Dissertations / Theses on the topic 'Semi-linear'

Optimisation problems occur in many branches of science, engineering, and economics, as well as in other areas. The diversity of the various types of optimisation problems is extremely large, and so a unified approach is not attempted here. This thesis concentrates on a specific type of problem: non-linear semi-infinite programming.

In this thesis, a new way of using predisortion for linearization of power amplifiers is evaluated. In order to achieve an adequate power level for the jamming signal, power amplifiers are used in military jamming systems. Due to the nonlinear characteristic of the power amplifier, distortion will be present at the output. As a consequence, unwanted frequencies are subject to jamming. To decrease the distortion, linearization of the power amplifier is necessary.

In the system of interest, a portion of the distorted power amplifier output signal is fed back. Using this measurement, a predistortion signal is synthesized to allow suppression of the unwanted frequency components. The predistortion signal is updated a number of times in order to achieve a good outcome. Simulations are carried out in Matlab for testing of the algorithm.

The evaluation of the new linearization technique shows promising results and that good suppression of distortion components is achieved. Furthermore, new predistortion features are possible to implement, such as predistorsion in selected frequency bands. However, real hardware testing needs to be carried out to confirm the results.

Este trabalho apresenta uma metodologia para obtenção de benchmarks e prontuários de soluções para flexão de placas semi-espessas sob grandes deslocamentos. O modelo de placa de Mindlin foi o empregado para considerar a deformação cisalhante, e soluções semi-analíticas foram obtidas através de uma variação do método de Rayleigh-Ritz. O método, denominado pb- 2, facilita a imposição das condições de contorno cinemáticas, ampliando consideravelmente a aplicabilidade do método de Rayleigh-Ritz convencional. A metodologia foi implementada utilizando programas de computação simbólica, o que permitiu a obtenção de soluções analíticas aproximadas para diversos problemas lineares. A geração de soluções similares no âmbito não linear não foi possível, e neste caso recorreu-se a ajuste de parâmetros para obtenção de superfícies de resposta representativas de um grande número de análises realizadas através do método dos elementos finitos. Esta abordagem permitiu incorporar às soluções as diversas variáveis que influenciam na resposta, particularmente a espessura, razão de aspecto da placa e a compressibilidade do material. Uma nova parametrização do carregamento transversal foi proposta a fim de minimizar a influência da compressibilidade nos resultados para deslocamento central da placa, levando assim a soluções parecidas com as já reportadas para placas finas. Curvas carga ´ deslocamento podem assim ser extraídas diretamente dos ajustes realizados. Resultados para diversos casos de geometria e condições de contorno foram comparados com soluções disponíveis na literatura, mostrando boa concordância.
This work presents a methodology for generating of benchmark solutions and reference formulas for large displacement analysis of thick plates under bending. The Mindlin’s plate model was used to take into account the shear deformability, and semi-analytical solutions were obtained through a variation of the Rayleigh-Ritz method. The method, called pb-2, facilitates the imposition of kinematically admissible conditions, extending considerably the applicability of the conventional Rayleigh-Ritz method. The methodology was implemented in a symbolic computation program, and approximated analytical solutions were generated for linear cases. Similar solutions for non-linear problems were not possible, and in such cases response surfaces were obtained using data provided by finite element analysis. The approach allowed incorporating explicitly to the approximate solution the influence of parameter such as thickness of the plate, aspect ratio of the plate, and the compressibility of the material. A new nondimensional loading is proposed in order to minimize the influence of the compressibility on the response surfaces for central displacement, leading to displacement solutions similar to those reported for thin plates. Load ´ displacement curves can be extracted directly from the fitted response. Results for several cases of geometry and boundary conditions are compared with other available solutions, and good agreement was found.

Bibliography: leaves 176-182.
Certain properties associated with these classes are stable under small perturbation, i.e. stable under additive perturbation by continuous operators whose norms are less than the minimum modulus of the relation being perturbed, and are also stable under perturbation by compact, strictly singular or strictly cosingular operators. In this work we continue the study of these classes and introduce the classes of α-Atkinson and β-Atkinson relations. These are subclasses of upper and lower semi-Fredholm relations respectively, having generalised inverses and defined in terms of the existence of continuous projections onto their ranges and nullspaces.

The main goal of our thesis is to understand qualitative properties of solutions to the Cauchy problem for the semi-linear wave model with time-dependent speed and dissipation. We greatly benefited from very precise estimates for the corresponding linear problem in order to obtain the global existence (in time) of small data solutions. This reason motivated us to introduce very carefully a complete description for classification of our models: scattering, non-effective, effective, over-damping. We have considered those separately.

The main result of this thesis is an existence result for parabolic semi-linear problems. This is done by reformulating the semi-linear problem as an abstract Cauchy problem ut(t) = Au(t) + f(t; u(t)), t > 0 u(0) = u0 (1) for u0 2 X, where X is a Banach space. We then develop and use the theory of compact semigroups to prove an existence result. In order to make this result applicable, we give a characterization of compact semigroups in terms of its resolvent operator and continuity in the uniform operator topology. Thus, using the theory of analytic semigroups, we are able to determine under what conditions on A a solution to (1) exists. Furthermore, we consider the asymptotic behaviour and regularity of such solutions. By developing perturbation theory, we are easily able to apply our existence result to a larger class of problems. We then demonstrate these results with an example. This work is signi cant in providing a novel approach to a group of previously established results. The content can be considered pure mathematics, but it is of signi cant importance in real world situations. The structure of the thesis, and the choice of certain de nitions, lends itself to be easily understood and interpreted in the light of these real world situations and is intended to be easily followed by an applied mathematician. An important part of this process is to develop the problem in a real Hilbert space and then to consider the complexi cation of the problem in order to reset it in a complex Hilbert space, in which we can apply the theory of analytic semigroups. A large number of real world problems fall into the class of problems discussed here, not only in biology as demonstrated, but also in physics, chemistry, and elsewhere.
Dissertation (MSc)--University of Pretoria, 2017.
Mathematics and Applied Mathematics
MSc
Unrestricted

Dissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico.
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O presente trabalho apresenta os procedimentos para a análise numérica do comportamento de pórticos planos com conexões metálicas semi-rígidas entre vigas e pilares de estruturas de aço. Apesar de, tradicionalmente, o cálculo de estruturas metálicas ser realizado imaginando ligações rígidas ou articuladas, constata-se através de ensaios experimentais que a maioria das ligações das estruturas se enquadra em outro tipo de classificação, denominada semi-rígida, onde as conexões apresentam resistência ao giro relativo das peças conectadas, mas não possuem rigidez suficiente para impedir todo o deslocamento entre elas. Verifica-se, também, que a rigidez das ligações tem uma grande influência na distribuição das forças internas, nas deflexões e na estabilidade global da estrutura. Primeiramente são apresentados os tipos usuais de arranjos destas conexões e sua classificação de acordo com seu comportamento à flexão, fornecendo dados importantes para projeto. Estas conexões são modeladas através de uma formulação matricial pelo Método dos Deslocamentos, considerando a flexibilidade da ligação por meio de "molas" nas extremidades dos elementos de barras. Foram implementadas rotinas que permitem a consideração de uma relação não-linear entre o momento fletor e a rotação das ligações, permitindo uma melhor aproximação do modelo com os resultados experimentais.

