Accompanying the increasing interest on Vehicle Ad-hoc Network (VANET), there is a request for high quality and real-time video streaming on VANET, for safety and infotainment applications. Video Streaming on VANET faces extra issues, comparing to the Mobile Ad-hoc Network (MANET), like the high dynamic topology. However, there are also benefits in VANET, like large buffer and battery capacity, predictable motion of vehicles and powerful CPU and GPU. Video streaming on VANET can be highly improved by these features. However the poor performance of wireless networks is an critical issue for video streaming in VANET. The high packet loss probability of wireless networks significantly reduces the quality of the transmitted video. An error recovery process is proposed in our research for high quality and real-time video streaming in VANET, which is call Multi-path Error Recovery Video Streaming (MERVS). The performance improvement of wireless networks is also considered in our research. The cross layer technique is adopted in our research, in order to increase the accuracy on the network condition monitoring and to guarantee the fairness on network resource distribution. Cross layer protocols on both the Media Access Control (MAC) layer and the Network layer are proposed to improve the performance collaboratively. The contribution of my researches are: 1) I proposed a MERVS, which provides high quality and real-time video streaming; 2) several improvement techniques are also designed to improve the performance of MERVS; 3) simulation results verifies that MERVS can have a higher quality on transmitted video comparing to the existing protocols in an acceptable delay.

Block-structured matrices arise in several contexts in circuit simulation problems. These matrices typically inherit the pattern of sparsity from the circuit connectivity. However, they are also characterized by dense spots or blocks. Direct factorization of those matrices has emerged as an attractive approach if the host memory is sufficiently large to store the block-structured matrix. The approach proposed in this thesis aims to accelerate the direct factorization of general block-structured matrices by leveraging the power of multiple OpenCL accelerators such as Graphical Processing Units (GPUs). The proposed approach utilizes the notion of a Directed Acyclic Graph representing the matrix in order to schedule its factorization on multiple accelerators. This thesis also describes memory management techniques that enable handling large matrices while minimizing the amount of memory transfer over the PCIe bus between the host CPU and the attached devices. The results demonstrate that by using two GPUs the proposed approach can achieve a nearly optimal speedup when compared to a single GPU platform.

The world of today is increasingly dependant on a functional, globalized economy. The defence and security establishments’ reliance on supplies and logistics is not new. First responders rely on many tools and systems that are critical to their endeavours. Somewhat disjoint at first glance, these domains share a common need for complex physical or logistical infrastructures such as power plants, ports, supply chains, to name a few examples.All of these are potentially vulnerable to attacks, disruptions, breakdowns, or other activities that disable the infrastructure and consequently cause important physical or economic damage. An obligation exists to protect these critical infrastructures and a decision support system that is able to detect, identify, and mitigate the risk of unwanted events would be invaluable in preventing the disastrous consequences of compromised infrastructure.This thesis explores the design and application of such a system. It starts with a pre-existing, actively researched risk management framework and proposes a methodology to apply it in new contexts, as well as contributions to provide the framework with the ability to solve new problems. Relevant case studies in critical infrastructure protection are presented, as well as applications of the developed methodology with the proposed modifications when suitable. Simulations, results, and insightful discussions are provided for each of the case studies. Finally, research trends, future work, and a conclusion are given, completing this thesis.

L'interaction tactile multi-points co-localisée procure un fort sentiment de contrôle direct mais introduit des problèmes d'occultation, de précision et de fatigue. Ces problèmes sont exacerbés sur les écrans de grandes dimensions, qui supportent la manipulation de grandes quantités de données, souvent en collaboration avec d'autres utilisateurs. Pour résoudre ces problèmes, cette thèse s'intéresse à l'introduction d'indirections dans l'interaction multi-points sur grands écrans. Nos travaux portent sur l'étude des facteurs qui influencent la précision dans les tâches de sélection sans prévisualisation du contact. Les résultats de deux expériences contrôlées ont ainsi permis d'estimer la précision attendue selon les caractéristiques des périphériques d'entrée et de sortie et des conditions d'utilisation. Sur la base de ces connaissances, nos travaux portent également sur le développement de nouvelles techniques d'interaction pour écrans de grandes dimensions. Nous avons d'abord proposé une technique permettant d'interagir indirectement avec une tablette tactile, en introduisant la gestion de plusieurs curseurs contrôlés relativement. Nous avons ensuite conçu une interaction reposant sur la création de plusieurs périphériques virtuels qui supportent une interaction à la fois directe et indirecte tout en permettant de réorganiser les éléments d'une interface. Parallèlement à cela, nous avons transformé un écran mural de 6*2,4m en une surface tactile multi-points afin de pouvoir tester les techniques et scénarios discutés dans ces travaux. / Co-localized multi-touch interaction affords a high feeling of directness but introduces problems of occlusion, precision and fatigue. These problems are even more acute with large displays, supporting the interaction with large data sets, often in collaboration with other users. To solve these problems this thesis focuses on the introduction of indirections in multi-touch interaction on large displays. We first study factors impacting accuracy in selection tasks without contact preview. Results of two controlled experiments allowed to estimate the expected accuracy depending on input and output device characteristics and input conditions. Based on this knowledge, we developed new interaction techniques for large displays. We first introduced a technique to interact indirectly using a tactile tablet by introducing the control of several cursors using a relative mapping. Then we proposed an interaction technique based on the creation of multiple soft-devices that supports both direct and indirect interaction and allows to re-arrange the interface of legacy applications. In order to design, test and evaluate these techniques, we turned a back projected wall display (6*2,4m) into an interactive multi-touch surface.

