Esse trabalho teve como objetivo verificar o efeito da adição do ácido oléico na moagem de alta velocidade/energia na obtenção de pós magnéticos em escala nanométricas da liga Pr12Fe65,9Co16B6Nb0,1. A primeira etapa deste trabalho, envolveu a obtenção de pós magnéticos por meio do processo de hidrogenação, desproporção, dessorção e recombinação (HDDR), utilizando a pressão de H2 de 930 mbar (hidrogenação e desproporção) e temperatura de dessorção e recombinação de 840 ºC. Inicialmente, os pós HDDR foram submetidos à moagem de alta velocidade/energia a 900 rpm, com variação do volume do meio de moagem (ciclohexano) sem adição de ácido oleico. Em seguida, os pós HDDR foram submetidos à moagem com adição de ácido oleico, variando o tempo de moagem. Após a moagem, foi realizado tratamento térmico dos pós a 700 ºC ou 800 ºC durante 30 min., com a finalidade de cristalização do pó. Foi verificado que, a utilização de 6,6 ml de ciclohexano como meio de moagem e com adição de ácido oleico há uma melhora na eficiência da moagem dos pós. Para adições de surfactante, de 0,02 a 0,05 ml e tempos de moagem até 360 minutos, não ocorre a aglomeração dos pós magnéticos no pote de moagem, obtendo acima de 90% de eficiência na moagem. A segunda etapa deste trabalho envolveu a caracterização dos pós magnéticos: utilizando magnetômetro de amostra vibrante, microscopia eletrônica de Varredura, microscopia eletrônica de transmissão e difração de raios-X. Os resultados obtidos mostraram que a adição de ácido oléico na moagem de alta velocidade/energia proporciona uma melhora nas propriedades magnéticas. Com a variação do tempo de moagem a fase Fe-α presente no pó HDDR apresenta diminuição no tamanho do cristalito (de 35 para ~ 10 nm) enquanto que, na fase Pr2Fe14B verifica-se menor grau de cristalinidade. / This work verified the effect caused by adding the surfactant in the high speed/energy milling in order to obtain Pr12Fe65.9Co16B6Nb0.1 magnetic nanopowders. The first part of this work involved the magnetic powder obtainment through the process of hydrogenation, disproportionation, desorption and recombination (HDDR). The pressure of H2 during the hydrogenation and disproportion steps was 930 mbar and the temperature of desorption and recombination was 840 ºC. Initially, the HDDR powders were subjected a highspeed milling process at 900 rpm, with quantity variations of the milling medium (cyclohexane) and without the addition of oleic acid. Then, the HDDR powders were subjected to the milling process with the addition of oleic acid and with milling time variations. After the milling process, heat treatments of the powder were carried out at 700 °C or 800 °C for 30 minutes in order to obtain the crystallization of the powder. By performing the procedures, it was verified that the milling efficiency improved with the addition of 6.6 ml of cyclohexane as the milling medium and with the addition of oleic acid. It was determined that for the surfactant additions of 0.02 ml to 0.05 ml, with a milling time of up to 360 minutes, powder agglomeration does not occur in the milling pot and the milling efficiency is higher than 90%. The second stage of this work involved the magnetic powders characterization obtained by using vibrating sample magnetometer, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Through the characterizations it was found that the powders magnetic properties improved when the addition of oleic acid in a high-speed /energy milling occurred. It was also verified that the α-Fe phase, present in the powder, shows a crystallite size decrease (from 35 nm to ~ 10 nm) when the time milling variation occurred; meanwhile, the crystallinity degree was lower in the Pr2Fe14B phase when the time milling variations was carried out.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-01-16T13:19:07Z No. of bitstreams: 1 josefelipesalomaopessoa.pdf: 2240048 bytes, checksum: 698aecc874e0df59ca702e747e6bf1be (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2017-01-31T10:34:55Z (GMT) No. of bitstreams: 1 josefelipesalomaopessoa.pdf: 2240048 bytes, checksum: 698aecc874e0df59ca702e747e6bf1be (MD5) / Made available in DSpace on 2017-01-31T10:34:55Z (GMT). No. of bitstreams: 1 josefelipesalomaopessoa.pdf: 2240048 bytes, checksum: 698aecc874e0df59ca702e747e6bf1be (MD5) Previous issue date: 2016-07-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo do estudo foi fornecer informações sobre a