Browsing by Author "Duarte, Duarte"
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- A hidrodinâmica e o transporte sedimentar no estuário do Rio MondegoPublication . Duarte, Duarte; Boski, T.; Reis, Rui Paulo Bento Pena dos; Dias, João Manuel AlveirinhoEsta dissertação teve por principal objectivo o estudo da hidrodinâmica e do transporte sedimentar de fundo no estuário do Mondego, através da caracterização dos processos de mistura, estratificação e da circulação nos principais canais do estuário. Avaliaram-se os impactes das obras de regularização do braço norte. A fisiografia regularizada do braço norte facilitou a circulação dos escoamentos fluviais ao longo do canal principal, e favoreceu a entrada da maré para o interior do estuário em resultado da redução significativa do atrito de fundo deste canal, que por sua vez se traduziu numa entrada de sedimentos marinhos localizados no seu sector distal. A propagação da maré no canal principal foi definida por um domínio da enchente, com um comportamento hipo-síncrono, estacionário com uma pequena componente progressiva. Aquando de maiores caudais do Mondego, passou a definir um domínio de vazante e uma distorção estacionária+progressiva+fluvial. No braço sul apresentou-se praticamente estacionária e foi caracterizada por uma ligeira tendência evolutiva de domínio de vazante e por um comportamento hipso-síncrono. Nos regimes bem misturados e dominados pela maré, a resultante do transporte sedimentar de fundo tendeu a fazer-se para dentro do estuário, enquanto nos quadros muito estratificados processou-se inversamente.
- Metal contamination in Ria Formosa saltmarsh sediments and halophyte vegetationPublication . Silva, Manuela; Duarte, Duarte; Chicharo, LuisSaltmarsh vegetation may retain certain substances from anthropogenic activities in surrounding areas, providing a control of contaminants such as heavy metals, coming from industry, agriculture and urbanization. In the last decades there are been na increase in urbanization and industrialization of the area surrounding Marim – Ria Formosa, where this study was performed.
- Modelo de maturação de processos em Instituições de Ensino SuperiorPublication . Duarte, Duarte; Martins, Paula VenturaA adopção de estratégias de melhoria de processos de negócio é actualmente uma procupação de qualquer organização. Os benefícios desta melhoria na optimização dos recursos e na capacidade de resposta das organizações tem suscitado diversas propostas de metodologias de melhoria de processos. Estas diferem quer nos princípios que as suportam, quer na área específica a que se destinam. No entanto, são ainda escassas as propostas e os resultados de investigação científica acerca da melhoria de processos em instituições de ensino superior, extremamente complexas e com características únicas. Este projecto de investigação pretende propôr a extensão de um modelo de melhoria de processos para este tipo específico de organizações. Este trabalho está a ser desenvolvido no âmbito do projecto de Doutoramento em Engenharia Informática.
- Numerical analysis of the flow field and cross section design implications in a multifunctional artificial reefPublication . Maslov, Dmytro; Pereira, Eduardo; Duarte, Duarte; Miranda, Tiago; Ferreira, Vasco; Tieppo, Marcos; Cruz, Fábio; Johnson, JessicaNowadays, multifunctional artificial reefs are integrated in coastal areas all around the world. The design of such structures is currently complex and subjective. In this context, it is essential to improve overall design approaches to more effectively relate artificial reef geometry, function and optimal performance to specific deployment sites. Part of the solution to this challenge may lie in the use of in situ data to study the hydrodynamic performance of prospective artificial reefs. This research addresses this issue by performing a numerical investigation of the flow transformation of two similar artificial reef geometries, and the analysis of performance indicators based on (i) artificial reef assembly cross section, (ii) upwelling and (iii) wake regions evaluation, (iv) efficiency indices and (v) streamlines particles. Based on typical data related to wave action, a velocity inlet boundary condition was defined adopting the non-uniform velocity distribution, aimed at simulating the most realistic boundary con-dition at the chosen deployment location. The results showed that the multifunctional artificial reef assembly with the droplet shape cross section exhibited enhanced function performance when compared to a circular shape cross section by providing significantly higher values of the upwelling velocity, wake region and associated efficiency indices. In addition, the procedure presented in this study, which considers oceanographic data at the deployment site, the geometry of the artificial reef, in situ flow characteristics and boundary conditions, as well as the devised fluid flow performance indicators, can be used for the design of artificial reefs during the concept stage in an objective manner to consider the local design requirements.
- Postglacial sea-level rise and sedimentar response in the Guadiana Estuary, Portugal/Spain borderPublication . Boski, T.; Moura, Delminda; Veiga-Pires, C.; Camacho, Sarita; Duarte, Duarte; Scott, David; Fernandes, SandroThe study of sedimentological features, foraminifera and molluscan fauna in samples recovered from four rotary boreholes permitted, after 14C dating, the first assessment of the post-glacial transgression in Guadiana River Estuary. The Holocene sequence is underlain by coarse sediments from delta fan enclosing continental swamp deposits dated 16980 year BP. The Holocene sedimentary sequence was deposited either directly on this delta fan gravels or on top of fluvial sands deposited probably between 11000 and 10000 yr BP. An accelerated phase of the estuary infilling by clayey sediments containing the saltmarsh foraminifer Trochammina, began ca. 9800 year BP, when sea level was about 39 m below present. Between 7500 and 7000 year BP, the central part of the estuary started to accommodate coarser sediments, partially introduced from the continental shelf. The first phase of Holocene sea-level rise at a rate of 0.85 m/century terminated ca. 6500 year BP. Since then, lagoonal sediments in the vicinity of the estuary have been enclosed behind sand spits and predominantly sandy sedimentation was initiated within the estuary. After a second phase of slower rise at the rate of 0.3 m/century, which lasted until ca. 5000 year BP, the sea approached the present level.
