Dans cette thèse, nous nous intéressons aux équations aux dérivées fractionnaires et leurs applications au traitement d'images. Une attention particulière a été apportée à un système non linéaire d'équations différentielles fractionnaires. En particulier, nous avons étudié les propriétés qualitatives des solutions d'un système non linéaire d'équations différentielles fractionnaires qui explosent en temps fini. L'existence des solutions locales pour le système, le profil des solutions qui explosent en temps fini sont présentés. Nous étudierons le problème inverse pour l'équation de diffusion linéaire en une dimension et en deux dimensions. Nous sommes intéressés par trouver un terme source inconnu d'une équation de diffusion non locale. Les conditions aux limites considérées sont non locales et le problème spectral est non auto-adjoint. L'existence et l'unicité de la solution du problème inverse sont présentées.D'autre part, nous proposons un modèle basé sur l'équation de la chaleur linéaire avec une dérivée fractionnaire en temps pour le débruitage d'images numériques. L'approche utilise une technique de pixel par pixel, ce qui détermine la nature du filtre. En contraste avec certain modèles basés sur les équations aux dérivées partielles pour le débruitage de l'image, le modèle proposé est bien posé et le schéma numérique est convergent. Une amélioration de notre modèle proposé est suggéré. / In this thesis we study a nonlinear system of fractional differential equations with power nonlinearities; the solution of the system blows up in a finite time. We provide the profile of the blowing-up solutions of the system by finding upper and lower estimates of the solution. Moreover, bilateral bounds on the blow-up time are given.We consider the inverse problem concerning a linear time fractional diffusion equation for the determination of the source term (supposed to be independent of the time variable) and temperature distribution from initial and final temperature data. The uniqueness and existence of the continuous solution of the inverse problem is proved. We also consider the inverse source problem for a two dimensional fractional diffusion equation. The results about the existence, uniqueness and continuous dependence of the solution of the inverse problem on the data are presented.We apply the linear heat equation involving a fractional derivative in time for denoising (simplification, smoothing, restoration or enhancement) of digital images. The order of the fractional derivative has been used for controling the diffusion process, which in result preserves the fine structures in the image during denoising process. Furthermore, an improvement in the proposed model is suggested by using the structure tensor of the images.

Este trabalho analisa, a partir dos pontos de vista conceitual e sociocultural, o fenômeno de sobrecarga de informação. Este termo designa uma situação em que os indivíduos, tendo em vista uma tarefa, não se sentem capazes de lidar com certa quantidade de informação, a qual, assim definida por critérios pessoais, profissionais e societais, lhes parece necessária para seus objetivos. Assim sendo, se assimila a outros, como multitudo librorum, explosão da informação, fadiga da informação e infobesidade. Para abordar esse objeto, o método usado é o da pesquisa exploratória, isto é, estruturam-se e aprofundam-se os debates presentes na literatura. O material de base do estudo são referências sobre a história da produção da informação e do conhecimento e uma seleção de artigos com os termos \"information overload\" e \"sobrecarga de informação\" encontrados em bases de dados na área da Ciência da Informação. Com tal apanhado, elencamos na pesquisa ocorrências da sobrecarga -- ou de casos análogos -- desde a Antiguidade à Idade Contemporânea, de modo a substanciar uma exposição das características do conceito e esclarecer as relações entre ele e as várias expressões (como as citadas acima) que o manifestam. Com esse estudo, torna-se claro que precisam ser repensadas as perspectivas que entendem os danos advindos do excesso de informação como produtos únicos da contemporaneidade -- é preciso compreender esses acontecimentos nas interrelações de fatores em cada momento e recuperar aprendizados possivelmente esquecidos. Portanto, destacamos o vínculo entre as situações de sobrecarga e o desenvolvimento de novos recursos de tratamento informacional, principalmente no que se refere à Ciência da Informação. / This work analyses, conceptually and socioculturally, the phenomenon of information overload. The term designates a situation in which individuals, having a task in mind, don\'t feel capable of dealing with a certain amount of information that is deemed necessary to their assignment, based on personal, professional and social criteria. Therefore, \"information overload\" is comparable to others notions as multitudo librorum, information explosion, information fatigue and infobesity. To understand this subject, the exploratory research method is used, that is, we structure and deepen previous debates concerning the theme. Our basic material are references in the history of the production of information and knowledge and a selection of articles with the incidence of the terms \"information overload\" and \"sobrecarga de informação\", found in Information Science databases. By these means, we compile instances of overload -- or analogous cases -- since Antiquity to the Contemporary Age, so as to be able to expose the concept\'s characteristics and clarify the relations between it and the various expressions (as the ones cited above) around it. Considering what we found, it becomes clear that it is necessary to rethink perspectives which believe that the damages caused by the information excess are an exclusive product of our days -- it is necessary to understand these circumstances from the point of view of the interrelations of factors in each moment and retrieve possibly forgotten learnings. Hence, we underline the conection between the situations of overload and the development of new informational tools, principally regarding Information Science.