La problématique générale de cette thèse, qui s'inscrit dans le contexte du projet européen InTraDE (Intelligent Transportation for Dynamic Environment), concerne la modélisation de systèmes de systèmes (SdS). Un SdS est un système composé d'une hiérarchie de systèmes autonomes présents à différents niveaux de représentation. Cette thèse répond au besoin d'outils de modélisation généralistes respectant les caractéristiques fondamentales des SdS, en proposant un formalisme multi-agents mullti-niveaux et les algorithmes qui assurent le respect de ces caractéristiques. L'utilisation d'un modèle multi-agents permet de profiter de l'autonomie naturelle des agents et l'aspect multi-niveaux de notre modèle permet aux entités modélisées de raisonner à propos de l'organisation hiérarchique du système en leur offrant la notion explicite de niveau. En plus de la modélisation des systèmes complexes, cette thèse aborde les problèmatique liées à leur simulation, en particulier, le fait que les ressources informatiques (mémoire et microprocesseur utilisés) nécessaires pour simuler avec précision de tels systèmes sont particulièrement importantes. Nous proposons ainsi une méthodologie pour tirer partie de la capacité des simulations multi-niveaux à produire un compromis entre la précision de la simulation et les ressources informatiques utilisées. / The main problematic of this thesis, which takes place in the context of the european project InTraDE (Intelligent Transportation for Dynamic Environment), deals with the modeling of systems of systems (SoS). A SoS is a system composed of a hierarchy of autonomous systems present in several representation levels. This thesis answers the need of generic modeling tools respecting the fundamental characteristics of SoS, proposing a multi-level multi-agent formalism and algorithms wich insure their respect. The use of a multi-agent model allows to take advantage of the natural autonomy of agents and the multi-level aspect of our model permits to modeled entities to reason about the organisational hierarchy of the system, carrying the explicit notion of level. Besides the modeling of complex systems, this thesis also deals with the problematic related to their simulations, particularly, the fact that computer resources (used memory and microchips) needed to simulate with precision such systems are truly important. We propose a methodology to benefit from the muli-level simulations capacity to produce compromise between the simulation precision and the used computer resources.

Multiple Input Multiple Output (MIMO) systems use multiple transmit and receive antennas to achieve higher data rates by transmitting multiple independent data systems. Transmission errors can be reduced by using Hybrid Automatic Repeat request (HARQ) combining techniques with MIMO systems. In this thesis, the use of HARQ for MIMO multi-hop communication is studied. We propose two MIMO HARQ combining methods which are based on using pre-combiningonly and a joint pre and post combining techniques. In addition to conventional single-hop transmission, HARQ schemes for MIMO multi-hop relay systems are also investigated. A novel approach is proposed to deal with the parallel HARQ processes in MIMO relay scenario. An information theoretic throughput analysis is performed to evaluate the performance of the relay system by employing various transmission techniques for relay-destination link. Evaluation is carried out on the delay involved while employing the relay systems as compared to single hop systems. Simulation results show that the proposed system can enhance the overall throughput performance of MIMO single-hop and multi-hop relay systems. Considering the recent research interest in green radio and requirements of reduced energy consumption by the wireless networks, we evaluated the energy efficiency of existing and proposed MIMO HARQ techniques for sensor and cellular networks. The results show that the proposed scheme is more energy efficient compared to other schemes in single-hop as well as multi-hop scenarios.