Orientador : Nilson Tadeu Mascia
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
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Doutorado

The stability of the semi-infinite Stokes layer is explored. This is the flow generated in a semi-infinite region of otherwise stationary fluid by the sinusoidal oscillation of a bounding plate and is described by an exact solution to the Navier--Stokes equations. A linear stability analysis is carried out, based on Floquet theory, that reduces the disturbance equations to an eigenvalue problem that determines the asymptotic temporal behaviour of disturbances. This method is also applied to the finite Stokes layer (being the flow in a channel bounded by oscillating plates) and modifications incorporating a mean flow. Linear disturbances are simulated numerically and intriguing features of the spatial/temporal evolution are reproduced and expanded on. Consistency between the linear stability analysis and the simulations is demonstrated, as is evidence suggesting some disturbances exhibit temporal growth at every spatial location (absolute instabilities). Through modification of Briggs' method, the conditions for absolute instability in temporally periodic flows are discussed. It is shown that the Stokes layer is indeed subject to absolute instability by appealing to the symmetries of the flow. This approach provides further insight into the spatial/temporal evolution of disturbances. Finally, the Stokes layer is modified by a low-amplitude, high-frequency oscillation to approximate the noise associated with the mechanical generation of plate motion in experiments. It is shown that the introduction of noise can be dramatically destabilising and can have a significant effect on the disturbance evolution. In cases where the flow is subject to a high level of noise, the spatial/temporal evolution of the disturbance holds little resemblance to the evolution of disturbances in the pure Stokes layer.

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Universidade Federal Rural de Pernambuco
Estudamos o sistema parabólico não-local acoplado ut − Δu = ∫ t 0 (t − s)−1 |v|p−1v(s)ds, vt − Δv = ∫ t 0 (t − s)−2 |u|q−1u(s)ds onde 0 ≤ γ1, γ2 < 1 e p, q ≥ 1. Consideramos o problema em (0, T)×RN e um problema de Dirichlet em (0, T)×Ω, com Ω ⊂ RN domínio limitado e fronteira regular. Admitimos que os dados iniciais u(0), v(0) ∈ C0(RN) e u(0), v(0) ∈ C0(Ω), respectivamente. Encontramos condições que garantem a existência de solução global e a explosão num tempo finito de qualquer solução do sistema em questão

Programa de Pós Graduação em Engenharia Civil. Departamento de Engenharia Civil, Escola de Minas, Universidade Federal de Ouro Preto.
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O comportamento de pórticos planos metálicos com ligações semi-rígidas é analisado através de um modelo numérico que incorpora a não-linearidade geométrica nos moldes do Método dos Elementos Fintitos (MEF). É empregado um algoritmo combinado que associa os aspectos de convergência do método incrementalinterativo tangente, calculando-se o vetor de cargas desequilibradas através da consideração de movimentos de corpo rígido. Os efeitos devidos às não-linearidades adicionais oriundas da presença das ligações semi-rígidas são considerados através do modelo B-Splines Tensionada para representar o comportamento não-linear da relação momento-rotação das ligações. Com a finalidade de avaliar a performance dos modelos adotados, resultados numéricos obtidos são comparados com resultados experimentais de pórticos planos, deslocáveis e indeslocáveis. Desta forma, também é possível verificar o efeito do contraventamento por diagonais ou apoios laterais nos pórticos com ligações semi-rígidas. _______________________________________________________________________
ABSTRACT : The behavior of steel plane frames witíi semi-rigid connections is focused through the results of a geometrically non-linear analysis by the finite element method. The effects of additional non-linearity arising from the presence of semi-rigid connections are accounted for by representing the non-linear moment-rotation curves as tensioned B-spline curves. The equilibrium path is traced with the aid of a hybrid algorithm which combines the convergence properties of the iterative-incremental tangent method, calculating the unbalancing forces by the consideration of the element rigid body motion. A comparison between experimental and nurnerical results for a particular example is also presented. By the finality to valuation the performance of the adopted modes, numerical results are got and compared with experimental results of plane frame, deslocavable and undeslocavable. Thus, it is possible too verify the effect of bracing for diagonal or lateral beams in the frame with semi-rigid connections.

L'amélioration permanente de la qualité et des performances des systèmes automatiques constitue un défi majeur dans la théorie du contrôle. La théorieHinf a permis d'améliorer considérablement les performances des correcteurs. Ces derniers reposent sur des modèles mathématiques qui sont potentiellement d'ordre élevé (c.-à-d. comprenant un nombre élevé d'équations différentielles). De plus, l'ajout de poids de pondérations spécifiant les performances à respecter accroit encore plus leur ordre. La complexité algorithmique résultante peut alors rendre leur implantation difficile voire même impossible pour un fonctionnement en temps réel.Les travaux présentés visent à réduire l'ordre de correcteurs Hinf dans le but de faciliter leur intégration tout en respectant les performances imposées d'une part et proposent une majoration de l'erreur introduite par l'étape de réduction d'autre part.Dans la littérature, de nombreuses méthodes pour la réduction d'ordre de modèles et de correcteurs des systèmes LTI ont été développées. Ces techniques ont été étudiées, comparées et testées sur un ensemble de benchmarks. S'appuyant sur ces travaux, nous proposons une extension aux systèmes linéaires à paramètres variants (LPV). Pour valider leurs performances, une application sur une commande d'une suspension semi-active a montré l'efficacité des algorithmes de réduction développés
The work presented in this dissertation is related to the Hinf-LPV-controller orderReduction. This latter consists of the design of a robust reduced-order LPV-controller for LPV-systems. The order reduction issue has been very fairly investigated. However, the case of LPV-control design is slightly discussed. This thesis focuses primarily on two topics: How to obtain an LPV-reduced-order controller even the high order generated by the classical synthesis and how this reduced order controller can deal with a practical engineering problem (semi-active suspension control). In view of this, the order-reduction topic and the Hinf-synthesis theory have been widely studied in this thesis. This study, has allowed the development of a new method forH1-LPV-controller order reduction

In this thesis we consider approximate travelling wave solutions for stochastic and generalised KPP equations and systems by using the stochastic elementary formula method of Elworthy and Truman. We begin with the semi-classical analysis for generalised KPP equations. With a so-called "late caustic" assumption we prove that the global wave front is given by the Hamilton Jacobi function. We prove a Huygens principle on complete Riemannian manifolds without cut locus, with some bounds on their volume elements, in particular Cartan-Hadamard manifolds. Based on the semiclassical analysis we then consider the propagation of approximate travelling waves for stochastic generalised KPP equations. Three regimes of perturbation are considered: weak, mild, and strong. We show that weak perturbations have little effect on the wave like solutions of the unperturbed equations while strong perturbations essentially destroy the wave and force the solutions to decay rapidly. In the more difficult mild case we show the existence of a 'wave front', in front of which the solution is close to zero (of order exp(-c1μ-2) as μ~0 for c1 random) and behind which it has at least order exp(-c2μ-1) for some random c2 depending on the increment of the noise. For an alternative stochastic equation we classify the effect of the noise by the Lyapunov exponent of a corresponding stochastic ODE. Finally we study the asymptotic behaviour of reaction-diffusion systems with a small parameter by using the n-dimensional Feynman-Kac formula and Freidlin's large deviation theory. We obtain the travelling wave with nonlinear ergodic interactions and a special case with nonlinear reducible interactions.

