Dissertations / Theses on the topic 'Pressure cover'

The phenomenon of concrete cracking due to corrosion of embedded reinforcement steel bars in concrete has been investigated for years. As a consequence of the steel corrosion that is accelerated by cold climates, sea water, spray and from chloride-based acceleration agents, internal cracks form. These agents originate a slow propagation of corrosion products around the embedded steel, forming a passive film, which can be elementary understood as a radial force present all around the steel, creating compressive stresses in concrete. This pressure causes the formation of microcracks that permit the passive film to infill in the structure and propagate. A finite element analysis will be carried out, in order to study the relationship of reinforced concrete features. These are the bar diameter, space between the rebars, concrete strength and the cover thickness. In order to simulate and describe the behaviour of the concrete, the Concrete Damaged Plasticity – CDP, is used. The elastic is easily described by the elastic modulus and the Poisson’s ratio, while the non-linear is more complex. The CDP method considers both compression and tension strengths, gaining as output the cracking pattern. The simulation proposed consists by the modelling of a two-dimensional model, in which the reinforced steel bars will be inserted as holes in the geometric features. The model features internal boundary conditions placed on each side of the rebars/holes. At the end, four groups of simulations are proposed, in which various combinations of the parameters considered, are provided. These corresponds of four different concrete strengths, three different diameters of the steel rebars, five different cover thicknesses and four different spacings between the rebars. The simulations show the probable cracking paths, based on the internal displacement given by the pressure formed by the corrosion products.

This thesis presents three different approaches to model corrosion-induced crack propagation in reinforced concrete structures. The first approach is solved numerically using finite differences to model the softening behaviour of concrete in tension. The second approach idealizes the concrete cover as either a brittle elastic or an elastoplastic material so that it may be solved using a closed-form solution. Both approaches are based on a thick-walled cylinder (TWC) analogy and consider rust compressibility and rust diffusion into cracks. The third approach uses finite element modelling to validate the application of the TWC and perform a parametric study. The results obtained using each approach are compared against each other as well as against experimental results. The TWC was found to be an appropriate analogy for the geometries and reinforcement configurations considered. Analytical models were found to provide upper and lower limits to the results based on the numerical model. The experimental data found in the literature showed reasonable agreement with predictions from the numerical and elastoplastic models.

This paper describes the design of the ventilation pressure cover of the demonstrator GFR. The first part is a brief research project GFR and the effects of temperature on the inside structures. In the following part is calculated balance heat losses within the pressure cover for three cases: non-insulated, fully-insulated and partially insulated surface of the reactor. The following is a design of a heat sink for partially insulated surface.

This thesis focuses on the design of new high pressure injection system application on diesel engine. The design came from company Zetor’s demands. For this application was chosen system Common Rail supplied by company Bosch. Assignment was separated into several tasks. Research of suitable components for low pressure section, design of waste system and high pressure injection tubes design including injector clamping. Due to injectors used in this system was necessary to redesign cover for valves and even new system to lead wires from outside of the engine to injectors. Injector is attached by screw connection, which is composed from screw and clamping jaw. These parts are subjected to an analytic calculations. Clamping jaw of injector is even subjected to a FEM analysis, which focuses on fatigue life. Finally, the drawings were documented.

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The largest Brazilian coal mine is located in the municipality of Candiota, Rio Grande do Sul state. Carbon seams lie near the surface around 10 to 25 meters deep, it can be mined open-pit. This mining method uses a dragline, a large machine for removing carbon, it involves changes in topography, vegetation and hydrological regime of the area. Density, porosity and water retention are directly affected. The major change of constructed soil physical attributes comes from removal of layers of original soil and deposition on the regeneration areas. Excessive machinery traffic during soil construction causes compaction of the area, it makes difficult water infiltration into soil profile facilitating water erosion, and inhibiting the vegetation of the area. The use of soil uncompressed plants is an important strategy on recovering soil structural quality. The knowledge of physical parameters as density and aggregation of constructed soils in mining areas must be considered of great importance for evaluating physical attributes since it can indicates changes in porosity, degree of compaction, root penetration, and water and air permeability. Mechanical parameters as pre- consolidation pressure and compression index can indicate soil bearing capacity. The general objective of the work was analyze the potential of different cover crops on recovery of coal mining degraded areas, by determining physicmechanical parameters of the constructed soil over time. Treatments with single plants established in October-November, 2007 were analyzed T1- Capim vaquero (Cynodon dactilon), T2 - Braquiaria brizanta (Brachiaria brizantha), T3 - Tanzânia (Panicum maximun), T4 - Braquiaria humidícola (Brachiaria humidicola), T7 - Hemartria (Hemarthria altissima), T8 - Grama Tifton (Cynodon dactilon). Constructed soil without cover crops was used as a control SCSP in order to observe the action of plants on constructed soil attributes recovery. As general conclusions we can state that because of little time for establishing the experiment, the cover crop had incipient action on improvement of physical attributes, but when compared with control presented highest density and porosity, DPM, and percentage of macroaggregates, highlighting Brachiaria.
