We study the problem on the exact estimation of the value of the best mean-square approximation on the period to an arbitrary complex-valued periodic function by trigonometric polynomials of degree not exceeding a given number in terms of its nonclassical L2 -modulus of continuity generated by the finite-difference operator of order 2m-1, m>= 2, with alternating constant coefficients equal to 1 in absolute value. / Исследуется задача о точной оценке величины наилучшего среднеквадратического приближения на периоде произвольной комплекснозначной периодической функции тригонометрическими полиномами порядка не выше заданного через ее неклассический L2 -модуль непрерывности, порожденный конечно-разностным оператором порядка 2m-1, m>= 2, с постоянными знакочередующимися коэффициентами, равными по модулю единице.

Orientador: Marcelo Esteban Coniglio / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciencias Humanas / Made available in DSpace on 2018-08-11T21:55:18Z (GMT). No. of bitstreams: 1 Reis_TeofilodeSouza_M.pdf: 733611 bytes, checksum: 0e64d330d9e71079eddd94de91f141c2 (MD5) Previous issue date: 2008 / Resumo: Neste trabalho apresentamos um novo formalismo de decomposição de Lógicas, as Coberturas por Traduções Possíveis, ou simplesmente CTPs. As CTPs constituem uma versão formal das Semânticas de Traduções Possíveis, introduzidas por W. Carnielli em 1990. Mostramos como a adoção de um conceito mais geral de morfismo de assinaturas proposicionais (usando multifunções no lugar de funções) nos permite definir uma categoria Sig?, na qual os conectivos, ao serem traduzidos de uma assinatura para outra, gozam de grande flexibilidade. A partir de Sig?, contruímos a categoria Log? de lógicas tarskianas e morfismos (os quais são funções obtidas a partir de um morfismo de assinaturas, isto é, de uma multifunção). Estudamos algumas características de Sig? e Log?, afim de verificar que estas categorias podem de fato acomodar as construções que pretendemos apresentar. Mostramos como definir em Log? o conjunto de traduções possíveis de uma fórmula, e a partir disto definimos a noção de CTP para uma lógica L. Por fim, exibimos um exemplo concreto de utilização desta nova ferramenta, e discutimos brevemente as possíveis abordagens para uma continuação deste trabalho. / Abstract: We present a general study of a new formalism of decomposition of logics, the Possible- Translations Coverings (in short PTC 's) which constitute a formal version of Possible-Translations Semantics, introduced by W. Carnielli in 1990. We show how the adoption of a more general notion of propositional signatures morphism allows us to define a category Sig?, in which the connectives, when translated from a signature to another one, enjoy of great flexibility. Essentially, Sig? -morphisms will be multifunctions instead of functions. From Sig? we construct the category Log? of tarskian logics and morphisms between them (these .are functions obtained from signature morphisms, that is, from multifunctions) . We show how to define in Log? the set of possible translations of a given formula, and we define the notion of a PTC for a logic L. We analyze some properties of PTC 's and give concrete examples of the above mentioned constructions. We conclude with a discussion of the approaches to be used in a possible continuation of these investigations. / Mestrado / Mestre em Filosofia

Orientador: Antonio Vidiella Barranco / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-04T01:43:39Z (GMT). No. of bitstreams: 1 Soares_AntonioAugusto_M.pdf: 2924266 bytes, checksum: 4d4a9d494dd74748d57e8bd6dbe14108 (MD5) Previous issue date: 2002 / Resumo: Não informado / Abstract: Not informed / Mestrado / Física / Mestre em Física

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No / The latest advances in mesocrystal formation and non-classical crystallization of pre-synthesised nanoparticles have been reviewed with the focus on providing a fuller description of a number of complex systems and their properties and applications through examination of the crystallisation mechanisms at work. Two main crystallization principles have been identified; classical crystallization and particle based aggregation modes of non-classical pathways. To understand the non-classical pathways classical crystallization and its basics are introduced before non-classical pathways, such as oriented attachment and mesocrystal formation, are examined. In particular, the various destabilization mechanisms as applied to the pre-synthesized building blocks in order to form mesocrystalline materials as well as the interparticular influences providing the driving forces are analyzed and compared to the mechanisms at work within classical crystallization. Furthermore, the new properties of the mesocrystalline materials that derive from the collective properties of the nanoparticular building units, and their applications potential are presented. It is shown that this new class of materials has the potential to impact in a number of important areas such as sensor applications, energy conversion, photonic crystals as well as for energy storage, optoelectronics and heterogeneous catalysis or photocatalysis.

