Investigation of green water in FPSO by a particle-based numerical offshore tank

The green water is a highly non linear hydrodynamic phenomenon that occurs when the wave height exceeds the freeboard of the floating structures in harsh environments, and may compromise the operation and security of the on deck equipment. In the present study, in order to assess the effects of the green water phenomenon in FPSO and FLNG systems, the Moving Particle Semi-implicit (MPS) method, which is a fully lagrangian particle-method for incompressible flow, is adopted to model the complex fluid structure interaction problem. This article is focused on the recent developments of the MPS based simulation system of Numerical Offshore Tank (TPN-USP) and its application to the real scale offshore engineering problem. Results of large scale simulations using distributed memory architecture for models from 30 million to 100 million particles are presented

Geologia e geomorfologia do quaternário costeiro do estado do Rio Grande do Norte

This study presents the regional geological-geomorphological map of the Quaternary coastal record of Rio Grande do Norte State, Brazil, with emphasis on the aeolian deposits. The Quaternary record comprises aeolian, alluvial, and marine deposits (peat, intertidal, and tidal flat deposits). They were dated by thermoluminescence (TL) and 14C methods. One active and three inactive aeolian geomorphological domains have been identified, which formed since the early Quaternary by the accumulation of sands from the coastal plain and such continental sources as the Barreiras Formation. TL dates indicate that aeolian deposits were formed in six main phases: 390,000 - 326,000, 270,000 - 240,000, 210,000 - 150,000, 63,000 - 24,000, 11,000 - 9,000, 6,500 years - till the present. These dates also indicate that aeolian deposits formed during both interglacial and glacial stages related to relative sea-level highstands and relative sea-level falls, respectively. Two marine terrace deposits have also been identified: a 210,000 - 214,000 year BP deposit between Natal and Baía Formosa on the N-S-trending coast; and a 120,000 - 114,000 year BP deposit between São Bento and Zumbi, mostly on the E-W-trending coast. Extensive Holocene intertidal deposits, mainly beachrocks, located on the N-S-trending coast exhibit ages of 7,000 - 6,000 and 5,500 - 4,500 cal. yr BP.O objetivo deste trabalho é a apresentação de um mapa geológico-geomorfológico preliminar para o Quaternário costeiro do Estado do Rio Grande do Norte, com destaque para os depósitos eólicos. O mapa foi elaborado a partir de fotografias aéreas, escala 1:70.000, imagens de satélite (P/B, banda 4), escala 1:100.000, mapas topográficos e trabalhos de campo. Foram feitas datações 14C em rochas praiais e depósitos de paleomangues e datações por termoluminescência em sedimentos eólicos e marinhos. Nos depósitos eólicos foram identificados três domínios geomorfológicos de dunas inativas e um de dunas ativas. Eles formaram-se no Quaternário a partir de retrabalhamento de areias da própria planície costeira e de sedimentos da Formação Barreiras. As idades TL de 36 amostras indicam que os depósitos eólicos foram formados durante seis intervalos principais: 390.000 - 326.000, 270.000 - 240.000, 210.000 - 150.000, 63.000. - 24.000, 11.000 - 9.000 e, 6.500 anos - presente. Essas idades sugerem sua deposição tanto durante estágios glaciais como interglaciais, relacionados a níveis relativos de mar baixos e altos respectivamente. Dois terraços marinhos foram identificados, com idades de 210.000 a 214.000 anos e 110.000 a 120.000 anos. O primeiro ocorre entre Natal e Baía Formosa, onde a costa se orienta na direção N - S; o segundo encontra-se no trecho da costa entre São Bento e Zumbi, com orientação E - W. Extensos depósitos de intermaré holocênicos, principalmente de arenitos praiais, estão localizados na costa orientada N - S e apresentam idades entre 7.000 - 6.000 anos AP. e 5.500 - 4.500 anos AP

