A turbulência gerada em equipamentos de grade oscilante presta-se a uma série grande de comprovações experimentais de proposições teóricas. Isto ocorre tanto para a turbulência propriamente dita, como para os fenômenos de transporte a ela associados. Usualmente não se considera a presença de correntes preferenciais nas constatações experimentais conduzidas nesses equipamentos. Entretanto, para que as previsões teóricas possam ser definitivamente corroboradas, é preciso quantificar as correntes preferenciais e a sua forma, de modo que se possa inferir a sua influência nos fenômenos medidos. No presente estudo apresentam-se resultados da quantificação das correntes preferenciais em escoamentos gerados por grades oscilantes. / Turbulence generated by oscillating grids is used in a series of experimental procedures to support or to test theoretical proposals. This way to conduct the studies is usual for turbulence itself and also for associated transport phenomena. Usually the preferential currents are not taken into account during the experiments conducted in oscillating grids equipments. However, to definitively corroborate theoretical predictions, it is necessary to quantify the preferential currents and to determine the shape of the flow, in a way that permits to infer the effects on the measured phenomena. In the present study, results related to preferential currents generated in a stirred grid equipment are presented.

De par ses propriétés physiques et chimiques particulières du bois de chêne, une barrique est le siège de phénomènes de transfert très complexes. Les tonnelleries souhaitent apporter de plus en plus de précision pour le choix des barriques en ce qui concerne les arômes transmis au bois mais aussi en ce qui concerne les échanges entre l’atmosphère du chai et le vin. Le projet a permis d’améliorer les connaissances sur les phénomènes de transfert d’oxygène au travers des douelles et à l’inter-douelle et de quantifier l’importance des paramètres interagissant sur les transferts tels les phénomènes d’absorption, le type de chauffe et les caractéristiques du bois. Cette étude a permis de définir des paramètres de caractérisation des barriques par rapport au transfert d’oxygène afin de mieux conseiller les utilisateurs pour le choix des barriques et leur mise en œuvre. L’objet du projet repose sur une approche pluridisciplinaire. Nous avons caractérisé les barriques pour émettre des hypothèses de transfert, puis nous avons quantifié la cinétique de désorption d’oxygène du bois et de son imprégnation. De plus, nous avons évalué la quantité d’oxygène consommé par les polyphénols. Enfin, grâce au développement d'un perméamètre permettant de placer les morceaux de douelles dans des conditions opératoires variées, nous avons mesuré des flux d’oxygène de part et d’autre de la cellule. La désorption est le phénomène prépondérant dans l'apport d'oxygène. Le transfert d'oxygène se fait essentiellement à l'inter-douelle dans les zones de faibles pressions. / Many complex transfer phenomena occur in Oak barrels, due to the physical and chemical properties of Oak wood. Coopers want to provide their consumers with more and more advice according to the aromas given by the wood of the barrel to the wine but also according to the interactions between the winery atmosphere and the wine. The aim of this project is to improve the knowledge of oxygen transfer through staves and between two staves. It is also to quantify the parameters that influence the oxygen transfer such as absorption phenomena, type of barrel toasting and oak wood characteristics. This study should bring to light characteristic parameters of barrels according to oxygen transfer in order to give better advice to users. This would allow them to choose the best barrels and know how to implement them. This project uses a multidisciplinary approach. The first part is to characterize barrels is order to suggest hypothesis about transfer phenomena. Then, kinetics of impregnation and desorption of oxygen contained in oak wood are quantified. Moreover, we try to evaluate the quantity of oxygen consumed by polyphenols. Finally, oxygen transfer evaluation is possible thanks to the development of a new cell allowing us to place a piece of stave in various operating conditions and to measure the flux of oxygen on both sides of the cell. Thus, the laws of transfer can be described; modeling of the quantity of oxygen transferred to wine could be done according to the utilization conditions and to the type of staves.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / NÃs investigamos a teoria dos modelos de LÃgicas Preferenciais, LÃgica HÃbrida e fragmentos da LÃgica de Segunda-Ordem com relaÃÃo a modelos finitos. A semÃnticas dessas lÃgicas diferem da abordagem clÃssica pelo uso de relaÃÃes entre modelos ou por restringir a cardinalidade dos modelos a cardinais finitos. Este trabalho tem trÃs partes. Na primeira parte deste trabalho nÃs estudamos a teoria dos modelos de lÃgicas preferenciais. LÃgicas preferenciais surgem no contexto do raciocÃnio nÃo-monotÃnico em InteligÃncia Artificial. A principal caracterÃstica dessas lÃgicas à a existÃncia de uma relaÃÃo entre modelos. Isso permite a definiÃÃo de uma relaÃÃo de consequÃncia nÃo monotÃnica considerando-se os modelos minimais de um conjunto de sentenÃas. Usando