The aim of this thesis is to provide a generic approach to the study of semi-linear parabolic partial differential equations when the nonlinearity fails to be Lipschitz continuous, but is in the class of Hӧlder continuous functions or the class of upper Lipschitz continuous functions. New results are obtained concerning the well-posedness (in the sense of Hadamard) of the initial value problem, namely, uniqueness and conditional continuous dependence results for upper Lipschitz continuous nonlinearities, and an existence result for Hӧlder continuous nonlinearities. To obtain these results, two new maximum principles have been obtained, for which examples have been provided to exhibit their applications and limitations. Additionally, new derivative estimates of Schauder-type have been obtained. Once the general theory has been established, specific problems are studied in detail. These show how one can apply the general theory, as well as problem specific approaches, to obtain well-posedness results.

In a generalized linear mixed model (GLMM), the random effects are typically uncorrelated and assumed to follow a normal distribution. However, findings from recent studies on how the misspecification of the random effects distribution affects the estimated model parameters are inconclusive. In the thesis, we extend the randomization approach for deriving linear models to the GLMM framework. Based on this approach, we develop an algorithm for estimating the model parameters of the randomization-based GLMM (RBGLMM) for the completely randomized design (CRD) which does not require normally distributed random effects. Instead, the discrete uniform distribution on the symmetric group of permutations is used for the random effects. Our simulation results suggest that the randomization-based algorithm may be an alternative when the assumption of normality is violated. In the second part of the thesis, we consider an RB-GLMM for the randomized complete block design (RCBD) with random block effects. We investigate the effect of misspecification of the correlation structure and of the random effects distribution via simulation studies. In the simulation, we use the variance covariance matrices derived from the randomization approach. The misspecified model with uncorrelated random effects is fitted to data generated from the model with correlated random effects. We also fit the model with normally distributed random effects to data simulated from models with different random effects distributions. The simulation results show that misspecification of both the correlation structure and of the random effects distribution has hardly any effect on the estimates of the fixed effects parameters. However, the estimated variance components are frequently severely biased and standard errors of these estimates are substantially higher.

Photogrammetry and Laser Scanning can be used to complement one another, during instances where digital images are taken of the object of interest with the intention to merge the 3D data and image in order to reconstruct photorealistic virtual models with photo quality and metric realism. Laser scanning acquires 3D data points and intensity information of objects but is unable to directly obtain photorealistic colour in most cases. To get photorealistic colour, some laser scanners come with an onboard camera, or alternatively a separate camera is used, and registration is required for both cases. One example uses a specially designed camera mounting for the laser scanner and another is to transfer colour information from 2D images captured from near the scanner to the 3D points using close-range photogrammetry. Currently limited methods exist for the registration of the data from multiple-sensors. This research outlines the evaluation and semi-automated registration of a single colour image to laser scanning point cloud data, using the canonical transformation and Direct Linear Transformation (DLT) methods for registration.The method presented in this thesis is to directly reconstruct three dimensional data from a single image with the assistance of estimated depth information. Laser scanning point cloud information is used to supplement the recovery of the estimated depth information, which is then assigned to the image data. Two primary aspects for this research are (1) the Synthetic Camera Image, following on from previous work reported in the literature on utilising synthetic imagery created from point-clouds, and (2) the Direct Linear Transformation model, which is used to provide the transformation parameters between the 2D and 3D datasets.Synthetic datasets were used to provide an indication of expected results in terms of range, incidence angle and image resolution. The image resolution is an important factor to consider. It should be as high as possible as it affects the outcome of precision. Testing with real data, the proposed method resulted in a precision of 2 mm for the data of a model T-Rex dinosaur dataset, and 19mm for a typical indoor scene. The variations in precision levels are due to different values for range, incidence angle and image resolution. Overall the results achieved the expectations producing a colour point cloud with metric assessment.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A comunidade científica tem conhecimento de que uma das etapas mais relevantes no projeto de estruturas de aço e mistas, diz respeito a uma avaliação precisa sobre os modelos estruturais que representam o comportamento real das ligações viga-coluna. Este assunto tem sido objeto de vários trabalhos de pesquisa nas ultimas décadas. Na prática corrente do projeto de estruturas de aço, a grande maioria das ligações viga-coluna é representada por modelos flexíveis (rótulas) ou rígidos (engastes). Contudo, na maior parte dos casos práticos, essas ligações assumem um comportamento intermediário, ou seja, semi-rígido. Um outro ponto importante acerca do assunto diz respeito à avaliação da resposta dinâmica de estruturas de aço com a consideração pertinente do efeito das ligações, especialmente, no que tange as semi-rígidas, já que a maioria dos trabalhos de pesquisa concentra-se apenas no estudo da resposta estática dos modelos. Assim sendo, esta investigação apresenta uma contribuição inicial no que tange ao emprego de elementos que representem mais fielmente os efeitos das ligações estruturais na análise dinâmica de estruturas de aço, evidentemente, com a consideração do efeito de semi-rigidez dessas ligações. Desta forma, este trabalho de pesquisa propõe o uso de um modelo mecânico com elementos de mola rotacionais não-lineares, objetivando simular adequadamente o efeito das ligações viga-coluna especificamente em pórticos de aço. Inicialmente, foi feita uma calibração do modelo computacional desenvolvido, comparando os resultados obtidos mediante o uso do modelo de mola rotacional com os dados obtidos na literatura técnica sobre o assunto. Na seqüência, desenvolve-se uma analise paramétrica extensa, com a inclusão de todos os efeitos mencionados no parágrafo anterior, de forma a avaliar mais detalhadamente a resposta dinâmica dos pórticos de aço, deslocamentos e esforços, com base no estudo de um edifício residencial de quatro pavimentos.
The scientific community has realized that one of the most relevant stages in the design of steel and composite structures concerns to an accurate evaluation about the structural models that represent the actual behaviour of the beam-to-column connections. This issue has been the subject of many studies over the last decade. In the current design of steel structures, most of the beam-to-column connections are represented by pinned or rigid models. However, in most of the current cases, the connections have an intermediate behaviour between these two cases. Another important issue about the correct evaluation of the dynamic response of steel structures its about the consideration of the effects of the joints, especially of the semi-rigid joints, since most of the studies consider only a static analysis of the models. Therefore, this dissertation has proposed the use of a mechanical model of rotational springs with a nonlinear behaviour, objectifying a proper simulation of the beam-to-column effects in steel frames. The numeric results were obtained along the present study, and calibrated based on many computer models available on the literature. On the sequence, a large parametric analysis is developed, including all the effects mentioned before, objectifying evaluate more precisely the dynamic response of the steel frames (displacements and forces), based on the static and dynamic response of a four storey edifice.

