In this thesis, three different types of polymer-based gels are fabricated and characterized for passive and active applications. Silica aerogel is a 3D mesoporous solid material that can be used for thermal insulation or in the biomedical industry. In this thesis, silica aerogel is cross- linked with diisocyanate to improve its strength and flexibility, which greatly opens up the range of applications. Then, soft polymer gel with tissue equivalent characteristics is fabricated to mimic the spin-lattice (T1) and spin-spin (T2) relaxation times for the magnetic resonance imaging (MRI) phantom of a liver with lesions. This study demonstrates a relationship between the composition of a gelling agent, and T1 and T2 modifiers on its dielectric, mechanical and imaging properties. Finally, an ionic electroactive polymer (EAP) that can be actuated on an electric field is fabricated, and its swelling and bending behaviours on design parameters are closely examined.

Magnetic resonance imaging is a widely used medical imaging technique, and accelerated data acquisition is critical for clinical utility. In this thesis, new techniques that incorporate radial acquisition, compressed sensing and sparse regularization for improved rapid imaging are presented. Sufficiently accelerated imaging methods can lead to new applications. Here we demonstrate a solution to lung imaging during forced expiration using accelerated MRI. A technique for dynamic 3D imaging of the lungs from highly undersampled data is developed and tested on six subjects. This method takes advantage of image sparsity, both spatially and temporally, including the use of reference frames called bookends. Sparsity, with respect to total variation, and residual from the bookends, enables reconstruction from an extremely limited amount of data. Dynamic 3D images can be captured at an unprecedented sub-150 ms temporal resolution, using only three (or less) acquired radial lines per slice per time point. Lung volume calculations based on image segmentation are compared to those from simultaneously acquired spirometer measurements. Additionally, accelerated imaging methods can be used to improve upon widely used applications; we also present a technique for improved T₂-mapping. A novel model-based compressed sensing method is extended to include a sparse regularization that is learned from the principal component coefficients. The principal components are determined by a range of T₂ decay curves, and the coefficients of the principal components are reconstructed. These coefficient maps share coherent spatial structures, and a spatial patch--based dictionary is a learned for a sparse constraint. This transformation is learned from the coefficients themselves. The proposed reconstruction is suited for non-Cartesian, multi-channel data. The dictionary constraint leads to parameter maps with less noise and less aliasing for high amounts of acceleration.

The Cambrian section in the subsurface of southern Alberta has a maximum thickness of 1860'. It is composed of sandstones, shales, limestones, and dolomites. The grand cycles characteristic of the Cambrian Sections in the Foothills and Front Ranges can be traced to some distance in the subsurface. However, the section changes facies eastwards into clastics and the grand cycles become less defined. The present correlations indicate that the Waterfowl-Arctomys grand cycle extends to the subsurface but is restricted to the northwest corner of the study area. Two new stratigraphic units have been informally defined in this study: The Crow Indian Formation of fine clastics and restricted to the southeast corner of Alberta. It is equivalent to the Cathedral, Stephen and Eldon Formations. The second unit is the Sakwatamau Member of the Eldon Formation, a clastic and carbonate deltaic unit restricted to the northwest corner of the study area. The Cambrian sediments were deposited in a broad shallow shelf-lagoon bordered to the east by the Canadian Shield and to the west by a shoal (the Kicking Horse Rim). Facies and thickness of the Cambrian section were controlled by six paleogeographic elements: 1) The Peace River Arch, 2) the Sweet Grass