a abordagem da Teoria dos Modelos Abstrata, nÃs generalizamos alguns resultados de expressividade para classes de lÃgicas preferenciais. NÃs mostramos que sempre que uma classe de modelos minimais de um conjunto finito de sentenÃas à axiomatizÃvel, entÃo tal classe à finitamente axiomatizÃvel. NÃs mostramos que se tal classe define implicitamente um sÃmbolo do vocabulÃrio, existe uma axiomatizaÃÃo finita de uma forma particular, a saber, o conjunto finito de sentenÃas inicial mais uma definiÃÃo explÃcita para o sÃmbolo definido. Na segunda parte desse trabalho, nÃs investigamos a teoria dos modelos finitos da LÃgica HÃbrida. LÃgicas HÃbridas sÃo extensÃes da lÃgica modal atravÃs de termos hÃbridos que se referem a estados individuais em um modelo de Kripke. NÃs estudamos a complexidade computacional dos problemas de model- e frame- checking para a LÃgica HÃbrida. NÃs mostramos que para cada problema de grafos na Hierarquia Polinomial e cada nÃmero n, existe uma fÃrmula que exprime esse problema para grafos de cardinalidade n. NÃs mostramos que o tamanho das fÃrmulas à limitado por um polinÃmio em n. NÃs mostramos que podemos abrir mÃo das modalidades globais se nos limitarmos a grafos conexos com loops. NÃs definimos fragmentos da LÃgica HÃbrida que correspondem a cada nÃvel da Hierarquia Polinomial. Isso nos leva a uma prova alternativa da NP-dificuldade do problema de model-checking para um fragmento especÃfico de da LÃgica HÃbrida. Na Ãltima parte desse trabalho, nÃs exploramos a complexidade descritiva da lÃgica obtida ao restringirmos a quantificaÃÃo de segunda-ordem a relaÃÃes de grau limitado. Baseados em trabalhos anteriores de Schwentick et al. e de Grandjean e Olive, nÃs introduzimos a LÃgica de Segunda-Ordem de Grau Limitado e mostramos que ela captura a classe ALIN de classes de estruturas unÃrias aceitas por uma mÃquina de acesso randÃmico em tempo linear e um nÃmero fixo de alternÃncias dependente apenas do problema. NÃs estendemos essa lÃgica com o operador de fecho transitivo sobre relaÃÃes de ordem superior sobre relaÃÃes de grau limitado. NÃs mostramos que a LÃgica de Segunda- Ordem de Grau Limitado com Fecho Transitivo captura quantidade linear de registradores em uma mÃquina de acesso randÃmico nÃo-determinÃstica onde os valores armazenados em cada registrador durante a computaÃÃo sÃo limitados por uma funÃÃo linear na cardinalidade da estrutura de entrada. / We investigate the model theory of Preferential Logics, Hybrid Logic and fragments of Second-Order Logic with respect to finite models. The semantics of these logics differ from the semantics of classical logics either by using relations between models or by restricting the cardinality of the models considered. This work has three main parts. In the first part of this work we study the model theory of preferential logics. Preferential logics arise in the context of nonmonotonic reasoning in Artificial Intelligence. The main characteristic of those logics is the existence of a relation between models. It allows the definition of a nonmonotonic consequence relation by considering the minimal models of a set of sentences. Using the approach of Abstract Model Theory we generalize some expressiveness results to classes of preferential logics. We show that whenever a class of minimal models of a finite set of sentences is axiomatizable, without considering the preference relation, then it is finitely axiomatizable. We also show that when such class of minimal models implicitly defines a symbol, then the finite axiomatization can be put in a very specic form, namely, the initial set of sentences plus a explicit definition for the symbol. In the second part of this work, we investigate the finite model theory of Hybrid Logic. Hybrid Logics are extensions of modal logics with hybrid terms which refer to single states in a Kripke model. We study the complexity of the model- and frame-checking problems for Hybrid Logic. We show that for each graph problem in the Polynomial Hierarchy and each natural number n there is a formula which expresses this problem for graphs of cardinality n. We also show that the size of such formulas is bounded by a polynomial in n. We show that one can disregard the global modalities if one consider only connected graphs with loops. We define fragments which correspond to each degree of the Polynomial Hierarchy. This leads to an alternative proof of the NP-hardness of the model-checking problem for an specic fragment of Full Hybrid Logic. In the last part of this work, we explore the descriptive complexity of the logic obtained by restricting second-order quantication to relations of bounded degree. Based on previous work from Schwentick et al. and Grandjean and Olive, we introduce the Bounded-Degree Second-Order Logic and show that it captures the class ALIN of classes of unary structures accepted by a alternating random access machine in linear time and bounded number of alternations. We also extend this logic with the transitive closure operator on high-order relations on bounded-degree relations. We show that the Bounded-Degree Second-Order Logic with Transitive Closure Operator captures linear number of registers in a nondeterministic random access machine provided that registers store values bounded by a linear function in the cardinality of the input structure.