De nombreuses recherches sont aujourd’hui consacrées à l’étude et au développement de stratégies de réduction du bruit et des vibrations. Dans le domaine de l’acoustique comme dans le domaine des vibrations, différentes approches peuvent être envisagées. Une tendance actuelle est d’appliquer des techniques actives qui sont reconnues pour être efficaces sur une large bade de fréquence, mais qui souffrent cependant d’une complexité de mise en oeuvre et d’une nécessité d’un apport d’énergie extérieur qui rendent ces systèmes peu robustes et potentiellement instables. Les techniques passives, qui utilisent par exemple des matériaux isolants, sont quand à elles très efficaces pour les hautes fréquences mais plus limitées en basse fréquence pour un problème de poids et d’encombrement, ce qui peut être un inconvénient dans certaines applications aéronautiques ou aérospatiales où la légèreté est un paramètre primordial. Afin de diminuer le bruit engendré par les vibrations des structures, il est possible d’adopter une approche différente basée sur l’utilisation de systèmes semi-passifs. Cette technique, qui sera utilisée dans ce travail, est réalisée grâce des éléments piézo-céramiques collés à la structure et connectés à un circuit électrique de type shunt résonant avec un interrupteur (switch shunt). L’interrupteur permet d’ouvrir et de fermer le circuit électrique à des moments bien précis de façon à maximiser l’atténuation des vibrations. Par rapport aux systèmes actifs, ce type d’approche est relativement simple à mettre en oeuvre, robuste et stable. De plus, par rapport aux techniques piézoélectriques purement passives, il n’est pas nécessaire de fournir de l’énergie extérieur au système ni d’accorder précisément les composants électrique pour garder une efficacité sur une bande de fréquence relativement large. L’objectif du travail est double. Il s’agit de développer un outil de calcul par éléments finis (basé sur les logiciels Matlab et Nastran) pour simuler la réponse dynamique de système couplés élasto-acoustiques amortis grâce à l’utilisation de pastilles piézoélectriques connectées à un circuit de type shunt avec interrupteur. De plus, des expérimentations sont réalisées de façon à tester un dispositif piézoélectrique original et valider certains développements numériques. Concernant l’expérimentation, une approche originale basée sur l’utilisation d’un tachymètre et de circuits intégrés CMOS (nécessitant une alimentation de 12 V) a été développée. Une adaptation est également proposée pour l’utilisation simultanée de plusieurs patches piézoélectriques. Une modélisation éléments finis d’une structure élastique couplée à une cavité acoustique est tout d’abord réalisée. Les matrices globales des parties fluide, structure et couplage fluidestructure sont extraites du code de calcul Nastran et sont réassemblées dans Matlab selon la formulation classique non symétrique en termes de déplacement de la structure et de pression dans le fluide. Ensuite, la matrice de couplage électro-mécanique est ajoutée pour prendre en compte les effets piézoélectriques. Enfin, le comportement du circuit résonnant avec interrupteur est modélisé et simulé. Etant donné les temps de commutation très courts, une approche temporelle directe (basée sur le shéma de Newmark) a été utilisée de façon à calculer la réponse transitoire du système couplé
Among the different strategies oriented to the noise and vibration control, due to their promising properties in terms of limited required power supply, broad band and no tuneable nature, semi-active switched shunt architectures have well done for themselves. The idea of using piezo transducers to convert mechanical into electrical energy and elaborating related signal within an external time variant electrical circuit, represents the inspiring principle of this type of control. A wide amount of efforts has been spent on the semi-active switched shunt control with specific interest in the “synchronised” one; theoretical, numerical, experimental investigations, proved in different ways pros and cons of applications generally confined to the vibration field, in the low frequency band. Also the idea of extending this control to acoustics has been taken into account: problems like the structure-borne sound have been dealt with, implementing switch logic onto piezo networks mounted on structural components. An interesting industrial application in the field of aeronautics and automotive in general, is the interior sound level reduction: in this case a distribution of piezoelectric transducers suitably collocated may lead to remarkable effects, without excessive power consumption. In the present work, a semi analytic approach aimed at estimating the effects on the reduction of pressure sound level by synchronised switched shunt logic, is described. The displacement field within a 1D longitudinal air column through a Fourier series ;expansion has been formalised by assigning a sinusoidal perturbation and fluid–structure interface condition on the left and right boundaries, respectively. At first, a validation procedure has been implemented: both the convergence of the series coefficients and the satisfaction of boundary and initial conditions have been verified. To simulate the no control operative condition, the solution has been computed for the entire time domain, keeping invariant all circuitry properties; then for the switch working modality, solution has been computed by splitting the entire time domain into partitions, each one delimited by the instants at which the circuit is switched on (i. E. , by maxima and minima of the displacement on the right boundary domain); for any partition, specific circuitry properties (e. G. Piezo voltage, electrical field…) have been selected. Based on displacement information, related sound pressure level has been compared for no controlled and controlled operative conditions, with and without signal amplification

The main goal of this thesis is to prove the global (in time) existence of small data Sobolev solutions to semi-linear damped σ-evolution equations from suitable function spaces basing on L^q spaces by mixing additional L^m regularity for the data on the basis of L^q-L^q estimates for solutions, with q∈(1,∞) and m∈[1,q), to the corresponding linear models. To establish desired results, we would like to apply the theory of modified Bessel functions, Faà di Bruno's formula and Mikhlin-Hörmander multiplier theorem in the treatment of linear problems. In addition, some of modern tools from Harmonic Analysis play a fundamental role to investigate results for the global existence of small data Sobolev solutions to semi-linear problems. Finally, the application of a modified test function method is to devote to the proof of blow-up results for semi-linear damped σ-evolution models, where σ≥1 and δ∈[0,σ) are assumed to be any fractional numbers.

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Os avanços tecnológicos industriais, nas últimas décadas, geraram o desenvolvimento de máquinas de alta performance e precisão que, por sua vez, têm demandado projetos otimizados de suas fundações. Cada vez mais, diversas tentativas têm que ser consideradas para se obter projetos de fundações que conciliem a máxima eficiência com custos aceitáveis. A modelagem via método dos elementos finitos se constitui uma poderosa ferramenta que pode ser utilizada para prever, de maneira mais precisa, o comportamento desses elementos estruturais quando comparada com os métodos analíticos simplificados, disponíveis na literatura, que levam em conta, na sua formulação, várias hipóteses a fim de que possam ser utilizados. A presente pesquisa aborda os conceitos básicos da análise dinâmica de fundações de máquinas, discute sobre alguns métodos analíticos e numéricos disponíveis de projeto e apresenta algumas recomendações de projeto e prescrições normativas. Blocos de fundações de concreto armado para máquinas alternativas e de impacto, bem como fundações aporticadas de concreto armado para turbomáquinas foram analisadas. As freqüências naturais e amplitudes da análise de elementos finitos foram comparadas com os resultados decorrentes da utilização dos métodos analíticos. Além disso, foram considerados os esforços seccionais e as tensões necessárias para o detalhamento das armações. Os resultados das análises de elementos finitos mostraram boa concordância com aqueles obtidos com a utilização dos métodos analíticos