Made available in DSpace on 2016-04-27T17:27:04Z (GMT). No. of bitstreams: 1 Diogo Henrique Bispo Dias.pdf: 817652 bytes, checksum: a9c449589ddd37e8416ba66f62fb6285 (MD5) Previous issue date: 2013-06-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This master' s thesis comprehends the philosophical aspects of paraconsistent logic. It will analyze the history of the fundamental logical principles to this particular logic, namely: the law of non-contradiction and the principle of explosion, as well as the history of paraconsistency. Moreover, an interpretation of paraconsistency that defends the existence of true contradiction, known as dialetheism, will be discussed, as well as the criticism to' this position, and, in general, to paraconsistent logics. The philosophical character of this thesis does not mean that the text will be exempt from theorems, formulas, demonstrations and other formal questions. But this formal aspect will not be treated as a end in itself. The formalism will be used to present two proposicional paraconsistent systems, namely: paraclassicallogic and paraclassical logic with inclusion, and to compare them with classical logic. The theoretical framework built for such aim is philosophically relevant, for the discussion on central points in logic, such as the existence of logical laws, its a priori character, and even the very definition of logic. Finally, a method will be proposed in order to find, from a given logic, its paraconsistent version. Due to the multiplicity of paraconsistent systems,' I this study is important in order to explore the general features of paraconsistent logics, their specificities and, mainly, abstract methods for generation of paraconsisent logic / Este trabalho abordará os aspectos filosóficos das lógicas paraconsistentes. Analisaremos a história dos princípios lógicos fundamentais para esta lógica, a saber: a lei de não-contradição e o princípio de explosão, bem como a história do surgimento da paraconsistência. Ademais, discutiremos uma interpretação da paraconsistência que defende a existência de contradições verdadeiras, denominada dialeteismo, e as possíveis críticas ao dialeteismo e, de forma geral, às lógicas paraconsistentes. O caráter filosófico do trabalho não significa que o texto estará isento de teoremas, fórmulas, demonstrações e outras questões formais. Porém, este aspecto formal não será tratado como um fim em si mesmo. O formalismo será utilizado para apresentar dois sistemas proposicionais paraconsistentes - lógica para clássica e lógica para clássica com inclusão - e compará-los com a lógica proposicional clássica. O arcabouço teórico construído para tal fim é filosoficamente relevante para discutir questões centrais à lógica" como a existência de leis lógicas, seu caráter a priori e, até mesmo, a própria definição de lógica. Por fim, será apresentado um método para encontrar, a partir de uma lógica dada, sua versão paraconsistente. Face à multiplicidade, de sistemas lógicos paraconsistentes, este estudo é importante, pois permite explorar as possíveis características gerais das lógicas paraconsistentes, suas especificidades e, principalmente, métodos abstratos para gerar lógicas paraconsistentes