estrutura, composição florística e o estado de conservação do Parque Natural Municipal da Lajinha, Juiz de Fora, MG. Foram alocadas, aleatoriamente e georreferenciadas 25 parcelas permanentes, de 20 x 20 m, totalizando 1393 indivíduos arbóreos vivos e 145 mortos em pé (CAP ≥ 15,7 cm), pertencentes a 155 espécies, 100 gêneros e 51 famílias. Nectandra nitidula, Eugenia hiemalis, Bathysa australis, Virola bicuhyba, Alchornea triplinervea são as cinco espécies com maior VI, enquanto Fabaceae (23), Myrtaceae (14), Lauraceae (11), Euphorbiaceae (8), Sapindaceae (7), Meliaceae (5), Monimiaceae (5) e Rubiaceae (5) são as famílias com maior riqueza de espécies. O índice de diversidade de Shannon (H’) foi um dos mais altos registrados para florestas da região (H’ = 4,36 nats.ind-1), contendo inclusive espécies ameaçadas (Ocotea odorifera, Virola bicuhyba, Dicksonia sellowiana), segundo critérios do Livro vermelho da flora do Brasil. Metade da comunidade e a maioria das mortas se enquadram na primeira classe diamétrica proposta (7,5 cm), o que reflete elevado grau de competição. A distribuição diamétrica da comunidade seguiu o modelo “J-reverso”, padrão para comunidades florestais tropicais. O elevado índice de equabilidade de Pielou (J’ = 0,866) mostra baixa dominância ecológica e alta heterogeneidade florística da comunidade, confirmadas pelas análises de agrupamento florístico (coeficiente de Morisita-Horn), inferior a 0,5, e DCA (Análise de Correspondência Distendida), que apresentou altos valores, superiores a 0,3 (Eixo 1 = 0,49 e Eixo 2 = 0,33). O resultado da análise de similaridade florística nas unidades amostrais, utilizando o coeficiente qualitativo de Jaccard, evidencia a importância das espécies de baixa densidade na amostra. Esses resultados expõem a complexidade da dinâmica de funcionamento dos processos bióticos presentes em uma comunidade florestal secundária. Estudos com medições posteriores poderão analisar aspectos e atributos funcionais dessas espécies e seu papel efetivo na comunidade. A presença de espécies raras para o Estado de Minas Gerais e o alto índice de diversidade encontrado evidencia o potencial biológico do Parque Natural da Lajinha e reforça a necessidade da adequação do mesmo para se tornar Unidade de Conservação. / The aim of this study is to provide information about the conservation status, structure and composition of the Parque Natural Municipal da Lajinha, Juiz de Fora, Minas Gerais State, Brazil. Randomly placed and georeferenced 25 permanent plots of 20 x 20 m, totaling 1393 individuals living arboreal and 145 dead in sampled (CAP ≥ 15,7 cm), belonging to 155 species, 100 genera and 51 families. Nectandra nitidula, Eugenia hiemalis, Bathysa australis, Virola bicuhyba, Alchornea triplinervea are the five species with higher IV as Fabaceae (23), Myrtaceae (14), Lauraceae (11), Euphorbiaceae (8), Sapindaceae (7), Meliaceae (5), Monimiaceae (5) and Rubiaceae (5) are families with the highest species richness. The Shannon diversity index (H’) was one of the highest recorded for the region's forests (H’ = 4,36 nats.ind-1), containing including endangered species (Ocotea odorifera, Virola bicuhyba, Dicksonia sellowiana), according to Red Book of Brazilian flora. Half community and most dead fall within the first class proposal diameter (7,5 cm), which reflects the high degree of competition. The community diametric distribution followed the model "J-reverse" standard for tropical forest communities. The high evenness index of evenness (J’ = 0.866) shows low ecological dominance and high floristic heterogeneity of the community, floristic confirmed by cluster analysis (Morisita-Horn coefficient) is less than 0,5, and DCA, which showed values greater than 0,3 (Axis 1 = 0,49 and Axis 2 = 0,33). The result of floristic similarity analysis using qualitative coefficient of Jaccard highlights the importance of species of low density in the sample. These results expose the complexity of the operating dynamics of biotic processes present in a secondary forest community. Further resampling studies may analyze functional aspects and attributes of these species and their effective role in community. The presence of rare species for the state of Minas Gerais, the availability of resources for the regional fauna and high diversity index shows the biological potential of the Natural Park of Lajinha and reinforces the need to adapt the same to become a Unit Conservation.