A maior jazida brasileira de carvão mineral localiza-se em Candiota-RS. Nesta localidade o carvão encontra-se próximo à superfície, em torno de 10 a 25m de profundidade, podendo ser minerado a céu aberto. Este método de lavra emprega a dragline , máquina de grande porte, para remoção do carvão, acarretando em modificações na topografia, na vegetação e no regime hidrológico da área. Logo, a principal alteração dos atributos físicos do solo construído advém da remoção das camadas do solo original e deposição nas áreas de regeneração. O excessivo tráfego de máquinas durante a construção do solo acarreta na compactação da área, dificultando a infiltração da água ao longo do perfil, facilitando a erosão hídrica e inibindo a revegetação da área. O uso de plantas que atuam como descompactadoras do solo constitui-se importante estratégia na recuperação da qualidade estrutural de solo. O conhecimento de parâmetros físicos como a densidade e a agregação de solos construídos em áreas de mineração deve ser considerado de grande importância na avaliação dos atributos físicos, já que poderá indicar as mudanças ocorridas na porosidade, grau de compactação, penetração das raízes e permeabilidade da água e do ar. Os parâmetros mecânicos como a pressão de pré-consolidação e o índice de compressão podem indicar a capacidade de suporte de carga do solo, podendo evitar a compactação adicional da área. Neste contexto, o objetivo geral do trabalho foi analisar o potencial de diferentes plantas de cobertura na recuperação de áreas degradadas pela mineração de carvão, através da determinação de parâmetros físico-mecânicos do solo construído, ao longo do tempo. Foram analisados os tratamentos com as plantas solteiras, implantadas em outubro/novembro de 2007: T1- Capim vaquero (Cynodon dactilon), T2 - Braquiaria brizanta (Brachiaria brizantha), T3 - Tanzânia (Panicum maximun), T4 - Braquiaria humidícola (Brachiaria humidicola), T7 - Hemartria (Hemarthria altissima), T8 - Grama Tifton (Cynodon dactilon). Como testemunha usou-se o solo construído sem plantas de cobertura SCSP, no intuito de observar a ação das plantas na recuperação dos atributos do solo construído. Como conclusões gerais pode-se dizer que devido ao pouco tempo de implantação do experimento, as plantas de cobertura tiveram ação incipiente na melhoria dos atributos físicos-mecânicos, mas ao serem comparadas com a testemunha, apresentaram melhores valores de densidade, porosidade total, DMP e porcentagem de macroagregados, destacando as braquiarias, até o presente momento.

