O pastejo é considerado um fator determinante para a manutenção e conservação da vegetação campestre (campos) no sul do Brasil, sendo considerado o responsável por construir a heterogeneidade estrutural, a composição de espécies e a diversidade dos campos. Porém o manejo do pastejo é fundamental para sucesso da atividade pecuária, uma vez que longos períodos de pastejo excessivo e intenso ao invés de manter áreas campestres pode degradá-las, diminuindo a diversidade e produtividade, tornando os campos suscetíveis a invasão por espécies exóticas. Para o sucesso da relação construída entre o manejador, os animais e a vegetação, as estratégias de manejo que possibilitem uma pecuária rentável, mas que busque conservar a vegetação campestre, são fundamentais. O objetivo desta tese foi verificar os efeitos do pastejo sobre a vegetação campestre, tendo como ferramenta principal para isso, diferentes manejos. Os efeitos do pastejo foram avaliados através de índices de diversidade taxonômica e funcional, e da variação de atributos funcionais de gramíneas, analisando especificamente: (1) como estratégias de manejo contínuo e rotativo influenciam a dinâmica da vegetação campestre (biomassa, diversidade, riqueza e equitabilidade); (2) a influência do manejo do pastejo na composição e diversidade funcional de comunidades campestres descritas por gramíneas, e os efeitos sobre a variação intra- e interespecífica de atributos foliares (SLA e LDMC) das espécies de gramíneas; (3) o efeito de diferentes intensidades de pastejo (ofertas de forragem) nas diversidades alfa e beta das comunidades de plantas. Foram verificadas mudanças na diversidade, equitabilidade, riqueza de espécies, biomassa condicionadas pelo pastejo rotativo, que se mostrou benéfico para vegetação campestre. O pastejo rotativo proporcionou também um incremento na diversidade funcional, condicionado pela variação intra- e interespecífica nos atributos das gramíneas. Diferentes intensidades de pastejo promoveram diferenças de alfa e beta diversidade sob diferentes intensidades de pastejo. O pastejo demonstrou exercer papel determinante em toda a dinâmica campestre, tendo efeitos consideráveis em todos os níveis de avaliação, desde a riqueza de espécies até na diversidade funcional, ficando evidente que a decisão do manejo é fundamental tanto para a produtividade quanto para a manutenção da vegetação campestre. / Grazing is considered a determining factor for the maintenance and conservation of grasslands in southern Brazil and is considered one of the main driver of the structural heterogeneity, species composition and diversity of the grasslands. But the management of grazing is key to the success of livestock farming, since long periods of excessive and intense grazing instead of maintaining grassland, can degrade them, reducing the diversity and productivity, leading the grassland susceptible to invasion of exotic species. For the success of the relationship built between managers, animals and vegetation, a strategic management that allows an efficient farming together with the conservation of grassland vegetation is essential. The objective of this thesis was to investigate the effects of grazing on the grassland, based on different managements of grazing. The effects of grazing were evaluated by taxonomic and functional diversity indices, and the variation of functional traits of grasses, analyzing specifically: (1) how continuous and rotational grazing management influence the dynamics of grassland vegetation (biomass, diversity, richness and evenness); (2) the influence of grazing management on the functional composition and functional diversity in grassland communities described by grasses, and its effects on the intra- and interspecific variation of leaf traits (SLA and LDMC) of grass species; (3) the effect of different grazing intensities (forage dry matter offer) in the alpha and beta diversity of plant communities. Changes in diversity, evenness, species richness, and biomass were verified, which were conditioned by the rotational grazing that proved beneficial to grassland. The rotational grazing provided also an increase in functional diversity, due to intra and interspecific variation of the grasses traits. Different grazing intensities promoted differences in alpha and beta diversity under different grazing intensities. Grazing demonstrated to have a decisive role in the whole dynamics of grassland communities, with considerable effects on all levels here assessed, from the species richness to the functional diversity, becoming apparent that the management decision is very important for both the productivity and the maintenance of grassland structure and diversity.