Arch, 3) the West Alberta Ridge, 4) the Kicking Horse Rim, 5) a shoal area immediately south of the Peace River Arch, and 6) a shoal area immediately north of the Sweet Grass Arch. When circulation in the shelf-lagoon was restricted, carbonate deposition dominated, especially in the shoal areas, and when open marine conditions prevailed, deposition of quartzarenites and glauconitic sandstones took place. Nine lithofacies have been recognized; 1) Mottled dolomitic mudstones and wackestones; 2) Mudstones, wackestones, and packstones; 3) Grainstones; 4) Cryptalgalaminates, cryptalgalaminate breccia, and algal-laminated sediments; 5) Flat-pebble conglomerates; 6) Glauconitic sandstones; 7) Quartzarenites; 8) Hybrid sandstones or iron-formations, and 9) Coquinas. These facies reflect deposition in environments ranging from supratidal to subtidal. Facies analysis also suggests that storms played a major role during the deposition of these sediments. Diagenesis (in both clastics and carbonates) appears to be the product of early, shallow freshwater phreatic-, marine phreatic-, and mixing zones. Dolomitization has developed in the mixing zone, as a result of pressure-solution, and/or dolomitization of glauconitic illites. Illite, kaolinite, authigenic K-feldspars, and quartz overgrowths were formed in the mixing zone depending on the K⁺ and H₄SiO₄ activity of the solutions. Fibrous calcite cement was formed in the marine-phreatic zone. Blocky calcite cement, syntaxial rims around echinoderm fragments, and fracture-filling sparry calcite were probably precipitated in the freshwater phreatic zone. Saddle dolomite occurs as burrow-filling and pore-filling in carbonates and as poikilotopic cement and in burrows (concretions) in sandstones. Saddledolomite (in carbonates and clastics) and chlorite (in clastics) were probably the last diagenetic products to form at deep burial and higher temperatures.

L’émergence des utilisateurs mobiles et la popularité croissante des services multimédias linéaires ont entrainé, ces dernières années, une augmentation impressionnante du trafic de données au sein des réseaux mobiles. En effet, le principal moteur de cette croissance est lié à la consommation de contenus vidéo de façon linéaire (télévision) ou non (vidéo à la demande) par de nombreux utilisateurs sur des appareils mobiles (tablettes, smartphones, ordinateurs portables, etc.) connectés aux réseaux cellulaires. Cependant, l’acheminement de ce trafic via le mode de transmission unicast traditionnel des réseaux cellulaires risque de générer un engorgement rapide du réseau au détriment de la qualité du service rendu. Ainsi, pour faire face cette demande continuellement croissante en débit des utilisateurs mobiles et devant la raréfaction croissante du spectre radioélectrique, les opérateurs n’ont d’autre choix que de densifier leurs infrastructures d’accès au réseau radio (RAN) et déployer des réseaux d’accès hétérogènes et hybrides exploitant plusieurs technologies (WiFi/small cells (3G/4G)) permettant le délestage du trafic de données mobiles. Dans cette optique, cette thèse porte sur la modélisation et l’optimisation d’un réseau hybride de diffusion de contenus multimédias pouvant exploiter de façon complémentaire deux infrastructures réseaux existantes et radicalement différentes, à savoir les réseaux cellulaires (LTE) et les réseaux de diffusion (DVB-T2 Lite, DVB-NGH ou éventuellement le mode broadcast LTE-eMBMS).Dans un premier temps nous nous consacrons à la modélisation et à la simulation du réseau hybride en considérant un scénario d’extension de couverture, où les deux réseaux coopèrent pour distribuer des services linéaires aux utilisateurs mobiles. A l’aide d'un simulateur système, nous évaluons les performances du réseau hybride en termes de capacité, consommation de puissance et efficacité énergétique.Dans un second temps, nous nous intéressons à l’optimisation de la capacité, de la consommation énergétique et de l’efficacité énergétique du réseau hybride pour la diffusion de ces services linéaires. Sur la base du modèle hybride, nous proposons une approche théorique, basée sur la distribution des utilisateurs, pour trouver une