Dans ce travail, nous nous intéressons à deux problèmes de la théorie des systèmes hyperboliques faisant intervenir des interfaces. Le premier concerne des modèles de couplages entre un fluide compressible et une particule ponctuelle et le second concerne la capture numérique précise des chocs, ces discontinuités qui apparaissent dans les solutions des systèmes hyperboliques.Sur la première thématique, nous commençons par introduire les différents modèles, dans lesquels la particule et le fluide interagissent à travers une force de frottement qui tend à rapprocher leurs vitesses. Le couplage est singulier car il fait intervenir le produit d’une fonction discontinue par une mesure de Dirac. On peut toutefois définir précisément le système en voyant la particule comme une interface à travers laquelle des relations liant les propriétés du fluide et celle de la particule sont imposées. Lorsque le fluide suit une équation de Burgers, nous démontrons la convergence d’une classe de schéma numérique, et nous obtenons l’existence d’une solution au problème de Cauchy pour une donnée initiale à variation totale bornée. Dans le cas plus complexe où le fluide est décrit par les équa- tions d’Euler isothermes, on prouve l’existence et l’unicité d’une solution autosemblable au problème de Riemann lorsque la particule est immobile. Des simulations numériques sont également présentées.La dernière partie de la thèse est consacrée à la construction de schémas non diffusifs pour les systèmes hyperboliques. Ces schémas, de type volumes finis, sont construits pour être exact lorsque la donnée initiale est un choc isolé. Ils sont basé sur une reconstruction discontinue de la solution au début de chaque itération en temps, dans le but de reconstituer des chocs à l’intérieur de certaines cellules du maillage. Cette stratégie mène à des schémas très peu diffusifs qui, lorsque l’opérateur de reconstruction est bien choisi, approchent correctement les solutions de cas tests problématiques (chocs lents, chocs forts, réflexions pour la dynamique des gaz, chocs non classiques pour les systèmes qui ne sont pas vraiment non linéaires). / In this work, we study two problems concerning hyperbolic systems involving interfaces. The first one concerns the study of models of coupling between a compressible fluid and a pointwise particle. The second one deals with the sharp numerical approximation of shocks, which are discontinuities that appear in the solutions of hyperbolic systems.In the first two parts of the manuscript, we introduce different models of fluid-particle couplings. The fluid and the particle interact on each other through a drag force, which brings their velocities closer to one another. The coupling is singular because it can be written as the product of a discontinuous function by a Dirac measure. However, the system can be precisely defined as follows. The particle is seen as an interface through which interface conditions linking the properties of the fluid with those of the particle are imposed. When the fluid follows the compressible Burgers equations, we prove the convergence of a family of finite volume schemes and obtain the existence of a solution when the initial data has total bounded variation. In the more difficult case where the fluid is described by the isothermal Euler equations, we prove the existence and uniqueness of a selfsimilar solution to the Riemann problem, when the particle is motionless. Numerical experiments are also presented.In the last part of this work, we build non diffusive numerical schemes for different hyperbolic systems. These finite volume schemes are built to be exact when the initial data is an isolated shock. They are based on a discontinuous reconstruction of the solution at the beginning of each time step, in order to reconstruct shocks inside some specific cells of the mesh. The schemes we present have a very low numerical diffusion and, when the reconstruction operator is well chosen, they are able to correctly approximate the solution on various problematic test cases. These cases include slowly moving shocks, strong shocks and shock reflections for gas dynamics, as well as the apparition of nonclassical shocks for systems that are not truely nonlinear.