Climate change and changes in the use and coverage of land, caused by human activities, have been changing the soil loss in the Brazilians watershed. Therefore, this paper estimated soil loss by extensive erosion in the watershed of the Piauitinga-SE river and assessed the possible effects of climate change and land use and land cover over the loss of soils in the basin. For this, we used the Universal Soil Loss Equation of (USLE) associated with GIS and remote sensing techniques. Historical series were used (between 15 and 68 years) daily rainfall and data on climate projections coming from the Global Climate Model (GCM), generated by the Community Climate System Model (CCSM) to the fourth assessment report of the Intergovernmental Panel on Climate Change ( IPCC). In the physiographic characteristics of the watershed, were used soil map, hydrographic network, slope information and images of high spatial resolution of the RapidEye sensor to year 2013. With this data, two estimates of soil loss were realized. The first estimate was considered two scenarios for the watershed: Scenario 1 (C1) with physiographic and usage conditions and current land cover; Scenario 2 (C2) with changes in land use and land cover, considering the preserved the Permanent Preservation Areas (PPAs), as Law No. 12,651/2012. In the second estimate it was considered four climate scenarios of rainfall: Current Scenario, Scenario optimistic (Low B1), Scenario Medium (Medium A1B) and scenario Pessimistic (High A2), and, for them, was only considered natural factors of erosion in the basin. In the first estimate, the two scenarios (C1 and C2) of use and assessed land cover presented most of the basin area with erosion between classes Very Low (0-5 ton-1.ha-1.year), Low ( 5-10 ton-1.ha-1.year) and moderate (10-50 ton-1.ha-1.year). Considering the scenario 2, there was a reduction in soil loss values, especially in the PPAs, proving the importance of maintaining these areas preserved for conservation of soil and water in the basin. As for the second estimate, it was observed that, when compared to the Current Scenario, the climate projections scenarios (Optimistic B1, Medium A1B and Pessimistic A2) caused reduction of rainfall erosivity and soil loss in the basin river Piauitinga - SE / As mudanças climáticas e as modificações no uso e cobertura da terra, provocadas pela ação antrópica, vêm causando alterações nas perdas de solos das bacias hidrográficas brasileiras. Portanto, este trabalho teve como objetivo principal estimar as perdas de solo por erosão laminar na bacia hidrográfica do rio Piauitinga-SE e avaliar os possíveis impactos das mudanças climáticas e do uso e cobertura da terra sobre as perdas dos solos na bacia. Para tal, utilizou-se a Equação Universal de Perdas de Solo (USLE) associada à técnicas de geoprocessamento e sensoriamento remoto. Foram utilizadas séries históricas (entre 15 e 68 anos) de precipitações diárias e dados de projeções climáticas oriundos do Global Climate Model (GCM), gerados pelo Community Climate System Model (CCSM) para o quarto relatório de avaliação do Painel Intergovernamental das Mudanças Climáticas (IPCC). Na caracterização fisiográfica da bacia, foram utilizados mapas de tipo de solos, rede hidrográfica, informações de relevo e imagens de alta resolução espacial do sensor RapidEye do ano de 2013. De posse dos dados, foram realizadas duas estimativas de perdas de solo. Na primeira estimativa foram considerados dois cenários para a bacia: Cenário 1 (C1), com as condições fisiográficas e de uso e cobertura da terra atuais; Cenário 2 (C2) com alterações no uso e cobertura da terra, considerando as Áreas de Preservação Permanentes Preservadas, conforme Lei nº 12.651/2012. Na segunda estimativa foram avaliados quatro cenários climáticos de precipitação pluviométrica: Cenário Atual, Otimista B1, Médio A1B e Pessimista A2, sendo que, para estes, foram considerados apenas os fatores naturais de erosão da bacia. Na primeira estimativa, os dois cenários (C1 e C2) de uso e cobertura da terra avaliados apresentaram maior parte da área da bacia com erosão entre as classes Muito Baixa (0-5 ton-1.ha-1.ano), Baixa (5-10 ton-1.ha-1.ano) e Moderada (10-50 ton-1.ha-1.ano). Considerando o Cenário 2, houve uma redução nos valores de perda de solos, principalmente nas APPs, comprovando a importância de manter estas áreas preservadas para a conservação do solo e da água na bacia. Já para a segunda estimativa, foi observado que, quando comparado ao Cenário Atual, os cenários de projeções climáticas (Otimista B1, Médio A1B e Pessimista A2) provocaram redução da erosividade das chuvas e perdas de solo na bacia do rio Piauitinga - SE.

