Inversão de dados de ondas de superfície Rayleigh

Neste trabalho compilamos informações sobre um grande número de medidas de velocidade de grupo para ondas Rayleigh do modo fundamental, com período até 100 segundos. Tais dados consistiram de informações retiradas da literatura geofísica e cobriram toda a Terra. Parte dos dados foi organizada em trabalhos anteriores e uma segunda parte foi apresentada aqui de forma inédita. Para a América do Sul, selecionamos os principais conjuntos de dados de tais ondas e elaboramos diversos perfis onde a distribuição de velocidade de ondas cisalhantes foi obtida a partir da inversão das curvas de dispersão de velocidade de grupo. Tais perfis serviram para termos uma ideia inicial da estrutura interna da Terra em nosso continente. Com o conjunto global de dados de velocidade de grupo foi possível obtermos os mapas de distribuição lateral de valores de velocidade para cada período referencial entre 20 e 100 segundos. Tais mapas foram produzidos da mesma forma que os mapas de velocidade de fase de ROSA (1986), onde a amostragem for para realizada para blocas medindo 10x10 graus, englobando toda a Terra, em projeção mercator. O valor de velocidade de grupo em cada bloco, para cada período, foi obtido a partir da inversão estocástica dos dados de anomalia de velocidade em relação aos modelos regionalizados de JORDAN (1981) com os valores de velocidade de grupo de ROSA et al. (1992). Os mapas de velocidade de grupo obtidos aqui foram então empregados, na América do Sul, com os valores de velocidade de fase dos mapas obtidos por ROSA (1986). Assim, foi possível determinarmos, em profundidade, os mapas de variação de velocidade de onda cisalhante e os mapas de distribuição de valores de densidade. Com isto, pudemos construir o primeiro mapa de profundidade do Moho (todo do Manto Superior) da América do Sul.

Interpretação quantitativa de anomalias gravimétricas ar-livre da margem continental norte brasileira, setor nordeste

Anomalias gravimétricas ar-livre de perfis perpendiculares a margem continental do tipo passiva apresentam uma configuração padrão. Esta configuração é, satisfatoriamente, explicada por um modelo geofísico formado por uma distribuição de descontinuidades horizontais bidimensionais. Um processo automático de busca aleatória é proposto para a interpretação quantitativa dos dados. Através do método de poliedros flexíves (Simplex), os parâmetros principais do modelo - o contraste de densidade, a profundidade, o rejeito e a localização de cada descontinuidade, puderam ser encontrados, admitindo uma relação número de pontos/número de parâmetros, a determinar, conveniente. Sobre a região do talude, as anomalias ar-livre da margem continental podem ser explicadas por uma única descontinuidade horizontal (degrau simples); e tendo que a resposta dos dados gravimétricos no domínio do número de onda contém informações sobre esta anomalia, foi proposto um procedimento gráfico iterativo para a análise espectral deste sinal. Aplicando a transformada de Fourier é possível determinar a profundidade e o rejeito da descontinuidade, e conhecendo estes parâmetros a densidade é calculada unicamente. O objetivo básico do uso destes procedimentos seria combinar os dois métodos de interpretação nos domínios do espaço e do número de onda, com a finalidade de obter soluções vinculadas mais plausíveis quanto ao contexto geológico esperado para a área estudada. Os dois procedimentos de interpretação foram aplicados nas anomalias gravimétricas ar-livre da margem continental norte brasileira, setor nordeste, abrangendo os estados do Maranhão ao Rio Grande do Norte. As respectivas capacidade de resolução de cada procedimento foram então analisadas. Demonstrou-se que a inversão realizada diretamente no domínio do espaço é mais favorável na interpretação das anomalias ar-livre, embora o tratamento espectral seja relativamente mais simples.