Seções de referência de subsuperfície da aloformação Paranavaí

A Aloformação Paranavaí é uma unidade geológica quaternária definida na Bacia Hidrográfica do Alto Rio Paraná (SP, PR e MS), composta por depósitos coluviais originados a partir de unidades litoestratigráficas cretáceas da Bacia do Paraná. Os depósitos sedimentares são arenosos, inconsolidados, de coloração vermelho-acastanhada, homogêneos e maciços, comumente confundidos com solos e formações superficiais. Para o estabelecimento de seções de referência de subsuperfície para a Aloformação Paranavaí, foram obtidos testemunhos de sondagem em duas regiões no oeste paulista. Foi conduzido um estudo com diversos parâmetros (texturais, mineralógicos, geoquímicos, isotópicos e geocronológicos) nos sedimentos da Aloformação Paranavaí e do Grupo Bauru. Foram estabelecidas duas novas seções de referência para completar o estratótipo-de-unidade composto estabelecido: seção de referência Rancharia (idades luminescentes entre 71.650 ± 9.000 a 557.000 ± 65.000 AP) e seção de referência Oriente (83.000 ± 8.500 a 436 ± 53.000 anos AP). Idades luminescentes obtidas são crescentes de acordo com a profundidade da Aloformação Paranavaí, enquanto que os sedimentos do Grupo Bauru apresentam idades superiores ao alcance do método geocronológico empregado. Os dados obtidos nas seções de referência apresentam variabilidade em padrões de diversos parâmetros, comprovando diferentes gerações de deposição coluvial ao longo do Quaternário, no oeste paulista.The Paranavaí Alloformation is a Quaternary geological formation found in the Upper Paraná River Hydrographic Basin (states of São Paulo, Paraná and Mato Grosso do Sul), composed of colluvial deposits originated from the Cretaceous lithostratigraphic units of the Paraná Basin. The sedimentary deposits are reddish brown in color, sandy, non-consolidated, homogeneous, massive, and commonly confused with surface soils and formations. In order to obtain subsurface reference sections for the Paranavaí Alloformation, core samples were collected in two regions of the western part of the state of São Paulo. The study was conducted involving several parameters (textural, mineralogical, geochemical, isotopic and geochronological) of the sediments of the Paranavaí Alloformation and Bauru Group. Two new reference sections were obtained in order to establish the composite-stratotype of its constituent formations: Rancharia reference section (luminescence ages between 71650 ± 9000 and 557000 ± 65000 years BP) and Oriente reference section (luminescence ages between 83000 ± 8500 and 436 ± 53000 years BP). The luminescent ages obtained in this study increase according to the depth of the Paranavaí Alloformation, whereas the sediments of the Bauru Group have ages greater than the maximum limit of the geochronological method used. The information obtained from the reference sections shows variability in the patterns of various parameters, proving there were different generations of colluvial deposition throughout the Quaternary period in the western part of the state of São Paulo

Rheological behavior of PMMA/PS polymer blends compatibilized or not.