La deformación permanente es una de las principales responsables del deterioro temprano de la capa asfáltica de carreteras. Este tipo de fenómeno, se ve impulsado en el país debido a la carga vehicular pesada y la variedad climática, en particular, las altas temperaturas. Se sabe que el comportamiento de la mezcla asfáltica, depende directamente de los materiales que la constituyen. Y ante condiciones desafiantes, estos materiales son insuficientes. En ese sentido, la presente investigación busca mejorar las propiedades de una mezcla asfáltica convencional mediante la adición de fibras de basalto y lignina, de tal manera que sea menos propensa a sufrir deformaciones permanentes. Para la parte experimental, se contó con agregados procedentes de la cantera Conchán, en Lima. Mediante la metodología de Marshall, se diseñaron dos mezclas asfálticas. La primera mezcla fue elaborada sin aditivos y en base a expedientes técnicos de la zona. La segunda mezcla se elaboró con los mismos componentes y con adición de 0.3% fibras de basalto y 0.3% de fibras de lignina. Las muestras fueron sometidas a ensayos de estabilidad y flujo, índice de rigidez, vacíos de agregado mineral y resistencia a la compresión. Los resultados de la investigación mostraron que al incorporar fibras de basalto y fibras de lignina se aumentan la estabilidad de la mezcla en 7%, el índice de rigidez de Marshall en 6%, el porcentaje de vacíos de agregado mineral en 2% y la resistencia a compresión en 4%. De lo anterior de infiere que la mezcla asfáltica propuesta tiene una mayor capacidad para distribuir la carga, mayor resistencia a la deformación por fluencia, mayor capacidad de expansión para contrarrestar las altas temperatura y, en consecuencia, mayor resistencia a las deformaciones permanentes. / Permanent deformation is one of the main causes of the early deterioration of the asphalt layer of roads. This type of phenomenon is driven in the country due to the heavy vehicle load and the climatic variety, in particular, the high temperatures. It is known that the behavior of the asphalt mixture depends directly on the materials that make it up. And in challenging conditions, these materials are insufficient. In this sense, the present research seeks to improve the properties of a conventional asphalt mixture by adding basalt and lignin fibers, in such a way that it is less prone to permanent deformation. For the experimental part, it was used aggregates from the Conchán quarry, in Lima. Using Marshall's methodology, two asphalt mixes were designed. The first mixture was made without additives and based on technical files in the area. The second mixture was made with the same components and with the addition of 0.3% basalt fibers and 0.3% lignin fibers. The samples were subjected to stability and flow tests, stiffness index, mineral aggregate voids and compressive strength. The results of the investigation showed that when incorporating basalt fibers and lignin fibers the stability of the mixture is obtained in 7%, the Marshall stiffness index in 6%, the percentage of voids of mineral aggregate in 2% and the resistance a compression in 4%. From the foregoing, it can be inferred that the proposed asphalt mix has a greater capacity to distribute the load, greater resistance to creep deformation, greater expansion capacity to counteract high temperatures and, consequently, greater resistance to permanent deformations. / Tesis

Les prairies permanentes sont reconnues pour les nombreux services agronomiques et environnementaux qu’elles fournissent. Cependant, elles sont aujourd’hui encore retournées ou menacées de l’être au profit de productions plus rentables, ou abandonnées dans le cas des prairies humides où les conditions d’exploitation sont soumises à de nombreuses contraintes. Concilier objectifs de production et environnementaux afin de maintenir une activité agricole extensive au sein des prairies temporaires s’avère alors indispensable. Dans ce contexte, des études multi-services ont été réalisées au sein des prairies humides du Parc Naturel Régional (PNR) des marais du Cotentin et du Bessin (Normandie) ainsi que dans des prairies mésophilesaux conditions pédoclimatiques contrastées situées en Normandie, en Lorraine et en Auvergne. L’étude s’est focalisée sur 3 catégories de services écosystémiques (SE) telles que définis par le Millenium Ecosystem Assessment: la diversité floristique et fonctionnelle comme services de support, la qualité et la production du fourrage comme services d’approvisionnement et les stocks de carbone organique et les teneurs en carbone soluble du sol comme services de régulation. Afin de mettre en évidence la part du fonctionnement des communautés végétales dans le déterminisme des SE, la mesure de traits fonctionnels foliaires a été réalisée à l’échelle de l’espèce et/ou de la communauté végétale. Une partie de ces travaux se focalise sur les relations entre le fonctionnement des communautés végétales et la qualité du fourrage ainsi que l’impact des conditions hydriques du solsur les teneurs en micronutriments des espèces dans les prairies humides.Les résultats ont mis en évidence, qu’en fonction du groupe fonctionnel considéré, le SLA ou le LDMC étaient de bons proxies de la digestibilité des fourrages des prairieshumides. Les dicotylédones ont des teneurs en micronutriments plus élevées que les monocotylédones. Nos résultats montrent que l’inondation influence plus la composition élémentaire des espèces intolérantes aux inondations que les espèces adaptées et qu’elle n’a pas incidence sur la production de biomasse. De manière générale, le fonctionnement des communautés