Programa de Pós-Graduação em Geofísica - CPGF/IG
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2355
O Programa de Pós-Graduação em Geofísica da UFPA (CPGF) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA). Foi o segundo no Brasil a formar recursos humanos em Geofísica em nível de pós-graduação stricto sensu. Criado em 1972, funcionou até 1992 junto com os Cursos de Pós-Graduação em Geoquímica e Geologia.
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Item Acesso aberto (Open Access) Investigação de pavimento asfáltico por meio do método geofísico radar de penetração do solo(Universidade Federal do Pará, 2011) AMARAL, Carolina Narjara Mazzini; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774Most public paved roads may have some sort of imperfection that leads to unsafe traffic, increased transport costs, and pollution. These problems could be avoided if the defects were identified on the floors before they show up at the surface because in general they begin in the underlying layers of the asphalt coverage. This paper proposes the use of GPR to identify problems in pavements based on numerical simulations of the GPR and on field surveys. Simulation of two physical models has been made: i) pavement in use, in which pipe and the most common defects (voids and infiltration) have been inserted, and ii) recent floors, both above a substrate. The interfaces of the pavement layers and the channeling were easily individualized whereas the imperfections show similar patterns of reflection, differing in the polarity of the signal amplitude and in its attenuation (smaller in the voids and higher in the infiltration). Differently from what occurs in other places, the layer interfaces in recent pavements were more easily identified with the frequency of 400 MHz than with a frequency of 900 MHz because of the conductivity of the products deriving from weathering, which occurs in the Amazon. These responses were used then to investigate two places in the city of Belém (PA): a sector of MauritiTv. which presents recurrent defects on pavement, and a newly paved stretch at Federal University of Pará (UFPA). The first survey identified and mapped defects and permitted to infer their possible causes (water loss from the drainage system) while the latter helped in delineating layers and the contact with the substrate (showing that the thickness of pavement layers differ from the projected ones). The results show how the GPR can be an important tool in maintaining and planning the recovery of paved roads by providing a diagnosis in a fast, safe, and low cost.Item Acesso aberto (Open Access) Investigação geofísica da contaminação por derivados de hidrocarbonetos nas redondezas do Posto Cristal (Belém-Pa)(Universidade Federal do Pará, 2013) SILVA, Márcio Antonio dos Santos; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774Item Acesso aberto (Open Access) Modelagem eletromagnética 2.5-D de dados geofísicos através do método de diferenças finitas com malhas não-estruturadas(Universidade Federal do Pará, 2014-10-23) MIRANDA, Diego da Costa; RÉGIS, Cícero Roberto Teixeira; http://lattes.cnpq.br/7340569532034401; HOWARD JUNIOR, Allen Quentin; http://lattes.cnpq.br/6447166738854045We present a 2.5D electromagnetic formulation for modelling of the marine controlledsource electromagnetic (mCSEM) using a Finite Diference frequency domain (FDFD) method. The formulation is in terms of secondary fields thus removing the source point singularities. The components of the electromagnetic field are derived from the solution of the magnetic vector potential and electric scalar potential, evaluated in the entire problem domain that must be completely discretized for the use of the FDFD. Finite difference methods result in large sparse matrix equations that are efficiently solved by sparse matrix algebra preconditioned iterative methods. To overcome limitations imposed by structured grids in the traditional FDFD method, the new method is based upon unstructured grids allowing a better delineation of the geometries. These meshes are completely adaptable to the models we work with, promoting a smooth design of their structures, and may only be refined locally in regions of interest. We also present the development of RBF-DQ method, (radial basis function differential quadrature) which makes use of the technique of functions approximation by linear combinations of radial basis functions (RBF) and the technique of differential quadrature (DQ) for approximation of the derivatives. Our results show that the FDFD method with unstructured grids when applied to geophysical modeling problems, yield improved quality of modeled data in comparison with the results obtained by traditional techniques of FDFD method.