A asma é definida como uma doença inflamatória crônica de caráter multifatorial, caracterizada pela obstrução reversível das vias aéreas, denso infiltrado inflamatório e hiper-reatividade brônquica a estímulos externos. Clinicamente, a doença é marcada por sintomas episódicos de dispneia, sibilo, tosse seca e sensação de aperto no peito. A terapia convencional da asma compreende o uso de anti-inflamatórios e broncodilatadores. A budesonida é um glicocorticoide esteroide e é dos fármacos mais utilizados na terapêutica da asma. No entanto, a budesonida apresenta baixa biodisponibilidade oral e o uso prolongado pode levar a efeitos adversos graves como afinamento da pele e supressão adrenocortical. No desenvolvimento de novas formulações, a avaliação da toxicidade é de extrema importância. Por conseguinte, o uso de cultura celular é de grande valia no desenvolvimento de protocolos para avaliação da toxicidade de novas formulações. Adicionalmente, a nanotecnologia é uma ferramenta importante para resolver problemas de biodisponibilidade e para contornar efeitos adversos da terapêutica convencional. Desta forma, o objetivo desta tese foi desenvolver um novo sistema nanoestruturado na forma de pó seco para inalação (Dry powders inhalers – DPI), obtido por aspersão contendo budesonida encapsulada, visando o tratamento da asma aguda e crônica. Essa proposta foi baseada na obtenção de um sistema pulverulento nanoestruturado com tamanho reduzido e controlado, visando a entrega pulmonar da budesonida. Na etapa de pré-formulação foi realizado um estudo fatorial avaliando diferentes métodos de preparação das nanocápsulas e os adjuvantes de secagem utilizados. As análises de tamanho de partícula, da formulação selecionada (nanocápsulas contendo budesonida e secas por aspersão com leucina) mostraram um tamanho reduzido e adequado para a administração pulmonar (2,7 μm). A morfologia demonstrou que estas partículas possuem um tamanho reduzido, forma esférica e superfície irregular, características importantes para a administração pulmonar. Quando analisada a distribuição pulmonar in vitro, em Impactador de Andersen, a formulação apresentou uma fração de partículas finas (Fine Particle Fraction – FPF) de 28%. Analisando os resultados dos experimentos em modelos de asma aguda e crônica induzidos por ovalbumina, os resultados da mecânica respiratória e função pulmonar mostraram uma diminuição na resistência e na elastância pulmonar, quando a budesonida nanoencapsulada foi utilizada, quando comparada com uma formulação comercial de budesonida, nas duas doses utilizadas (0,5 e 1,0 mg/Kg). Esse tratamento com nanocápsulas também mostrou eficiência na redução da inflamação, pela redução do número de leucócitos totais no fluido de lavagem bronco alveolar (Broncho Alveolar Lavage Fluid – BALF) e, principalmente, redução significativa no número dos eosinófilos no infiltrado pulmonar. Corroborando esses resultados, a quantificação da eotaxina – 1 e das citocinas pró-inflamatórias foram reduzidas, quando comparadas ao tratamento comercial. A análise histopatológica mostrou que quando o tratamento com as nanocápsulas foi utilizado, a produção de muco foi reduzida, bem como a produção de fibrose sub-epitelial, sugerindo um possível efeito sobre o remodelamento tecidual. Os resultados de toxicidade utilizando linhagem celular epitelial pulmonar (H441) mostrou uma redução na toxicidade da budesonida, quando encapsulada nas nanopartículas, tanto na forma de suspensão como na forma pulverulenta. Essa redução da toxicidade foi de 75% e de 50%, na dose de 100 μg/mL, para a suspensão e para o DPI, respectivamente. O conjunto dos resultados obtidos mostrou a potencial aplicabilidade da budesonida nanoencapsulada para o tratamento da asma, utilizando esse novo sistema DPI. / Asthma is characterized as a chronic inflammatory disease developed by multifactorial aspects such as genetic predisposition and exposure to environmental factors such as pollution, smoke and microorganisms. The conventional asthma therapy comprises the use of bronchodilators and anti-inflammatory. Budesonide is a glucocorticoid and is the most frequently used therapy in the treatment of asthma. However, this drug has low oral bioavailability and long term use may lead to adverse effects such as skin thinning and adrenal suppression. The evaluation of the toxicity of new formulation has critical role in the pharmaceutical development. The use of cell culture experiments can help this aspect. Additionally, nanotechnology is an important tool to solve problems regarding bioavailability and to