végétales n’explique pas à lui seul les relations entre les SE. La qualité du fourrage est liée au fonctionnement des communautés végétales ainsi qu’à la diversité floristique et fonctionnelle mais seulement en prairies humides. En prairies mésophiles, l’historique de la gestion ou la structure du paysage pourrait être déterminants. Par ailleurs, nos résultats montrent que les stocks de C organique dans le sol des prairies mésophiles et humides sont étroitement liés à sa nature.Les indicateurs des SE combinent les prairies humides en 4 groupes distincts en selon la nature du sol et la gestion (fauche ou pâturage). Globalement, les bouquets de services rendus par les prairies humides sont mieux équilibrés que ceux rendus par les prairies mésophiles, ces derniers ne se distinguant pas les uns des autres selon la localisation géographique des prairies mésophiles. Les prairies gérées de manière extensive fournissent de meilleurs services environnementaux que des prairies gérées de manière intensive et une qualité fourragère équivalente. / Permanent grasslands are recognized for the many agronomic and environmental services they provide. However, they are still plowed or threatened to be in favor of more productive cultures, or abandoned in the case of wet grasslands, where the conditions of exploitation are subjected to many constraints. Reconciling production and environmental objectives in order to maintain extensive agricultural activities is therefore essential in permanent grasslands. In this context, multi-service studies have been carried out in the wet grasslands of the Regional Natural Park (PNR) of the Cotentin and Bessin marshes (Normandy, France) as well as in a set of mesophilous grasslandsofcontrasting pedoclimatic conditions located in Normandy, Lorraine and Auvergne. The study focused on 3 categories of Ecosystem Services (ES) as defined by the Millennium Ecosystem Assessment: floristic and functional diversity as support services, quality and forage production as supply services and stocks of organic carbon and soluble carbon soil contents as regulatory services. In order to analyzethe role of plant community functioning in the ES determinism, the measurement of leaf functional traits was carried out at the species and/or the plant community scales. Part of this work focuses particularly on the relationships between plant communities functioning and forage quality, and soil moisture conditions impact on micronutrient contents of species in wet grasslands. The results showed that, depending on the functional group, SLA or LDMC were good proxies for the digestibility of wet grassland forages. Dicots have higher micronutrient contents than Monocots. Our results show that flooding influences the elemental composition of flood-intolerant species more than adapted species and does not affect biomass production. In general, the plant community functioning does not explain all the relationship between ESs. Forage quality is linked to the plant community functioning as well as thefloristic and functional diversity but only forwet grasslands. In mesophilic grasslands, the history of management or the landscape structure could be important drivers. In addition, our results show that organic C stocks in the soil of wet and mesophilic grasslands are closely related to soil nature. ESs indicators have brought together 4 distinct groups of wet grasslands according to soil nature and management practices (mowing or grazing). Overall, the ESs packages offered by wet grasslands are better balanced than those provided by mesophilic grasslands, the latter being indistinguishable from another according to the geographical location. Extensively managed grasslands provide better environmental services than intensively managed grasslands and equivalent forage quality.

Les systèmes d’élevages laitiers herbagers montagnards sont d’autant plus sensibles aux changements de contraintes de production (types de fourrages et niveaux d’aliments concentrés autorisés dans les cahiers des charges AOP par exemple) et aux aléas climatiques que le milieu est contraignant et que le système fourrager repose sur l’utilisation exclusive de prairies permanentes. Une meilleure adéquation entre les dynamiques de besoins des animaux et d’offre herbagère permettrait à ces systèmes d’atteindre un meilleur degré d’autonomie fourragère et alimentaire, et d’être ainsi plus robustes face aux changements. Pour explorer des stratégies contrastées de conduite et comprendre les compromis qu’il est possible d’atteindre entre niveau de production, autonomie fourragère et utilisation durable des prairies, un modèle de simulation déterministe à l’échelle de l’exploitation a été construit, nommé Dynamilk. Ce modèle simule les interrelations entre le troupeau laitier, les ressources alimentaires et herbagères et la conduite du système. Dynamilk est composé de deux sous-modèles biotechniques avec, d’une part, le parcellaire comportant un module de croissance de l’herbe prenant en compte la diversité botanique des prairies, et d’autre part, le troupeau laitier. Un modèle de structure démographique du troupeau simule les différentes catégories d’animaux selon leur âge et leur stade physiologique, et, un modèle dynamique simule l’ingestion et la production pour chaque catégorie d’animaux. La production laitière résulte des besoins énergétiques, de l’énergie offerte par la ration et de la capacité des animaux à mobiliser ou reconstituer leurs réserves corporelles. Le modèle de conduite est composé des éléments stratégiques définissant les objectifs de production et les règles de pilotage des principales pratiques (constitution