Neste trabalho, foi estudado o comportamento reológico nos regimes de viscoelasticidade linear (VEL) e não linear (VENL) da mistura polimérica de polimetacrilato de metila/poliestireno (PMMA/PS), compatibilizada ou não com os copolímeros: estatístico P(S-co-MMA) (VEL e VENL) e bloco P(S-b-MMA) (VEL). No estudo do comportamento de VEL, ensaios de cisalhamento oscilatório de pequenas amplitudes (COPA) foram realizados utilizando-se um reômetro de tensão controlada. O comportamento de VEL das misturas poliméricas foi comparado com os modelos teóricos de Bousmina[1] e generalizado de Palierne[2]. Os tempos de relaxação das misturas poliméricas foram obtidos analisando o comportamento reológico no regime de VEL utilizando o software desenvolvido por Honerkamp e Weese[3]. Os tempos obtidos foram comparados com o modelo de Jacobs et al.[4]. O estudo do comportamento de VENL foi conduzido através de ensaios de relaxação de tensão utilizando-se um reômetro de deformação controlada. Os resultados do comportamento reológico no regime de VEL indicaram a presença de quatro tempos de relaxação, para as blendas compatibilizadas com P(S-co- MMA) (composições menores de 10% de fase dispersa e concentrações maiores de 4% de copolímero): dois picos relacionados às fases puras; F, relacionado com a relaxação das gotas da fase dispersa e o relacionado com a relaxação do compatibilizante na interface entre as fases matriz e dispersa. Os valores experimentais de F e foram utilizados para os cálculos de tensão interfacial () e do módulo complexo de interface () das blendas poliméricas compatibilizadas. Os resultados indicaram uma diminuição de com o aumento da concentração de copolímero. Os resultados do comportamento reológico no regime de VEL, para as blendas compatibilizadas com P(S-b-MMA), também apresentaram a presença de quatro tempos de relaxação. Observou-se que o aumento da adição de P(S-b-MMA) proporcionou uma redução no .. Os resultados de VENL de relaxação de tensão mostraram a presença de três fenômenos de relaxação, relacionados com: 1) as fases puras, 2) a relaxação das gotas da fase dispersa e um terceiro mais rápido. A adição de P(S-co-MMA) resultou numa diminuição do processo de relaxação das gotas da fase dispersa.In this work, the dynamic behavior of polymethylmetacrylate/polystyrene (PMMA/PS) blends to which P(S-co-MMA) was added was studied. Several blend composition and copolymer concentrations were studied. The rheological behavior of blends was compared to Bousminas[1] and Paliernes generalized[2] models. The relaxation spectra of the blends were also inferred, and the results were analyzed in light of the analysis of Jacobs et al.[4]. The relaxation spectra of the blends with smaller dispersed phase (below 10 wt%) and larger copolymer concentrations (above 0.4 wt%) showed the presence of four relaxation times, two corresponding to the blend phases, F, corresponding to the relaxation of the shape of the dispersed phase of the blend, and , that can be attributed to the relaxation of Marangoni stresses tangential to the interface between the dispersed phase and matrix. The experimental values of F and were used to infer the interfacial tension () and the interfacial complex shear modulus () for the different blends, decreased with increasing copolymer concentration. decreased with increasing blend dispersed phase concentration and decreasing copolymer concentration. The predictions of Paliernes generalized model were found to corroborate the experimental data once the values of and found analyzing the relaxation spectra were used in the calculations. Bousminas model was found to corroborate the data only for larger dispersed phase concentration. The stress relaxation behavior of PMMA/PS blends with or without random copolymer addition, submitted to step shear strain experiments in the linear and nonlinear regime was studied. The effect of blend composition, viscosity ratio and random copolymer was evaluated. All blends presented three relaxation stages, a first relaxation which was attributed to the relaxation of the pure phases, a second one which was characterized by the presence of plateau and a third fast one

Compatibilization mechanism induced by organoclay in PMMA/PS blends

In this work, the effect of adding organoclay (Cloisite 20A) to a poly(methyl metacrylate) (PMMA)/polystyrene (PS) blend was evaluated in order to understand the compatibilization mechanism taking place. The blend morphology was quantified using micrographs obtained by scanning electron microscopy and observed by transmission electron microscopy. The state of dispersion of the clay was studied using small angle X-ray scattering and wide angle X-ray scattering and by applying the Carreau-Yasuda with a yield stress model to small amplitude oscillatory shear (SAOS) data. Morphological analyses revealed that the clay was intercalated, that its addition resulted in a decrease in the size of the dispersed phase and that it was preferentially located at the interface, except in the case of saturated interfaces, in which case the remaining clay was dispersed in PMMA. By applying the simplified Palierne model to SAOS experiments, the interfacial tension between the polymers forming the blend was inferred and shown to decrease upon addition of clay. The relaxation spectra inferred from the SAOS data, using the Honerkamp and Weese method, revealed four relaxation times: Relaxation of PMMA and PS chains, relaxation of the droplet shape, as well as an additional relaxation phenomenon attributed to the Marangoni stress. Although Marangoni stresses have already been studied in the case of blends compatibilized by block copolymers, this is the first time that it has been evidenced in the case of a clay as compatibilizer. (C) 2017 The Society of Rheology.Natural Sciences and Engineering Research Council of Canada (NSERC)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Ecole de technologie superieure (ETS)Mines Douai, Dept Polymer & Composites Technol & Mech Engn, Douai, FranceEcole Technol Super, Dept Mech Engn, Montreal, PQ H3C 1K3, CanadaUniv Sao Paulo, Met & Mat Engn Dept, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Sea Sci, Santos, BrazilUniv Sao Paulo, Met & Mat Engn Dept, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Sea Sci, Santos, BrazilNSERCFAPESPCNPqCAPESETSWeb of Scienc