<p>Trade in agricultural products between Mexico and the EU only counts for a small percentage of total trade between them. With the entry into force of the EU-Mexico FTA in 2000, the tariffs on a number of agriculture commodities between the two parties was eliminated or reduced. This will lead to an opening in the trade of agricultural products between the two markets, something that could affect the welfare of the Mexican people positively, if new trade is created. The elimination and reduction of tariffs on agricultural goods could also lead to positive consumption effects as prices on these goods could be lowered. Lower prices on agricultural goods could help a large number of people, especially the poor people of Mexico. </p><p>In this thesis, using theories on preferential trade, I aim to examine the effects on the Mexican people due to the elimination of traiffs on agricultural goods between Mexico and the EU consequential to the EU-Mexico Free Trade Agreement. The investigation was carried out for the first two years after integration between the two parties, focusing on agricultural goods in particular. I also aim to determine if there is any group in the Mexican society that has benefited more in terms of welfare as a consequence of the new FTA.</p>

Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes) than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale) and binary indicator maps (for the long-term and hillslope scale). Annual dynamics of soil moisture and decimeterscale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a datascarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to self-reinforcing flow paths.

Rain fall-runoff response in temperate humid headwater catchments is mainly controlled by hydrolo gical processes at the hillslope scale. Applied tracer experiments with fluore scent dye and salt tracers are well known tools in groundwater studies at the large scale and vadose zone studies at the plot scale, where they provide a means to characterise subsurface flow. We extend this approach to the hillslope scale to investigate saturated and unsaturated flow path s concertedly at a forested hill slope in the Austrian Alps. Dye staining experiments at the plot scale revealed that crack s and soil pipe s function as preferential flow path s in the fine-textured soils of the study area, and these preferenti al flow structures were active in fast subsurface transport of tracers at the hillslope scale. Breakthrough curves obtained under steady flow conditions could be fitted well to a one-dimensional convection-dispersion model. Under natural rain fall a positive correlation of tracer concentrations to the transient flows was observed. The results of this study demon strate qualitative and quantitative effects of preferential flow feature s on subsurface stormflow in a temperate humid headwater catchment. It turn s out that / at the hill slope scale, the interaction s of structures and processes are intrinsically complex, which implies that attempts to model such a hillslope satisfactorily require detailed investigation s of effective structures and parameters at the scale of interest.

Trade in agricultural products between Mexico and the EU only counts for a small percentage of total trade between them. With the entry into force of the EU-Mexico FTA in 2000, the tariffs on a number of agriculture commodities between the two parties was eliminated or reduced. This will lead to an opening in the trade of agricultural products between the two markets, something that could affect the welfare of the Mexican people positively, if new trade is created. The elimination and reduction of tariffs on agricultural goods could also lead to positive consumption effects as prices on these goods could be lowered. Lower prices on agricultural goods could help a large number of people, especially the poor people of Mexico. In this thesis, using theories on preferential trade, I aim to examine the effects on the Mexican people due to the elimination of traiffs on agricultural goods between Mexico and the EU consequential to the EU-Mexico Free Trade Agreement. The investigation was carried out for the first two years after integration between the two parties, focusing on agricultural goods in particular. I also aim to determine if there is any group in the Mexican society that has benefited more in terms of welfare as a consequence of the new FTA.

