1,720,961 research outputs found
Caracterização da hidrodinâmica e do transporte de sedimentos dos três principais afluentes do rio Doce
Get PDFOn November 5, 2015, in the municipality of Mariana, Minas Gerais, there was the biggest tailings dam accident in Brazil. The Fundão dam collapsed, spilling 32 million cubic meters of waste, causing a severe socioeconomic and environmental impact on the Doce River. After the accident, much research has been carried out to understand and minimize the impacts. One of the ways to understand the dynamics of the Mariana – MG disaster, from the perspective of hydrodynamics, is through models. With the aim of understanding the role of tributaries in the recovery of the Doce River, hydrodynamic and sediment transport simulations were carried out in this work, using the two-dimensional version of the HEC-RAS model, at the confluences of the Gualaxo do Norte River with the Carmo River, of the do Carmo with the Piranga river, the Suaçuí Grande river with the Doce river and the Manhuaçu river with the Doce river. The results of the 2D hydrodynamic model showed the hydrographs and areas flooded by the disaster in Mariana – MG, that the reservoir of the Risoleta Neves Hydroelectric Plant would hypothetically hold the waste from the disaster if the floodgates had been kept closed, that the narrowing of the Doce river channel in the municipality of Governador Valadares – MG caused the flow speed to increase substantially, and the topographic conditions of the confluence of the Manhuaçu River with the Doce River meant that the simulation was varied with slow speeds in the reservoirs and high speeds in narrow stretches. The results of the 2D sediment transport model showed erosion and sedimentation in the studied areas, that the Carmo river exerts a mixing and dilution function of the sediments transported by the Gualaxo do Norte river, which the Suaçuí Grande river and the Manhuaçu river do not have capacity to perform a mixing and dilution function of the sediments transported by the Doce River in a short period, and that the dams interfere considerably with the sediment transport regime. In addition to these results, the sediment transport model showed that large amounts of sediment were retained on the banks of the rivers at the confluence of the Carmo River with the Piranga River and on the rock banks, which makes this confluence an important location for the retention of contaminated sediments, with significant influences on downstream water quality. However, these results can contribute to decision-making, to identify stretches with greater susceptibility to erosion and sediment deposition and to plan the restoration of these rivers.Em 5 de novembro de 2015, no município de Mariana, Minas Gerais, houve o maior acidente de barragem de rejeitos do Brasil. A barragem do Fundão rompeu, derramando 32 milhões de metros cúbicos de rejeitos, causando um severo impacto socioeconômico e ambiental no rio Doce. Após o acidente muitas pesquisas vêm sendo feitas para entender e minimizar os impactos. Uma das maneiras de entender a dinâmica do desastre de Mariana – MG, sobre a perspectiva da hidrodinâmica, é através de modelos. Com objetivo de entender a função hidrodinâmica dos afluentes na recuperação do rio Doce, foram realizadas neste trabalho, simulações hidrodinâmicas e de transporte de sedimentos, a partir da versão bidimensional do modelo HEC-RAS, nas confluências do rio Gualaxo do Norte com o rio do Carmo, do rio do Carmo com o rio Piranga, do rio Suaçuí Grande com o rio do Doce e do rio Manhuaçu com o rio Doce. Os resultados do modelo hidrodinâmico 2D mostraram os hidrogramas e as áreas inundadas pelo desastre de Mariana – MG, que o reservatório da Usina Hidroelétrica Risoleta Neves hipoteticamente comportaria os rejeitos do desastre caso as comportas tivessem sido mantidas fechadas, que o estreitamento do canal do rio Doce no município de Governador Valadares – MG fez com que a velocidade do escoamento aumentasse substancialmente, e que as condições da topografia da confluência do rio Manhuaçu com o rio Doce fizeram com que a simulação fosse diversificada com velocidades lentas (inferior a 0,5 m/s) nos reservatórios e altas nos trechos estreitos. Os resultados do modelo de transporte de sedimentos 2D apresentaram as erosões e sedimentações nas áreas estudadas, que o rio do Carmo exerce uma função de mistura e diluição dos sedimentos transportados pelo rio Gualaxo do Norte, que o rio Suaçuí Grande e o rio Manhuaçu não têm capacidade para exercer uma função de mistura e diluição dos sedimentos transportados pelo rio Doce num curto período (dias), e que as barragens interferem consideravelmente no regime de transporte de sedimento. Além desses resultados, o modelo de transporte de sedimento apontou que grandes quantidades de sedimentos foram retidas nas margens dos rios da confluência do rio do Carmo com o rio Piranga e nos bancos de rocha, o que torna esta confluência um local importante para a retenção de sedimentos contaminados, com influências significativas para a qualidade de água a jusante. Esses resultados podem contribuir para a tomada de decisões, para identificação de trechos com maior suscetibilidade à erosão e à deposição de sedimentos e para planejamento da restauração desses rios
Modelagem Hidrodinâmica com a integração do mapeamento das inundações do rio Sapucaí do município de Itajubá/MG
Get PDFAs inundações são fenômenos naturais que podem gerar grandes danos e, em função das açõesantrópicas, como ocupação desordenada, obras projetadas de maneira errôneas ou por má gestão, tem seus impactos potencializados. Em Itajubá, município localizado no sul do estado de Minas Gerais, já foram registrados diversos eventos de inundação, desde sua fundação, sendo o último grande evento ocorrido em janeiro de 2000. O objetivo desse trabalho é simular este evento no programa HEC RAS, partir da modelagem a montante de Itajubá, e a partir do hidrograma do evento, considerando a rede de drenagem do município, gerar manchas de inundação usando o programa Global Mapper. Os resultados das simulações obtidas foram analisados e comparados com os dados históricos e se mostraram coerentes ao que ocorreu no evento do ano de 2000, considerando as devidas modificações de topografia ao longo dos últimos anos
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
