Incertezas na medição das características acústicas dos materiais

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia MecânicaSeja em aeronaves, automóveis ou ambiente de trabalho, uma das principais ferramentas para o controle de ruído são os materiais de absorção sonora. O estudo das propriedades desses materiais começaram no século XIX. Com o surgimento de computadores, vieram as técnicas numéricas que permitiram que os modelos dos materiais de absorção acústica pudessem ser simulados computacionalmente, permitindo a predição do comportamento acústico dos materiais de absorção acústica. Isto reduziu tempo e custo que antes eram gastos com protótipos. Vale lembrar que a tecnologia também permitiu o desenvolvimento de técnicas mais eficazes e rápidas para a determinação das propriedades acústicas desses materiais. Este trabalho apresenta uma metodologia de estimar a incerteza associada ao processo de medição da resistividade ao fluxo, porosidade, coeficiente de absorção e impedância sonora de materiais porosos tipicamente utilizados em aplicações de controle de ruído. Isto é de fundamental importância já que estas propriedades são utilizadas na caracterização destes materiais. Modelos teóricos de propagação sonora em meios porosos utilizam tais propriedades no processo de predição das propriedades acústicas de materiais porosos. In aircrafts, automobiles or work environment, one of the main tools for noise control is sonorous absorption materials. The study of these materials properties started in the 19th century. With the computes appearance, numerical techniques arisen, allowing that sonorous absorption materials could be simulated by computers as well as its acoustics behavior. By using this computational simulation, time and cost spent with prototypes were reduced. It is worth noticing that technology also allowed developing more efficiently, fast techniques to determine these materials acoustics properties. This work presents a methodology to estimate the uncertainty associated with the process of air flow resistivity, porosity, absorption coefficient and sonorous impedance measurement of porous materials typically used in noise control applications. This measurement has a fundamental importance, since these properties are used in the characterization of these materials. Theoretical models of sonorous propagation in porous means use such properties in the process of porous materials acoustics properties prediction

Los riesgos nutricionales en escolares que pertenecen a familias de clase baja de la costa catarinense

The objective of the present study was to assess nutritional risks of 5-12 year-old low family income students enrolled in public schools in the city of Camboriú - SC. We evaluated 819 students (579 children and 240 adolescents). The nutritional risks found were related to anthropometrical classification, and it was observed that 78% of the sample was eutrophic, 13% undernourished, and 9% overweight. Food intake analysis showed high consumption of proteins (48%) and low consumption of carbohydrates (96%), vegetables (80%), fats (68%), cereals (68%) and fruits (48%). Socio-economic data showed that class D was predominant (43%), followed by classes C (30%), E (22%) and B (5%). Iron deficiency anemia was diagnosed in 46% of the students. The present study suggests that more efficient intervention strategies can be developed through identification, diagnosis, and analysis of nutritional factors, highlighting nutritional matters such as an essential health promotion component.El presente estudio tuvo como objetivo verificar los riesgos nutricionales de los escolares entre 5 y 12 años de edad de las familias de clase baja pertenecientes a la red de enseñanza pública de la ciudad de Camboriú - SC. Fueron evaluados 819 escolares (579 niños y 240 adolescentes). Los riesgos nutricionales fueron verificados mediante la clasificación antropométrica y se constató que el 78% estaban eutróficos, 13% desnutridos y 9% con sobrepeso. La ingestión alimenticia indicó un consumo excesivo de proteínas (48%) e insuficiente en azúcares (96%), vegetales (80%), grasas (68%), cereales (68%) y frutas (48%). Los datos socio-económicos demonstraron que la clase predominante fue la D (43%), seguida de la C (30%), E (22%) y B (5%). Se encontró que un 46% de escolares presentavan anemia ferropriva. El estudio sugiere que por medio de la identificación y el análisis de los factores nutricionales será posible la construcción de estrategias de intervención más eficaces para la promoción de la salud, siendo la cuestión nutricional un elemento primordial.Este estudo objetivou verificar os riscos nutricionais de escolares entre 5 a 12 anos de idade em famílias de baixa renda, pertencentes à rede de ensino pública do município de Camboriú - SC. Foram avaliados 819 escolares (579 crianças e 240 adolescentes). Os riscos nutricionais foram verificados em relação à classificação antropométrica e constatou-se que 78% se encontravam eutróficos, 13% desnutridos e 9% com sobrepeso. A ingestão alimentar apontou consumo excessivo de proteínas (48%) e insuficiente em açúcares (96%), vegetais (80%), gorduras (68%), cereais (68%) e frutas (48%). Os dados socioeconômicos demonstraram que a classe predominante foi a D (43%), seguida da C (30%), E (22%) e B (5%). Encontraram-se 46% de escolares com anemia ferropriva. A pesquisa sugere que, por meio da identificação, diagnóstico e análise dos fatores nutricionais, poderão ser construídas estratégias de intervenção mais eficazes, colocando a questão nutricional como componente fundamental de promoção de saúde.Universidade Federal de São Paulo (UNIFESP)Universidade do Vale do ItajaíUniversidade de SevilhaUNIFESPSciEL

