Submitted by Aline Amarante (1146629@mackenzie.br) on 2017-07-20T15:06:23Z No. of bitstreams: 2 PETER VAZ DA FONSECA.pdf: 1498175 bytes, checksum: e3e91e821efd763f7a19620494a46809 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Eliana Barboza (eliana.silva1@mackenzie.br) on 2017-08-01T18:50:55Z (GMT) No. of bitstreams: 2 PETER VAZ DA FONSECA.pdf: 1498175 bytes, checksum: e3e91e821efd763f7a19620494a46809 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-08-01T18:50:55Z (GMT). No. of bitstreams: 2 PETER VAZ DA FONSECA.pdf: 1498175 bytes, checksum: e3e91e821efd763f7a19620494a46809 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-02-13 / In finance studies taxation is recognized as having influence on corporate financing decisions. According to the trade-off theory, the company, encouraged by the debt tax shield, recourse to third-party capital up to the level where the costs, associated with the bankruptcy risks outcome that advantage. Thus, this study aims to check the existence of a positive effect of the tax shields on the indebtedness of 259 public Brazilian non-financial companies, during the period between 2008 and 2015. Considered as proxies of tax benefit are the variables marginal tax rate (MTR), kink, standardized kink and tax payment. To verify the existence of the mentioned effect, regression models are used with data in static and dynamic panels. As a result, the variables kink and standardized kink confirm the hypothesis of this research for both regression models. It means that tax benefit effectively influences the level of corporate indebtedness. As for the dynamic panel, another feature to be highlighted refers to the fact that - for all independent tax variables – there is a reversal of signals between the level variables and their lagged variables, in relation to the specific models of each one. This suggests that there is a short-term adequacy dynamic – 1 year – in relation to the capital structure of companies. On the control variables, dynamic panel shows more adherence to finance theories, presenting statistical significance for the variables intangible assets, profitability, size, business risk, growth and age. Finally, another contribution of this work is the understanding of the conservative use of debts by Brazilian companies, for capturing the benefits of tax deduction. Further studies may verify what reasons else direct financial leverage, as well as the economic feasibility of investment decisions. / É reconhecido nos estudos de finanças, que a tributação possui influência nas decisões corporativas de financiamento. Segundo a teoria de trade-off, incentivada pelo benefício fiscal do endividamento, a empresa recorre a capitais de terceiros, até o nível em que os custos associados aos riscos de falência superem essa vantagem. Assim, o presente trabalho tem como objetivo verificar a existência de um efeito positivo do benefício fiscal no endividamento de 259 empresas brasileiras não financeiras de capital aberto, durante o período de 2008 a 2015. São consideradas como proxies do benefício tributário, as seguintes variáveis: alíquota de imposto marginal, kink, kink padronizada e pagamento do imposto. Para verificar a existência do efeito mencionado, utilizam-se modelos de regressão com dados em painel – estático e dinâmico. Como resultado, as variáveis kink e kink padronizada comprovam a hipótese dessa pesquisa, para ambos os modelos de regressão. O que significa dizer que o benefício tributário efetivamente influencia o nível de endividamento das empresas. No caso do painel dinâmico, outro aspecto a ser destacado refere-se ao fato de que – para todas as variáveis fiscais independentes – há uma inversão de sinais entre as variáveis em nível e suas defasadas, com relação aos modelos específicos de cada uma delas. Isso sugere existir uma dinâmica de adequação de curto prazo em relação à sua estrutura de capital. Sobre as variáveis de controle, o painel dinâmico mostra-se mais aderente às teorias de finanças, apresentando significância estatística para as variáveis ativos intangíveis, lucratividade, tamanho, risco do negócio, crescimento e idade. Por fim, outra contribuição dessa pesquisa consiste na compreensão do uso conservador das dívidas, pelas empresas brasileiras, para fins de captura dos benefícios da dedução tributária. Estudos posteriores podem verificar quais outros motivos direcionam a alavancagem financeira, além da viabilidade econômica das decisões de investimento.