expression analytique de la zone de couverture optimale du réseau de diffusion tout en tenant compte de la qualité du service rendu aux utilisateurs. Les résultats théoriques et ceux obtenus à l’aide du simulateur système sont très proches. Nous étudions également l’impact de la popularité du service (en termes de nombre d’utilisateurs demandant le service) sur cette zone de couverture optimale.Enfin, nous proposons une extension au modèle de réseau hybride pour la diffusion des services non linéaires comme la vidéo à la demande, le téléchargement de fichiers, etc. Nous proposons une formalisation du problème d’optimisation en tenant compte des contraintes liées à ces services non-linéaires, en particulier le temps d’attente et de téléchargement ainsi que la fiabilité des transmissions radios.L’approche analytique proposée dans cette thèse constitue un atout précieux pour l’hybridation des réseaux cellulaires et des réseaux de diffusion. Ce modèle pourrait également permettre, d’une part d’évaluer le gain de telles approches hybrides, et d’autre part, de mettre en évidence les scénarios et stratégies de transmission de contenus multimédias les plus avantageux en fonction de critères donnés dans le contexte des réseaux « 4G avancés » voire « 5G ». / The increasing popularity of linear multimedia services such as mobile TV, broadcasting live and sports events to mobile and portable devices, has led to a dramatic growth of the mobile data traffic. Indeed, the reason of this growth is related to the consumption of video content either as a linear service (live TV) or as a non-linear service (time-shifted or on demand), by many users on different devices (tablets, smartphones, laptops, etc.) connected to a cellular network. In cellular networks, these types of services are usually delivered over unicast connections, i.e. as many times as the number of users. This strategy is likely to lead to critical situations, e.g. network congestion at the expense of the quality of service. Thus, to deal with this mobile data traffic explosion and the lack of frequency bands, operators need to densify their radio access network infrastructure (RAN) and deploy heterogeneous and hybrid access networks using multiple technologies (WiFi / small cell (3G / 4G)), that enable data offloading.In this context, this thesis focuses on the definition and optimization of a hybrid network, where a unicast network (LTE) and a broadcast network (DVB-T2 Lite, DVB-NGH, LTE-eMBMS, etc.) cooperate to deliver multimedia content to mobile and portable devices.Firstly, we focus on the modeling and simulation of the hybrid unicast-broadcast network for the delivery of linear services. We consider a coverage extension scenario, where the coverage area of the broadcast network can be adjusted with respect to the distribution of the users and the number of users requesting the service. Using the TU-Wien system level simulator, we evaluate the performance of the hybrid network in terms of capacity, power consumption and energy efficiency.Secondly, with the proposed model, we provide a theoretical method to find an analytical expression of the broadcast coverage area that optimizes the service capacity, the power consumption and the energy efficiency of the hybrid network with respect to the quality of service requirements. Indeed, the theoretical results are in agreements with the simulation ones. Based on the proposed model, we analyze the impact of the number of users requesting the service on the optimal broadcast coverage area.Finally, we focus on the extension of the proposed hybrid network for the delivery of the non-linear services such as video on demand and file download services. We state an optimization problem regarding the constraints of these non-linear services, especially the waiting and downloading time and the transmission errors. This thesis provides great insights on the potential benefits that such hybrid approaches may bring in a context of “4G advanced” and “5G” networks where the UHF broadcasting spectrum is under pressure for being partly or completely attributed to mobile broadband operators due to the predicted explosion of the mobile data traffic.