With signing of Agreement on Textile and Clothing which entered into force in 1995, it was decided to abolish quantity limitations applied by the developed countries since the second half of 20th century. By this way, restrictions in the developed country markets against the developing countries would be lifted gradually in a ten year period and the liberalization in textile and clothing markets would be realized from 2005 onwards. This would provide smooth access to major markets for all the developing and least developed countries. However, China&rsquo / s accession to WTO in 2001 created a breakthrough in this assumption. Hereafter, China increased its shares in the developed countries&rsquo / markets at the expense of other developing countries. One of the matters wondered most during this period was how would the developing and least developed countries, that had quota-free entrance to the developed countries&rsquo / markets, perform against China. This study focuses on the export performances of developing and least developed countries, that have had preferential trade agreements with European Union and the United States of America, against China in those markets.

Unlike municipal water supplies, provincial regulations do not require systematic testing of domestic well water, which may adversely impact local residents should contamination occur. Private wells are typically shallow relative to municipal wells, and thus, are particularly vulnerable to sources of surficial contamination if preferential recharge pathways such as natural fractures or faulty seals are present. In order to determine the relative importance of well seal integrity as a preferential pathway, a practical detection method was developed based on infiltrometry. This method successfully detected faulty well seals in a wide range of geological settings across Canada, including: Hobbema, Alberta; Lindsay, Ontario; and Chelsea, Québec. It was most successful in areas of minimal heterogeneity and where the surficial geology is composed of fine-grained sediments. The community of Chelsea (Québec) was also the primary study site to examine a range of factors affecting water quality including physical characteristics, faulty well seals, other anthropogenic activities and seasonality. Water samples were collected over a period of 14 months and analyzed for bacteria and major-ion chemistry. The results show that the consideration of physical features alone is not enough to predict vulnerability in the study area. Seasonal fluctuations in ionic concentrations (e.g. ionic strength, NO3-N and Cl-) and coliform bacteria are observed and result from disperse and rapid recharge events. Multivariate analysis techniques (e.g. principal components analysis and hierarchical cluster analysis) demonstrate that preferential recharge pathways and anthropogenic activities, such as domestic effluents affect the groundwater quality. The data and findings of this study were used to assist in the design of a probabilistic risk assessment model based on the Poisson distribution. This study demonstrates the complexity and the challenges related to bacterial contamination in drilled wells. In spite of these challenges, this analysis was useful as a baseline to assess the impact of anthropogenic activities, and may be used in future studies to assist municipalities in the evaluation and protection of groundwater supplies.

Unlike municipal water supplies, provincial regulations do not require systematic testing of domestic well water, which may adversely impact local residents should contamination occur. Private wells are typically shallow relative to municipal wells, and thus, are particularly vulnerable to sources of surficial contamination if preferential recharge pathways such as natural fractures or faulty seals are present. In order to determine the relative importance of well seal integrity as a preferential pathway, a practical detection method was developed based on infiltrometry. This method successfully detected faulty well seals in a wide range of geological settings across Canada, including: Hobbema, Alberta; Lindsay, Ontario; and Chelsea, Québec. It was most successful in areas of minimal heterogeneity and where the surficial geology is composed of fine-grained sediments. The community of Chelsea (Québec) was also the primary study site to examine a range of factors affecting water quality including physical characteristics, faulty well seals, other anthropogenic activities and seasonality. Water samples were collected over a period of 14 months and analyzed for bacteria and major-ion chemistry. The results show that the consideration of physical features alone is not enough to predict vulnerability in the study area. Seasonal fluctuations in ionic concentrations (e.g. ionic strength, NO3-N and Cl-) and coliform bacteria are observed and result from disperse and rapid recharge events. Multivariate analysis techniques (e.g. principal components analysis and hierarchical cluster analysis) demonstrate that preferential recharge pathways and anthropogenic activities, such as domestic effluents affect the groundwater quality. The data and findings of this study were used to assist in the design of a probabilistic risk assessment model based on the Poisson distribution. This study demonstrates the complexity and the challenges related to bacterial contamination in drilled wells. In spite of these challenges, this analysis was useful as a baseline to assess the impact of anthropogenic activities, and may be used in future studies to assist municipalities in the evaluation and protection of groundwater supplies.