized performance, increased costs and system wide-area stability deterioration. This research investigates the development of a novel supervisory control scheme that optimally coordinates a parallel operation of multiple FACTS devices and an HVDC link distributed across a power system. The control system is based on Linear Quadratic Gaussian (LQG) modern optimal control theory. The proposed new control scheme provides coordinating control signals to WAMS based FACTS devices and HVDC link, to optimally and coherently counteract inter-area modes of low frequency power oscillations inherent in the system. The thesis makes a thorough review of the existing and well-established improved stability practises a power system benefits from through the implementation of a single FACTS device or HVDC link, and compares the case –and hence raises the issue–when all active components are integrated simultaneously and uncoordinatedly. System identification approaches are also in the core of this research, serving as means of reaching a linear state space model representative of the non-linear power system, which is a pre-requisite for LQG control design methodology.

The modern day power system is witnessing a tremendous change. There has been a rapid rise in the distributed generation, along with this the deregulation has resulted in a more complex system. The power demand is on a rise, the generation and trans-mission infrastructure hasn't yet adapted to this growing demand. The economic and operational constraints have forced the system to be operated close to its design limits, making the system vulnerable to disturbances and possible grid failure. This makes the study of voltage stability of the system important more than ever. Generally, voltage stability studies are carried on a single phase equivalent system assuming that the system is perfectly balanced. However, the three phase power system is not always in balanced state. There are a number of untransposed lines, single phase and double phase lines. This thesis deals with three phase voltage stability analysis, in particular the voltage stability index known as L-Index. The equivalent single phase analysis for voltage stability fails to work in case of any unbalance in the system or in presence of asymmetrical contingency. Moreover, as the system operators are giving importance to synchrophasor measurements, PMUs are being installed throughout the system. Hence, the three phase voltages can be obtained, making three phase analysis easier. To study the effect of unbalanced system on voltage stability a three phase L-Index based on traditional L-Index has been proposed. The proposed index takes into consideration the unbalance resulting due to untransposed transmission lines and unbalanced loads in the system. This index can handle any unbalance in the system and is much more realistic. To obtain bus voltages during unbalanced operation of the system a three phase decoupled Newton Raphson load ow was used. Reactive power distribution in a system can be altered using generators voltage set-ting, transformers OLTC settings and SVC settings. All these settings are usually in balanced mode i.e. all the phases have the same setting. Based on this reactive power optimization using LP technique on an equivalent single phase system is proposed. This method takes into account generator voltage settings, OLTC settings of transformers and SVC settings. The optimal settings so obtained are applied to corresponding three phase system. The effectiveness of the optimal settings during unbalanced scenario is studied. This method ensures better voltage pro les and decrease in power loss. Case studies of the proposed methods are carried on 12 bus and 24 bus EHV systems of southern Indian grid and a modified IEEE 30 bus system. Both balanced and unbalanced systems are studied and the results are compared.