- Postglacial sea-level rise in South Portugal as recorded in Guadiana EstuaryPublication . Boski, T.; Moura, Delminda; Camacho, Sarita; Duarte, Duarte; Scott, David; Veiga-Pires, C.; Pedro, Paulo; Santana, PauloThe Guadiana River Estuary is located in the terminal part of a deeply incised river valley, which accumulated several tens of meters of sediments during the Holocenic transgression. Five cored boreholes (see Fig.1 for localisation) that reached the pre-Holocenic substratum were drilled recently in order to recognize the architecture of sedimentary facies and to quantify the accumulation of organic carbon trapped in sediments during the valley infilling by marine waters. It was assumed that due to structural constraints imposed by Palaeozoic and Mezozoic substratum, the main estuarine channel did not change its position significantly. Consequently borehole locations were chosen in order to represent different sedimentary environments in the estuary: proximity to the main channel (CM1 and CM3), external sea facing (CM4) and lagoonal (CM2 and CM5) environments.
- Preenchimento sedimentar em três estuários do Algarve durante o HolocénicoPublication . Boski, T.; Moura, Delminda; Veiga-Pires, C.; Duarte, Duarte; Santana, Paulo; Pedro, PauloAs bacias hidrográficas são distintas quer do ponto de vista hidrológico quer na forma e àrea de captação.
- Sarcocornia fruticosa and Spartina maritima as heavy metals remediators in an European southwestern salt marsh (Ria Formosa, Portugal)Publication . F. G. M. Silva, Manuela; Aníbal, J.; Duarte, Duarte; Chícharo, LuísSalt marshes are transition zones between land and sea, exposed to several sources of different pollutants, including heavy metals, which tend to be accumulated in sediments. Halophyte vegetation which colonises sediments affects retention and biovailability of the pollutants that reach salt marsh areas. The accumulation capacity and the pattern of metal distribution in salt marsh plant tissues vary among plant species, and with sediment characteristics. The aim of this study was to survey the behaviour of Spartina maritima and Sarcocornia fruticosa on heavy metals contents and distribution amongst sediment and plant tissues in an European Southwestern lagoon (Ria Formosa, Portugal). Both species could fix metals from the surrounding belowground environment and accumulate them mainly in roots (and in rhizomes for S. maritima). Metal translocation to aerial organs was residual. S. maritima acted as a more effective metal stabiliser than S. fruticosa.
- Stress approach by media artPublication . Figueiredo, Mauro; Jesus, Saúl; Duarte, Duarte; Cabral, FernandoWith a background in conceptual art and media art, and the relations between science and art, we tried to approach the concept of stress through art. Stress is a recent problem of people in several countries, and could be caused by external factors, such as social pressure, or be derived from internal factors, such as the requirement that the subject puts himself. Stress had a negative impact at several organs of the human body, but heart is the main one. Taking into account all of these aspects, and from photos of two drawings of the heart ...setup program EDIUS, that integrate all the images and sounds planned to perform the stress.
- A subida do nível do mar durante o Holocénico no Golfo de Cadiz – tendência regional e diferenças locaisPublication . Moura, Delminda; Boski, T.; Duarte, Duarte; Veiga-Pires, C.; Pedro, Paulo; Lourenço, Nuno; Diniz, FilomenaIn Guadiana River Estuary, the Holocene sequence is underlain by pebbly delta fan formed in two stages, prior to 5E and 3 highstands. The Holocene sedimentary sequence was lain either directly on gravels or on top of fluvial sands deposited between 11000 and 10000 yr. BP. An accelerated phase of infilling of the estuary by clayey sediments, containing marsh foraminifer Trochammina, began at ca. 9800 yr. BP when the sea level was about 39 m below the present.At ca. 7000 BP the central part of the estuary started to accommodate coarser sediments, partially introduced from the shelf. The first phase of the Holocene sea level rise at a rate of 0.85 m/century terminated at ca 6500yr. BP. Since then, the lagoonal bodies in the vicinity of estuary started to enclose behind sand spits and predominantly sandy sedimentation initiated within the estuary. After the second phase of a slower rise at the rate of 0.3 m/century, which lasted until ca. 5000 yr.BP, the sea approached the present level. Data from Guadalete Estuary published in Spain set the beginning of Holocene transgression at shallower level (ca 10m)than in Guadiana Estuary.This discrepancy may be explained by isostatic uplift of Betic Cordillera or slumping of Guadiana terrace on which the Holocene sediments are lain. Since 7500 yr. BP the data from Odiel-Tinto, Guadalete and Guadiana are in a relatively good agreement.