et gestion des fourrages, alimentation et pâturage du troupeau). Le modèle animal et le modèle global ont été validés sur des données expérimentales ou de référentiels de fonctionnement d’exploitations. Ces deux modèles présentent des résultats et un fonctionnement cohérent. Dynamilk a permis de tester deux systèmes contrastés selon leur dynamique annuelle de production (période des vêlages « groupés de septembre à février » (GA) vs « groupés de mars à mai » (GP)) à chargement (0,94 UGB/ha) et apports de concentrés (1 200 kg/VL/an) identiques. Dans un plan d’expérience virtuel, chaque système a été simulé sur deux séries climatiques, une sans aléa climatique (1993-1999) et l’autre avec (2005-2011), avec une augmentation du chargement et une diminution des apports de concentrés. Les résultats de simulation montrent qu’à faible chargement les deux systèmes sont autonomes pour les fourrages et sous-utilisent les ressources herbagères au pâturage. L’augmentation du chargement améliore l’utilisation de l’herbe pâturée sans pénaliser les performances laitières, mais réduit l’autonomie en fourrages récoltés. Diminuer les apports de concentrés améliore également l’utilisation de l’herbe, mais réduit la production laitière. La production laitière du système GA est plus sensible que celle du système GP à la qualité des fourrages récoltés qui varie selon les années climatiques. Ainsi le système GP, grâce à plus d’utilisation de l’herbe pâturée, serait moins sensible aux aléas. Dynamilk permet d’analyser la réponse de systèmes laitiers herbagers sur des séries climatiques longues et de tester pas à pas des modifications de structure et de pilotage du système dans une démarche de conception de systèmes ex ante. / Dairy systems based on grasslands are sensitive towards environmental variations (climatic events) and production constraints changes. A better match between dynamic of dairy cattle needs and herbage supply could enable the farming system to lean towards a better forage self-sufficiency at farm-scale and to be more resilient to changes. Modeling approach is used to study, over many years, several scenarios with contrasted strategies of biotechnical subsystems management in order to test different calving distributions, cattle and grasslands characteristics, or practices on pastures and meadows. Such a dynamic model, called Dynamilk, has been created and implemented. Dynamilk is focused on relationships among dairy cattle, management and resources. This model is based on a bio-technical approach focused on grassland use by animals. Grassland sub model which consists in biodiversity characteristics and grass growth components has been developed by Jouven (2006). Dairy cattle sub model consists in 2 units: demographic structure unit and intake, milk production and body reserve use unit. This model considers calving period and distribution, dairy cattle characteristics (ability of animals to produce milk and use its body reserve) in order to test the match between animal needs and feed supply. Milk production according to herbage and feed supply is the main output of Dynamilk. Decisional sub-system describe the main practices to rule the production system which are forage system management with mowing practices, forage stores, winter diet, concentrate distribution and grazing management. Validation of dairy cattle sub model and whole model has been carried out by comparison against experimental data and case-study data of real farms. Two systems has been simulated with Dynamilk, the first one based on calving distribution from august to february, called GA, and the second one from march to june, called GP (stocking rate 0.94 LU.ha-1 and concentrate amount 1200 kg.cow-1.year-1). Simulation results have pointed out that both system achieved forage self-sufficiency and grass offer is underused. Several simulations has been accomplished to evaluate impacts of stocking rate increase and concentrate decrease on animal production, herbage utilisation and forage self-suficiency rate. The simulation have indicated that matching animal needs with feed and herbage supply to better cope with climatic events and constraints changes.

La mise en place d’une agriculture plus durable nécessite une compréhension de l’impact des pratiques de gestion sur le fonctionnement des agroécosystèmes et sur la fourniture de services écosystémiques. En représentant près de 68% des terres agricoles mondiales et contribuant à la subsistance de plus de 800 millions de personnes, les prairies sont l’un des agroécosystèmes où l’optimisation des pratiques agricoles apparaît comme cruciale. Ce travail de thèse porte sur le chaulage, une pratique agricole connue pour lutter contre les effets de l’acidification des sols – qu’elle soit naturelle ou induite par la gestion – mais dont l’efficacité est variable en prairie permanente. De fait, la littérature documentant l’impact du chaulage en prairie permanente est limitée et ne prend en compte que rarement la multifonctionnalité de ces agroécosystèmes. Par une approche intégrant différents types d’expérimentations, mon travail de thèse a cherché à répondre à ce besoin et à renforcer les connaissances du chaulage sur le fonctionnement de l’écosystème prairial. Le développement d’expérimentations au champ (in situ), en conditions semi-contrôlées (mésocosmes) et d’incubations de sol au laboratoire (microcosmes) a permis d’explorer les effets du chaulage sur les différents compartiments de l’écosystème prairial (végétation, microorganismes, sol) ainsi que l’influence de facteurs modulant ces effets. Dans l’ensemble des expérimentations, le chaulage a effectivement