The natural dynamics are not ideal or linear. To understand their complex behavior, we needs to study the nonlinear dynamics in more simple models. This thesis is consist of two main setups. Both setups are simplified models for the behavior occurs in the complex systems. We studied in both systems the same nonlinear dynamics such as higher-harmonics, sub-harmonics, solitary waves,...etc. In Chapter (2), the propagation of nonlinear waves in a lattice of repelling particles is studied theoretically and experimentally. A simple experimental setup is proposed, consisting in an array of coupled magnetic dipoles. By driving harmonically the lattice at one boundary, we excite propagating waves and demonstrate different regimes of mode conversion into higher harmonics, strongly in influenced by dispersion. The phenomenon of acoustic dilatation of the chain is also predicted and discussed. The results are compared with the theoretical predictions of FPU equation, describing a chain of masses connected by nonlinear quadratic springs. The results can be extrapolated to other systems described by this equation. We studied theoretically and experimentally the generation and propagation of kinks in the system. We excite pulses at one boundary of the system and demonstrate the existence of kinks, whose properties are in very good agreement with the theoretical predictions, that is the equation that approaches, under the conditions of our experiments, the one corresponding to full model describing a chain of masses connected by magnetic forces. The results can be extrapolated to other systems described by this equation. Also, In the case of a lattice of finite length, where standing waves are formed, we report the observation of subharmonics of the driving wave. In chapter (3), we studied the propagation of intense acoustic waves in a multilayer crystal. The medium consists in a structured fluid, formed by a periodic array of fluid layerswith alternating linear acoustic properties and quadratic nonlinearity coefficient. We presents the results for different mathematicalmodels (NonlinearWave Equation,Westervelt Equation and Constitutive equations). We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g. cubic) nonlinearities, or extremely linear media. In chapter (4), the oscillatory behavior of a microbubble is investigated through an acousto-mechanical analogy based on a ring-shaped chain of coupled pendula. Observation of parametric vibration modes of the pendula ring excited at frequencies between 1 and 5 Hz is considered. Simulations have been carried out and show spatial mode, mixing and localization phenomena. The relevance of the analogy between a microbubble and the macroscopic acousto-mechanical setup is discussed and suggested as an alternative way to investigate the complexity of microbubble dynamics. / La dinámica natural no es ideal ni lineal. Para entender su comportamiento complejo, necesitamos estudiar la dinámica no lineal en modelos más simples. Esta tesis consta de dos configuraciones principales. Ambas configuraciones son modelos simplificados de el comportamiento que se produce en los sistemas complejos. Estudiamos en ambos sistemas la misma dinámica no lineal como son la generación de armónicos superiores, los sub-armónicos, las ondas solitarias, etc. En elCapítulo (2), se estudia, tanto teórica comoexperimentalmente, la propagación de ondas no lineales en sistemas periodicos de partículas acopladas mediante fuerzas repulsivas. Se propone una configuración experimental simple, que consiste en una matriz de dipolos magnéticos acoplados. Inyectando armónicamente la señal en un extremo, excitamos ondas de propagación y demostramos diferentes regímenes de conversión de modos en armónicos, fuertemente influenciados por la dispersión. También se predice y se discute el fenómeno de dilatación acústica de la cadena. Los resultados se comparan con las predicciones teóricas de la ecuación FPU, describiendo una cadena de masas conectadas por muelles cuadráticos no lineales. Los resultados pueden ser extrapolados a otros sistemas descritos por esta ecuación. Estudiamos también teórica y experimentalmente la generación y propagación de kinks. Excitamos pulsos en la