Comportamento de fratura sob carga estática e cíclica das cerâmicas odontológicas quando unidas a um substrato análogo à dentina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Eros e Tanatos no discurso labiríntico de Valêncio Xavier

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação macroscópica e microscópica de implante de Biomembrana em estômago de coelhos (Oryctolagus cuniculus)

In this study, biomembrane of natural latex was utilized to replace a section of the stomach wall of New Zealand rabbits, adult and non-castrated males (n=12), in order to evaluate the tissue repair process in regards to its biocompatility, scar formation ability and possible complications. The animals were euthanized at fifteen, 30 and 60 days post operation, by use of sodium thiopental (200mg kg-1), followed by macroscopic and histopathological analysis of the implant interface with the native tissue. Macroscopically, at fifteen, 30, and 60 days post operation adherence was observed in the serosal wall. At 60 days post operation, the biomembrane is not in the stomach. Under light microscopy, at fifteen and 30 days, discontinuity of muscle layer and mucosa layer, and presence of polimorfonuclear population of inflammatory cells was observed. New vessels and muscle fibers were observed. At 60 days, the mucosa and muscle layers were complete reconstituted. The implants were biocompatible and had provided the mainframe for orientation and development of the tissue layers through repairing processes, thus reestablishing the organ structure.

Efeitos de descontinuidades na propagação de ondas em estruturas unidimensionais

Pós-graduação em Engenharia Mecânica - FEIS

A racionalização das tradições na modernidade: o diálogo entre Anthony Giddens e Jürgen Habermas

Based on the reflections of Habermas and his conception of modernity, understood as an unfinished project, Giddens stresses that in all societies the maintenance of personal identity and its connection to broader social identities is a primordial requirement for ontological security. To achieve ontological security, modernity had to (re) invent traditions and get away from genuine traditions, that is, those values radically linked to the pre-modern past. This is a character of the discontinuity of modernity, the separation between what is presented as the new and that which persists as the legacy of the old. This article discusses the relationship between tradition and modernity and the dialogue between Giddens and Habermas. The goal is to identify the points of contact and the differences in the theses defended by both authors, in order to assess their contributions to discussions of the rationalization of contemporary societies. Late or reflexive modernity is an uninterrupted process of changes that affect the foundations of Western society. Faced with a reality of constant change, it is necessary to choose between the certainty of the past and a new reality of continuous change. In this sense, and according to the Habermasian perspective, the reflexive character of modernity is found in this process of choosing between the certainties inherited from the past and new social forms, a process that that leads to the reflection on - or even the recasting of - social practices, causing the rationalization and (re) invention of various aspects of life in society.

From west to east: Environmental influences on the rate and pathways of Polynesian colonization

The prime movers behind the prehistoric colonization of Remote Oceania, and in particular the large c. 2000-year temporal gap (i.e. long pause') seen between West and East Polynesia, has long been major point of interest in the Pacific. To address these events and the processes that may have led to the known chronological disparity of these diasporas, we present results from two different, but equally powerful, analytical tools which are used to examine Polynesian seafaring capabilities and trajectories. The first is a statistical model known as Seascape, which simulates voyages, while the second uses ease of eastward travel estimates based on land distribution and wind pattern analysis. These analyses were done with the goal of determining the potential role of environmental factors in the colonization process, particularly as they relate to the long pause. We show that the eastern boundary of West Polynesia, the limit of the initial colonization pulse, is marked by a discontinuity in land distribution, where the distances travelers would have to cross in order to reach islands further to the east become significantly larger. At the same time, in West Polynesia, the frequency and intensity of winds favorable to eastward displacement decrease continuously from west to east. As far as winds are concerned, eastward travel in West Polynesia is favored in the northern and southern areas and much more difficult across the central portion. Favorable winds have a clear seasonality, and eastward displacement along the northern area is much easier under El Nino conditions. Voyaging simulations show that intentional eastward voyages departing from Tonga and Samoa, when undertaken with vessels capable of sailing efficiently against the wind, afford a viable route toward several island groups in East Polynesia, with trips starting in Samoa having a higher probability of success.

Limit Cycles for a Class of Continuous and Discontinuous Cubic Polynomial Differential Systems

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A local-global scheme for tracking crack path in three-dimensional solids

This paper aims to contribute to the three-dimensional generalization of numerical prediction of crack propagation through the formulation of finite elements with embedded discontinuities. The analysis of crack propagation in two-dimensional problems yields lines of discontinuity that can be tracked in a relatively simple way through the sequential construction of straight line segments oriented according to the direction of failure within each finite element in the solid. In three-dimensional analysis, the construction of the discontinuity path is more complex because it requires the creation of plane surfaces within each element, which must be continuous between the elements. In the method proposed by Chaves (2003) the crack is determined by solving a problem analogous to the heat conduction problem, established from local failure orientations, based on the stress state of the mechanical problem. To minimize the computational effort, in this paper a new strategy is proposed whereby the analysis for tracking the discontinuity path is restricted to the domain formed by some elements near the crack surface that develops along the loading process. The proposed methodology is validated by performing three-dimensional analyses of basic problems of experimental fractures and comparing their results with those reported in the literature.