Este trabalho analisa, a partir dos pontos de vista conceitual e sociocultural, o fenômeno de sobrecarga de informação. Este termo designa uma situação em que os indivíduos, tendo em vista uma tarefa, não se sentem capazes de lidar com certa quantidade de informação, a qual, assim definida por critérios pessoais, profissionais e societais, lhes parece necessária para seus objetivos. Assim sendo, se assimila a outros, como multitudo librorum, explosão da informação, fadiga da informação e infobesidade. Para abordar esse objeto, o método usado é o da pesquisa exploratória, isto é, estruturam-se e aprofundam-se os debates presentes na literatura. O material de base do estudo são referências sobre a história da produção da informação e do conhecimento e uma seleção de artigos com os termos \"information overload\" e \"sobrecarga de informação\" encontrados em bases de dados na área da Ciência da Informação. Com tal apanhado, elencamos na pesquisa ocorrências da sobrecarga -- ou de casos análogos -- desde a Antiguidade à Idade Contemporânea, de modo a substanciar uma exposição das características do conceito e esclarecer as relações entre ele e as várias expressões (como as citadas acima) que o manifestam. Com esse estudo, torna-se claro que precisam ser repensadas as perspectivas que entendem os danos advindos do excesso de informação como produtos únicos da contemporaneidade -- é preciso compreender esses acontecimentos nas interrelações de fatores em cada momento e recuperar aprendizados possivelmente esquecidos. Portanto, destacamos o vínculo entre as situações de sobrecarga e o desenvolvimento de novos recursos de tratamento informacional, principalmente no que se refere à Ciência da Informação. / This work analyses, conceptually and socioculturally, the phenomenon of information overload. The term designates a situation in which individuals, having a task in mind, don\'t feel capable of dealing with a certain amount of information that is deemed necessary to their assignment, based on personal, professional and social criteria. Therefore, \"information overload\" is comparable to others notions as multitudo librorum, information explosion, information fatigue and infobesity. To understand this subject, the exploratory research method is used, that is, we structure and deepen previous debates concerning the theme. Our basic material are references in the history of the production of information and knowledge and a selection of articles with the incidence of the terms \"information overload\" and \"sobrecarga de informação\", found in Information Science databases. By these means, we compile instances of overload -- or analogous cases -- since Antiquity to the Contemporary Age, so as to be able to expose the concept\'s characteristics and clarify the relations between it and the various expressions (as the ones cited above) around it. Considering what we found, it becomes clear that it is necessary to rethink perspectives which believe that the damages caused by the information excess are an exclusive product of our days -- it is necessary to understand these circumstances from the point of view of the interrelations of factors in each moment and retrieve possibly forgotten learnings. Hence, we underline the conection between the situations of overload and the development of new informational tools, principally regarding Information Science.

L’étude des seuils de tolérance du corps humain aux impacts requiert des expérimentations sur des sujets humains vivants ou post-mortem, ce qui soulève naturellement des questions d’éthique. Pour pallier à ces limitations, le développement des outils numériques a conduit, au fil des dernières années à la mise en place des mannequins numériques plus ou moins capables de reproduire fidèlement le comportement mécanique du corps humain lorsqu’ils sont soumis à divers types de sollicitations. C’est dans ce contexte que le modèle de mannequin numérique HUByx (Hermaphrodite Biomechanics yx-model) a été développé au sein du département de recherche COMM du laboratoire ICB à l’UTBM. Ce travail de thèse a pour but la validation et l’amélioration de la biofidélité de la partie thoracique du modèle HUByx, et vise à comprendre les mécanismes de lésions et à rechercher des critères de prédiction des lésions thoraciques à travers la reconstruction numérique des chargements violents dans des contextes civils et militaires. Des simulations numériques ont été réalisées dans le cadres des études de chutes libres de personnes, des impacts balistiques non-pénétrants de projectiles non létaux et dans le cadre du phénomène de l’explosion. De bonnes corrélations ont été obtenues entre les résultats numériques et expérimentaux, contribuant ainsi à renforcer la capacité du modèle HUByx à répondre de manière biofidèle aux différentes sollicitations auxquelles il est soumis. Mots-clés : Biomécanique d’impacts, éléments finis, blessures thoraciques, critère visqueux, reconstruction d’accident, chutes libres, balistique, explosion. / The study of human tolerance thresholds to impacts requires experiments on living or post mortem human subjects, which naturally raises ethical questions. To overcome these limitations, the development of numerical tools has led over the last few years to the implementation of numerical models more or less capable to accurately reproduce the mechanical behavior of the human body when subjected to various types of stresses. It is in this context that the numerical model HUByx (Hermaphrodite Biomechanics yx-model) has been developed within the research department COMM of the ICB lab at UTBM. This PhD work aims at validating and improving the biofidelity of the thoracic part of the HUByx model and also aims to understand the mechanisms of lesions and to seek criteria for the thoracic injury prediction through the numerical reconstruction of violent loadings in civil and military contexts. Numerical simulations were carried out in the framework of human free falls studies, non-penetrating ballistic impacts of non-lethal projectiles and finally in the context of explosion phenomenon. Good correlations were obtained between the numerical and experimental results, thus contributing to reinforce the capacity of the HUByx model to respond in a biofidelic manner to the different stresses to which it is subjected. Keywords : Impact biomechanics, finite elements, thoracic injuries, viscous criterion, accident reconstruction, free falls, ballistics, explosion.