circumvent adverse effects of conventional therapy. The aim of this work was to develop a nanostructured system as dry powder inhaler (DPI) containing budesonide loaded, obtained by spray-drying, targeting the treatment of acute and chronic asthma. This proposal was based on obtaining a nanostructured powder system with reduced and controlled size, aiming an alternative to treatment of asthma. A factorial study comparing different methods to produce the nanocapsules as well as the type of drying adjuvants was performed. The particle size of the selected formulation was 2.7 μm, an adequate reduced size suitable for pulmonary administration. The morphology of these particles showed a small size, spherical shape and irregular surface. All these characteristics are important for pulmonary administration. When analyzed the in vitro pulmonary distribution of the DPI, using an Andersen Cascade Impactor, showed a fine particle fraction (FPF) of 28%. Analyzing the results of the biological experiments, the mechanical respiratory and pulmonary function showed a decrease in lung elastance and resistance when budesonide was used nanoencapsulated compared with a commercial formulation of budesonide in two doses (0.5 and 1.0 mg / kg). Both treatments also showed nanocapsules efficiency in reduction of inflammation by reducing the total of leukocytes in the bronchial alveolar lavage fluid (BALF) and especially significant reduction in eosinophil infiltration in the lung tissue. Corroborating with these results, the quantification of eotaxin - 1 and proinflammatory cytokines was reduced when compared to commercial budesonide treatment. Histopathological analysis showed that when treatment with the nanocapsules was used, mucus production was reduced and reversed the phenomena of airway remodeling. The cytotoxicity assay by Alamar blue using the bronchial epithelium cell line (H441) showed a reduction on the toxicity of budesonide when the nanocapsules were used even in suspension or in the DPI. The cytotoxicity reduction were 75 and 50%, at 100 μg/mL, for the suspension and the DPI, respectively. All these results show that budesonide-loaded nanocapsules in dry powder inhaler is a promising approach for the treatment of asthma.

Este trabalho fez parte de um projeto de pesquisa financiado pelo ITV - Instituto Tecnológico Vale, realizado em parceria com a UFRGS. Devido a heterogeneidade dos carvões, partículas que apresentam baixo ou nenhum contéudo de carbono estão misturadas ao carvão de excelente qualidade podendo representar uma parcela significativa do carvão ROM, implicando em aumento de custos no processamento de estéreis e transporte de rejeitos. Diante da disponibilidade de equipamento comerciais utilizados na separação de minerais grosseiros em unidades móveis ou semi-móveis junto as minas, estima-se que a técnica de SBS possa ser utilizada na pré-concentração de carvões Moçambicanos, com objetivo de reduzir a quantidade de rejeitos enviados a planta de beneficiamento, reduzindo custos operacionais e impactos ao meio ambiente, uma vez que a pré-concentração é realizada a seco. A técnica de SBS foi aplicada a 4 diferentes camadas do carvão da mina de Moatize e sua eficiência avaliada. Os resultados demonstraram ser possível reduzir o teor de cinzas da alimentação de minério ROM. Por meio da remoção de minério de baixa qualidade foi possível reduzir de 10 a 14% da massa, promovendo a redução do teor de cinzas de 10 a 20%, na fração grosseira estudada. / This research is part of a project financed by ITV - Vale Technological Institute, in partnership of UFRGS. Due to coal heterogeneity, particles with low or no content of carbon are mixed with high quality coals and constitute a significant part of the run of mine, which promotes an increase in costs of waste processing and transportation. Commercially available mobile and semi-mobile sorting equipments for mining ores implement dry processes for preconcentration. Therefore, it is estimated that the SBS technique could be used in preconcentration of Mozambique's coal, with the aim to reduce the waste sent to the concentration plant, thus reducing operational costs and environmental impacts. The SBS technique was applied to four different coal's of the Moatize Mine seam and the efficiency was evaluated. The results shows it is possible reduce the ash content in the coarse fraction from feed plant. Through removal of the low quality ore was possible reduce 10 to 14% of mass, which promoted the reduction of ash content from 10 to 20% in coarse fraction feeding the concentration plant.