The current 'gold standard method' of detecting cancer relies on microscopic examination by specialised pathologists. However, there are risks associated with surgery and biopsies and so the ability to diagnose cancer and other diseases in a non-invasive manner is highly attractive. There are many imaging techniques suitable for this, each with their own advantages and disadvantages, which can be improved by the use of contrast agents. The incorporation of targeting vectors allows for the specific imaging of desired tissues. Further to this, the incorporation of more than one contrast agent into one imaging agent allows for multi-modal imaging of cancerous tissue and other diseases. This allows for the advantages of different techniques to be used simultaneously and is an emerging field. The methods for the synthesis of these drugs can be synthetically demanding and low yielding due to linear synthetic strategies. The use of multi-component reactions would be a major benefit and the Ugi reaction is particularly attractive due to the incorporation of four components and the biocompatible bis-amide motif of Ugi products. This work serves as an extension to previous work based on Ugi reactions of metal complexes, which showed that amine and carboxylic acid appended lanthanide and carboxylic acid appended d-metal complexes can be used as stable building blocks in the formation of mono-metallic complexes. This work presents the synthesis of aldehyde appended lanthanide complexes and their use in Wittig and Ugi chemistry in the synthesis of mono-metallic complexes. The previously synthesised amine appended lanthanide complexes 1, 3, 4 were also synthesised to be used as a feedstock in subsequent Ugi reactions. A number of carboxylic acid appended d-metal complexes and cyanine dyes were synthesised according literature procedures. Both the bis-acid appended d-metal complexes and cyanine dyes were used unsuccessfully in the Ugi reaction. However, the mono-acid d-metal complexes were used successfully in the Ugi reaction in keeping with previous reports. These were used as the third feedstock for the synthesis of trimetallic complexes along with the aldehyde and amine appended lanthanide complexes via the Ugi reaction. In addition, a number of Ugi reactions were performed on organic compounds. The use of p-toluic acid gave five Ugi compounds, which were characterised and gave the expected results. However, the use of biotin as the carboxylic acid component gave four compounds that were complex to characterise and suggested that the incorporated biotin may not serve as a viable targeting vector. One of the p-toluic acid Ugi products was reacted further and a biotin moiety was incorporated with a (CH2)6 spacer. Spectroscopic evidence suggested that the biotin would still act as a viable targeting vector. Overall, this work serves to set the scene for the synthesis of targeted tri-metallic multi-modal imaging agents using stable metal complexes as building blocks in the Ugi reaction.

La représentation de phénomènes de rupture localisée (fissure, décohésion…) rend nécessaire l'utilisation de modèle de plus en plus fin et couteux en calcul. Pour pallier à ce problème de nombreux modèles multi-échelles ont permis de faire cohabiter deux échelles de modèles différents dont l'un plus grossier permet des gains de calculs substantiels. Cependant, coupler deux modèles différents peut entrainer un certain nombre d'incompatibilités qui peuvent générer notamment des réflexions parasites au niveau des interfaces. La première partie de mes travaux traite de l'incompatibilité issue du passage d'un comportement non-local à un comportement local dans un milieu discret. De nouveaux schémas de construction à l'interface sont proposés afin de réduire in fine les phénomènes de réflexions. La deuxième partie aborde une seconde source d'incompatibilité due au changement d'échelle de discrétisation dans un milieu continu local. Une nouvelle méthode de dissipation sélective permet de réduire les phénomènes de réflexions en absorbant les phénomènes microscopiques. Finalement, l'ensemble de ces démarches sera mis en place sur un modèle de béton fibré pour observer l'évolution de phénomène localisé en dynamique explicite. / Representation of localized phenomena like failures or cracks requires models increasingly precise and cpu consuming. To overcome this problem many multiscale models allowed to coexist two scales of different models including a coarser one that enables to gain substantial time calculations. However, coupling two different models may cause a number of incompatibilities that can generate difficulties such as spurious reflections at the interfaces. The first part of my work deals with the incompatibility after the passage of a non-local behavior at a local behavior in a discreet environment. New construction schemes at the interface are proposed to reduce the reflection phenomena. The second part deals with a second source of incompatibility due to the scaling of discretization in a local continuum. A new method for selective dissipation reduces reflection phenomena absorbing microscopic phenomena. Finally, all of these steps will be implemented on a model of fiber-reinforced concrete to observe the evolution of localized phenomenon in explicit dynamics.

This research investigates the ‘performativity’ of the ‘author function’ through collaging the audio recordings of American poet Sylvia Plath. The ‘author function’ is a term by Michel Foucault to describe how readers attribute certain characteristics that they believe belong to the author and ascribe them to the writing. ‘Performativity’ is a term used by Judith Butler to describe a set of actions that ascribe and predetermine a set of attributes to a subject through his or her gender, age, timeframe, nationality and race. The ‘performativity’ of the ‘author function’ appropriates these characteristics and attributes them to the author. How the determination of an authorial identity translates to the interaction of the practice component of the project, which includes several components of digital collage, is through attributions that readers make in the creation of an author. The practice component of the project consists of the collage of audio and video recordings, the programming of video with Max/MSP/Jitter, ‘performative’ elements and collage poetry on Twitter. The audio component was collaged from two poems entitled ‘Lady Lazarus’ and ‘The Applicant’ that Plath read to the British Council in 1962 to form a new poem entitled Lady/Applicant: The Lazarus. The video component consists of collaging recorded video clips of storefront and street signs in Camden, London, where she is associated with living and committing suicide at. A second video collage entitled Shadows/Shadows/Tomb takes place at a cemetery close to my residence in 2011 and documents symbols of death that reference my own authorial identity. The second set of videos run on a Max/MSP/Jitter patch that display four screens of filmed texts inscribed on tombstones that play four streaming poems through a systematic structure of boxes. The screens are displayed in each box and sourced from separate folders to display and play the film clips. The practice of collage and constraint-based poetry complicates the constitution of being the author when the collagist of Plath’s poetry is a different gender than hers. This research then expands on how identity radically shifts in the text when the subject and the collagist have very different identities. The radical shift in a collage takes place within a predefined and generalized concept of the reader as determined by Stanley Fish, a prominent writer on the subject of ‘reader-response criticism’, who believes that one way a reader could be approached is through his or her relationship with the writing.