frontera del sistema y demostramos la existencia de kinks cuyas propiedades están en muy buen acuerdo con las predicciones teóricas, es decir, con la ecuación que aproxima bajo las condiciones de nuestros experimentos la correspondiente al modelo completo que describe un cadena de masas conectadas por fuerzas magnéticas. Los resultados pueden ser extrapolados a otros sistemas descritos por esta ecuación. Además, en el caso de una red finita, donde se forman ondas estacionarias, describimos la observación de subarmónicos del armónico principal. En el capítulo (3), estudiamos la propagación de ondas acústicas intensas en un cristal multicapa. El medio consiste en un fluido estructurado, formado por un conjunto periódico de capas fluidas con propiedades acústicas lineales alternas y coeficiente de no linealidad cuadrática. Presentamos los resultados de diferentes modelos matemáticos (ecuación de ondas no lineal, ecuación de Westervelt y ecuaciones constitutivas). Mostramos que la interacción entre la fuerte dispersión y la no linealidad conduce a nuevos escenarios de propagaciónde ondas. El proceso de distorsión de la onda clásica, típico de las ondas acústicas intensas en medios homogéneos, puede ser alterado de forma importante cuando los armónicos generados no linealmente se encuentran dentro o cerca del gap. Esto permite la posibilidad de diseñar un medio con el fin de obtener una forma de onda en particular. Ejemplos de esto incluyen el diseño demedios con no linealidad efectiva (por ejemplo, cúbica) o medios extremadamente lineales. En el capítulo (4), el comportamiento oscilatorio de una microburbuja se investiga a través de una analogía acusto-mecánica basada en una cadena en forma de anillo de péndulos acoplados. Se estudian los modos de vibración paramétrica del anillo pendular excitado a frecuencias entre 1 y 5 Hz. Se han llevado a cabo simulaciones que muestran la presencia de modos espaciales, mixtos y fenómenos de localización. Se discute la relevancia de la analogía entre una microburbuja y la configuración macroscópica acústico-mecánica y se sugiere como una vía alternativa para investigar la complejidad de la dinàmica de microburbujas. / La dinàmica natural no és ideal ni tampoc lineal. Per entendre el seu comportament complex, es necessita estudiar la dinàmica no lineal dels models més simples. Aquesta tesi consisteix en l'estudi de dues configuracions principals, que són models simplificats del comportament que es produeix en els sistemes complexos. Estudiem en ambdós sistemes la mateixa dinàmica no lineal, com és la generació d'harmònics superiors, sub-harmònics, ones solitàries, etc. En el capítol (2), estudiem, tant teòrica com experimentalment, la propagació de les ones no lineals en sistemes periòdics de partícules acoblades mitjançant forces repulsives. Es proposa una configuració experimental simple, que consisteixen en una matriu de dipols magnètics acoblats. En conduint harmònicament la xarxa en un límit, excitemla propagació de les ones i demostrem diferents règims de conversió de modes en harmònics més alts, força influenciada per la dispersió. El fenomen de la dilatació acústica de la cadena també es prediu i es discuteix. Els resultats es comparen amb les prediccions teòriques que descriu una cadena de masses conectades per molls quadràtics no lineals. Els resultats es poden extrapolar a altres sistemes descrits per aquesta equació. Hem estudiat teòrica i experimentalment la generació i propagació de Kinks. Excitem polsos a la frontera del sistema i demostrem l'existència d'Kinks, les propietats desl quals estan en molt bon acord amb les prediccions teòriques, és a dir, de l'equació que aproxima sota les condicions dels nostres experiments la corresponent al model complet que descriu un cadena demasses connectades per forcesmagnètiques. Els resultats es poden extrapolar a altres sistemes descrits per aquesta equació. A més, en el cas d'una xarxa finita, on es formen ones estacionàries, descrivim l'observació de subarmónicos de l'harmònic principal. En el capítol (3), s'estudia la propagació d'ones acústiques intenses en un medi multicapa. El medi consisteix en un fluid estructurat, format per una matriu periòdica de capes de fluid amb