Orientador: Jane Maria Bertocco Ezequiel / Banca: Leandro das Dores Ferreira da Silva / Banca: Leonardo de Oliveira Fernandes / Banca: Mauro Dal Secco de Oliveira / Banca: Ricardo Andrade Reis / Resumo: Foram realizados três experimentos com o objetivo de avaliar o comportamento ingestivo de bovinos submetidos a diferentes estratégias de suplementação e seus efeitos sobre o desempenho. No primeiro experimento foram utilizados 24 bovinos da raça Nelore, machos,castrados com aproximadamente 14 meses de idade, com peso médio aproximado de 320 kg de PV distribuídos em três lotes de oito animais cada e mantidos em três piquetes providos de bebedouros e cochos. A suplementação protéica (24%PB) foi fornecida diariamente na quantidade de 1 kg/animal/dia para avaliar o efeito, sobre o desempenho dos animais, das variáveis comportamentais em pé (EP), em pé ruminando (EPR), comendo o suplemento (C) e pastejando (P). Os animais foram acompanhados em cinco períodos diários contínuos de 8 h (das 9 às 17h), usando-se a coleta instantânea, com intervalo amostral a cada cinco minutos. Não foram observadas diferenças significativas para as variáveis comportamentais nos diferentes lotes e dias de observação, sendo obtidas as médias EPR= 0,84; 0,82 e 1,10; EP= 1,26; 1,02 e 1,3; C = 1,06; 1,26 e 1,26; P = 3,14; 3,2 e 2,96 h, por período de observação diário, e os ganhos médios foram 0,23, 0,19 e 0,18 kg/animal respectivamente para os lotes 1, 2 e 3. Concluiu-se que as variáveis comportamentais não influenciaram o ganho de peso, que deve ter sido atribuído a fatores de ordem social e características qualitativas da pastagem. No segundo experimento foram utilizadas trinta novilhas mestiças... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Were conducted three experiments with the objective to evaluate the ingestive behaviour of bovines submitted different strategies of supplementation and its effect on the performance .In the first experiment were used 24 Nelore steers, males castrated approximately 14 months, and medium weight of 320 kg BW The animals were designated to three groups of eight animals each and maintained in three provided pickets of drinking fountain and hod. The daily proteic (24%PB)supplementation being the supplement supplied in the amount of 1 Kg/animal/day for evaluate the effect in performance animals recording the behavioural categories standing up an still(EP),standing up and ruminating(EPR)eating the supplement( C) and grazing( P ). For this study the animals were accompanied in three continuous periods of 8 h (9:00 the 17:00), totaling 40 hours of visual observations with continuous assessment and focal sampling, with interval every five minutes for the recording the behavioural categories. There was no significant difference for the behavioural categories in differents groups and daily period of observation the means obttid were EPR= 0,84; 0,82 e 1,10; EP= 1,26; 1,02 e 1,3; C = 1,06; 1,26 e 1,26; P = 3,14; 3,2 e 2,96 h in period of observation, in weight gain on the animal performance in the different groups were as 0,230, 0,195 and 0,183 kg/animal/day respectively in the groups 1,2 e 3 ist must have the factors of social order and qualitative characteristics in the pasture. In second were used thirty crossbred heifers, with age and corporal weight average initials of 10 months and 234 kg PV. All the experimental animals daily received the supplement in the amount from 0,5%PV in individual pens of 8 m2 (4x2 m), containing concrete hod and drinking fountain. / Doutor

<p>Prinos zrna predstavlja jednu od najznačajnijih i najsloženijih osobina u oplemenjivanju biljaka. Poznavanje razvića, rastenja i akumulacije suve materije, omogućava pravilan odabir genotipova i odgovarajuće tehnologije gajenja. Cilj istraživanja je bio da se izvr&scaron;i ispitivanje filohrona, akumulacije i translokacije suve materije nadzemnog dela biljaka, prinosa zrna i komponenti prinosa, različitih genotipova ozime p&scaron;enice i ječma sejanih u vi&scaron;e rokova setve i vegetacionih sezona. Zatim da se utvrdi odgovarajuća jednačina koja opisuje akumulaciju suve materije i pojavu listova na glavnom stablu ječma i p&scaron;enice u funkciji sume temperatura tokom različitih rokova setve i vegetacionih sezona. U ogled je bilo uključeno po &scaron;est genotipova ozimog dvoredog ječma i ozime p&scaron;enice različitog porekla, pedigrea i agronomskih osobina, sejanih dve sezone u četiri roka setve. Sredinom cvetanja i u punoj zrelosti, uzeto je 10 slučajno odabranih biljaka. Na uzetim biljkama određena je masa pojedinačnih organa i komponente prinosa, kao i translokacija suve materije i doprinos asimilata akumuliranih pre cvetanja u masi zrna. Za utvrđivanje filohrona i ukupnog broja listova, dva puta nedeljno se očitavao broj listova na obeleženim biljkama tokom čitave sezone. Istovremeno se uzimao i uzorak od pet biljaka u cilju praćenja akumulacije suve materije. Sezona, rok setve i sorta su imali značajan uticaj na variranje ukupnog broja listova i filohrona kod ječma i p&scaron;enice. U proseku, sorte ječma su formirale vi&scaron;e listova u odnosu na p&scaron;enicu, dok se p&scaron;enica karakteri&scaron;e dužim filohronom. Kasnija setva dovela je do značajnog smanjenja broja listova i skraćenja filohrona kod obe vrste. U zavisnosti od sezone, roka setve, sorte i njihove interakcije menjala se