South Africa (SA) currently faces a major pollution problem from mining impacted water, including acid rock drainage (ARD), as a consequence of the mining activities upon which the economy has been largely built. The environmental impact of ARD has been further exacerbated by the country's water scarce status. Increasingly scarce freshwater reserves require the preservation and strategic management of the country's existing water resources to ensure sustainable water security. In SA, the primary focus on remediation of ARDcontaminated water has been based on established active technologies. However, these approaches are costly, lead to secondary challenges and are not always appropriate for the remediation of lower volume discharges. Mostly overlooked, ARD discharges from diffuse sources, associated with the SA coal mining industry, have a marked impact on the environment, similar to those originating from underground mine basins. This is due to the large number of deposits and their broad geographic distribution across largely rural areas of SA. Semi-passive ARD treatment systems present an attractive alternative treatment approach for diffuse sources, with lower capital and operational costs than active systems as well as better process control and predictability than traditional passive systems. These semi-passive systems typically target sulphate salinity through biological sulphate reduction catalysed by sulphate reducing bacteria (SRB). These anaerobic bacteria reduce sulphate, in the presence of a suitable electron donor, to sulphide and bicarbonate. However, the hydrogen sulphide product generated is highly toxic, unstable, easily re-oxidised and poses a significant threat to the environment and human health, so requires appropriate management. An attractive strategy is the reduction of sulphate to sulphide, followed by its partial oxidation to elemental sulphur, which is stable and has potential as a value-added product. A promising approach to achieve partial oxidation is the use of sulphide oxidising bacteria (SOB) in a floating sulphur biofilm (FSB). These biofilms develop naturally on the surfaces of sulphide rich wastewater streams. Its application in wastewater treatment and the feasibility of obtaining high partial oxidation rates in a linear flow channel reactor (LFCR) has been described. The use of a floating sulphur biofilm overcomes many of the drawbacks associated with conventional sulphide oxidation technologies that are costly and require precise operational control to maintain oxygen limiting conditions for partial oxidation. In the current study a hybrid LFCR, incorporating a FSB with biological sulphate reduction in a single reactor unit, was developed. The integration of the two biological processes in a single LFCR unit was successfully demonstrated as a ‘proof of concept'. The success of this system relies greatly on the development of discrete anaerobic and microaerobic zones, in the bulk liquid and at the airliquid interface, that facilitate sulphate reduction and partial sulphide oxidation, respectively. In the LFCR these environments are established as a result of the hydrodynamic properties associated with its design. Key elements of the hybrid LFCR system include the presence of a sulphate-reducing microbial community immobilised onto carbon fibres and the rapid development of a floating sulphur biofilm at the air-liquid interface. The floating sulphur biofilm consists of a complex network of bacterial cells and deposits of elemental sulphur held together by an extracellular polysaccharide matrix. During the Initial stages of FSB development, a thin transparent biofilm layer is formed by heterotrophic microorganisms. This serves as ‘scaffolding' for the subsequent attachment and colonisation of SOB. As the biofilm forms at the air-liquid interface it impedes oxygen mass transfer into the bulk volume and creates a suitable pH-redox microenvironment for partial sulphide oxidation. Under these conditions the sulphide generated in the bulk volume is oxidised at the surface. The biofilm gradually thickens as sulphur is deposited. The produced sulphur, localised within the biofilm, serves as an effective mechanism for recovering elemental sulphur while the resulting water stream is safe for discharge into the environment. The results from the initial demonstration achieved near complete reduction of the sulphate (96%) at a sulphate feed concentration of 1 g/L with effective management of the generated sulphide (95-100% removal) and recovery of a portion of the sulphur through harvesting the elemental sulphur-rich biofilm. The colonisation of the carbon microfibres by SRB ensured high biomass retention within the LFCR. This facilitated high volumetric sulphate reduction rates under the experimental conditions. Despite the lack of active mixing, at a 4-day hydraulic residence time, the system achieved volumetric sulphate reduction rates similar to that previously shown in a continuous stirred-tank reactor. The outcome of the demonstration at laboratory scale generated interest to evaluate the technology at pilot scale. This interest necessitated further development of the process with a particular focus on evaluating key challenges that would be experienced at a larger scale. A comprehensive kinetic analysis on the performance of the hybrid LFCR was conducted as a function of operational parameters, including the effect of hydraulic residence time, temperature and sulphate loading on system performance. Concurrently, the study compared the utilisation of lactate and acetate as carbon source and electron donor as well as the effect of reactor configuration on system performance. Comparative assessment of the performance between the original 2 L LFCR and an 8 L LFCR variant that reflected the pilot scale design with respect to aspect ratio was conducted. Pseudo-steady state kinetics was assessed based on carbon source utilisation, volumetric sulphate reduction, sulphide removal efficiency and elemental sulphur recovery. Additionally, the hybrid LFCR provided a unique synergistic environment for studying the co-existence of the sulphate reducing (SRB) and sulphide oxidising (SOB) microbial communities. The investigation into the microbial ecology was performed using 16S rRNA amplicon sequencing. This enabled the community structure and the relative abundance of key microbial genera to be resolved. These results were used to examine the link between process kinetics and the community dynamics as a function of hydraulic residence time. Results from this study showed that both temperature and volumetric sulphate loading rate, the latter mediated through both sulphate concentration in the feed and dilution rate, significantly influenced the kinetics of biological sulphate reduction. Partial sulphide oxidation was highly dependent on the availability and rate of sulphide production. Volumetric sulphate reduction rates (VSRR) increased linearly as hydraulic residence time (HRT) decreased. The optimal residence time was determined to be 2 days, as this supported the highest volumetric sulphate reduction rate (0.21 mmol/L.h) and conversion (98%) with effective sulphide removal (82%) in the 2 L lactate-fed LFCR. Lactate as a sole carbon source proved effective for achieving high sulphate reduction rates. Its utilisation within the process was highly dependent on the dominant metabolic pathway. The operation at high dilution rates resulted in a decrease in sulphate conversion and subsequent increase in lactate metabolism toward fermentation. This was attributed to the competitive interaction between SRB and fermentative bacteria under varying availability of lactate and concentrations of sulphate and sulphide. Acetate as a sole carbon source supported a different microbial community to lactate. The lower growth rate associated with acetate utilising SRB required longer start-up period and was highly sensitive to operational perturbations, especially the introduction of oxygen. However, biomass accumulation over long continuous operation led to an increase in performance and system stability. Microbial ecology analysis revealed that a similar community structure developed between the 2 L and 8 L lactate-fed LFCR configurations. This, in conjunction with the kinetic data analysis, confirmed that the difference in aspect ratio and scale had minimal impact on process stability and that system performance can be reproduced. The choice of carbon source selected for distinctly different, highly diverse microbial communities. This was determined using principle co-ordinate analysis (PCoA) which highlighted the variation in microbial communities as a function of diversity and relative abundance. The SRB genera Desulfarculus, Desulfovibrio and Desulfomicrobium were detected across both carbon sources. However, Desulfocurvus was found in the lactate-fed system and Desulfobacter in acetate-fed system. Other genera that predominated within the system belonged to the classes Bacteroidetes, Firmicutes and Synergistetes. The presence of Veillonella, a lactate fermenter known for competing with SRB, was detected in the lactate-fed systems. Its relative abundance corresponded well with the lactate fermentation and oxidation performance, where an apparent shift in the dominant metabolic pathway was observed at high dilution rates. Furthermore, the data also revealed preferential attachment of selective SRB onto carbon microfibers, particularly among the Desulfarculus and Desulfocurvus genera. The microbial ecology of the floating sulphur biofilm was consistent across both carbon sources. Key sulphur oxidising genera detected were Paracoccus, Halothiobacillus and Arcobacter. The most dominant genera present in the FSB were Rhizobium, well-known nitrogen fixing bacteria, and Pannonibacter. Both genera are members of the class Alphaproteobacteria, a well-known phylogenetic grouping in which the complete sulphur-oxidising, sox, enzyme system is highly conserved. An aspect often not considered in the operation of these industrial bioprocess systems is the microbial community dynamics within the system. This is particularly evident within biomass accumulating systems where the proliferation of non-SRB over time can compromise the performance and efficiency of the process. Therefore, the selection and development of robust microbial inoculums is critical for overcoming the challenges associated with scaling up, particularly with regards to start-up period, and long-term viability of sulphate reducing bioreactor systems. In the current study, long-term operation demonstrated the robustness of the hybrid LFCR process to maintain relatively stable system performance. Additionally, this study showed that process performance can be recovered through re-establishing suitable operational conditions that favor biological sulphate reduction. The ability of the system to recover after being exposed to multiple perturbations, as explored in this study, confirms the resilience and long-term viability of the hybrid process. A key feature of the hybrid process was the ability to recover the FSB intermittently without compromising biological sulphate reduction. The current research successfully demonstrated the concept of the hybrid LFCR and characterised sulphate reduction and sulphide oxidation performance across a range of operating conditions. This, in conjunction with a clearer understanding of the complex microbial ecology, illustrated that the hybrid LFCR has potential as part of a semi-passive approach for the remediation of low volume sulphate-rich waste streams, critical for treatment of diffuse ARD sources.