Basé sur des documents authentiques rares et inédits, ce travail a pour but d’étoffer une nouvelle image de la Révolution russe via les revues satiriques de l’époque. Ces revues sont de véritables œuvres d’art révolutionnaires qui interrogent la liberté de la presse et l’art durant une période charnière en Russie. Il s’agit d’une témoignage direct de cette année révolutionnaire, véhiculé par des artistes avant-gardistes libérés de la censure, et qui vont, au fil des semaines, composer une image originale de l’année 2017 et des deux révolutions russes de février et d’octobre au travers des couvertures illustrées. Afin de conserver la dynamique chronologique des événements, les revues ont été mises en parallèle avec les témoignages écrits d’époque, de personnalités diverses telles que Claude Anet, Pierre Pascal, Maxime Gorki, Maurice Paléologue, ou encore John S. Reed. Tous ont accompagné les bouleversements révolutionnaires à leur manière et constituent l’écho historique de ces revues satiriques illustrées qui nous permettent de plonger au cœur même du quotidien des révolutions russes caractérisant une nouvelle image de la Révolution, mouvante, singulière et remarquable
Based on rare and authentic documents, this work endeavors to elaborate a new image of the Russian Revolution through satirical magazines of the time. These illustrated reviews are genuine works of art that question freedom of the press and art itself during a transnational period in Russia. They serve as a direct testimony of this revolutionary year, providing an original image of the two Russian revolutions of February and October and featuring on the review’s front cover week after week avant-garde artists freed from censorship of the press. In order to preserve the chronological dynamic of the events, satirical reviews are coupled with historical testimony of various writers such as Claude Anet, Pierre Pascal, Maxime Gorki, Maurice Paleologue, and John S. Reed, among others. All of them had supported the revolutionary turmoil in their own way and constitute an historical echo of the illustrated satirical reviews allowing us to plunge into the heart of daily life during the two Russian revolutions, and thus creating a new image of the Revolution, set in motion, single-minded, and noteworthy

The thesis is devoted to analysing of flexible buried arch structures. Modelling of the flexible concrete arch is carried out via a nonlinear finite element model that accounts for soil constitutive relations, soil-structure interactions, sequential construction stages and soil compaction. Advanced FE-model was verified by measurement obtained by full-scale field testing of two buried arches. Mathematical optimization methods of genetic algorithms and Levenberg-Marquardt method are applied to already calibrated complex computational models in order to reduce bending and associated flexural stresses in the concrete section of buried arch. Centre line of the arch is parameterized by cubic Bezier curve to reach interpolation of thrust line. Optimization technique is applied with extensive parametrical study which shows the optimal shapes for buried arches of various span/rise ratios, backfill depths and foundation soil types. For practical application are given coordinates of Bézier curve control polygons of particular resulting shape. Subsequently is applied optimization method for a theoretical reduction of tensile stresses obtained by shape optimization of previously verified numerical model of buried arch. Comparisons of earth pressure, bending moment axial force and deflection of flexible structure during sequential construction of different span/raise ratios of buried arches are presented. The behaviour of flexible buried arch with effect of local traffic load model LM1 has been analysed via 3D finite elements model with respect to different depth of backfill above crown.

MENVSC
Department of Ecology and Resource Management
The study investigated the impact of cover crops (Medicago sativa, Lotus corniculatus, Trifolium pratense, Melilotus alba and Phacelia tanacetifolia), bare soil and natural ground cover on pest and beneficial arthropods, soil health, crop yield, pest damage and weed suppression in avocado orchards. The trial plots were sited within established commercial avocado orchards with trees of similar cultivar (‘Hass’), soil-type and age, located in Levubu, Limpopo, South Africa. Mixtures of cover crops were planted in the alleys of avocado orchards and the effects were compared to that of a control (other half of the orchard). Mechanical clearing of vegetation in half of the alleys of different avocado orchards were compared to the other half that was left undisturbed. Data were collected during the flowering and fruit set stages of the avocado trees in the months of September - November 2019. Results revealed that there was higher abundance and diversity of flowering plants in the orchard alleys of the cover crop treatment compared to the control comprising of natural vegetation. Cover crops had a significantly positive effect on the soil health of the orchard but little or no effect on beneficial arthropods within the orchard nor any positive effect on the pests of avocados. However, the number of thrips scouted on the fruit were significantly less where cover crops were established. Avocado scale infection rates were also significantly lower where cover crops were established. There were significantly less arthropods, and specifically pests, pollinators and herbivores where the topsoil was removed mechanically. The yield resulting from the orchard half where cover crops were established were significantly higher. More research still needs to be done about the use, management and impact of cover cropping on not only commercial avocado orchards but on other fruit crops. This study shows good evidence for the benefits for using cover crops and the negative effects in having no vegetation cover in the orchards.