augmenté le pH des sols. Toutefois, cette amélioration du statut acido-basique du sol ne s’est pas toujours traduite par une augmentation de la productivité du fourrage ou des biomasses microbiennes et racinaires. Mes travaux ont montré que le chaulage contribue aux émissions de gaz à effet de serre par différentes voies (réémission du carbone apporté sous forme de chaulage et stimulation de la minéralisation) et peut potentiellement réduire les émissions de CO2 à l’échelle de la respiration de l’écosystème. Collectivement mes résultats soulignent l’importance du contexte pédoclimatique sur l’impact du chaulage en prairie permanente, et la difficulté d’extrapoler les effets du chaulage, en particulier sur la production de fourrage et les émissions de gaz à effet de serre, d’une échelle d’étude fine à l’échelle de la parcelle en prairie permanente. L’efficacité du chaulage semble dépendre du type d’amendement et de son dosage et peut également interagir avec d’autres pratiques de gestion telles que la fertilisation azotée et le niveau d’intensité de gestion. / The development of sustainable agriculture requires greater understanding of the impact of management practices on agroecosystem functioning, and on the ecosystem services provided by these agroecosystems. Representing nearly 68% of world's agricultural surfaces and contributing to the livelihoods of more than 800 million people, grasslands are one of the major agroecosystems where optimized agricultural practices are of concern. This PhD focuses on liming, a well-known practice for counteracting soil acidification (due to ongoing natural processes or accelerated by management practices), but which has variable efficiency in permanent grasslands. Indeed, liming effects on grassland are poorly documented and existing studies rarely take into account grassland multifunctionality. My thesis uses an integrated approach to improve the knowledge of liming impacts on grassland functioning. Different types of experiments – in the field (in situ), in semi-controlled conditions (mesocosms) and laboratory soil incubations (microcosms) – were used to study liming effects on different grassland compartments (vegetation, microorganisms, soil) along with possible interacting factors. Liming effectively increased soil pH in all the experiments. However, improving pH status did not always lead to greater forage production or increases in microbial and root biomass. My results showed that liming can enhance greenhouse gas emissions through several pathways (reemission of lime-derived carbon or stimulation of carbon mineralization), but may also reduce CO2 emissions from ecosystem respiration. Collectively, my findings emphasize the importance of pedoclimatic conditions for liming impacts on permanent grasslands and highlight the difficulty of upscaling liming effects, particularly on forage production and greenhouse gas emissions. The efficiency of liming appears to depend on the type and dose of soil improvers and can also interact with other management practices such as nitrogen fertilization and management intensification.

O objetivo deste estudo in vitro foi avaliar e comparar a microestrutura e a composição mineral do esmalte e da dentina de dentes decíduos e permanentes. Terceiros molares hígidos e segundos molares decíduos foram selecionados e distribuídos aleatoriamente em grupos, de acordo com o método de análise dos substratos utilizado: Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Energia Dispersiva de Raio X (EDX), Difração de Raio X (DRX) e Microscopia Óptica (MO). Foi realizada comparação qualitativa e quantitativa da estrutura dental. As medidas de densidade numérica e diâmetro dos prismas de esmalte/túbulos dentinários e, de espessura do esmalte, dentina e dentina peritubular foram realizadas por meio de fotomicrografias obtidas pela MEV. Os resultados obtidos por meio da SEM foram analisados estatisticamente pelo teste não-paramétrico de Kruskal-Wallis. A quantidade relativa de íons cálcio (Ca) e fósforo (P) foram determinadas por meio de EDX e as fases químicas presentes em ambos os substratos, por análise de DRX. O valor das medidas de espessura observado para o esmalte e dentina dos dentes decíduos foi de 1.14 mm e 3.02 mm, respectivamente. Para os dentes permanentes, obtiveram-se valores de 2.58 mm para o esmalte e 5.95 mm para a dentina. Com relação ao diâmetro da cabeça dos prismas de esmalte, os resultados foram estatisticamente semelhantes para os dentes decíduos e permanentes, demonstrando uma ligeira diminuição do diâmetro da superfície externa para a região próxima a junção amelodentinária (JAD). A densidade numérica dos prismas foi maior nos dentes decíduos, principalmente próximo à JAD, sendo estatisticamente diferente dos valores observados nos dentes permanentes, independente da região analisada. Na análise do diâmetro e densidade numérica dos túbulos dentinários verificou-se semelhança estatística entre os dentes decíduos e permanentes, havendo aumento gradativo do número de túbulos a partir da JAD em direção a região próxima a polpa. A espessura da dentina peritubular, na região próxima a JAD e central foi, respectivamente, 0.91 e 0.59 mm nos dentes decíduos 1.16 e 0.98 mm nos dentes permanentes. A porcentagem de Ca e P foi maior nos dentes permanentes. Observou-se ainda, que a quantidade de colágeno nos dentes decíduos foi aparentemente menor quando analisados por meio da MO. De acordo com os resultados obtidos neste estudo, pode-se concluir que, de maneira geral, os dentes decíduos apresentam menor porcentagem de Ca e P, menor espessura de esmalte e dentina, maior densidade numérica de