A 3D lithosphere-scale model of the Barents Sea and Kara Sea region

The Barents Sea and Kara Sea encompass one of the wide shelf margins of the Arctic Ocean. Since the 70-ies, scientific and economic studies contributed to a comparatively broad geological and geophysical database with regard to the remaining Arctic. A dense grid of seismic reflection profiles and few deep seismic refraction profiles clearly image that subregions experienced fundamentally different modes of basin formation. Extrapolation of structural geological information from onshore geology implies the presence of different tectonic provinces as a result from Precambrian to Paleozoic basement amalgamation. The deep crustal and lithospheric structure is only insufficiently imaged by seismic data across the Barents Sea and Kara Sea and the spatial extent of orogenic provinces and their potential influence on different stages of basin evolution from Paleozoic to early Cenozoic times remains only poorly understood. Therefore, the scope of this PhD thesis is to develop a 3D lithospheric model that captures first-order structural, compositional and thermal information on the sediments, the crystalline crust and the lithospheric mantle to understand the main factors controlling the evolution of these basins. Published datasets on the structural configuration, on physical properties and the temperature distribution are available but heterogeneously distributed across the study area. Therefore, a 3D modelling workflow is established. In a first step, all available geological and geophysical data, including interpreted seismic refraction and reflection data, seismological data, geological maps and previously published 3D models are integrated into one consistent model. This approach provides several advantages. The geological model can be constrained in more detail for regions where different types of observations exist such as for the top basement. In addition, the interpretation of coarsely scattered data can essentially be improved by applying physical principles in the frame of 3D gravity modelling in underexplored regions. In this context, 3D gravity modelling was used to constrain the configuration of the continental upper and lower crust. The final model resolves four major megasequence boundaries (earliest Eocene, mid-Cretaceous, mid-Jurassic and mid-Permian), the top crystalline crust, the top of the lower continental crust, the Moho and a newly calculated lithosphere–asthenosphere boundary. In addition, the 3D gravity modelling approach provides the base for a lithology-controlled parameterization of the crust (with mechanical and thermal properties) to allow for 3D calculations of the conductive thermal field and strength of the lithosphere. The structural and physical configuration of the lithosphere correlates with the orogenic and subsidence history of the Barents Sea and Kara Sea region. The southwestern Barents Sea is underlain by a thinned lithosphere (80 km) and high geothermal gradients as the result of multiple Phanerozoic rifting episodes. Thereby, rifting followed predominantly the Caledonian grain and culminated in the opening of the NE Atlantic from Paleocene/Eocene times on. Net horizontal forces exerted by the mid-oceanic ridge are high enough in Miocene times to overcome the lithospheric strength and could explain compressional deformation along the Vestbakken margin and at the Bjørnøyrenna Fault Complex in the western Barents Sea as observed in seismic lines. Thinnest continental lithosphere is present below northwestern Barents Sea including Svalbard (60 km), where late Cenozoic uplift was most pronounced. The East Barents Basin is assumed to encompass Timanian basement. The lithosphere thickens in two major steps to 150 km and follows the curvature of Novaya Zemlya. This correlation indicates that the lithosphere was possibly reworked during the Uralian collision. Elevated mantle densities as observed below the eastern Barents Sea seem to isostatically compensate thicknesses of the less dense sediments. This spatial relationship further exposes mantle density variations as a driving force for significant late Permian–earliest Triassic subsidence. Similar lithospheric thicknesses are found in the northern Kara Sea, which is also probably underlain by Timanian basement. Thickest lithosphere (200 km) and elevated upper mantle velocities distinguish the South Kara Basin from the surrounding regions. The positive mantle velocity anomaly may indicate a different upper mantle composition and support the affinity to the Siberian Craton. Beyond the discussion of the basin history, the shallow thermal and pressure configuration of the sediments was extracted to calculate the potential gas hydrate distribution at present-day and future alterations with regard to ocean warming. The modelling results show that thickest potential gas hydrates at present-day occur along the western Svalbard continental margin where their existence was revealed by numerous bottom-simulating reflectors in seismic profiles. Considering moderate ocean warming models, the gas hydrate stability zones along the continental margin will thin by several tens of meters within the next 100 years. In summary, this thesis demonstrates that the 3D lithospheric model is consistent with geological and geophysical data and reproduces independent observables including the gravity and thermal fields. The model is the first one to link the deep and shallow lithospheric structural and physical configuration with tectonic processes both onshore and offshore across the Barents Sea and Kara Sea region. The derived thermal field and rheological configuration could potentially serve as boundary condition for new projects covering different spatial scales including plate tectonic models as well as high-resolution basin models and geothermal projects

Evidence for mantle exhumation since the early evolution of the slow-spreading Gakkel Ridge, Arctic Ocean