NRF

Mestrado de dupla diplomação com o Institute Agronomic and Veterinary Hassan II
Extensive grazing systems are characterised by low stocking densities, with positive impacts on the landscape, promoting diversity and heterogeneity. In order to manage this type of systems, we have implemented a robust tool which is the evaluation of the grazing pressure. This latter can establish the relationship between the ruminant and the pasture. This study is made in Bragança region, situated in the northeast part of Portugal. We used available databases such as: land use and cover (LUC) map of Portugal (COS2018), parishes’ administrative boundaries (CAOP2012) and sheep and goats’ locations and headcounts of the study area (OTSA). We define eight LUC classes: permanent crops (PC), annual crops (AC), grasslands (G), shrublands (S), grazed (GF) and ungrazed forests (UF), urban (U) and water bodies (W). The stocking densities and the distribution of the grazing pressure over the LUC classes was done by GIS geoprocessing techniques involving multiple ring buffer zones, data overlapping and spatial interpolation. We used two different methods for spatial interpolation of stocking densities; the weighted inverse distance (IDW) and the ordinary kriging (OK), with better results for the latter, with average prediction errors of 0.0003. Overlapping the grazing areas of the LUC map and the stocking densities, it allows us to obtain the grazing pressure (GP). The most common GP in Bragança is about 1-1.5 sheep or goats/ha. The LUC class with the highest grazing pressure is annual crops (2.22 sheep or goat/ha), the less grazed class is shrublands (1.42 sheep or goat/ha). Regarding the availability of LUC, shrublands have the highest coverage in Bragança region (26.8%), followed by PC (20.5%), GF (18.5%), AC (15.7%), UF (9.2%), G (5.5%), U (3.1%) and W (0.7%). The herds in the study area are globally composed of 11.42% goats and 88.58% sheep. The grazing pressure is related to the food preferences of each species and has been taken into account in this assessment in order to increase the accuracy of the results obtained.
Os sistemas de pastoreio extensivos caracterizam-se por baixos encabeçamentos, com impactos positivos sobre a paisagem, promovendo a diversidade e a heterogeneidade. A fim de gerir este tipo de sistemas, implementámos uma ferramenta robusta que é a avaliação da pressão de pastoreio. Este último pode estabelecer a relação entre o ruminante e o pasto. Este estudo é realizado na região de Bragança, situada na parte nordeste de Portugal. Utilizámos bases de dados disponíveis, tais como: mapa de uso e cobertura do solo (LUC) de Portugal (COS2018), limites administrativos das freguesias (CAOP2012) e localizações e efectivos pecuários de ovinos e caprinos da área de estudo (OTSA). Definimos oito classes de LUC: culturas permanentes (PC), culturas anuais (AC), prados (G), matos (S), florestas pastoreadas (GF) e florestas não pastoreadas (UF), áreas urbanas (U) e massas de água (W). As densidades de pastoreio e a distribuição da pressão de pastoreio sobre as classes LUC foram feitas por técnicas de geoprocessamento GIS envolvendo “multiple ring buffer zones”, sobreposição de dados e interpolação espacial. Utilizámos dois métodos diferentes para a interpolação espacial das densidades de pastoreio; a distância inversa ponderada (IDW) e o kriging normal (OK), com melhores resultados para este último, com erros de predição médios de 0,0003. Sobrepondo as áreas de pastagem do mapa LUC e as densidades de pastoreio, permite-nos obter a pressão de pastoreio (GP). O GP mais comum em Bragança é cerca de 1-1,5 ovelhas ou cabras/ha. A classe LUC com maior pressão de pastoreio é a de culturas anuais (2,22 ovelhas ou cabras/ha), a classe menos pastoreada é a de matos (1,42 ovelhas ou cabras/ha). Relativamente à disponibilidade do LUC, os matos têm a maior cobertura na região de Bragança (26,8%), seguidos pelo PC (20,5%), GF (18,5%), AC (15,7%), UF (9,2%), G (5,5%), U (3,1%) e W (0,7%). Os rebanhos na área de estudo são compostos globalmente por 11,42% de caprinos e 88,58% de ovinos. A pressão de pastoreio está relacionada com as preferências alimentares de cada espécie e foi tomada em consideração nesta avaliação a fim de aumentar a exactidão dos resultados obtidos.