l'alternança de propietats acústiques lineals i coeficient de no linealitat de segon grau. Es presenten els resultats per a diferents models matemàtics no lineals (equació d'ones no lineal, equació de Westervelt i les equacions constitutives). Es demostra que la interacciò entre la forta dispersió i no linealitat condueix a nous escenaris de propagació de l'ona. El procés de distorsió en formad'ona clàssica, típica de les ones acústiques intenses en medis homogenis, es pot alterar de manera significativa quan els harmònics generats de forma no lineal es troben dins o a prop del gap. Això obri la possibilitat de dissenyar unmedi per tal d'obtenir una forma d'ona particular. Exemples d'això inclouen el disseny delsmedis amb una no linealitat efectiva (per exemple cúbica), o medis extremadament lineals. En el capítol (4), el comportament oscilatori d'una micro-bombolla és investigat a través d' una analogia acústica-mecànica basada en una cadena en forma d'anell de pèndols acoblats. Es considera l'observació dels modes de vibració paramètriques de l'anell pendular excitat amb freqüències entre 1 i 5 Hz. S'han dut a terme simulacions que mostren la presència de moes espacilas, mixtes i fenòmens de localització. Es discuteix la relevància de l'analogia entre les microbambolles i la configuració macroscòpica acústica-mecànica i es suggereix una formaalternativa per a investigar la complexitat de la dinàmica demicrobombolles. / Mehrem Issa Mohamed Mehrem, A. (2017). Nonlinear acoustics in periodic media: from fundamental effects to applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80289 / TESIS

Isogeometric analysis is aimed to mitigate the gap between Computer-Aided Design (CAD) and analysis by using a unified geometric representation. Thanks to the exact geometry representation and high smoothness of adopted basis functions, isogeometric analysis demonstrated excellent mathematical properties and successfully addressed a variety of problems. In particular, it allows to solve higher order Partial Differential Equations (PDEs) directly omitting the usage of mixed approaches. Unfortunately, complex CAD geometries are often constituted by multiple Non-Uniform Rational B-Splines (NURBS) patches and cannot be directly applied for finite element analysis.parIn this work, we presents a dual mortaring framework to couple adjacent patches for higher order PDEs. The development of this formulation is initiated over the simplest 4th order problem-biharmonic problem. In order to speed up the construction and preserve the sparsity of the coupled problem, we derive a dual mortar compatible C1 constraint and utilize the Bezier dual basis to discretize the Lagrange multipler spaces. We prove that this approach leads to a well-posed discrete problem and specify requirements to achieve optimal convergence. After identifying the cause of sub-optimality of Bezier dual basis, we develop an enrichment procedure to endow Bezier dual basis with adequate polynomial reproduction ability. The enrichment process is quadrature-free and independent of the mesh size. Hence, there is no need to take care of the conditioning. In addition, the built-in vertex modification yields compatible basis functions for multi-patch coupling.To extend the dual mortar approach to couple Kirchhoff-Love shell, we develop a dual mortar compatible constraint for Kirchhoff-Love shell based on the Rodrigues' rotation formula. This constraint provides a unified formulation for both smooth couplings and kinks. The enriched Bezier dual basis preserves the sparsity of the coupled Kirchhoff-Love shell formulation and yields accurate results for several benchmark problems.Like the dual mortaring formulation, locking problem can also be derived from the mixed formulation. Hence, we explore the potential of Bezier dual basis in alleviating transverse shear locking in Timoshenko beams and volumetric locking in nearly compressible linear elasticity. Interpreting the well-known B projection in two different ways we develop two formulations for locking problems in beams and nearly incompressible elastic solids. One formulation leads to a sparse symmetric symmetric system and the other leads to a sparse non-symmetric system.

