110 resultados para Weathering


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Currently with the growing technological advancement and global, new areas are being devastated, and as a result, the erosion became more frequent causing loss of soil, infiltration capacity of the surface and weathering of rocks. In this way, environmental studies are increasingly frequent to understand the environment in which we live, but also to avoid any degradation of the same and of finite natural resources, which are essential for human life. From this, this work has as main goal, analyzing the rates of chemical and mechanical erosive watershed of Ribeirão Jacutinga, at its mouth, in the city of Rio Claro, supporting environmental studies and sustainable development today. Order to reach these values were measured and total dissolved solids in suspension in the stream during the months from January to July 2012. As results included higher rates of both physical and chemical weathering in the rainy months, especially january

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Geological and geomorphological mapping is an important tool for the characterization of physical environment, thus enabling the planning and use of areas more efficiently. This work represents a geological- geomorphologic mapping on the scale of 1:20.000 in the rural area of Quirinópolis – GO town, where outcrop rocks of Paraná Sedimentary Basin, specifically the Bauru Group. Through the methodology of analysis of integrated elements of the physical environment, it was possible to delineate geological- geomorphological five units, which were characterized as lithology, topography, soil conditions, and operating processes, and the development of weathering profiles bring of great importance for planning of land use as occupation thus avoiding further degradation of the physical environment

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The evaluation of soil permeability throughout the weathering profile is one of the most important features to be considered in environmental studies. This study, developed from field testing and analysis of data obtained by geostatistical methods, aims at mapping the permeability around the Ribeirão Claro river. The intent is to simulate an accident with toxic liquids where soil permeability is of fundamental importance. Another purpose of the research was to determine the minimum time that, in the event of an accident, a possible contaminant to reach the water table level and be routed to the nearest drain, in this case, the Ribeirao V Claro river constitutes fundamental information. The studied area of approximately 4 km² is located within the UNESP-Rio Claro campus, consisting of colluvial soil from Fm. Rio Claro superimposed on residual soil of Fm. Corumbataí. The method used to determine the permeability is the concentric cylinders performed on a sampling grid with 64 points containing spacing of 5 meters EW and 10 meters NS. In the places of permeability tests were collected samples for laboratory determination of the percentage of fines. From particle size analysis was performed and analysis statistical and geostatistical on this data. The histogram was based on the statistical studies, and the semivariograms were based on geostatistical estimation methods. Based on the comparison between the maps and the data obtained, it was determined that the percentage of fines in colluvial surface soil has little influence on permeability, which the proximity to the Ribeirao Claro river, the eastern portion, a factor that influences the distribution of permeability values

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Eight Mesoproterozoic granite suites are recognized in the Rondônia Tin Province, called Serra da Providência Intrusive Suite (1606-1532 Ma), Rio Crespo Intrusive Suite (1500 Ma), St. Anthony Intrusive Suite (1406 Ma), Teotonio Intrusive Suite (1387 Ma ), Santa Clara Intrusive Suite (1082-1074 Ma) and Younger Granites of Rondônia Intrusive Suite (998-974 Ma), represent successive magmatic type A (anorogenic) and the intra-plate basement rocks intruded in the metamorphic complex named Jamari separated into two distinct lithologic associations, a ortogneiss (U-Pb from 1.76 to 1.73 Ga) and a paragneiss (1675 + / - 12 Ma). Tin mineralization are widely found in the Tin Province and are associated with granitic intrusions known Mesoproterozoic more closely with the last two magmatic events, represented by the Santa Clara and Younger Granites of Rondônia. The tin mineralization are of primary and secondary, with the primary form deposits of different structural styles and is presented in the form of endo-or exogreisens, veins, stockworks and pegmatites. The secondary mineralization are related to natural processes of weathering and erosion of primary rocks, leading to placer deposits classified as colluvial, eluvial and colluvial-alluvial. The Target Alvo Sol Nascente is located in the central-eastern Rondônia Tin Province and has basement rocks of the metamorphic-magmatic region represented by Jamari Complex intrusive suites and Sierra Providence and Rio Crespo. The last tectonic event spa in the area was responsible for the intrusion of Younger Granites of Rondônia (São Carlos and Caripuanã Massifis). The anomalous levels of tin, sufficient to operate (Mina Rising Sun), indicate that there was possibly mineralization event, evidenced by pegmatite veins well defined, easily found relatively close to mine. Plaque deposits associated with Quaternary sedimentary sequences can also be observed