Large air-cooled heat exchangers (ACHEs) are most popularly implemented in the petrochemical and power industries at arid locations. They operate on a simple concept of convective heat transfer, whereby air in the surrounding atmosphere is caused to flow across a tube bundle, which in turn transports a process fluid. The distribution and direction of the process fluid flow may furthermore be guided via a set of appropriately located header boxes, which essentially consist of a collection of welded flat plates and nozzle attachments. Perforations on one of the faces of these boxes serve as an interface to the tube bundle. The overall design and construction of an ACHE is commonly regulated by an American Petroleum Institute (API) standard, which is required to be used in conjunction with acceptable design codes. In spite of this, the design of certain header box configurations remains of prominent concern. It is the focus of the present study to investigate the approach adopted for a header box variant labelled as the removable cover type. In this configuration, one of the plates used to construct the header box is fastened and sealed by a collection of bolted joints and a gasket, allowing it to be removed. One appropriate design code for the header box equipment is the ASME (American Society of Mechanical Engineers) boiler and pressure vessel code. However, it provides no specific approach pertaining to the removable cover design. Instead it has been commonplace in industry for a number of aspects from this code to be synthesized, together with a collection of assumptions surrounding the header box behaviour, into an all encompassing design by rule approach. In this approach, the header box behaviour is accepted as being planar, whilst circumstances such as nozzle attachments and associated loading would suggest that a more comprehensive approach should be undertaken. The aim of the present study is therefore to critically evaluate the current practice, and establish its adequacy. To do so, a detailed three-dimensional finite element model (FEM) of an example header box design is developed. Subsequent comparisons with the stress distribution predicted via current practice show that the existing analytical model gives inaccurate and, in cases, overly conservative results. A new analytical approach developed from rigid frame theory is demonstrated to provide improved correlation with FEM. The linear elastic design by analysis approach, presented in the ASME code, is also utilised as a method for establishing design adequacy. Results obtained via design by analysis incorporating the finite element method are shown to be less conservative than those arising from design by rule methods. The design by analysis approach is also used to conduct a more detailed investigation of nozzle placement and external loading. In general, the effect of including a nozzle did not result in a significant increase in side plate stress, with failure more likely to occur within the nozzle wall.
Dissertation (MEng)--University of Pretoria, 2011.
Mechanical and Aeronautical Engineering
unrestricted

Detailed mapping, U-Th-Pb monazite geochronology was combined with structural and metamorphic analysis on Nordøyane to date the thermotectonic evolution of UHP and HP units metamorphosed during the Late Silurian-Early Devonian collision between Baltica and Laurentia. The structurally higher unit contains microdiamond-bearing kyanite-garnet-graphite gneiss and associated kyanite eclogites that independently indicate probable diamond-forming conditions of 820°C, 39 kbar. Eclogitized mylonite from the Proterozoic Haram Gabbro, in the structurally lower unit, yields 780°C and 18 kbar. In situ monazite dating with the electron microprobe using a combination of high-resolution element imaging and trace-element analysis of U, Th, Pb, and Y yielded three mean ages of 407.0 ± 2.1, 394.8 ± 2.3, and 374.6 ± 2.7 Main the microdiamond sample and kyanite-garnet mylonite. The oldest two of these have been verified by the SHRIMP II ion probe. These indicate that the UHP unit reached its maximum depth of 125 km at approximately 407 Ma when monazite was included in garnet. This unit then experienced 65 km of exhumation at an average rate of 10.9 mm/yr during top-southeast thrusting that also brought it into contact with the HP unit. Structural features formed during this stage of exhumation include L > S fabrics and tubular folds with axes parallel to the transport direction. Later, both units were exhumed together at an average rate of 3.8 mm/yr to a depth of 37 km at 395 Ma where these rocks experienced extensive re-equilibration, and top-west, left-lateral shearing. During this stage, structural features included development of constrictional L > S fabrics and tubular folds formed at high angles to earlier structural features and evolved from an initial WNW orientation to near orogen parallel. After 395 Ma, these units continued to be exhumed at an average rate of 0.8 to 1.4 mm/yr until 375 Ma, the time of asymmetric monazite porphyroclasts in the late-stage mylonite. The exhumation histories of these units record a change in mechanism from syncollisional exhumation through late- to post-orogenic collapse that was a consequence of plate re-organization.