i biomasa biljaka u cvetanju i prinos zrna. Translokacija suve materije je bila u pozitivnoj korelaciji sa biomasom biljaka u cvetanju. Akumulacija biomase nadzemnog dela biljaka tokom sezone, pratila je tipičan sigmoidni obrazac u svim kombinacijama rokova setve i sorti. Od tri posmatrane nelinearne jednačine, Logistička jednačina se pokazala najprikladnijom za opisivanje akumulacije suve<br />materije tokom sezone kod ječma i p&scaron;enice. Rezultati istraživanja ukazuju na značaj vegetativne mase biljaka u cvetanju, koja predstavlja bitan izvor asimilata za translokaciju u zrno. Ovi rezultati ukazuju da je tokom oplemenjivanja strnih žita, neophodno stvarati genotipove sa većim brojem listova koji bolje nakupljaju biomasu, odnosno genotipove koji će u optimalnom roku setve, imati usklađen fenolo&scaron;ki razvoj sa agroekolo&scaron;kim uslovima u području Panonske nizije.</p> / <p>Grain yield is one of the most important and complex traits in plant breeding. Knowledge about crop development, growth and dry matter accumulation enables the appropriate selection of genotypes and field technology. The aims of this study were to investigate the variability of phyllochron, dry matter accumulation and translocation, grain yield and yield components of various wheat and barley genotypes, in relation to the sowing date and growing season. Furthermore, the goal was to find the equation that would appropriately describe dry matter accumulation and leaf appearance of wheat and barley. Six winter barley and six winter wheat genotypes, characterized by different origin, pedigree and agronomic traits, were sown in two growing seasons across four sowing dates. At the anthesis and physiological maturity, 10 randomly selected plants were manually cut at ground level. Dry mass of different plant organs, yield components, dry matter translocation and contribution of pre-heading dry matter to grain yield were determined. To determine the leaf number and phyllochron, measuring was done according to the Haun scale on three tagged plants per replication three times per week. Also, samples consisting of five plants were collected to determine dry matter accumulation. Growing season, sowing date and variety had significant influence on the final leaf number and phyllochron of wheat and barley. At average, barley varieties had more leaf compared to wheat, while wheat had higher phyllochron values. Late sowing reduced the final leaf number and phyllochron in both barley and wheat. Furthermore, growing season, sowing date, variety and sowing date &times; variety interaction had significant influence on crop biomass at anthesis and grain yield. Dry matter translocation was in positive correlation with dry matter content at anthesis. Dry matter accumulation across growing seasons had a typical sigmoid pattern in every combination of sowing date and variety. Among studied models, the logistic equation was the most appropriate for description of dry matter accumulation in wheat and barley. Results from this study highlight the importance of dry matter content at anthesis, which represent a significant source of assimilates for translocation into the grain. These results indicated that during the selection of small grain cereals, it is necessary to develop genotypes characterized by higher leaf number and increased biomass, i.e. genotypes that in optimal sowing dates, have an adjusted phenological development to the agro-ecological conditions of the Panonian plane.</p>

Os métodos de ensaio editados pela ABNT para caracterizar argamassas colantes foram um avanço em termos de normalização do produto e ajudaram a melhorar sua qualidade. Entretanto, os métodos apresentam dispersão expressivamente elevada e especificam condições de ensaios que não condizem com a realidade das condições de campo. Em vista dessas discrepâncias, o presente trabalho analisa a normalização nacional juntamente com a normalização dos principais organismos internacionais. Para avaliar os principais requisitos de qualidade, foram estudadas dez amostras comerciais de argamassa colante. Através da análise dos resultados obtidos são propostas alterações nos métodos de ensaio da normalização da ABNT, como o deslizamento, tempo em aberto teórico e resistência de aderência à tração. Os pontos principais visam à alteração de critérios de qualidade e a condição ambiental de laboratório. Entre as propostas estão: 1) especificação do ensaio deslizamento apenas para produtos com esse propósito, 2) a eliminação do requisito resistência de aderência à tração na condição de cura em estufa, 3) novo critério para o requisito de resistência de aderência à tração na condição de cura submersa, 4) especificação de nova faixa de temperatura para a condição de clima quente na avaliação do tempo em aberto teórico e 5) inclusão do método de ensaio de tempo em aberto com a ruptura da película superficial. Além disso, são propostas a incorporação de métodos de ensaios utilizados para avaliação da uniformidade da argamassa durante a produção como: a perda de massa, resíduo em peneira e densidade de massa aparente. Também são propostas alterações na especificação e caracterização do substrato-padrão utilizados nos ensaios. / The Associação Brasileira de Normas Técnicas essay methods to characterize cementitious adhesives for tiles represented an advance in terms of