<p>Active Galactic Nuclei (AGNs) are accreting supermassive black holes at the center of galaxies, known for rich spectral features and multi-time scale variability in their electromagnetic emission. The origin of the variability in AGN light curves can be either intrinsic, meaning related processes that take place inside the AGN system, or extrinsic, i.e., from the propagation of light towards Earth. In this dissertation, I present my work focusing on AGN variability. The first two works focus on the variability of blazars, a subclass of AGN with their relativistic jets beaming towards the observer. The first work combines 3D relativistic magnetohydrodynamics (RMHD) simulations with radiation transfer and shows the kink instability within the blazar jet can cause quasi-periodic radiation signatures within a typical period of time scales from weeks to months. The second work combines 2D Particle-in-Cell (PIC) simulations with radiation transfer and shows that isolated and merging plasmoids due to magnetic reconnection in a blazar environment could produce rich radiation and polarization signatures. The last work explores an extrinsic origin for AGN variability: a scenario in which interstellar medium (ISM) within our galaxy can refract light coming from AGNs. It suggests that plasma structures in ISM with an axisymmetric geometry can account for extreme scattering events (ESEs) in AGN observations. Future research directions include studies of the kink instability in jets that propagate in different environments and simulations of magnetic reconnection in 3D which may reveal additional particle acceleration mechanisms, which may play important role in the resulting radiation and polarization signatures. </p>

In nature, rock masses are not static, but constantly changing with erosion, metamorphosis, tectonics and more. Rocks that bend and buckle can be seen almost as nature's origami, being folded into new shapes and structures. During shortening of a sequence of sedimentary layers, they fold and/or thrust to accommodate the convergence. Folds initiate as kinks which may evolve into thrusts. These folds and thrusts form a wedge which grows in height and length with continued convergence. This study examines the sequence of formation of kinking in fold and thrust belts, specifically the development of forekinks from thrusting and the evolution of the wedge. This was done through geometric analysis of images taken of an analogue sandbox model, run in 2011, which consisted of horizontal layers shortened from one end to 25% bulk convergence above a rigid basement. In nature, such wedges are found as accretionary prisms in convergence zones and as fold and thrust belts on either side of an orogen. By simulating the creation of these wedges and kinks with controlled parameters, it is possible to gain an understanding of the mechanical processes involved in their creation, which allows for a better understanding of these processes in nature. This study is mainly based on measurements of separation created by kinking, dip of the kinks at different levels, and the dimensions of the wedge, in addition to other geometric features. The results showed clear trends for the evolution of these geometric features with progressive model shortening. Results show that, forekinks become inactive when a new kink develops in its foreland. The amount of separation within a kink is dependent on how soon a new kink is developed in front of it and the throw (vertical component) is generally larger than the heave (horizontal component). Dip of a forekink steepens as the forekink cumulatively rotates backwards by the creation of new forekinks in front of it. Evolution of the forekinks has a direct impact on wedge development. Wedge length is larger than height and as the shortened layers are compacted, the dimensions of the wedge increase at different rates. Generally the results of this study are in agreement with previous research conducted within the subject. If rock folding is nature’s origami, then the study of these processes can allow us to understand how fold and thrust belts develop, just as studying how a piece of paper folds, can show us how a napkin can transform into a swan. / I naturen är bergmassor inte statiska utan förändras ständigt av erosion, metamorfos, tektonik med mera. Berg som böjs och bänds kan nästan ses som naturens origami; veckandes till nya former och strukturer. Under förkortning av en sekvens sedimentära lager viker de sig och/eller förkastas för att tillgodose konvergensen. Ett veck i ett lager kan så småningom utvecklas till en förkastning. Dessa veck och förkastningar bildar en kil som växer både på höjden och längden med fortsatt konvergens. Denna studie undersöker veckbildning i bergskedjor, specifikt utvecklingen av framåtvända veck och kilens utveckling. Detta gjordes genom geometrisk analys av bilder tagna av ett försök utfört i en analog Sandbox-modell (gjort 2011) som bestod av horisontella lager förkortade från ena änden till 25% bulk-förkortning ovanför en fast bas. Kilar såsom de som ses i modellen hittas i naturen som accretionära prismor i konvergenszoner och på vardera sida om bergskedjor. Genom att simulera skapandet av dessa kilar och veck i en kontrollerad miljö är det möjligt att skapa sig en förståelse för de mekaniska processer som är involverade i dess skapande, vilket möjliggör en bättre förståelse av dessa processer i naturen. Denna studie är huvudsakligen baserad på mätning av separation skapad av veckning, veckens stupning vid olika djup och kilens dimensioner, tillsammans med andra geometriska egenskaper. Resultaten visade tydliga trender för utvecklingen av dessa geometriska egenskaper i samband med att modellen förkortades. Resultaten visar att framåtvända veck blir inaktiva när ett nytt veck utvecklas framför den. Mängden separation inom ett veck beror på hur snart det nya vecket utvecklas framför den och kast (vertikal komponent) är i allmänhet större än hiv (horisontell komponent). Stupning av ett veck blir brantare när vecket kumulativt roterar bakåt genom att det skapas nya veck framför den. Utvecklingen av vecken har en direkt inverkan på kilens utveckling. Kilen är längre än den är hög och då de förkortade lagren komprimeras växer kilens dimensioner i olika takt. Överlag överensstämmer resultaten av denna studie med tidigare forskning inom ämnet. Om veckandet av bergmassor är naturens origami, kan studerandet av dessa processer möjliggöra för oss att förstå hur bergskedjor utvecklas, precis som att studerandet av hur ett papper viker sig, kan visa oss hur en servett kan förvandlas till en svan.