Bei der theoretischen Beschreibung von spektroskopischen Experimenten wird in der Regel das Materiesystem quantenmechanisch beschrieben, während das Strahlungsfeld klassisch behandelt wird. Diese semiklassische Näherung ist zur Beschreibung von Experimenten, bei denen eine starke Kopplung zwischen dem Matriesystem und einzelnen Photonen besteht, nicht mehr gültig. Dies kann beispielsweise innerhalb eines optischen Resonators der Fall sein. In dieser Arbeit wird am Beispiel eines Pump-Test- Experiments zum Nachweis des optischen Stark-Effekts untersucht, welche zusätzlichen Effekte sich bei einer quantisierten Beschreibung des Strahlungsfeldes ergeben. Ein signifikanter Effekt ist, dass die Photonenstatistik des Pumpfeldes sich in der Linienform der verschobenen Resonanzlinie widerspiegelt. Weiter wurde in dieser Arbeit bei kleiner Pumpverstimmung ein Verstärkungseffekt gefunden, der ebenfalls auf der quantisierten Behandlung des Strahlungsfeldes beruht (nichtklassische Verstärkung). Es treten ferner bei grosseren Ensemblen von Zwei-Niveau -Systemen zusätzliche Unterstrukturen und Resonanzen auf. Auch kann der Nachweis des optischen Stark-Effekts Aufschluss über die Nichtdiagonalelemente bezüglich der Photonenzahl des quantisierten Pumpfeldes geben.Im Hinblick auf die Beschreibung komplexer Materiesystemen wurde in dieser Arbeit auch eine näherungsweise Berechnung der Testabsorption mit quantisiertem Strahlungsfeld im Rahmen einer Dichtematrixtheorie untersucht. Insbesondere war hier für die quantitative Beschreibung der nichtklassischen Verstärkung eine Berücksichtigung hoherer Korrelationen zwingend erforderlich. Auch wurden näherungsweise Entkopp- lungen unter Berücksichtigung der Erhaltungsgrossen durch- geführt. Die Dichtematrixtheorie wurde auf die Untersuchung des optischen Stark-Effektes an storstellengebundenen Exzitonen in Halbleitern angewandt. Da diese Resonanzen vergleichsweise kleine homogene und inhomogene Linienbreiten aufweisen,ist hier experimentell zu erwarten, dass sich feine Effekte des quantisierten Pumpfeldes bemerkbar machen konnen. / The theoretical description of spectroscopic experiments usu ally relies on a semiclassical approach where the matter system is described in terms of quantum mechanics while the radiation field is treated classically. This approach does n ot work well for systems with a strong coupling between the matter system and photons of the radiation field. The latter can be the case within an optical resonator.In this thesis, additional effects of a quantized radiation field are inves tigated on a pump-probe experiment for detecting the optical Stark effect. One significant effect is that the lineshape of the shifted resonance displays the photon statistics of the pump field. For small pump detuning probe gain results in a frequency regime where the semiclassical treatment predicts absorption. This effect is refered to nonclassical gain. For larger ensembles of two-level systems, additional substructures and resonances appear within the probe absorption spectrum. Also non- diagonal elements of the field density matrix can be detected in such an experiment. In order to describe a more complex matter systems, the optical Stark effect has been treated in terms of a density matrix approach with quantized radiation fields. For a quantitative description of nonclassical gain, higher correlation terms had to be treated properly. Moreover, conserved quantities were taken into account in approximate decouplings. The density matrix approach was applied to the description of the optical Stark effect on impurity-bound excitons in semiconductors. These systems are of high interest as their narrow resonances might allow the demonstration of fine effects of the quantized radiation field.