L'avènement de terminaux avancés permet l'accès à des services toujours plus gourmands en bande passante, avec notamment le déploiement de services de vidéo mobile sans couture offert par le mode diffusion mobile intégré standardisé par le 3GPP. Dans le même temps, la communauté << broadcast » s'est adaptée aux nouveaux usages de télévision mobile avec la norme DVB-NGH (Digital Video Broadcasting - Next Generation Handheld). Dans ce contexte, l'objectif de cette thèse est d'étudier la convergence spectrale entre les deux réseaux DVB et LTE en déployant une petite cellule LTE au sein d'une grande cellule DVB. Les deux technologies utilisent une forme d'onde OFDM (Orthogonal Frequency Division Multiplexing), en liaison descendante pour le LTE, ct possèdent donc quelques similarités tout en étant assez différentes par leurs caractéristiques. Dans ces travaux, nous nous intéressons aux performances atteignables lorsque les deux systèmes se recouvrent spectralement sans coopération. Le problème considéré étant analogue à un problème d’utilisateur secondaire opérant en mode recouvrement avec un utilisateur primaire, on commence par étudier le problème de la capacité ergodique du système secondaire, i.e. utilisateur LTE, sous contraintes de puissance moyenne générée par le secondaire sur le primaire, i.e LTE sur DVB, et de puissance crête au secondaire lorsque l'utilisateur primaire interfère sur le secondaire. Le problème est résolu analytiquement dans le cas général du canal croisé avec évanouissements de Rayleigh. Dans un deuxième temps nous étendons cette étude préliminaire au cas où la forme d'onde des deux systèmes primaire et secondaire est effectivement de type OFDM. En considérant d'abord un modèle simple de recouvrement total des sous-porteuses, nous délivrons la capacité ergodique globale ce qui nous permet d'évaluer l'influence des paramètres des systèmes, comme le nombre de sous-porteuses de chaque système ou les puissances interférentes, sur les capacités globales et individuelles. Nous nous intéressons ensuite à l'optimisation de la capacité globale où deux stratégies sont étudiées. D'une part, la capacité globale étant la somme de deux fonctions convexe et concave respectivement, la solution obtenue conduit au minimum de capacité globale mais mène à une situation d'équilibre entre les systèmes DVB et LTE. D'autre part, la maximisation de la capacité globale sous contrainte conduit à favoriser largement un système sur l'autre. Enfin, une étude fine de l'interférence causée par un système sur l'autre par recouvrement partiel est menée. L'effet de la variation du taux de recouvrement spectral entre les bandes du DVB et du LTE sur l'efficacité spectrale globale est étudié. On suppose ensuite que le récepteur possède une capacité de réjection de l'interférence permettant de déterminer le recouvrement optimal maximisant la capacité globale. Les différentes contributions de ces travaux ont permis d'avoir une approche théorique sur la modalité d'allocation de puissance des deux systèmes DVB et LTE co-existants et sur le taux de recouvrement approprié entre leurs spectres respectifs. Cette étude pourrait être ut le pour les opérateurs intéressés par un scénario de déploiement dense afin de choisir les configurations optimales des ressources dans une perspective de réutilisation agressive des fréquences. / Since the launch of the first numerical mobile telecommunications networks in the nineties, the quantity of the transmitted data over the networks is increasing year by year. Advanced user equipments enable to implement more and more bandwidth consuming services such as mobile T and multimedia internet, available in the integreted mobile broadcast mode recently standardized by the 3GPP group. In the meanwhile, the digital vide broadcasting - next generation handled (DVB-NGH) has been released in order to satisfy the increasing demand for mobile TV. These technologies compete for a more and more constrained spectral resource leading to question the possibility to deploy DVB and Long Term Evolution (LTE) service in a spectral overlay mode as it has been investigated by the Ml project funded by the National Research Agency. In this context, this thesis aims at studying the spectral convergence between DVB and LTE networks by deploying a small LTE cell in a large DVB cell. Both technologies present some similarities, i.e. both use orthogonal frequency division multiplexing (OFDM) waveform (in downlink for LTE), but technical characteristics remain rather different between those. In this work, we deal with achievable performance when DVB and LTE spectrally overlap without cooperation. The considered problem being analog to the Seconda1y User (SU) - Primary User (PU) coexistence in overlay scenario, the SU ergodic capacity under average power generated on PU and peak power at SU constaints is investigated. An analytic solution is proposed in X-Channel with Rayleigh fading. In a second time, SU and PU are considered to be LTE and DVB respectively with their particular OFDM signal characteristics. With a first model of overlapping subcarriers, LTE and DVB ergodic capacities and global capacity as well are derived in closed form allowing to study the influence of several system parameters on ergodic capacities. The global capacity is then optimized using a convex-concave procedure leading to the minimum on the global capacity but to balanced capacity on individual links. On a second hand, global capacity maximization leads to favor one system over the other. Last but not least, a careful study of the interference caused by one system over the other by partial overlay is led. The effect of spectral overlap ratio between DVB and LTE systems over the global spectral efficiency is investigated. Advanced interference rejection ability is then assumed at receivers and the optimal spectral overlap, i.e. maximizing the global capacity, is then derived in that case. The different contributions in this work give a theoretical approach on the power allocation modality of two coexisting DVB and LTE systems and on the appropriate spectral overlap ratio between their respective spectrums. This study can be useful for operators interested in dense network deployment scenarios to decide the operating point of allocated resources in a very aggressive frequency reuse pattern.