standardization of the product and helped to improve its quality. However, the methods present high dispersion of results and specify essay conditions that do not correspond to the site real conditions. In view of these discrepancies, the present work brings out an analysis of the national standards and a comparison to the main international standards. To check for the main quality requirements, a study was carried out with ten samples of comercial cimentitious adhesives for tiles. Through analysis of the results, changes in the ABNT essay methods are proposed as to slip, open time and tensile adhesion strength. The main issues aim at changing the performance criteria and the laboratory ambient conditions. Among the proposals are the following: 1) specification of essay slip only for products with this purpose, 2) the elimination of heat curing in the tensile adhesion strength essay, 3) new criterion for water immersion curing, a new band of temperature for the warm climate condition in the evaluation of theoretical open time and 5) the inclusion of an open time essay method with rupture of the superficial film. Moreover, it is proposed essay methods for evaluation of the uniformity of the mortar during its production process like mass loss, sieve residue and apparent mass density. Also, changes in the specification and characterization of the concrete slab used in essays are proposed.

Déterminer la durée de vie d'une pièce sous excitation vibratoire est l'un des enjeux majeurs dans l'ingénierie mécanique. Afin de donner une estimation fiable de la durée de vie, un calcul correct de champ de contrainte, qui est fortement lié à la forme et l'amplitude modale est obligatoire. Cependant, le calcul de réponse d'une structure assemblée est difficile, surtout avec la présence de frottement sec aux interfaces de liaisons qui entraîne un amortissement non linéaire. La recherche de la thèse commence par une identification phénoménologique de l'amortissement induit par le frottement sec avec 3 modèles analytiques, notamment la plaque sandwich, la rotule frottante et la plaque von Kármán. Après la caractérisation de l'amortissement structural au 1er et 2ème ordre, les influences des paramètres comme la pression de serrage, le rapport d'épaisseurs ainsi que le nombre de soudures sont analysés. La deuxième partie des travaux traite les problèmes d'amortissement avec une géométrie de dimension finie. La plaque de von Kármán est reprise dans l'étude et une méthode hybride de différences finies et d'éléments finis est adopté pour résoudre le couplage entre la flexion et les efforts internes. Une attention particulière est portée à la notion de modes non linéaires dans le cas de la plaque von Kármán. Les conditions nécessitant l'introduction de modes non linéaires sont identifiées. Le champ de force fictif qui est proposé dans l'étude sur la plaque von Kármán est ensuite introduit dans le cas de la plaque sandwich. Puis la propagation de glissement et l'influence de champ fictif sont étudiées. Afin de vérifier les phénomènes trouvés dans les études théoriques, une installation expérimentale est conçue et montée pour l'amortissement structural au premier ordre. Dans la dernière partie qui est basée sur les observations faites dans les études précédentes, une méthode de calcul de l'amortissement dans un environnement industriel est proposée. Cette méthode permet de donner un amortissement pour chaque mode isolé. / The determination of a component's lifetime under vibrational excitation is one of the most difficult challenges in mechanical engineering. In order to provide a reliable estimation of lifetime, a correct calculation of stress field, which depends on the modal form and its amplitude, is needed. However, the vibrational response calculation on an assembled structure is not easy, especially with the nonlinear structural damping induced by frictional contact surface. The research in the current thesis starts from the phenomenological identification of damping with the help of 3 analytical models, in particular the sandwich plate, rotational joint and von Karman plate. Structural damping of 1st and 2nd order are identified. The influence of parameters like clamping pressure, thickness ratio and number of welding points are also analyzed. The second part of the research focuses on problems with finite dimensions. The von Karman plate serves as the subject of the study and a hydride method which combines FDM and FEM is proposed to solve the coupling between defection and in-plane force field. A special attention is paid to nonlinear mode theory, the conditions under which the nonlinear mode is necessary are identified. The fictive force field proposed in the study of von Kármán plate is then applied to the sandwich plate model. The slipping's propagation as well as the influence of fictive force field are studied. To verify the existence of the found phenomena in the previous studies, an experimental setup is designed and mounted for the 1st order structural damping. In the last part of the research, which is based on the observations previously obtained from academic models, a calculation method of friction-induced damping in structures with complex geometries is proposed for the application in the industrial environment. This methods enables the estimation of damping for each isolated mode.