Tese de doutoramento em Biociência, na especialidade de Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
A Directiva-Quadro da Água reforça o papel dos usos do solo na avaliação da qualidade da água, mas a utilização de dados de ocupação do solo, no que respeita a águas de superfície, restringe-se à estimativa dos padrões de uso do solo para a identificação de pressões provenientes de fontes de poluição difusas. O principal objetivo deste estudo é identificar especificidades da ocupação dos usos do solo na avaliação das mudanças de estado (Capítulo I), pressões (Capítulo I e II) e forças motrizes (Capítulo III e IV) da qualidade das águas de superfície. Para o efeito, usamos dados da bacia hidrográfica do Rio Mondego, uma bacia costeira localizada em Portugal, onde as mudanças socioeconómicas têm sido observadas desde a década de 1990 e que resultaram na perda de representatividade do setor agrícola e ganho do setor da construção. Apesar das mudanças, a agricultura mantém-se como uma fonte de pressão sobre as águas de superfície que, associada a modificações hidromorfológicas, causaram um declínio da qualidade ecológica do estuário do Mondego. Em 1998, a implementação de medidas de mitigação permitiu a recuperação do sistema, mas a monitorização identificou elevadas concentrações de nutrientes que pediam uma avaliação da sua proveniência. Por esta razão, a bacia do Rio Mondego, emerge como um caso de estudo com as condições necessárias para identificar aplicações mais amplas de dados de ocupação do solo no âmbito da identificação de forças motrizes e pressões sobre a qualidade da água. O Capítulo I estabelece a linha de base para este trabalho através da aplicação de indicadores de nutrientes e de substâncias-consumidoras-de-oxigénio para analisar a evolução das concentrações de amónia, nitrato e fosfato no estuário do Mondego entre os períodos 2003-2007 e 2012-2013 (ANOVA no software R); para analisar as diferenças entre as concentrações médias anuais de nutrientes nos rios tributários em 2012-2013 e as concentrações médias anuais encontradas em rios europeus em três períodos diferentes (1992, 2000, 2012); e para avaliar as diferenças na variabilidade das concentrações de nutrientes no estuário e nos tributários em 2012-2013 (ANOVA em software R). Adicionalmente, o Capítulo I avalia a dependência das concentrações de nutrientes estuarinas das entradas de água doce provenientes dos tributários, em dois períodos distintos. Procurou-se a relação linear entre as concentrações de nutrientes e a salinidade, a precipitação e a temperatura (regressão linear no software R). Os resultados revelam diferenças entre os intervalos de tempo e mostram uma dependência das concentrações de nutrientes das entradas de água doce proveniente dos rios, o que indica pressão de cargas de nutrientes sobre o estuário. No Capítulo II a pressão exercida pela descarga de nutrientes nos rios da bacia hidrográfica é avaliada utilizando dados de ocupação do solo. Analisa-se a adequação de métricas de paisagem para descrever a variabilidade espacial de nitratos em toda a bacia do rio Mondego usando dados sazonais de 2001 e 2006 (modelo linear misto - software R). Os resultados revelam que os padrões de ocupação do solo são descritores fracos da variabilidade espacial de nitratos na bacia do rio Mondego. No Capítulo III caracterizam-se as forças motrizes da qualidade da água usando como proxy os processos de mudança da paisagem. Os mapas CORINE de 1990, 2000 e 2006 são utilizados para analisar as mudanças entre oito categorias de ocupação, através de uma análise alargada de matrizes de transição. A magnitude da mudança e a consistência das transições revelam que as forças motrizes mais relevantes incluem categorias com baixa percentagem de ocupação, mas elevado efeito potencial nos processos hidrológicos. No Capítulo IV, reconhecendo que a precisão dos mapas pode influenciar a nossa percepção acerca das forças motrizes que atuam no sistema, aplica-se uma Análise de Intensidade para avaliar a adequação dos mapas CORINE como indicadores de mudanças de ocupação. Transições inconsistentes indicam erros de classificação que se poderiam propagar para outras aplicações que utilizam mapas de mudança de ocupação do solo. Analisando os resultados concluímos que ainda há espaço para o desenvolvimento de indicadores, nomeadamente indicadores de eficácia-de-políticas; que os dados de ocupação do solo como indicadores de pressão podem revelar o efeito, a longo prazo, da implementação de políticas; que a magnitude e a consistência dos processos de mudança de ocupação do solo revelam informações adicionais relativamente à avaliação das forças motrizes de transições de ocupação e que os mapas CORINE, apesar de serem dados de elevada qualidade, têm limitações de precisão facilmente identificadas através de uma Análise de Intensidade. Em relação à concentração de nutrientes, o nosso estudo sugere