Ces dernières années, la popularité croissante de terminaux mobiles de plus en plus intelligents a provoqué une hausse considérable du trafic supporté par les réseaux de télécommunications cellulaires. Dans ce contexte, le déploiement de réseaux dits de quatrième génération basés sur le standard LTE (Long Term Evolution) et offrant des capacités significativement plus élevées que les réseaux de générations précédentes peut sembler être une solution idéale. Cependant, dans le cas d’un service à délivrer à un très grand nombre d’utilisateurs, ce standard, malgré la disponibilité de la technologie eMBMS (Evolved Multimedia Broadcast Multicast Services), n’est pas forcément le plus adapté. Dans le même temps, la télévision a achevé dans de nombreux pays sa transition vers le numérique. L’abandon de la transmission analogique a permis non seulement d’améliorer la qualité du service mais aussi d’occuper moins de spectre. En France, une partie du spectre libéré a déjà été attribué au déploiement de réseaux LTE. Une autre méthode permettant d’exploiter ce spectre au profit des réseaux de communications mobiles est proposée dans cette thèse : le réseau hybride. Le réseau hybride est constitué d’un réseau cellulaire au standard LTE accompagné d’un émetteur DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial). Les aires de couverture de ces deux composantes se superposent et un service peut être transmis aux utilisateurs présents dans ces aires indifféremment par l’une ou l’autre des composantes. Ce concept permet de pallier un point faible du standard LTE, c’està- dire la capacité à délivrer efficacement un même service à un grand nombre d’utilisateurs simultanément. Après une étude approfondie des deux standards utilisés, un modèle mathématique du réseau hybride est proposé. Ce modèle se base sur les propriétés géométriques du réseau hybride, les performances des deux types de signaux utilisés, et sur plusieurs types de répartition des utilisateurs pour évaluer les performances du réseau hybride selon différents critères. Le premier critère étudié est un critère énergétique. Le modèle proposé permet de comparer les efficacités énergétiques des deux composantes pour transmettre un service en fonction de son nombre d’utilisateurs. L’efficacité de la composante DVBT2 dépasse celle de la composante LTE à partir d’un seuil dont la valeur varie avec les propriétés géométriques du réseau et le type d’affaiblissement de propagation auquel sont soumis les signaux. Il est de plus possible, dans certaines circonstances, d’améliorer encore l’efficacité énergétique du système en utilisant conjointement les deux composantes. Le second critère étudié est celui de l’encombrement du réseau cellulaire. En effet, un service consommé par un grand nombre d’utilisateurs peut avoir un impact conséquent sur le trafic à transmettre par un réseau LTE. Utiliser la composante DVB-T2 pour distribuer un tel service permet de réduire la charge du réseau cellulaire, et ceci même dans le cas où la composante DVB-T2 ne couvre pas l’ensemble de la zone à desservir globalement. Ces différentes études ont permis de bien mettre en évidence les avantages et inconvénients des deux types de réseaux broadcast et unicast. En particulier, l’intérêt d’une approche reposant sur l’utilisation d’un réseau hybride exploitant la complémentarité des deux composantes broadcast et unicast a été démontré. / During the last few years, the growing popularity of smarter and smarter mobile devices has led to a tremendous growth of cellular data traffic. In such a context, the deployment of fourth generation networks based on the LTE (Long Term Evolution) standard and with capacities significantly higher than previous generations networks can be seen as an ideal solution. However, when the number of users requiring a given service is large, this standard, despite the availability of the eMBMS (Evolved Multimedia Broadcast Multicast Services) technology, is not necessarily the most suitable. Meanwhile, television has completed its transition to the digital transmission in many countries. The analog switch-off has not only allowed a better quality of service but has also freed some spectrum. In France, some of this spectrum has already been used for the deployment of LTE networks. This thesis introduces another way to use this spectrum to the benefit of mobile data networks: the hybrid network. The hybrid network consists of a LTE cellular network and a DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial) transmitter. The coverage areas of the two components are overlapping and a service can be delivered to the users located in these areas by either one or the other of the components. This concept can compensate one weakness of the LTE standard, which is the ability to deliver efficiently the same service to a large number of users simultaneously. After a thorough study of the two