Projected increasing temperatures and reduced summer precipitation in the UK raises questions about the sustainability of aspects of the agriculture industry and food security. This study investigates the potential impact of precipitation changes on sugar beet yield in Eastern England. Observations of precipitation was examined for the period 1971-2000 and the expected changes in precipitation were investigated using seven CMIP5 climate models for the historical phase (1971-2000) and RCP45 and RCP85 future scenarios (2021-2050). Three out of the seven models were found to show good agreement with observations but the MOHC ensemble mean was the closest to the observed means and was used for further precipitation analyses. Statistical analysis of the future precipitation changes were performed using the Met Office Hadley Centre (MOHC) model focused on changes between the historical phase and RCP45 and RCP85. Results showed a consistent and significant reduction in annual May-October precipitation under future scenarios. The study then investigated the impact of reduced future precipitation changes on sugar beet yield by applying controlled watering regimes informed by the CMIP5 projections to sugar beet plants in a greenhouse experiment over two seasons - the use of CMIP5 projections in this way is a first. In the first experiment carried out in 2014, a climatological watering regime (i.e. where the total seasonal rainfall for the different scenarios was applied in equal and regular watering events) was applied to the plants, which meant a 16% reduction in precipitation in the "future" category relative to a "control" category. Analysis of the yields indicated a statistically significant reduction in mean tuber wet mass: mean of 360g for the control and 319g for the future (p-value 0.03). This implies a potential yield reduction of 11% by 2050. In the second experiment carried out in 2015, a "realistic distribution" watering regime (i.e. where the total seasonal rainfall is applied in a series of watering events that reflect the analysed sizes and distribution of rainfall events in the different categories), this meant a reduction in precipitation in the months of June (-15.6%), July (-7.7%) and August (-3.7%). This resulted in statistically significant reduction in mean tuber wet mass between control (153g) and RCP85 (113g) with a p-value of 0.01. This implies a reduction of 26% in future yields under RCP85 by 2050. Results in this thesis further show how changes and variation in precipitation are intertwined with changes in soil moisture and yield of sugar beet plants. The findings will enable UK sugar beet farmers to identify potential areas of challenges in order to adapt their management practices to ensure maximum crop yield in future growing seasons. Moreover, from a global perspective, the findings here are also broadly applicable to a variety of agricultural crops in different parts of the world, where changes in yield may have important consequences to food security and food prices.

Climate models predict changes to the frequency and intensity of extreme events, with large effects on tropical forests likely. Predicting these impacts requires understanding how landscape configuration and land-use change influence the susceptibility of forests to disturbances such as wind, drought, and fire. This is important because most tropical forests are regenerating from anthropogenic disturbance, and are located in landscape mosaics of forest, agriculture, and other land use. This dissertation consists of four chapters that combine remote sensing and field data to examine causes and consequences of disturbance and land-use change in tropical second-growth forests. In Chapter 1, I use satellite data to identify factors associated with permanence of second-growth forest, and assess how estimates of carbon sequestration vary under different assumptions about second-growth forest permanence. I show that most second-growth forest is cleared when young, limiting carbon sequestration. In Chapter 2, I combine data from weather stations, remote sensing, and landowner surveys to model fire activity on 732 farms in the study area over ten years. The relative importance of these factors differs across scales and depending on the metric of fire activity being considered, illustrating how implications for fire prevention and mitigation can be different depending on the metric considered. Chapter 3 combines Landsat imagery and field data to map wind damage from a severe convective storm, providing strong empirical evidence that vulnerability to wind disturbance is elevated in tropical forest fragments. Finally, in Chapter 4 I integrate annual forest census data with LiDAR-derived topography metrics and tree functional traits in a hierarchical Bayesian modeling framework to explore how drought, topography, and neighborhood crowding affect tree growth, and how functional traits modulate those effects. The results from these studies demonstrate innovative approaches to understanding spatial variation in forest vulnerability to disturbance at multiple scales, and the results have implications for managing forests in a changing climate.