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The increasing application of structural composites in the aerospace industry is mainly due to its low specific weight coupled with its excellent mechanical properties when in service. As a result of climatic variations that pass the aircraft is of paramount importance to study the influence of weathering on this type of material when subjected to such changes. The purpose of this work is to evaluate the mechanical behavior of specimens of kevlar fiber /epoxy matrix composites, by dynamic mechanical thermal analysis (DMA) and interlaminar shear strength tests (ILSS), after passing through three environmental conditioning: saline fog, hygrothermal and ultraviolet radiation. From the results, we concluded that the laminate was molded supplied homogeneously, not presenting problems such as porosity, delaminations or cracks inside. After a period of 625 hours of exposure to hygrothermal conditioning, we observed a 1,2% maximum of absorption of moisture. Samples subjected to the conditioning by UV irradiation (600 hours) and salt spray showed a reduction of about 24,30% and 32,30%, respectively, on the shear strength (ILSS). In DMA analysis is not observed significant changes on the glass transition temperature. However, when considering the storage modulus of the samples conditioned by UV radiation (1200 hours), salt spray and hygrothermal conditioning there is an increase of 5,34% , 7,19% and 5,57% respectively

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This graduation work done study of polyamide 6.6/composite carbon fibres, since its processing, characterization of the main properties. Besides the influence of temperature, UV radiation, salt spray and moisture on the mechanical and viscoelastic behavior. To achieve this goal, the first composite was processed from the heat compression molding using known variables of the process and using the empirical method to find the best value for other parameters. The method processing molding was chosen because it common in composites processing in order to evaluate the influence of crystallinity of the properties that influence the mechanical and viscoelastic behavior laminates. From the obtained laminate specimens were evaluated in weathering, such as: in hygrothermal chamber, UV, salt spray and thermal shock. In another step, the effect produced by these constraints were evaluated by optical microscopy, ultrasound, dynamic mechanical analysis and vibration tests. This project was conducted at the Department of Technology and Materials of UNESP in Guaratingueta, where all the equipment and techniques for the implementation of this project met available. After the tests proved the applicability of the composite polyamide 6.6/carbon fibers in aeronautical applications with resistance the main climatic influences

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Based on field work, prospection and petrographic studies ultramafic complexes and their mineral deposits from eastern Minas Gerais in southeastern Brazil are generally outlined to form a basis for future investigations in this region. The bodies dealt with occur at Ipanema, Córrego Novo, Bela Vista de Minas, Rio Pomba and Liberdade. These ultramafic bodies are generally enclosed in high-grade gneisses and consist of serpentinized peridotites and harzburgites which were metamorphosed together with their country rocks in upper amphibolite to granulite facies. Weathering of these rocks gives rise to nickeliferous laterite, while metamorphism has resulted in anthophyllite asbestos and talc deposits. © 1985 Springer-Verlag.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This paper presents some results of MFI and OIT tests performed on HDPE geomembranes of 0,8 and 2,5 mm that were exposed to weathering effects and leachate after 30 months (2,5 years). The aim of this work is the evaluation of the oxidative degradation process by comparison of fresh and exposed samples results. The expositing and tests were performed according the following standards recommendations: ASTM D1435 (weathering), ASTM D5747 e D5322 (leachate), ASTM D1238 (MFI) e D3895 (OIT). The results shows, for instance, that the MFI values presented high increases on the HDPE (2.5 mm) showing that polymeric chain break occurred for both exposures and, therefore, oxidative degradation. Concerning the OIT values all the geomembranes presented very low values even in the fresh samples. This demonstrates that there wasn’t an antioxidant package appropriate for these membranes.

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

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)