Investigation of green water in FPSO by a particle-based numerical offshore tank

The green water is a highly non linear hydrodynamic phenomenon that occurs when the wave height exceeds the freeboard of the floating structures in harsh environments, and may compromise the operation and security of the on deck equipment. In the present study, in order to assess the effects of the green water phenomenon in FPSO and FLNG systems, the Moving Particle Semi-implicit (MPS) method, which is a fully lagrangian particle-method for incompressible flow, is adopted to model the complex fluid structure interaction problem. This article is focused on the recent developments of the MPS based simulation system of Numerical Offshore Tank (TPN-USP) and its application to the real scale offshore engineering problem. Results of large scale simulations using distributed memory architecture for models from 30 million to 100 million particles are presented

Age of depositional and weathering events in Central Amazonia

In the last three decades, several studies have been devoted to understanding the role of Late Pleistocene Holocene climate changes in the Amazonia lowlands environment. However, most of these studies used data obtained from sedimentary deposits (lakes, swamps, and colluvium) located away from the central plain or on the edges of the Amazonia region. This article integrates optically stimulated luminescence and accelerated mass spectrometry C-14 ages with sedimentological and geomorphological data obtained during this study or compiled from the literature for fluvial and lacustrine deposits of the central alluvial plain of the Solimoes-Amazon River. The age data allow us to present a chronological framework for the Late Pleistocene Holocene deposits and conclude that (i) the dryness of the LGM in central Amazonia lowlands is recorded by the formation of fluvial terraces and their weathering to pedogenic hematite between 25.3 ka and 17.7 ka(ii) floodplain deposition was contemporaneous with terrace weathering and occurred in a context of decreased water volume in fluvial channels, lowering of river base level and sea level, and isostatic rebound of the continentand (iii) lateral and mid-channel fluvial bars in the Solimoes-Amazon River have a minimum age of 11.5 1.5 ka, and their deposition responded to increased precipitation at the beginning of the Holocene. (C) 2017 Elsevier Ltd. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ São Paulo, Sch Arts Sci & Humanittes, Av Arlindo Bettio 1000, BR-03828000 São Paulo, SP, BrazilUniv São Paulo, Inst Energy & Environm, Av Prof Luciano Gualberto 1289, BR-05508010 São Paulo, SP, BrazilUniv Fed Amazonas, Inst Exact Sci, Dept Geosci, Av Gen Rodrigo Octavio Jordao Ramos,6200, BR-69077000 Manaus, Amazonas, BrazilUniv São Paulo, Inst Geosci, Rua Lago 562, BR-05508080 São Paulo, SP, BrazilUniv Fed São Paulo, Campus Baixada Santista,Avenida Saldanha,Gama 89, BR-11030400 São Paulo, SP, BrazilUniv Fed São Paulo, Campus Baixada Santista,Avenida Saldanha,Gama 89, BR-11030400 São Paulo, SP, BrazilFAPESP: 2007/58319-1FAPESP: 2009/53198-7FAPESP: 2010/01807-7CNPQ: 307871/2010-0Web of Scienc