Les équations de Kadomtsev-Petviashvili (KP) décrivent les ondes de faible amplitude et de grande longueur se déplaçant à la surface de l'eau, principalement dans la direction (Ox). Quant à l'équation de Benjamin-Ono (BO), elle décrit de telles ondes se déplaçant à l'intérieur de l'eau. On s'intéresse à ces équations vue en tant qu'équations de type Benjamin-Bona-Mahony (BBM).<br />Notre travail se divise alors en trois parties. Dans la première partie, on rappelle la modélisation des différentes équations. On montre plus particulièrement que les modèles BBM s'obtiennent à partir du principe fondamental de la dynamique via une analyse asymptotique. On compare alors les solutions des équations de KP, respectivement de BO, avec les solutions des équations de type BBM.<br />Dans la seconde partie, on s'intéresse à certaines propriétés qualitatives des équations généralisées de type BBM. Des résultats de prolongement en temps des bornes sur les normes de Sobolev, de décroissance en temps et de prolongement unique des solutions sont établis.<br />Enfin, on termine avec une étude numérique des solutions des équations KP généralisées en dimension 3 d'espace. Dans cette dernière partie, en collaboration avec F. Hamidouche et S. Mefire, on inspecte numériquement les phénomènes de dispersion, d'explosion en temps fini, de comportement solitonique et d'instabilité transversale.

Dans cette thèse nous étudions l'asymptotique de petits bruits pour des perturbations aléatoires d'équations de Schrödinger non linéaires. Les bruits sont Gaussiens, la plupart du temps blancs en temps et toujours colorés en espace, additifs ou multiplicatifs. Un évènement de grandes déviations est un évènement où le système diffère significativement du système déterministe. Lorsque le bruit tend vers zéro, la probabilité d'un tel évènement rare tend vers zéro sur une échelle logarithmique avec pour vitesse l'amplitude du bruit. Nous prouvons des principes de grandes d´eviations trajectoriels. Dans ce cas le facteur multiplicatif de la vitesse, le taux, est relié à un problème de contrôle optimal. Les résultats sont appliqués aux temps d'explosion. Nous étudions ensuite l'asymptotique de petits bruits des queues de la masse et de la position du signal dans une "limite bruit blanc". Les fluctuations de ces quantités sont les causes principales d'erreur de transmission par solitons dans les fibres optiques. Nous considérons également le problème des temps moyens et des points de sortie d'un voisinage de zéro pour des équations faiblement amorties. Enfin, nous présentons un principe de grandes déviations et un théorème de support pour des bruits Gaussiens fractionnaires additifs.

En 1997, le volcan Soufrière Hills a connu deux périodes d'activité vulcanienne, impliquant 88 explosions. Chacune de ces explosions a vidangé la partie supérieure du conduit sur 0,5 à 2 km. Ce travail de thèse visait à comprendre et quantifier par analyse texturale des produits naturels, les processus de vésiculation du magma se produisant durant ces explosions vulcaniennes. Cette étude comporte des mesures en 2D par analyses d'images, des mesures en 3D par microtomographie à rayons X, une étude texturale détaillée de bombes en croûte de pain et des analyses chimiques comprenant notamment des mesures de teneurs en eau (par microspectrométrie Raman) et en chlore dans les verres matriciels. L'analyse en 2D nous a permis de mettre en évidence la présence de plusieurs populations de vésicules. Les plus petites (inférieures à quelques dizaines de microns) sont syn-explosives, tandis que la plupart des grandes vésicules (> plusieurs centaines de μm), dans les ponces, sont pré-explosives. Environ 15% des grandes vésicules dans les ponces et toutes celles présentes dans les bombes en croûte de pain sont créées par la fracturation synexplosive de phénocristaux d'amphiboles. Une population de vésicules de taille intermédiaire, formées par la coalescence des petites vésicules, est visible dans les ponces. La nucléation syn-explosive s'est produite de façon hétérogène sur des microlites de magnétite, les bulles ont ensuite grandi principalement par décompression. La coalescence a affecté toutes les bulles plus grandes que quelques dizaines de microns. La microtomographie à rayons X nous a permis d'obtenir une vision en 3D du système. Pour la première fois, des distributions de tailles de vésicules et de cristaux ont été réalisées jusqu'à ~2 μm en combinant plusieurs jeux de données. Les observations effectuées ainsi que les paramètres quantitatifs extraits de ces données sont en accord avec ceux issus de l'analyse en 2D. De plus, la 3D nous a permis de contraindre quantitativement la coalescence. Celle-ci s'est produite entre vésicules voisines, sans distinction de tailles. L'analyse texturale des bombes en croûte de pain a montré que ces échantillons ont subi un processus de vésiculation intermédiaire entre les échantillons denses provenant du bouchon dégazé et les ponces. La vésiculation post-fragmentation de leur intérieur représente le mécanisme principal provoquant la fracturation de la bordure plus dense, donnant l'aspect croûte de pain. Les analyses chimiques ont montré qu'il existe une corrélation entre la teneur en eau des verres matriciels et la texture des échantillons. Les ponces peuvent retenir beaucoup d'eau (jusqu'à 2,8 %pds) tandis que les échantillons denses et les bombes en croûte de pain sont plus dégazés. La teneur en chlore mesurée est constante dans tous les échantillons et peut s'expliquer par un coefficient de distribution faible (~5) entre la phase vapeur et le liquide. Le dégazage s'est fait en système partiellement ouvert entre deux explosions successives (~10h). Nous avons démontré que la vésiculation syn-explosive était importante lors de chaque explosion vulcanienne de la Soufrière Hills en 1997 et que le développement des textures était contrôlé par l'intervalle de temps entre la décompression et le début du refroidissement de la surface du claste. Les taux de décompression syn-explosifs estimés à partir des densités numériques de vésicules (> 0,3-6,5 MPa s-1), sont cohérents avec ceux prédits par les modélisations numériques.