The single plate framing connections are those where a plate is shop welded to the support element, either a beam or a column, and field bolted to the web of the supported beam. Usually, a single plate connection is assumed to be flexible but, actually, it is semi-rigid. This connection type was studied mainly by Richard, and his tests indicated that a significant moment can be developed at the end of the supported beam. Nonlinear finite element analyses of single plate framing connections are carried out. The assumed Load-Deformation behaviorof single bolt connections was based on the tests made by Richard. Shell and beam elements are used, suitable for plastic analyses with large displacements. Nonlinear spring elements are associated with the individual Load-Deformation behavior of the bolts. This research is extended to the case of beams connected to column webs. All the results are presented as Moment-Rotation curves and relevant ultimate strengths.
As ligações por chapa simples são aquelas em que uma chapa é usualmente soldada de fábrica ao elemento suporte, podendo o mesmo ser uma viga ou um pilar, e tal chapa é parafusada, no campo, na alma da viga apoiada. Na prática, uma ligação por chapa simples é considerada flexível, porém, na verdade, é semi-rígida. Este tipo de ligação foi estudado principalmente por Richard, e seus ensaios indicaram que pode-se desenvolver um significativo momento na extremidade da viga apoiada. Neste trabalho, apresenta-se ummodelo de elementos finitos para a análise não-linear de ligações por chapa simples, onde os comportamentos Carga-Deslocamento de ligações com um parafuso são os obtidos por Richard. Utilizam-se elementos de casca e de barra, adequados para análise plástica com grandes deslocamentos, e elementos de molas não-lineares, aos quais foi associado o comportamento Carga-Deslocamento individual dos parafusos. Estendeu-se o estudo ao caso de vigas apoiadas em almas de pilares. Todos os resultados obtidos são apresentados sob a forma de curvas Momento-Rotação e de resistências últimas aplicáveis.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
In this dissertation we present a semi-local convergence analysis for the Gauss-Newton method to solve a special class of systems of non-linear equations, under the hypothesis that the derivative of the non-linear operator satisfies a majorant condition. The proofs and conditions of convergence presented in this work are simplified by using a simple majorant condition. Another tool of demonstration that simplifies our study is to identify regions where the iteration of Gauss-Newton is “well-defined”. Moreover, special cases of the general theory are presented as applications.
Nesta dissertação apresentamos uma análise de convergência semi-local do método de Gauss-Newton para resolver uma classe especial de sistemas de equações não-lineares, sob a hipótese que a derivada do operador não-linear satisfaz uma condição majorante. As demonstrações e condições de convergência apresentadas neste trabalho são simplificadas pelo uso de uma simples condição majorante. Outra ferramenta de demonstração que simplifica o nosso estudo é a identificação de regiões onde a iteração de Gauss-Newton está “bem-definida”. Além disso, casos especiais da teoria geral são apresentados como aplicações.

Neste trabalho foi proposto o modelo linear parcial generalizado simétrico, com base nos modelos lineares parciais generalizados e nos modelos lineares simétricos, em que a variável resposta segue uma distribuição que pertence à família de distribuições simétricas, considerando um preditor linear que possui uma parte paramétrica e uma não paramétrica. Algumas distribuições que pertencem a essa classe são as distribuições: Normal, t-Student, Exponencial potência, Slash e Hiperbólica, dentre outras. Uma breve revisão dos conceitos utilizados ao longo do trabalho foram apresentados, a saber: análise residual, influência local, parâmetro de suavização, spline, spline cúbico, spline cúbico natural e algoritmo backfitting, dentre outros. Além disso, é apresentada uma breve teoria dos modelos GAMLSS (modelos aditivos generalizados para posição, escala e forma). Os modelos foram ajustados utilizando o pacote gamlss disponível no software livre R. A seleção de modelos foi baseada no critério de Akaike (AIC). Finalmente, uma aplicação é apresentada com base em um conjunto de dados reais da área financeira do Chile.
In this work we propose the symmetric generalized partial linear model, based on the generalized partial linear models and symmetric linear models, that is, the response variable follows a distribution that belongs to the symmetric distribution family, considering a linear predictor that has a parametric and a non-parametric component. Some distributions that belong to this class are distributions: Normal, t-Student, Power Exponential, Slash and Hyperbolic among others. A brief review of the concepts used throughout the work was presented, namely: residual analysis, local influence, smoothing parameter, spline, cubic spline, natural cubic spline and backfitting algorithm, among others. In addition, a brief theory of GAMLSS models is presented (generalized additive models for position, scale and shape). The models were adjusted using the package gamlss available in the free R software. The model selection was based on the Akaike criterion (AIC). Finally, an application is presented based on a set of real data from Chile\'s financial area.