Dans cette thèse, nous abordons le problème fondamental de l'accès au spectre opportuniste dans un système de communication multi-canal. Plus précisément, nous considérons un système de communication dans lequel un utilisateur a accès à de multiples canaux, tout en étant limité à la détection et la transmission sur un sous-ensemble de canaux. Nous explorons comment l'utilisateur intelligent exploite ses observations passées et les propriétés stochastiques de ces canaux afin de maximiser son débit. Formellement, nous fournissons une analyse générique sur le problème d'accès au spectre opportuniste en nous basant sur le problème de `restless multi-bandit’ (RMAB), l'une des généralisations les plus connues du problème classique de multi-armed bandit (MAB), un problème fondamental dans la théorie de décision stochastique. Malgré les importants efforts de la communauté de recherche dans ce domaine, le problème RMAB dans sa forme générique reste encore ouvert. Jusqu'à aujourd'hui, très peu de résultats sont connus sur la structure de la politique optimale. L'obtention de la politique optimale pour un problème RMAB général est intraçable dû la complexité de calcul exponentiel. Par conséquent, une alternative naturelle est de se focaliser sur la politique myopique qui maximise la récompense à immédiate, tout en ignorant celles du futur. Donc, nous développons trois axiomes caractérisant une famille de fonctions que nous appelons fonctions régulières, qui sont génériques et pratiquement importantes. Nous établissons ensuite l'optimalité de la politique myopique lorsque la fonction de récompense peut être exprimée comme une fonction régulière et le facteur de discount est borné par un seuil déterminé par la fonction de récompense. Nous illustrons également l'application des résultats pour analyser une classe de problèmes RMAB dans l'accès opportuniste. Ensuite, nous étudions un problème plus difficile, où l'utilisateur doit configurer le nombre de canaux à accéder afin de maximiser son utilité (par exemple, le débit). Après avoir montré la complexité exponentielle du problème, nous développons une stratégie heuristique v-step look-ahead. Dans la stratégie développée, le paramètre v permet de parvenir à un compromis souhaité entre l'efficacité sociale et de la complexité de calcul. Nous démontrons les avantages de la stratégie proposée via des simulations numériques sur plusieurs scénarios typiques. / In the thesis, we address the fundamental problem of opportunistic spectrum access in a multi-channel communication system. Specifically, we consider a communication system in which a user has access to multiple channels, but is limited to sensing and transmitting only on one at a given time. We explore how the smart user should exploit past observations and the knowledge of the stochastic properties of these channels to maximize its transmission rate by switching channels opportunistically. Formally, we provide a generic analysis on the opportunistic spectrum access problem by casting the problem into the restless multi-armed bandit (RMAB) problem, one of the most well-known generalizations of the classic multi-armed bandit (MAB) problem, which is of fundamental importance in stochastic decision theory. Despite the significant research efforts in the field, the RMAB problem in its generic form still remains open. Until today, very little result is reported on the structure of the optimal policy. Obtaining the optimal policy for a general RMAB problem is often intractable due to the exponential computation complexity. Hence, a natural alternative is to seek a simple myopic policy maximizing the short-term reward. Therefore, we develop three axioms characterizing a family of functions which we refer to as regular functions, which are generic and practically important. We then establish the optimality of the myopic policy when the reward function can be expressed as a regular function and the discount factor is bounded by a closed-form threshold determined by the reward function. We also illustrate how the derived results, generic in nature, are applied to analyze a class of RMAB problems arising from multi-channel opportunistic access. Next, we further investigate the more challenging problem where the user has to decide the number of channels to sense in each slot in order to maximize its utility (e.g., throughput). After showing the exponential complexity of the problem, we develop a heuristic v-step look-ahead strategy. In the developed strategy, the parameter v allows to achieve a desired tradeoff between social efficiency and computation complexity. We demonstrate the benefits of the proposed strategy via numerical experiments on several typical settings.