Os sentidos da casa própria: condomínios horizontais populares fechados e novas práticas espaciais em Presidente Prudente e São Carlos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Classificação de centros e estudo de ciclos limite para sistemas lineares por partes em duas zonas no plano

Pós-graduação em Matemática - IBILCE

Modeling of multiple cracks in reinforced concrete members using solid finite elements with high aspect ratio

This paper presents a new technique to model interfaces by means of degenerated solid finite elements, i.e., elements with a very high aspect ratio, with the smallest dimension corresponding to the thickness of the interfaces. It is shown that, as the aspect ratio increases, the element strains also increase, approaching the kinematics of the strong discontinuity. A tensile damage constitutive relation between strains and stresses is proposed to describe the nonlinear behavior of the interfaces associated with crack opening. To represent crack propagation, couples of triangular interface elements are introduced in between all regular (bulk) elements of the original mesh. With this technique the analyses can be performed integrally in the context of the continuum mechanics and complex crack patterns involving multiple cracks can be simulated without the need of tracking algorithms. Numerical tests are performed to show the applicability of the proposed technique, studding also aspects related to mesh objectivity.

Systemic risk in dynamical networks with stochastic failure criterion

Complex non-linear interactions between banks and assets we model by two time-dependent Erdos-Renyi network models where each node, representing a bank, can invest either to a single asset (model I) or multiple assets (model II). We use a dynamical network approach to evaluate the collective financial failure -systemic risk- quantified by the fraction of active nodes. The systemic risk can be calculated over any future time period, divided into sub-periods, where within each sub-period banks may contiguously fail due to links to either i) assets or ii) other banks, controlled by two parameters, probability of internal failure p and threshold T-h ("solvency" parameter). The systemic risk decreases with the average network degree faster when all assets are equally distributed across banks than if assets are randomly distributed. The more inactive banks each bank can sustain (smaller T-h), the smaller the systemic risk -for some Th values in I we report a discontinuity in systemic risk. When contiguous spreading becomes stochastic ii) controlled by probability p(2) -a condition for the bank to be solvent (active) is stochasticthe- systemic risk decreases with decreasing p(2). We analyse the asset allocation for the U.S. banks. Copyright (C) EPLA, 2014

Litofácies e relações estratigráficas da formação Aquidauana no nordeste da Bacia do Paraná - São Sebastião do Paraíso (MG)

The Aquidauana Formation is characterized by sandstones of variable granulation, mudstones and diamectites abundant in clay, typical colors like brick red (vermelho tijolo) of glacial, fluvial and lacustrine origin. It’s chronostratigraphic equivalent to the Itarará group from the Neo Carboniferous age, that under the exploratory view, such units represent important intervals in the basin, occurring together with them minerals as well as energy resources as petroleum, underground water and coal – what requires a great paleogeography and stratigraphy knowledge for its exploration. By gathering information from the columnar sections of the area, it was possible to characterize the sedimentary facies, the stacking pattern as well as the association. It was also made an attempt of stratigraphic correlation, which showed great difficulties since glacial environments present a great lateral discontinuity of the facies besides the complex relationship process of formation. As a result, it was obtained 8 sedimentary facies, the lateral and vertical relations and genesis process. It is proposed that the sedimentary environment in the study area is the fluvio glacial, characterized by alluvial systems formed by defrosted water which transport the sediments that are deposited in plains in front of the glacier (distal outwash). Petrographic thin section analysis showed that the transportation process was ineffective. The grains present punctual to lobular contacts, characterizing good porosity and permeability to the rock, varying these qualities according to more or less existence of matrix. The presence of Iron Oxide deposited between the recrystallization border and feldspathic mineral indicates that this rock has possibly presented a primary rubefaction, intensified by alkaline fluid percolation