Este trabalho aborda a aplicação de uma máquina elétrica síncrona do tipo tubular linear de ímãs permanentes em um sistema de suspensão semiativa. O uso de amortecedores eletromagnéticos lineares em sistemas de suspensão não é uma ideia nova, mas a maioria dos trabalhos publicados sobre este assunto concebem soluções ativas e negligenciam as semiativas, sobretudo com estudos experimentais. Nesta pesquisa é discutido um modelo dinâmico eletromecânico acoplado de um sistema de suspensão semiativa, considerando um amortecedor eletromagnético linear e também apresentando dados experimentais. Leis da mecânica clássica e do eletromagnetismo são aplicadas para descrever o sistema que combina teoria de vibrações e máquinas elétricas. Um modelo virtual com vários subsistemas foi implementado no ambiente MATLABR /Simulink/Simscape para associar equações e simular o desempenho global. Para o caso passivo, os resultados numéricos e experimentais validam os parâmetros e confirmam a funcionalidade do sistema e a metodologia proposta. Simulações e testes experimentais para o caso semiativo são consistentes, mostrando uma melhoria na transmissibilidade de deslocamento, em relação ao modo passivo, e a possibilidade de regeneração de energia.
This work addresses the application of a tubular linear permanent magnet synchronous machine working as a damper for a semi-active suspension system. The use of linear electromagnetic dampers in suspension systems is not a new idea. However, most published papers on this subject outline active solutions and neglect semi-active ones, above all, with experimental studies. Here a dynamic mechanicalelectromagnetic coupled model for a semi-active suspension system is reported. This is in conjunction with a linear electromagnetic damper and also presents experimental data. Classical laws of mechanics and electromagnetics are applied to describe a dynamic model combining vibration and electrical machines theories. A multifaceted MATLABR /Simulink/Simscape model was implemented to incorporate equations and simulate global performance. For the passive case, numerical and experimental results validate the parameters and confirm system function and the proposed methodology. Simulation and practical results for the semi-active case are consistent, showing an improvement in the displacement transmissibility and the possibility of energy regeneration.

This paper proposes for the purposes of freight generation a spatial autoregressive model framework, combined with non-linear semi-parametric techniques. We demonstrate the capabilities of the model in a series of Monte Carlo studies. Moreover, evidence is provided for non-linearities in freight generation, through an applied analysis of European NUTS-2 regions. We provide evidence for significant spatial dependence and for significant non-linearities related to employment rates in manufacturing and infrastructure capabilities in regions. The non-linear impacts are the most significant in the agricultural freight generation sector.

Since the 60´s a group of searchers in front of same aspects as: geographic growing, food production, etc, looking for analyze the future situation of the man kind in related to Environment. In this aspect, in consequence of the environmental worry there is the Conference in Rio de Janeiro named Rio 92, with main subject the approval of 21st agenda, whose main objective is to stimulate the environmental conservation and preservation. In this context, the state of Paraná became the first in the creation and implementation of Ecological ICMS, an economic instrument that has as main functions: the compensatory function and stimulating function. This way, foundated in the Federal and State Constitution, in the study executed about the Sergipe´s ICMS and through the stimulating function, the present work has as objectives: the implementation and establishing of the Ecological ICMS in the semi-arid region in the Sergipe state. This way, we will search for identify groups of towns that present similitude and still establish tendency functions through the years in the resort available in the piece ICMS.
A partir da década de 60 um grupo de pesquisadores diante de aspectos como: crescimento geográfico, produção de alimentos, dentre outros, procura analisar a situação futura do homem em relação ao Meio Ambiente. Nesse aspecto, como reflexo dessa preocupação com o meio ambiente acontece a Conferência no Rio de Janeiro intitulada Rio 92, tendo como ponto principal à aprovação da Agenda XXI, cujo principal objetivo é incentivar a conservação e preservação ambiental. Nesse contexto, o Estado do Paraná torna-se precursor na criação e implementação do ICMS Ecológico, instrumento econômico que possui como principais funções: a função compensatória e a função incentivadora. Nesse sentido, embasado nas Constituições Federal e Estadual, no estudo realizado sobre o ICMS de Sergipe e através da função incentivadora, o presente trabalho tem como objetivo principal propor o ICMS Ecológico como uma política de gestão ambiental que possa vir a ser implantado e implementado na região do Semi-Árido. Dessa forma, buscou-se identificar grupos de municípios que apresentem similitude, e ainda estabelecer funções de tendência ao longo dos anos da disponibilidade de recursos através da cota-parte do ICMS.

Uma das principais preocupações da macroeconomia é a compreensão da dinâmica da inflação no curto prazo. Entender como a inflação se relaciona com a atividade econômica é decisivo para traçar estratégias de desinflação, assim como, de determinação da trajetória de política monetária. Uma questão que surge é qual a forma exata da relação inflação-produto. Ou seja, podemos caracterizar essa relação como não linear? Se sim, qual a forma dessa não linearidade? Para responder a essas perguntas, estimou-se a relação inflação-produto de forma não-paramétrica através de um local linear kernel estimator. O resultado da estimação gerou uma forma funcional a qual foi aproximada pela estimação, via GMM, de uma curva de Phillips Novo-Keynesiana Híbrida. Essa abordagem foi aplicada para o Brasil a partir de 2000. As estimações sugeriram que a dinâmica da inflação brasileira é melhor descrita quando adiciona-se um termo cúbico relativo ao hiato do produto, ou seja, a inflação brasileira mostrou-se state-dependent.
One of the most important macroeconomics’ concerns is the comprehension about sort-run inflation dynamic. To understand how inflation relates to economic activity is crucial to decision-making in disinflation strategies, as well as in monetary policy paths. A question that arises is what does real form of relation inflation-output trade-off? Could one characterize it as a non-linear relation? If does, what is the shape of this non-linear relation? To answer those questions, we estimate the inflation-output relation non-parametrically using a local linear kernel estimator. The functional form achieved was approximated by a New-Keynesian Hybrid Phillips Curve, which one was estimated by GMM. This approach was applied to Brazil since 2000. We have found evidence that Brazilian inflation dynamic is better described adding a cubic term related to output gap, in other words, the Brazilian inflation is state-dependent.

This thesis is concerned with the derivation of similarity solutions for one-dimensional coupled systems of reaction - diffusion equations, a semi-linear system and a one-dimensional tripled system. The first area of research in this thesis involves a coupled system of diffusion equations for the existence of two distinct families of diffusion paths. Constructing one-parameter transformation groups preserving the invariance of this system of equations enables similarity solutions for this coupled system to be derived via the classical and non-classical procedures. This system of equation is the uncoupled in the hope of recovering further similarity solutions for the system. Once again, one-parameter groups leaving the uncoupled system invariant are obtained, enabling similarity solutions for the system to be elicited. A one-dimensional pattern formation in a model of burning forms the next component of this thesis. The primary focus of this area is the determination of similarity solutions for this reaction - diffusion system by means of one-parameter transformation group methods. Consequently, similarity solutions which are a generalisation of the solutions of the one-dimensional steady equations derived by Forbes are deduced. Attention in this thesis is then directed toward a semi-linear coupled system representing a predator - prey relationship. Two approaches to solving this system are made using the classical procedure, leading to one-parameter transformation groups which are instrumental in elicting the general similarity solution for this system. A triple system of equations representing a one-dimensional case of diffusion in the presence of three diffusion paths constitutes the next theme of this thesis. In association with the classical and non-classical procedures, the derivation of one-parameter transformation groups leaving this system invariant enables similarity solutions for this system to be deduced. The final strand of this thesis involves a one- dimensional case of the general linear system of coupled diffusion equations with cross-effects for which one-parameter transformation group methods are once more employed. The one-parameter groups constructed for this system prove instrumental in enabling the attainment of similarity solutions for this system to be accomplished
Faculty of Business and Technology