que são necessárias medidas de mitigação para reduzir as entradas de concentrações de fosfato para o estuário, de preferência por meio de políticas a nível europeu. The European Water Framework Directive enhances the role of land use in determining water quality of all waters, but the use of land cover data, regarding surface waters, is restricted to the estimation of land use patterns for the identification of pressures on surface waters from diffuse source pollution. The main goal of this study is to uncover specificities of land cover in the assessment of state changes (Chapter I), pressures (Chapt er I and II) and drivers (Chapter III and IV) of water quality of surface waters. For this purpose, we use data from the Mondego river basin, a coastal watershed in Portugal , where socio - economic changes observed since the 1990 s resulted in the loss of rep resentativeness from the agricultural sector and gain from the construction sector. Despite the observed changes, agriculture remained a source of pressure on surface waters which, associated with hydro - morphological modifications, caused a decline of the ecological quality of the Mondego estuary. In 1998, the implementation of mitigation measures enabled the recovery of the system but routine monitoring identified high concentrations of nutrients deserving further assessment to understand its sources. For this reason, the Mondego river basin, as a case study, provided conditions to reveal wider applications of land cover data within the assessment of drivers and pressures of water quality. Chapter I establishes the baseline for our research applying indicat ors of nutrients and oxygen - consuming - substances to analyze progress in the concentrations of ammonia, nitrate and phosphate in the Mondego estuary from a former period (2003 - 2007) to a recent period (2012 - 2 2013) (ANOVA in R software); to analyze difference s between the annual mean concentrations of nutrients in the tributary rivers in 2012 - 2013 and the average annual mean concentrations found in European rivers in three different periods (1992, 2000, 2012); and to evaluate differences in the variability of nutrient concentrations between the estuary and the tributaries in 2012 - 2013 (ANOVA in R software). Additionally, Chapter I evaluates the dependency of estuarine nutrient concentration s on riverine freshwater inputs in two different periods. A linear relat ionship between the nutrient concentrations and salinity, precipitation and temperature was sought (linear regression in R software). Altogether the results indicate differences between time intervals and are able to establish a dependency of nutrient conc entrations on riverine freshwater inputs, indicating pressure from nutrient loadings on the estuary. In Chapter II pressure from nutrient flushing on the river basin is evaluated using land cover data as an indicator. The suitability of landscape metrics t o describe the spatial variability of nitrate across the Mondego river basin is assessed using seasonal data from the years 2001 and 2006 (linear mixed model - R software). The results reveal that land cover patterns are weak descriptors of nitrate spatial variability in the Mondego river basin. In Chapter III driving forces of water quality are characterized using processes of landscape change as proxy. CORINE Land cover maps at 1990, 2000 and 2006 are used to analyze changes among eight categories throug h an extended analysis of transition matrices. The magnitude of change and consistency of transitions reveal that the most relevant driving forces from land transitions include categories with low percentage of occupation but high potential effect on hydro logical processes. In Chapter IV, acknowledging that the accuracy of maps may influence our perception of the main driving forces acting in the system, the Intensity Analysis approach is applied to evaluate the suitability of the CORINE land cover maps as indicators of land change. Inconsistent transitions reveal the misclassification errors that could propagate to other land cover change applications, as in the assessment of hydrological processes. Through the analysis of the results we conclude that there is still space for the development of indicators, namely policy effectiveness indicators; land cover data as indicator of pressure may reveal the effect of policies’ implementation in the long - term; the magnitude and con sistency of the processes of land change reveal additional information regarding the assessment of driving Abstract 3 forces from land transitions and that CORINE maps, though being high quality datasets, have accuracy limitations that are easily accessed through Int ensity Analysis. Regarding nutrient concentrations, our study suggests that mitigation measures, preferably through policies at the European level, are needed to reduce the inputs of phosphate concentrations into the estuary.