A Baía de Guanabara, ambiente de localização do Arsenal de Marinha do Rio de Janeiro (AMRJ), sofre com a intensa pressão antrópica, principalmente no aspecto da qualidade das águas. Neste contexto, uma fração considerável da poluição decorre das atividades dos estaleiros, uma vez que a atividade industrial naval no Rio de Janeiro não tem mecanismo de controle de poluição à altura do seu real potencial poluidor. Esta ausência de fiscalização possibilita o lançamento na Baía de resíduos sólidos, esgotos sanitários, efluentes químicos, oleosos e tóxicos, tornando crescente a contaminação dessas águas, margens e mangues. Estes descartes cada vez mais são alvo das exigências ambientais da sociedade e das legislações. Devido a isto, a gestão de efluentes líquidos do Arsenal tornou-se prioritária, para tal, esse estudo foi proposto, tendo iniciado pela análise das oficinas do estaleiro, na qual as operações no dique foram identificadas como uma das mais impactantes do estaleiro. A partir desta constatação, estão apresentadas duas fontes de pesquisas para a redução dos impactos. Na primeira etapa, há o estudo das atividades geradoras de efluentes no dique de reparo, com os objetivos de propor a implantação das diretrizes de melhores práticas de gestão, de minimizar a geração de efluentes líquidos e de contribuir para a adoção de práticas ambientais proativas. Como segunda pesquisa, com base nas tecnologias mundiais, há a proposta de tratamento dos efluentes de um dique, na qual foram identificados os processos que irão atender às necessidades ambientais do estaleiro, com as opções de escolha entre o tratamento parcial, para o descarte na rede pública, ou com o prosseguimento do processo até o seu reúso. As conclusões deste estudo apontam para a implantação da gestão ambiental do dique sistematizada, rigorosa e integrada com a gestão das embarcações, acrescentando-se a isto, as necessidades de incorporação de tecnologias modernas e de sistema de tratamento dos efluentes, propiciando de maneira sustentável que haja a continuação do processo de produção do estaleiro e, ao mesmo tempo, permitindo o retorno da biodiversidade da Baía de Guanabara. / Guanabara Bay, located at Arsenal de Marinha do Rio de Janeiro (AMRJ), suffers from intense human pressure, especially on what is referred about water quality. In this context, a considerable part of the pollution comes from the shipyards activity, sine that the naval industrial activity in Rio de Janeiro has no mechanism for pollution control that matches its real potential polluter. This lack of inspection makes it possible the launch of solid waste in Guanabara Bay, in addition of sanitary sewage, chemical waste, oily and toxic, which increases the contamination of the water, shores and mangroves. These discard has been, more and more, a target of societys environmental demands and of laws also. Because of that, the management of wastewater from Arsenal has become a priority, for that, this study was suggested. Beginning with the analyses of the shipyard workshops, which dry docks activities have been identified as one of the most striking on the shipyard. From this conclusion, two research sources for impact reduction are presented. In the first stage there is a study of activities that creates wastewater in the dry dock of repair, with the purpose to propose the establishment of guidelines to improve the management practices, to minimize the production of liquid effluents and to help with the embracement of pro-active environmental practices. In the second research, with bases in world technologies, there is the purpose to treat the effluents from a dry dock, in which there were processes identified that would attend to the shipyards environmental needs, with options of choice between the partial treatment, for disposal in public network, or to the persecution of reuse procedure. The conclusions of this study point to the implantation of a systemized environmental management of the dry dock, rigorous and integrated with the management of vessels. Adding to it, the need to incorporate modern technologies and treatment systems of effluents, which will provide, in a sustainable way, that the process of production of the shipyard could proceed. And, at the same time, allowing the return of the biodiversity of the Guanabara Bay.