Advanced materials such as carbon fiber, composite materials et al. are more and more used in modern industry. They make the structures lighter and stiffer. However, they bring vibration problems. Researchers studied numerous methods to eliminate the undesirable vibrations. These treatments are expected to be a compact, light, intellectual and modular system. Recently, a nonlinear technique which is known as Synchronized Switch Damping (SSD) technique was proposed. These techniques synchronously switched when structure got to its displacement extremes that leading to a nonlinear voltage on the piezoelectric elements. This resulting voltage showed a time lag with the piezoelectric strain thus causing energy dissipation. Based on the developed SSD techniques, a new synchronized switch damping e.g. Synchronized Switch Damping with Energy Transfer (SSDET) was proposed in this document. This method damped the vibration by using the energy from other vibrating form. The objectives of the work reported in this document were threefold. The first one consisted of introduction of SSDET principle and developing its control law. This part aimed at establishing the mathematical model and verifying the proposed method by mathematical tools. Then, the experimental validations were carried out. Three experiments with different configurations demonstrated that SSDET can be implemented not only between structures but also vibrating modes in one structure. A SSDET scheme with multi-patches was also investigated for improving the damping. Finally, a bidirectional SSDET concept was introduced based on the original SSDET technique. This technique be regarded as a multimode control SSDET. Since it privileged the target vibration while keeps a decent control effect on the source vibration.

Contrôler la lumière avec de la lumière au niveau du photon unique est un objectif fondamental dans le domaine de l'information quantique, ou de l'ordinateur optique à très basse puissance. Un émetteur quantique constitué d'un unique système à deux niveaux est un milieu très non-linéaire, pour lequel l'interaction avec un photon peut modifier la transmission d'un photon suivant. Dans ce scenario, le défi pour obtenir une telle non-linéarité géante est d'optimiser l'interaction lumière matière. Une solution à ce défi est d’insérer l'émetteur quantique dans une structure photonique. Ce système est appelé « atome uni-dimensionnel » : la collection de la lumière, tout comme la probabilité d'absorber un photon se propageant dans la structure est maximum.Dans ce travail, nous avons utilisé ce type de système pour réaliser une non-linéarité géante à deux modes, dans laquelle la réflexion d'un des modes est contrôlée par un autre mode au niveau du photon unique. Le système est constitué d'une boite quantique semi-conductrice InAs/GaAs, qui peut être considéré comme un atome artificiel, insérée dans un fil photonique en GaAs opérant comme un guide d'onde. Le fil photonique définit un mode spatial unique autour de l'émetteur et offre une interaction lumière-matière avec une efficacité quasi-idéale. De plus, ce fil photonique présente cette propriété sur une large bande spectrale. Grâce à ces deux propriétés, nous avons démontré expérimentalement une non-linéarité géante à un mode et à deux modes à un niveau de quelques dizaines de photons par durée de vie de l'émetteur. Cela permet de réaliser un interrupteur tout optique intégré, à très faible seuil
Controlling light by light at the single photon level is a fundamental quest in the field of quantum computing, quantum information science and classical ultra-low power optical computing. A quantum light emitter made of a single two-level system is a highly non-linear medium, where the interaction of one photon with the medium can modify the transmission of another incoming photon. In this scenario, the most challenging issue to obtain a giant optical non-linearity is to optimize photon-emitter interaction. This issue can be overcome by inserting the quantum emitter inside a photonic structure. This system is known as “one-dimensional atom”: the light collection efficiency as well as the probability for an emitter to absorb a photon fed into the structure is maximum. In this study, we aim at using such kind of system to experimentally realize a two-mode giant non-linearity, in which the reflection of one light mode is controlled by another light mode at the single-photon level. The system consists of a semiconductor InAs/GaAs quantum dot, which can be considered as an artificial atom, embedded inside a GaAs photonic wire, which is an optical waveguide. The photonic wire defines a single spatial mode around the emitter and offers a close to unity light-emitter interaction efficiency. In addition, the photonic wire also possesses a spectrally broadband operation range. Thanks to these two excellent features of the system, we experimentally demonstrate in this thesis a single-mode and a two-mode giant non-linearity obtained at the level of just a few tens of photons per emitter lifetime. This realizes an integrated ultra-low power all-optical switch

On étudie l'existence de 'blow-up' et l'ensemble des points de 'blow-up' pour une équation de type chaleur dégénérée ou non avec un terme source uniforme fonction non linéaire de la température instantanée en un point fixé du domaine. L'étude est conduite par les méthodes d'analyse classique (fonction de Green, développements en fonctions propres, principe du maximum) ou fonctionnelle (semi-groupes d'opérateurs linéaires).

Cette these est composee de dix articles que nous avons regroupes en deux parties. La premiere partie est constituee par l'etude et la classification des singularites isolees, premierement, d'une equation elliptique avec diffusion, deuxiemement, de l'equation parabolique correspondante. Dans la seconde partie sont etablis des resultats d'existence pour des problemes elliptiques semi-lineaires. Ces problemes sont caracterises respectivement, par une non-linearite singuliere, une condition de neumann degeneree, une non-linearite sous lineaire et, enfin, des exposants de sobolev critiques

La spectrométrie gamma est une technique de mesure nucléaire répandue qui peut être utilisée pour détecter une source radioactive, identifier sa composition et quantifier son activité.Un spectre constitue un résultat de mesure brut qui n’est pas interprétable directement. L’analyse du spectre permet d’en extraire l’information utile.Pour répondre à la croissance du besoin de mesures, nous proposons dans ce mémoire une méthode automatique d’analyse des spectres, appelée Model based Full Spectrum Analysis (MFSA), qui permet d’unifier la résolution des différents problèmes d’analyse de spectre. La MFSA explique la mesure par reconstruction complète du signal en s’appuyant sur un modèle paramétrique pour le mélange de pics contenus dans le spectre.La présence d'un continuum non caractérisé dans le spectre est la principale difficulté de l'analyse. Si la MFSA met en exergue cette problématique, elle ne la résout pas seule.La solution complémentaire retenue dans ce mémoire repose sur la formulation du problème du continuum inconnu comme un problème de perception artificielle (comment percevoir un objet dans son environnement ?). Le critère dérivé de cette interrogation est finalement la proposition centrale de ce mémoire, pour laquelle la spectrométrie gamma apparaît comme un cas d'usage.Enfin, nous appliquons notre méthode sur des données simulées et sur des données réelles afin de valider les solutions proposées
Gamma-ray spectrometry is a widespread nuclear measurement technique that can be used to detect a radioactive source, identify its composition and quantify its activity.A spectrum is a raw measurement result that is not directly interpretable. Analysis of the spectrum allows useful information to be extracted.To meet the growing need for measurements, we propose in this thesis an automatic method of spectrum analysis, called Model based Full Spectrum Analysis (MFSA), which unifies the resolution of different spectrum analysis problems. MFSA explains the measurement by full signal reconstruction based on a parametric model for the mixture of peaks in the spectrum.The presence of an uncharacterised continuum in the spectrum is the main difficulty of the analysis. While MFSA highlights this problem, it does not solve it alone.The complementary solution adopted in this thesis is based on the formulation of the unknown continuum problem as a problem of artificial perception (how to perceive an object in its environment?). The criterion derived from this question is finally the central proposal of this thesis, for which gamma spectrometry appears as a use case.Finally, we apply our method on simulated and real data in order to validate the proposed solutions