The European Water Framework Directive enhances the role of land use in determining water quality of all waters, but the use of land cover data, regarding surface waters, is restricted to the estimation of land use patterns for the identification of pressures on surface waters from diffuse source pollution. The main goal of this study is to uncover specificities of land cover in the assessment of state changes (Chapter I), pressures (Chapter I and II) and drivers (Chapter III and IV) of water quality of surface waters. For this purpose, we use data from the Mondego river basin, a coastal watershed in Portugal, where socio-economic changes observed since the 1990s resulted in the loss of representativeness from the agricultural sector and gain from the construction sector. Despite the observed changes, agriculture remained a source of pressure on surface waters which, associated with hydro-morphological modifications, caused a decline of the ecological quality of the Mondego estuary. In 1998, the implementation of mitigation measures enabled the recovery of the system but routine monitoring identified high concentrations of nutrients deserving further assessment to understand its sources. For this reason, the Mondego river basin, as a case study, provided conditions to reveal wider applications of land cover data within the assessment of drivers and pressures of water quality. Chapter I establishes the baseline for our research applying indicators of nutrients and oxygenconsuming-substances to analyze progress in the concentrations of ammonia, nitrate and phosphate in the Mondego estuary from a former period (2003-2007) to a recent period (2012) - 2013) (ANOVA in R software); to analyze differences between the annual mean concentrations of nutrients in the tributary rivers in 2012-2013 and the average annual mean concentrations found in European rivers in three different periods (1992, 2000, 2012); and to evaluate differences in the variability of nutrient concentrations between the estuary and the tributaries in 2012-2013 (ANOVA in R software). Additionally, Chapter I evaluates the dependency of estuarine nutrient concentrations on riverine freshwater inputs in two different periods. A linear relationship between the nutrient concentrations and salinity, precipitation and temperature was sought (linear regression in R software). Altogether the results indicate differences between time intervals and are able to establish a dependency of nutrient concentrations on riverine freshwater inputs, indicating pressure from nutrient loadings on the estuary. In Chapter II pressure from nutrient flushing on the river basin is evaluated using land cover data as an indicator. The suitability of landscape metrics to describe the spatial variability of nitrate across the Mondego river basin is assessed using seasonal data from the years 2001 and 2006 (linear mixed model - R software). The results reveal that land cover patterns are weak descriptors of nitrate spatial variability in the Mondego river basin. In Chapter III driving forces of water quality are characterized using processes of landscape change as proxy. CORINE Land cover maps at 1990, 2000 and 2006 are used to analyze changes among eight categories through an extended analysis of transition matrices. The magnitude of change and consistency of transitions reveal that the most relevant driving forces from land transitions include categories with low percentage of occupation but high potential effect on hydrological processes. In Chapter IV, acknowledging that the accuracy of maps may influence our perception of the main driving forces acting in the system, the Intensity Analysis approach is applied to evaluate the suitability of the CORINE land cover maps as indicators of land change. Inconsistent transitions reveal the misclassification errors that could propagate to other land cover change applications, as in the assessment of hydrological processes. Through the analysis of the results we conclude that there is still space for the development of indicators, namely policy effectiveness indicators; land cover data as indicator of pressure may reveal the effect of policies’ implementation in the long-term; the magnitude and consistency of the processes of land change reveal additional information regarding the assessment of driving forces from land transitions and that CORINE maps, though being high quality datasets, have accuracy limitations that are easily accessed through Intensity Analysis. Regarding nutrient concentrations, our study suggests that mitigation measures, preferably through policies at the European level, are needed to reduce the inputs of phosphate concentrations into the estuary.

O presente estudo teve como objetivo analisar o papel das experiências nas relações próximas nas atitudes alimentares disfuncionais. A amostra é constituída por 246 estudantes universitários, do género feminino (n=176) e do género masculino (n=69), com idades compreendidas entre os 17 e os 53 anos (M=21.72; DP=5.38). Os instrumentos administrados incluíram um questionário sociodemográfico, o Questionário de Experiências em Relações Próximas – Estruturas Relacionais (ECR-RS) e o Teste de Atitudes Alimentares (TAA-25). Encontramos correlações significativas entre as dimensões da vinculação ansiosa e os Comportamentos Bulímicos, Dieta e Pressão Social para Comer. Encontramos diferenças significativas na Dieta em função do género, sendo que os homens apresentaram uma pontuação mais elevada. A vinculação evitante total revelou diferenças significativas em função do género, sendo que as mulheres apresentaram uma pontuação mais elevada. E a partir de uma regressão linear múltipla, foi possível demonstrar que apenas o género se revelou preditor de Dieta. Estes resultados, ainda que preliminares, contribuem para um melhor entendimento dos fatores que podem estar implicados nas atitudes alimentares disfuncionais.
The present study had as main objective to analyse the role of close relationship experiences in disfunctional eating attitudes. The sample is composed by 246 college students, 176 female and 69 male, with ages comprised among 17 and 53 years old (M=21.72; DP=5.38). The instruments administered included a socio-demographic questionnaire, the Experiences in Close Relationship-Relationships Structures Questionnaire (ECR-RS) and the Eating Attitudes Test-25 (EAT-25). Significant correlation was verified between attachment anxiety and bulimic behaviours and also between diet and social pressure to eat. There are significant gender differences in diet, with male subjects scoring higher than the female. The total attachment avoidance showed significant differences in gender, with the female showing a higher score. From a multiple linear regression analysis, it was possible to demonstrate that gender is a predictor of diet. These results, although preliminary, contribute to a better understanding of the factors that may be involved in dysfunctional eating attitudes.