As Si-manufacturing compatible SiGe HBTs are making rapid in-roads into RF through mm-wave circuit applications, with performance levels steadily marching upward, the use of these devices under extreme environment conditions are being studied extensively. In this work, test structures of SiGe HBTs were designed and put into extremely low temperatures, and a new negative differential resistance effect and a novel collector current kink effect are investigated in the cryogenically-operated SiGe HBTs. Theory based on an enhanced positive feedback mechanism associated with heterojunction barrier effect at deep cryogenic temperatures is proposed. The accumulated charge induced by the barrier effect acts at low temperatures to enhance the total collector current, indirectly producing both phenomena. This theory is confirmed using calibrated 2-D DESSIS simulations over temperature. These unique cryogenic effects also have significant impact on the ac performance of SiGe HBTs operating at high-injection. Technology evolution plays an important role in determining the magnitude of the observed phenomena, and the scaling implications are addressed. Circuit implication is discussed.

abstract: Polymer matrix composites (PMCs) are attractive structural materials due to their high stiffness to low weight ratio. However, unidirectional PMCs have low shear strength and failure can occur along kink bands that develop on compression due to plastic microbuckling that carry strains large enough to induce nonlinear matrix deformation. Reviewing the literature, a large fraction of the existing work is for uniaxial compression, and the effects of stress gradients, such as those present during bending, have not been as well explored, and these effects are bound to make difference in terms of kink band nucleation and growth. Furthermore, reports on experimental measurements of strain fields leading to and developing inside these bands in the presence of stress gradients are also scarce and need to be addressed to gain a full understanding of their behavior when UDCs are used under bending and other spatially complex stress states. In a light to bridge the aforementioned gaps, the primary focus of this work is to understand mechanisms for kink band evolution under an influence of stress-gradients induced during bending. Digital image correlation (DIC) is used to measure strains inside and around the kink bands during 3-point bending of samples with 0°/90° stacking made of Ultra-High Molecular Weight Polyethylene Fibers. Measurements indicate bands nucleate at the compression side and propagate into the sample carrying a mixture of large shear and normal strains (~33%), while also decreasing its bending stiffness. Failure was produced by a combination of plastic microbuckling and axial splitting. The microstructure of the kink bands was studied and used in a microstructurally explicit finite element model (FEM) to analyze stresses and strains at ply level in the samples during kink band evolution, using cohesive zone elements to represent the interfaces between plies. Cohesive element properties were deduced by a combination of delamination, fracture and three-point bending tests used to calibrate the FEMs. Modeling results show that the band morphology is sensitive to the shear and opening properties of the interfaces between the plies. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2016

No description available.

In this thesis, I examine whether unconditional cash transfers to poor femaleheaded households have an effect on children’s educational attainment. Using a historical Swedish child allowance policy that targeted unconditional cash transfers to widow mothers with an income below a poverty threshold, I lay out a credible identification strategy, to test the hypothesis with a regression kink design. The results, although statistically underpowered and thus to be taken with a pinch of salt, point towards that cash transfers at the extensive margin increased the probability of continuing school another year to eighth grade. While this tendency can not alone be interpreted causally, the method developed can be extended in future work. With the collection and matching of two uniquely rich micro datasets tracking individuals over their life trajectory, combined with this natural experiment setting, my study contributes to building the path to understanding the link between cash transfers and human capital development in childhood. Ultimately, it could add to the policy guidance literature.

No description available.