prismas e dentina peritubular mais delgada quando comparada aos dentes permanentes. / This study evaluated in vitro the microstructure and mineral composition of dental enamel and dentin comparing the permanent teeth with the deciduous teeth. Sound third molars and second primary molars were selected and randomly assigned to the following groups, according to the analysis methods of the substrates performed: Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), Energy dispersive X-ray spectrometer (EDS) and Optical Microscopy (OP). A qualitative and quantitative comparison of the dental structure was done. The measurements of the number and diameter of prisms/tubules, thickness of enamel, dentin and peritubular dentin were done in SEM photomicrographs. The microscopic findings were analyzed statistically by a non-parametric test (Kruskal- Wallis). The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Phase present in both types of teeth were observed by the XRD analysis. The mean thickness measurements observed in the deciduous teeth enamel and dentin was, respectively, 1.14 mm and 3.02 mm and in the permanent teeth, 2.58 mm and 5.95 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enameldentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The mean tubules number and diameter in deciduous teeth were statistically similar to that of permanent teeth, and this numerical density increased from the EDJ to the region near the pulp. The mean thickness measurements of peritubular dentin observed in the regions near EDJ and central were, respectively, 0.91 and 0.59 mm for the primary teeth / 1.16 and 0.98 mm for the permanent teeth. The percentage of Ca and P was higher in the permanent teeth. The collagen level was apparently lower in deciduous teeth when analyzed by OP. The primary teeth structure showed a lower level of Ca and P and a thinner enamel and dentin thickness. The deciduous enamel presented higher numerical density of rods. The peritubular dentin was thicker in the permanent teeth.

Este trabalho apresenta as características básicas de uma máquina elétrica com fluxo axial, ímãs permanentes, rotor duplo e estator com enrolamentos toroidais montado entre os rotores. A máquina foi construída no Laboratório de Máquinas Elétricas, Acionamentos e Energia da Escola de Engenharia da UFRGS. O trabalho contém modelos analíticos para as induções magnéticas dos ímãs permanentes e dos enrolamentos de armadura. A partir dos modelos foram desenvolvidas expressões para o cálculo de forças eletromotrizes e de conjugados, sendo utilizado um software de matemática simbólica para realização dos cálculos. É apresentada uma comparação entre os resultados obtidos através do modelo analítico e os resultados obtidos por simulação numérica. Alguns resultados são comparados também com valores experimentais. As expressões para o cálculo de conjugado desenvolvido pela máquina serão detalhadas em uma etapa posterior. Foi obtida uma razoável coerência entre os dados comparados. / This work presents the basic features of an axial flux, permanent magnet, double rotor and toroidal windings mounted between the rotors. The machine was built in the Laboratory of Electrical Machines, Drives and energy of the School of Engineering of the Federal University of Rio Grande do Sul. The work contains analytical models of permanent magnets and armature windings magnetic inductions. Based in models, expressions of electromotive forces and torques were derived. The calculations were performed with a symbolical mathematical software. It is presented a comparison between results obtained with analytical model and results of the numerical simulation. Some comparisons include experimental results. The expressions of machine torque will be detailed in a next phase. The compared results present an acceptable conformity.

Este trabalho apresenta as características básicas de uma máquina elétrica com fluxo axial, ímãs permanentes, rotor duplo e estator com enrolamentos toroidais montado entre os rotores. A máquina foi construída no Laboratório de Máquinas Elétricas, Acionamentos e Energia da Escola de Engenharia da UFRGS. O trabalho contém modelos analíticos para as induções magnéticas dos ímãs permanentes e dos enrolamentos de armadura. A partir dos modelos foram desenvolvidas expressões para o cálculo de forças eletromotrizes e de conjugados, sendo utilizado um software de matemática simbólica para realização dos cálculos. É apresentada uma comparação entre os resultados obtidos através do modelo analítico e os resultados obtidos por simulação numérica. Alguns resultados são comparados também com valores experimentais. As expressões para o cálculo de conjugado desenvolvido pela máquina serão detalhadas em uma etapa posterior. Foi obtida uma razoável coerência entre os dados comparados. / This work presents the basic features of an axial flux, permanent magnet, double rotor and toroidal windings mounted between the rotors. The machine was built in the Laboratory of Electrical Machines, Drives and energy of the School of Engineering of the Federal University of Rio Grande do Sul. The work contains analytical models of permanent magnets and armature windings magnetic inductions. Based in models, expressions of electromotive forces and torques were derived. The calculations were performed with a symbolical mathematical software. It is presented a comparison between results obtained with analytical model and results of the numerical simulation. Some comparisons include experimental results. The expressions of machine torque will be detailed in a next phase. The compared results present an acceptable conformity.