In this Thesis, two problems were studied: a direct vacuum acceleration of electrons by a tightly focused ultrashort relativistic laser pulse and ion acceleration in the process of spherical laser-heated plasma explosion. The electromagnetic field of a tightly focused laser pulse was evaluated numerically by means of Stratton-Chu integrals. The properties of the focused field were analyzed in detail for a plane wave or a macroscopically large Gaussian beam incident onto the mirror. Free electrons moving in the tightly focused field were found to accelerate by two possible mechanisms: focal spot acceleration and capture-and-acceleration scenario. The two mechanisms were studied in detail. Comparison of the mirror-focused field with first- and fifth-order paraxial fields is performed. A 3D electromagnetic PIC code SCPIC was created for simulations of pulse interaction with targets having a finite number of particles interacting with each other by collective fields. Atto-second bunch formation was observed in the interaction with ultra-small or ultra-thin targets. Physical mechanism of bunch formation is explained. The problem of electrostatic explosion of a nano-scale spherical plasma with initially hot electrons and cold ions was solved numerically. Expansion in a wide regime of electron temperature $0 < T leq infty$ was studied in detail for different initial density profiles of plasma. Favorable conditions for obtaining mono-energetic ions resulting from the explosion were specified in single and two ionic species cases. In case of a two-species explosion, the number of mono-energetic, $deltavarepsilon/varepsilon < 10\%$, ions can be as high as 70-80\% of the total light ions for a wide range of electron temperatures.

This thesis, Earth satellites and detection of air andground based activities by Ulf Ekblad of the Physics departmentat the Royal Institute of Technology (KTH), addresses theproblem of detecting military activities in imagery. Examplesof various techniques are presented. In particular, problemsassociated with "novelties" and "changes" in an image arediscussed and various algorithms presented. The imagery usedincludes satellite imagery, aircraft imagery, and photos offlying aircraft. The timely delivery of satellite imagery is limited by thelaws of celestial mechanics. This and other information aspectsof imagery are treated. It is e.g. shown that dozens ofsatellites may be needed if daily observations of a specificsite on Earth are to be conducted from low Earth orbit. New findings from bioinformatics and studies of small mammalvisual systems are used. The Intersecting Cortical Model (ICM),which is a reduced variant of the Pulse-Coupled Neural Network(PCNN), is used on various problems among which are changedetection. Still much more could be learnt from biologicalsystems with respect to pre- and post-processing as well asintermediate processing stages. Simulated satellite imagery is used for determining theresolution limit for detection of tanks. The necessary pixelsize is shown to be around 6 m under the conditions of thissimulation. Difference techniques are also tested on Landsat satelliteimagery with the purpose of detecting underground nuclearexplosions. In particular, it is shown that this can easily bedone with 30 m resolution images, at least in the case studied.Satellite imagery from SPOT is used for detecting undergroundnuclear explosions prior to the detonations, i.e. under certainconditions 10 m resolution images can be used to detectpreparations of underground nuclear explosions. This type ofinformation is important for ensuring the compliance of nucleartest ban treaties. Furthermore, the necessity for havingcomplementary information in order to be able to interpretimages is also shown. Keywords: Remote sensing, reconnaissance, sensor,information acquisition, satellite imagery, image processing,image analysis, change detection, pixel difference, neuronnetwork, cortex model, PCNN, ICM, entanglement, Earthobservation, nuclear explosion, SPOT, Landsat, verification,orbit.