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) Caracterização física do estuário do rio Mojuim em São Caetano de Odivelas - PA(Universidade Federal do Pará, 2015-02-25) ROCHA, Adriano Santos da; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471The present study has as objective describe the hydrodynamics, hydrologic and morphological aspects, of estuary of Mojuim River, it is localized in São Caetano de Odivelas city –PA (Salgado Paraense),it is analyzing the variations that happen according sea cycle seasonality (rain regime).The hydrologic and hydrodynamics data was collected in two seasonal period in 2014:March,it corresponds to rainy period (~500 mm)and September, it corresponds to dry period (~100 mm),both during tide of syzygy. The bathymetric survey happened only in the rainy period and it was realized with an echo sounder in a sampling grid with 116 spaced cross profile of 200m.In the estuarine channel,it was defined a section where it was realized profiles of strength measurement and current intensity and output, with ADCP, and in three fixed stations,right bank (RB), center(C),and left bank (LB)it was realized collections of conductivity and turbidity with a CDT and an OBS, in the water column. The pattern of tidal and the salinity they were also obtained with a pressure sensor and conductivity fixed in the LB during 56 days in the rainy period and 57 days in dry ones. The estuarine is shallow (4,5 m of average depth) and it is restrained by a regime of semidiurnal macrotidals. During a tidal cycle the salinity increases in the floods and decreases in the ebb tide in both seasonal periods. Turbidity increases in the floods and it decreases in the ebb tide of the rain period and the value measured in the center (C) is double found in the banks. In the dry period, the salinity was higher to rainy period (average 20 and 8, respectively) .This estuarine presents well mixed; it is vertically homogeneous in the rainy period and highly stratified in the dry. The flood flows occur predominantly at the center section, while the ebb flows predominate in the RB, in the two situations the highest intensity of the current occurs in the rainy season. The estuary is an importer in the two periods, however, more entering in the rainy period (resulting transport of 95,87 m³/s) .These data correspond to the first information on the hydrological and hydrodynamics characteristics of the estuary and they can support further studies in the region.Item Acesso aberto (Open Access) Exemplo de bom condicionamento inconveniente causado numericamente na inversão gravimétrica para a estimação das densidades de uma camada(Universidade Federal do Pará, 2014) SOARES, William Pareschi; MARTINS, Cristiano Mendel; http://lattes.cnpq.br/8303640454649778A well-conditioned sensitivity matrix can be inconvenient for estimating densities of a layer? We found an example of this inconvenience numerically caused in the gravimetric inversion when the horizontal dimensions of the elementary sources that make up the interpretive model are very small. Amazingly in this case a gravity inversion to obtain the equivalent layer is not effective and does not fit the data. We found that in this case the well-conditioning of the sensitivity matrix occurs simultaneously with low singular values. This feature of the sensitivity matrix leads to severe loss of resolution and leads to biased estimates and very smooth. It happens that part of the resolution would be mathematically possible to be obtained is lost due to this phenomenon numerical computational degradation of the sensitivity matrix . We present a procedure for repayment of the resolution for mapping the density distribution of a layer, which enables new perspectives on gravimetric applications, including environmental studies. We skirted the numerical problem with a semi-heuristic approach which extends the horizontal dimensions of the elementary sources and subsequently corrects the estimates. We obtained with this new procedure in synthetic tests the distribution of the density contrast outlining lateral contacts between regions of different density contrasts, which would only be possible to recover elemental sources larger. We apply this methodology to the dataset of the Thomas Farm landfill site landfill.