We study the basement configuration in the slow-spreading Eurasia Basin, Arctic Ocean. Two multichannel seismic (MCS) profiles, which we acquired during ice-free conditions with a 3600 m long streamer, image the transition from the North Barents Sea Margin into the southern Eurasia Basin. The seismic lines resolve the up to 5000 m thick sedimentary section, as well as the crustal architecture of the southern Eurasia Basin along 120 km and 170 km, respectively. The seismic data show large faulted and rotated basement blocks. Gravity modeling indicates a thin basement with a thickness of 1–3 km and a density of 2.8*103 kg/m3 between the base of the sediments and the top of the mantle, which indicates exhumed and serpentinized mantle. The Gakkel spreading ridge, located in northern prolongation of the seismic lines is characterized by an amagmatic or sparsely magmatic segment. From the structural similarity between the basement close to the ultra-slow spreading ridge and our study area, we conclude that the basement in the Eurasia Basin is predominantly formed by exhumed and serpentinized mantle, with magmatic additions. An initial strike-slip movement of the Lomonosov Ridge along the North Barents Sea Margin and subsequent near-orthogonal opening of the Nansen Basin is supposed to have brought mantle material to the surface, which was serpentinized during this process. Continuous spreading thinned the serpentinized mantle and subsequent normal faulting produced distinct basement blocks. We propose that mantle exhumation has likely been active since the opening of the Eurasia Basin

The paleozoic evolution of the Olga Basin region, Northern Barents Sea: A link to the Timanian orogeny

The evolution of the Olga Basin region in the northern Norwegian Barents Sea and its relation to the Caledonian and Timanian orogenies is poorly understood due to sparse geophysical data and the lack of well control. In 2015, the German Federal Institute for Geosciences and Natural Resources (BGR) acquired deep multichannel seismic lines as well as gravity and magnetic data. The new seismic data reveal that the Olga and Sørkapp Basins evolved as a W‐E striking half‐graben system along a major normal fault in the north and a smaller normal fault in the south, respectively. Deep crustal undulating high‐amplitude reflections below the Olga and Sørkapp Basins coincide with W‐E striking local magnetic maxima and may imply that the basins evolved on top of old collisional fabrics. The absence of major compressional deformation implies a post‐Caledonian onset of subsidence. The W‐E structural configuration of the sedimentary basins is difficult to reconcile with an earlier proposed NE striking Caledonian branch in the northern Barents Sea. Instead, the orientation of the Olga and Sørkapp Basins lines up with Timanian structural trends from the Pechora Basin. We propose that the Olga and Sørkapp Basins experienced transtensional deformation during the late Devonian/early Carboniferous NE‐SW regional extension phase whereby inherited Timanian lineaments controlled the final W‐E basin configuration. A salient pre‐Caledonian Olga‐Sørkapp crustal block in the central Barents Sea would also explain the recently proposed NNW rotation of Caledonian nappes and thrust sheets in the southwestern Barents Sea

Tectonic implications of the lithospheric structure across the Barents and Kara shelves

This paper considers the lithospheric structure and evolution of the wider Barents–Kara Sea region based on the compilation and integration of geophysical and geological data. Regional transects are constructed at both crustal and lithospheric scales based on the available data and a regional three-dimensional model. The transects, which extend onshore and into the deep oceanic basins, are used to link deep and shallow structures and processes, as well as to link offshore and onshore areas. The study area has been affected by numerous orogenic events in the Precambrian– Cambrian (Timanian), Silurian–Devonian (Caledonian), latest Devonian–earliest Carboniferous (Ellesmerian–Svalbardian), Carboniferous–Permian (Uralian), Late Triassic (Taimyr, Pai Khoi and Novaya Zemlya) and Palaeogene (Spitsbergen -Eurekan). It has also been affected by at least three episodes of regional-scale magmatism, the so-called large igneous provinces: the Siberian Traps (Permian–Triassic transition), the High Arctic Large Igneous Province (Early Cretaceous) and the North Atlantic (Paleocene–Eocene transition). Additional magmatic events occurred in parts of the study area in Devonian and Late Cretaceous times. Within this geological framework, we integrate basin development with regional tectonic events and summarize the stages in basin evolution. We further discuss the timing, causes and implications of basin evolution. Fault activity is related to regional stress regimes and the reactivation of pre-existing basement structures. Regional uplift/subsidence events are discussed in a source-to-sink context and are related to their regional tectonic and palaeogeographical settings

Gas hydrate stability zone of the Barents Sea and Kara Sea region

Published version. Source at http://dx.doi.org/10.1016/j.egypro.2016.10.005 In this study we assess the present-day gas hydrate stability zone for the Barents Sea and Kara Sea region. Thereby, we make use of a data-based 3D lithosphere-scale pressure and thermal model. The resulting gas hydrate stability zone varies within >1km across the study area and strongly correlates with the local geological settings and the corresponding geothermal gradient. Gas hydrates containing hydrocarbons from a thermogenic source (CH4+C2H3+C3H8) are potentially more widespread than previously assumed. The corresponding thermogenic feed gas may have derived from leaking petroleum systems during late Cenozoic basin inversion

Termos de Compromisso de Estágio de Agosto à Novembro de 2008

O termo de Compromisso de Estágio inclui um programa de atividades para formação complementar do estagiário no cursoUFS