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Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2013-04-23T12:16:29Z No. of bitstreams: 1 Jose Silva.pdf: 734957 bytes, checksum: 1ef37b8965ca5ceae7b3d5d5cf6b915c (MD5) / Made available in DSpace on 2013-04-23T12:16:29Z (GMT). No. of bitstreams: 1 Jose Silva.pdf: 734957 bytes, checksum: 1ef37b8965ca5ceae7b3d5d5cf6b915c (MD5) Previous issue date: 2004 / O propósito deste trabalho é mostrar que a ressonância não-sincronizada pode representar a deslocalização das ligações sigma em carbocátions, possibilitando uma descrição dos carbocátions com ponte mais articulada com outros conceitos da química. A tese é composta de duas partes, em dois níveis conceituais: a transposição do conceito de híbrido de ressonância não-sincronizada, da química de estado sólido para a química orgânica, e a avaliação da qualidade da transposição realizada, através de seu emprego na explicação do cátion C4H7+. A partir da constatação de que as regras de ressonância não-sincronizada podem ser aplicadas aos carbocátions, é formulada uma inter-relação destes conceitos. Os íons não-clássicos tornam-se, então, um caso particular de ressonância não-sincronizada de ligações. Estabelecida a relação conceitual entre íons não-clássicos e ressonância não-sincronizada, passa-se ao exame da estrutura interna desta relação, através de um estudo de caso. A crítica dos trabalhos que buscaram identificar a estrutura do cátion C4H7 + ? através de reações solvolíticas, de cálculos de geometria e energia e, de espectroscopia de RMN em soluções superácidas e sobre matriz superácida sólida ? revela a incerteza dos resultados teóricos e experimentais, que são reinterpretados como um complexo equilíbrio químico entre isômeros híbridos de ressonância não-sincronizada. O estudo do caso do cátion C4H7+ demonstra a potencialidade da ressonância não-sincronizada para explicar a deslocalização de ligações sigma nos carbocátions em geral. Desse modo, é sugerido que os problemas da descrição e da representação dos carbocátions com ponte encontram uma solução na ressonância não-sincronizada. Como conseqüência, os íons não-clássicos não podem ser mais considerados como anomalias, revelando-se tão clássicos quanto quaisquer outros carbocátions. / Salvador

Depuis l’avènement de la mécanique quantique, l’étude des interactions lumière-matière à l’échelle quantique s’est énormément développée en tant que domaine de recherche. Par exemple, grâce à des prédictions théoriques surprenantes, des interactions d’une force sans précédant ont été démontrées entre de la matière et des radiations terahertz et microonde. Ces résultats correspondent à un régime dit de couplage ultrafort, atteint lorsque l’énergie d’interaction devient comparable aux énergies propres de la lumière et de la matière lorsque celles-ci n’interagissent pas. Dans ce régime, des propriétés intrigantes peuvent subsister telles que la présence de photons même lors qu’aucune énergie n’est fournie au système. Cependant, ces photons ne peuvent, a priori, être émis du système vers l’extérieur de manière à pouvoir être mesurés et par conséquent démontrer ces propriétés.Dans cette thèse, nous avons étudié ces propriétés intrigantes et proposé plusieurs moyens permettant d’y accéder expérimentalement. Nous nous sommes appuyés sur plusieurs plate-formes physiques qui sont de bon candidats pour ces études, et pour chacun de ces systèmes nous avons mis au point un modèle mettant en évidence ces propriétés d’une manière ou d’une autre. De cette façon, nous avons exploré le lien entre le régime de couplage ultrafort et la génération d’états non-classiques de la lumière. En outre, dans une étude plus ouverte nous avons montré que les interactions lumière- matière dans l’une de ces plate-formes peuvent être utilisés pour concevoir des protocols de communication quantique. En plus de montrer un intérêt fondamental, nos résultats s’inscrivent dans une optique de développement d’applications pour les technologies quantiques en utilisant différents systèmes expérimentaux disponibles actuellement / Since the advent of quantum mechanics, the study of light-matter interactions at thequantum level has been greatly developed as a research field. For instance, surprisingtheoretical predictions gave rise to experiments with unprecedented interactionstrengths between matter, and terahertz and microwave radiations. These results correspondto the so-called ultrastrong coupling regime, that is reached when the interactionenergy becomes comparable to the typical energies of the light and matter when they arenot interacting. In this regime, intriguing properties can be found such as the presenceof photons even when no energy is given to the system. However, these photons cannot,a priori, be emitted from the system to the outside world in order to be measured andtherefore demonstrate these properties. In this thesis, we studied these intriguing properties and proposed several means toaccess them experimentally. We relied on several physical platforms which are goodcandidates for such studies, and for each one of these systems we devised a model thatcan evidence these properties one way or another. By doing so, we explored the linkbetween the ultrastrong coupling regime and the generation of nonclassical states oflight. Additionally, as an outlook we showed that the light-matter interactions in oneof these platforms could be used to design quantum communication protocols. On topof showing fundamental interest, our results fit in the line of developing applications forquantum technologies using different experimentally available systems.