standards in use, a mathematical model of the hybrid network is proposed. This model is based on the geometrical properties of the network, the performances of the two types of signal, and different types of users distribution to measure the performances of the hybrid network using different criteria. The first criterion is the energy efficiency. The proposed model allows the comparison of the two components in terms of energy efficiency for one service depending of the number of its users. The DVB-T2 component outperforms the LTE component when the number of users exceeds a given threshold whose value depends on the geometric properties of the network and the type of path loss attenuating the signals. It is possible, in some cases, to further improve the energy efficiency of the system by using both components together. The second criterion is the network congestion. Indeed, a service with a great number of users can induce significant data traffic for the LTE network. Transmitting such a service through the DVB-T2 component can decrease the cellular data traffic even if the DVB-T2 component does not cover the whole area of interest. These studies have brought out the benefits and drawbacks of both broadcast and unicast networks. Especially, the interest of the hybrid network based on the complementarities between the two components has been demonstrated.

The aim of the thesis is to define the dependency of the classification of patients affected by neurodegenerative diseases on the choice of the parcellation atlas. Part of this thesis is the application of the functional connectivity analysis and the calculation of graph metrics according to the method published by Olaf Sporns and Mikail Rubinov [1] on fMRI data measured at CEITEC MU. The application is preceded by the theoretical research of parcellation atlases for brain segmentation from fMRI frames and the research of mathematical methods for classification as well as classifiers of neurodegenerative diseases. The first chapters of the thesis brings a theoretical basis of knowledge from the field of magnetic and functional magnetic resonance imaging. The physical principles of the method, the conditions and the course of acquisition of image data are defined. The third chapter summarizes the graph metrics used in the diploma thesis for analyzing and classifying graphs. The paper presents a brief overview of the brain segmentation methods, with the focuse on the atlas-based segmentation. After a theoretical research of functional connectivity methods and mathematical classification methods, the findings were used for segmentation, calculation of graph metrics and for classification of fMRI images obtained from 96 subjects into the one of two classes using Binary classifications by support vector machines and linear discriminatory analysis. The data classified in this study was measured on patiens with Parkinson’s disease (PD), Alzheimer’s disease (AD), Mild cognitive impairment (MCI), a combination of PD and MCI and subjects belonging to the control group of healthy individuals. For pre-processing and analysis, the MATLAB environment, the SPM12 toolbox and The Brain Connectivity Toolbox were used.

This Master thesis is focused on detailed description of the DVB-T2 system. This work deals with the description of the particular parts of models and with typical RF transmission channels for fixed and mobile reception. In order to simulate the impact of the fading transmission channels on the transmitted signal there was developed an appropriate application in MATLAB. The graphic user interface of this application allows set the transmission parameters of DVB-T2 and the parameters of the transmission channels. Results of simulations with various settings are evaluated and compared with the results, obtained from the DVB-T measurements.

The aim of the thesis was familiarity of segmentation methods for automatic segmentation of MR images, using multiparametrical display. The theoretical part focuses on the description of methods of segmentation techniques. In the practical part are implemented K-means and level-set method. The methods are tested on the images of the brain obtained by different sequences (T1, T1c, T2, FLAIR). Segmentation methods are implemented in the program MATLAB. Implemented segmentation accuracy is demonstrated on data which there are reports reference results. Evaluation methods is performed using different classifiers decision. The K-means method is tested different metrics and different combinations of the input image. Finally, both methods are compared with one another and visually evaluated against the reference image.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18444号 / 理博第4004号 / 新制||理||1577(附属図書館) / 31322 / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 加藤 毅, 教授 堤 誉志雄, 教授 小野 薫 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM