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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Avaliação dos algoritmos de Picard-Krylov e Newton-Krylov na solução da equação de Richards / Evaluation of algorithms of Picard-Krylov and Newton-Krylov in solution of Richards equation

Marcelo Xavier Guterres 13 December 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A engenharia geotécnica é uma das grandes áreas da engenharia civil que estuda a interação entre as construções realizadas pelo homem ou de fenômenos naturais com o ambiente geológico, que na grande maioria das vezes trata-se de solos parcialmente saturados. Neste sentido, o desempenho de obras como estabilização, contenção de barragens, muros de contenção, fundações e estradas estão condicionados a uma correta predição do fluxo de água no interior dos solos. Porém, como a área das regiões a serem estudas com relação à predição do fluxo de água são comumente da ordem de quilômetros quadrados, as soluções dos modelos matemáticos exigem malhas computacionais de grandes proporções, ocasionando sérias limitações associadas aos requisitos de memória computacional e tempo de processamento. A fim de contornar estas limitações, métodos numéricos eficientes devem ser empregados na solução do problema em análise. Portanto, métodos iterativos para solução de sistemas não lineares e lineares esparsos de grande porte devem ser utilizados neste tipo de aplicação. Em suma, visto a relevância do tema, esta pesquisa aproximou uma solução para a equação diferencial parcial de Richards pelo método dos volumes finitos em duas dimensões, empregando o método de Picard e Newton com maior eficiência computacional. Para tanto, foram utilizadas técnicas iterativas de resolução de sistemas lineares baseados no espaço de Krylov com matrizes pré-condicionadoras com a biblioteca numérica Portable, Extensible Toolkit for Scientific Computation (PETSc). Os resultados indicam que quando se resolve a equação de Richards considerando-se o método de PICARD-KRYLOV, não importando o modelo de avaliação do solo, a melhor combinação para resolução dos sistemas lineares é o método dos gradientes biconjugados estabilizado mais o pré-condicionador SOR. Por outro lado, quando se utiliza as equações de van Genuchten deve ser optar pela combinação do método dos gradientes conjugados em conjunto com pré-condicionador SOR. Quando se adota o método de NEWTON-KRYLOV, o método gradientes biconjugados estabilizado é o mais eficiente na resolução do sistema linear do passo de Newton, com relação ao pré-condicionador deve-se dar preferência ao bloco Jacobi. Por fim, há evidências que apontam que o método PICARD-KRYLOV pode ser mais vantajoso que o método de NEWTON-KRYLOV, quando empregados na resolução da equação diferencial parcial de Richards. / Geotechnical Engineering is the area of Civil Engineering that studies the interaction between constructions carried out by man or natural phenomena with geological environment, which most of times is partially saturated soil. In this sense, work developing as stabilization, dam containing, retaining walls, foundations and highways are conditioned to a right prediction of water flow into the soil. However, considering the water flow, the studied region areas are commonly on the order of square kilometers, mathematical models solutions require computational meshes of large proportions, causing serious limitations linked to computational memory requirements and processing time. In order to overcome these limitations, efficient numerical methods must be used in the solution of the considered problem. Hence iterative methods for solving nonlinear and large sparse linear systems must be used in this type of application. In short, this study approached a solution to the Richard partial differential equation by the two dimensions finite volume method, bringing Picard and Newton method with greater efficiency. Linear system resolution iterative techniques based on Krylov space with pre-conditioners matrix were used. Portable Extensible Toolkit for Scientific Computation (PETSc) numerical library was a tool used during the task. The results indicate when a Richards equation is solved considering thr PICARD-KRYLOV method, no matter the soil evaluation model, the best combination for solving linear systems is the stabilized double gradient method and the SOR preconditioning. On the other hand, when the van Genuchten equations are used the gradients methods with the SOR preconditioning must be chosen. Adopting the NEWTON-KRYLOV method, the stabilized double gradient method is more efficient in soling Newton linear system, in relation to the preconditioning it must be giving preference to the Jacob block. Finally, there are strong indications that the PICARDKRYLOV method can be more effective than the NEWTON-KRYLOV one, when used for solving Richards partial differential equation.
62

Amélioration de la compréhension des fonctionnements hydrodynamiques du champ captant de Crépieux-Charmy / Improvement of the understanding of hydrodynamic functioning of the Crépieux-Charmy well field

Loizeau, Sébastien 14 June 2013 (has links)
Dans un champ captant, comme celui qui alimente l'agglomération lyonnaise, le fonctionnement de chaque « objet » (bassins d'infiltration, puits, rivières, nappe, zone non saturée) et leurs interactions sont complexes et mal connus. Dans un premier temps, une série d'essais d'infiltration à différentes échelles dans un bassin artificiel de réalimentation a permis de mieux appréhender le fonctionnement de cet ouvrage et de chiffrer les paramètres hydrodynamiques de la zone non saturée. Les résultats des interprétations par méthodes numériques fondées sur l'équation de Richards ont montré que les flux infiltrés dans les bassins dépendent principalement de la conductivité hydraulique à saturation d'une couche située directement sous le sable calibré couvrant le fond du bassin, identifiée comme étant moins perméable que la nappe. Cette couche conditionne l'existence d'une zone non saturée. La réalisation d'essais de pompage dans l'aquifère sur les forages d'exploitation et sur un dispositif spécialement mis en place durant ce travail a permis de déterminer les paramètres hydrodynamiques de la nappe. Une analyse des observations et une modélisation conceptuelle en 2D, puis en 3D ont permis d'identifier les mécanismes prépondérants (stratifications, apports et prélèvements) et de simuler correctement à la fois les flux infiltrés dans un des bassins d'infiltration et la remontée de la nappe. A l'échelle d'un bassin, les flux infiltrés sont variables dans le temps, ils dépendent de l'état de colmatage de la surface d'infiltration mais également de la température de l'eau infiltrée et de l'état hydrique initial du sol sous le bassin. Les analyses de sensibilité réalisées avec les modèles mis en place indiquent que la conductivité hydraulique à saturation de l'aquifère, mais également la proximité des conditions aux limites imposées dans la nappe (les rivières et les puits de pompage) influencent de manière prépondérante la remontée de la nappe. Une modélisation 3D d'un autre secteur du champ captant comprenant deux bassins d'infiltration, deux bras de rivière ainsi que des puits de pompage a été réalisée. La condition à la limite imposée sur les rivières est du troisième type en accord avec l'observation d'un sous-écoulement en nappe. Les échanges nappe/rivières sont calés sur des observations à partir d'une chronique de propagation d'une onde de crue dans la nappe. Des piézomètres en flûte de pan, spécifiquement implantés à proximité d'un bassin, ont permis d'observer des différences de charge hydraulique fortes à différents niveaux de l'aquifère lorsque le bassin d'infiltration est en eau. La modélisation 3D est conforme à ces observations. Elle a confirmé l'importance du rôle d'une hétérogénéité de type argilo-sableuse (de conductivité hydraulique à saturation inférieure aux autres lithologies présentes dans l'aquifère) dans les écoulements (direction et flux). Le modèle développé représente correctement les flux infiltrés via les bassins ainsi que les fluctuations de la piézométrie de la nappe. Il permet de vérifier l'inversion des écoulements par rapport aux infiltrations de la rivière, d'identifier les puits alimentés par les bassins d'infiltration et également de mettre en évidence les flux de nappe passant sous la rivière. / In a well field of the Lyon metropolitan area, designed for drinking water supply, behaviour of each object (infiltration basins, wells, rivers, aquifer, and unsaturated zone) and their interactions are complex and not well-known. As a first step, infiltration tests at different spatial scales in one artificial basin were performed to better understand the basin operation and to estimate the hydrodynamic parameters of the unsaturated zone. Results of interpretation, using numerical methods based on Richards equation, reveal that infiltrated basin fluxes mainly depend on saturated hydraulic conductivity of a layer located just below the calibrated sand layer that cover the basin bottom. Indeed this layer has been estimated to be less permeable than the aquifer, which allows the existence of the unsaturated zone below. Pumping tests in the groundwater have been performed using production wells and a well specially implemented during this thesis work in order to estimate aquifer hydrodynamic parameters. Observations analysis and a conceptual modelling, in 2D and then in 3D, lead to a better understanding of the controlling mechanisms (stratification, input and output) and to simulate both basin infiltration rates and water table rise. Considering the whole basin scale, input fluxes are transient, related to the clogging statement of the infiltration area but also to the temperature of inflow water and the initial statement of the soil just below the basin. Sensibility analyses using the models highlight that the amount of the water table rise is mainly influenced by the aquifer saturated hydraulic conductivity and also by the location of imposed boundaries in the aquifer (rivers and pumping wells). The model properly accounts basin inflow fluxes and water table fluctuations. The model is able to verify if flows are reversed in relation to river exchanges, if wells are fed by infiltration basins and it highlights aquifer flows below the river. A 3D modelling has been realised in another area of the well field, comprising two infiltration basins, two river arms and pumping wells. In agreement with underflow in the aquifer, rivers are imposed in the model as third kind boundary conditions. Aquifer and river exchanges are calibrated with observed data of one aquifer flood-wave propagation. Significant differences of hydraulic heads have been observed at different depths of the aquifer using panpipes piezometers, specifically implemented, close to one infiltration basin. Theses differences are closely related to basin operation. These observations are properly calculated by the 3D model. Using the model, the effect of one sandy-clay heterogeneous layer (whose saturated hydraulic conductivity is lower than the ones of other aquifer lithologies) on aquifer flows (direction and flux) is notable. The model properly accounts basin inflow fluxes and water table fluctuations. The model is able to verify if flows are reversed in relation to river exchanges, if wells are fed by infiltration basins and it highlights aquifer flow below the river.
63

Simulação de fluxo de água e transporte de solutos na zona não-saturada do solo pelo método de elementos finitos adaptativo / Simulation of water flow and solute transport in the unsaturated zone of the soil by adaptative finite element method

Maria de Lourdes Pimentel Pizarro 02 October 2009 (has links)
Devido aos riscos de contaminação dos recursos naturais solo e água, ao alto custo, ao tempo e ao esforço humano nas investigações de campo, os modelos matemáticos, aliados às técnicas numéricas e aos avanços computacionais, constituem uma ferramenta importante na previsão do deslocamento de solutos, contribuindo assim, para o controle de alterações ambientais. No Brasil, a modelação de fluxo e transporte de solutos na zona não-saturada é voltada, quase que exclusivamente, aos problemas relacionados às atividades agrícolas. Entretanto, tão importante quanto a problemática dos produtos químicos nas atividades agrícolas é a questão de poluição e contaminação do solo e da água por chorume, gerado pelos resíduos sólidos domiciliares. Neste trabalho, é desenvolvido e validado um modelo computacional unidimensional para simulação de fluxo e transporte de solutos na zona não-saturada do solo. O modelo matemático é dado pela equação diferencial parcial não-linear de Richards, que rege o movimento de água no solo, e a equação diferencial parcial linear de advecção-dispersão, do transporte de solutos, acompanhadas das condições iniciais e de contorno. A equação de Richards é dada em função do potencial matricial da água e a equação de transporte de solutos estima a evolução temporal da concentração de solutos no perfil do solo. Devido à dificuldade de se obter soluções analíticas destas equações, são resolvidas numericamente pelo método de elementos finitos. As referidas equações são resolvidas utilizando-se malhas uniformes inicialmente. Com a finalidade de obter simulações mais eficientes, a um custo computacional reduzido, é empregada a adaptatividade com refinamento h na malha de elementos finitos. A função interpolação polinomial utilizada é de grau 2 ou maior que garante a conservação de massa. Na equação de Richards, a derivada temporal é aproximada por um quociente de diferença finita e é aplicado o esquema de Euler explícito e na equação de advecção-dispersão, é aproximada por um quociente de diferença finita, aplicando-se o esquema de Euler implícito, devido à linearidade da equação. O sistema operacional é o Linux Ubuntu 32 bits, o ambiente de programação é o PZ, escrito em linguagem de programação C++. Na validação do modelo, utilizam-se dados disponíveis na literatura. Os resultados são comparados, utilizando-se malhas uniformes e malhas adaptativas com refinamento h. Usando-se as malhas uniformes para o problema de Richards e de transporte de potássio, o tempo de execução é de 22 minutos e a memória utilizada de 6164 Kb. Com as malhas adaptadas, o tempo de execução é de 3 minutos e 27 segundos, consumindo 5876 Kb de memória. Houve, portanto, uma redução de 84,32% no tempo de execução, usando-se malhas adaptativas. A utilização da função interpolação polinomial de grau 2 ou maior e o refinamento h, permitem uma boa concordância do modelo na comparação com soluções disponíveis na literatura. / Due to the risks of contamination of soil and water resources, the high cost, time and human effort in the field investigations, the mathematical models, combined with numerical techniques and computational advances, are important tools in forecasting the movement of solutes thereby contributing to the control of environmental alteration. In Brazil, modeling of flow and solute transport in the unsaturated zone is focused, almost exclusively, on problems related to agricultural activities. However, as important as the problematical of chemicals products in agricultural activities is the issue of pollution and contamination of soil and water by leachate, generated by municipal solid wastes. In this work, an one-dimensional computational model for simulation of flow and solute transport in the unsaturated soil has been developed and validated. The mathematical model is given by the Richards\'s non-linear partial differential equation, which determines the movement of water in the soil, and the advection-dispersion linear partial differential equation, of the solute transport, together with initial and boundary conditions. The Richards equation is a function of the water pressure head and the solute transport equation estimate the temporal evolution of the solutes concentration in the soil profile. Due to the difficulty of obtaining analytical solutions of these equations, they are solved numerically using the finite element method. The governing equations are solved using initially a uniform mesh. In order to obtain more efficient simulations with low computational cost, adaptativity with h refinement on the finite element mesh is implemented. The interpolation function is of degree two or higher, assuring mass conservation. In Richards\' equation, the temporal derivative is approximated by Euler explicit finite difference. For the advection-dispersion equation, due to the linearity of the equation, an implicit finite difference scheme is used. The code is written in the programming language C++ based on the programming environment PZ using operating system Linux Ubuntu 32 bit. Model results are validated in comparison with data available in the literature. The results are evaluated using uniform meshes and with h refinement adaptive mesh. Using the uniform meshes for the problem of Richards and transport of potassium, the running time is 22 minutes and 6164 Kb of memory is used. With the adapted meshes, the execution time is 3 minutes and 27 seconds, consuming 5,876 Kb of memory. Therefore there was a reduction of 84.32% in execution time, using adaptive meshes. The interpolation function with degree two or higher and the h refinement, with reduction of the computation time, showed a good agreement in comparison with the literature.
64

Avaliação dos algoritmos de Picard-Krylov e Newton-Krylov na solução da equação de Richards / Evaluation of algorithms of Picard-Krylov and Newton-Krylov in solution of Richards equation

Marcelo Xavier Guterres 13 December 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A engenharia geotécnica é uma das grandes áreas da engenharia civil que estuda a interação entre as construções realizadas pelo homem ou de fenômenos naturais com o ambiente geológico, que na grande maioria das vezes trata-se de solos parcialmente saturados. Neste sentido, o desempenho de obras como estabilização, contenção de barragens, muros de contenção, fundações e estradas estão condicionados a uma correta predição do fluxo de água no interior dos solos. Porém, como a área das regiões a serem estudas com relação à predição do fluxo de água são comumente da ordem de quilômetros quadrados, as soluções dos modelos matemáticos exigem malhas computacionais de grandes proporções, ocasionando sérias limitações associadas aos requisitos de memória computacional e tempo de processamento. A fim de contornar estas limitações, métodos numéricos eficientes devem ser empregados na solução do problema em análise. Portanto, métodos iterativos para solução de sistemas não lineares e lineares esparsos de grande porte devem ser utilizados neste tipo de aplicação. Em suma, visto a relevância do tema, esta pesquisa aproximou uma solução para a equação diferencial parcial de Richards pelo método dos volumes finitos em duas dimensões, empregando o método de Picard e Newton com maior eficiência computacional. Para tanto, foram utilizadas técnicas iterativas de resolução de sistemas lineares baseados no espaço de Krylov com matrizes pré-condicionadoras com a biblioteca numérica Portable, Extensible Toolkit for Scientific Computation (PETSc). Os resultados indicam que quando se resolve a equação de Richards considerando-se o método de PICARD-KRYLOV, não importando o modelo de avaliação do solo, a melhor combinação para resolução dos sistemas lineares é o método dos gradientes biconjugados estabilizado mais o pré-condicionador SOR. Por outro lado, quando se utiliza as equações de van Genuchten deve ser optar pela combinação do método dos gradientes conjugados em conjunto com pré-condicionador SOR. Quando se adota o método de NEWTON-KRYLOV, o método gradientes biconjugados estabilizado é o mais eficiente na resolução do sistema linear do passo de Newton, com relação ao pré-condicionador deve-se dar preferência ao bloco Jacobi. Por fim, há evidências que apontam que o método PICARD-KRYLOV pode ser mais vantajoso que o método de NEWTON-KRYLOV, quando empregados na resolução da equação diferencial parcial de Richards. / Geotechnical Engineering is the area of Civil Engineering that studies the interaction between constructions carried out by man or natural phenomena with geological environment, which most of times is partially saturated soil. In this sense, work developing as stabilization, dam containing, retaining walls, foundations and highways are conditioned to a right prediction of water flow into the soil. However, considering the water flow, the studied region areas are commonly on the order of square kilometers, mathematical models solutions require computational meshes of large proportions, causing serious limitations linked to computational memory requirements and processing time. In order to overcome these limitations, efficient numerical methods must be used in the solution of the considered problem. Hence iterative methods for solving nonlinear and large sparse linear systems must be used in this type of application. In short, this study approached a solution to the Richard partial differential equation by the two dimensions finite volume method, bringing Picard and Newton method with greater efficiency. Linear system resolution iterative techniques based on Krylov space with pre-conditioners matrix were used. Portable Extensible Toolkit for Scientific Computation (PETSc) numerical library was a tool used during the task. The results indicate when a Richards equation is solved considering thr PICARD-KRYLOV method, no matter the soil evaluation model, the best combination for solving linear systems is the stabilized double gradient method and the SOR preconditioning. On the other hand, when the van Genuchten equations are used the gradients methods with the SOR preconditioning must be chosen. Adopting the NEWTON-KRYLOV method, the stabilized double gradient method is more efficient in soling Newton linear system, in relation to the preconditioning it must be giving preference to the Jacob block. Finally, there are strong indications that the PICARDKRYLOV method can be more effective than the NEWTON-KRYLOV one, when used for solving Richards partial differential equation.
65

Modélisation couplée des écoulements de surface et de sub-surface dans un bassin versant par approches numériques à dimensions euclidiennes réduites / Coupled surface-subsurface flow in a watershed by using numerical approaches with reduced Euclidean dimensions

Pan, Yi 26 October 2015 (has links)
Les interactions entre les processus de surface et de sub-surface sont des composantes clés du cycle hydrologique que les modèles hydrologiques doivent représenter pour obtenir des prédictions cohérentes et précises dans un contexte de gestion durable de la ressource en eau. Les modèles hydrologiques intégrés qui décrivent de façon physique les processus et leurs interactions sont de conception récente. La plupart de ces modèles s‘appuient sur l’équation de Richards 3D pour décrire les processus d’écoulement souterrain. Cette approche peut être problématique compte tenu de contraintes importantes sur le maillage et sur la résolution numérique. Ce travail de thèse propose un modèle hydrologique intégré qui s’appuie sur approche innovante à dimension réduite pour simplifier les écoulements de surface et souterrains d'un bassin versant. Les différents compartiments du modèle sont d’abord testés indépendamment puis couplés. Les résultats montrent que l’approche proposée décrit précisément les processus hydrologiques considérés tout en améliorant de façon significative l’efficacité générale du modèle. / Interactions between surface and subsurface flow processes are key components of the hydrological water cycle. Accounting for these interactions in hydrological modelsis mandatory to provide relevant and accurate predictions for water quality and water resources management. Fully-integrated hydrological models that describe with aphysical meaning the hydrological processes and their interactions are recent. Most of these models rely upon the resolution of a 3D Richards equation to describe subsurface flow processes. This approach may become intractable because of the heavy constrains on both meshing and numerical resolution. This PhD proposes a new integrated hydrological model on the idea of dealing with dimensionally reduced flow in both the surface and sub-surface compartments of a watershed. The different compartments of the model are first tested independently and then coupled. The results show that the proposed approach allows for a proper and precise depiction ofthe hydrological processes enclosed in the model while providing significant gain incomputational efficiency.
66

Modélisation des processus biogéochimiques dans les sédiments variablement saturés soumis au forçage de la marée / Modelling of biogeochemical processes into variably saturated sédiments submitted to the tidal forcing

Chassagne, Romain 08 October 2010 (has links)
Afin de mieux appréhender la multiplicité et la complexité des processus biogéochimiques enzône cotière, un modèle 2D dé- crivant l’évolution d’espèces biogéniques dans les sédiments per-méables des zones intertidales a été développé. Ce modèle couple l’hydrodynamique générée parla marée aux processus de transport-réaction d’espèces biogéochimiques. L’infiltration de la maréedans ce milieu poreux variablement saturé est modélisée par l’équation de Richards. Des méthodesnumériques nécessaires à la ré- solution des équations décrivant le couplage ont été mises en place,comme la méthode de stabilisation SUPG (Streamline Upwind Petrov Galerkin) et une méthodede capture de choc. Le site très dynamique de la plage du Truc-Vert (côte Atlantique) a été choisicomme terrain de référence en raison principalement d’études biogéochimiques disponibles. Lesparamètres d’entrée du modèle font appel d’une part à ces données de terrain (missions ANR PRO-TIDAL et MOBISEA) et d’autre part à des paramètres issus de la bibliographie. La validation dumodèle a été effectuée à partir de la comparaison avec deux cas test issus de la littérature, le pre-mier concernant l’hydrodynamique sous le forçage de la marée et le second concernant l’équationde transport-réaction. Une première version du modèle a été déclinée pour décrire l’évolution de laconcentration en silice en milieu poreux sous le forçage de la marée. Les flux de silice vers l’océanet le temps de résidence de la silice dans les sédiments perméables des plages ont été estimés. Aubout de quelques jours, on peut observer la formation d’une lentille de faible concentration en si-lice dans la partie supérieure de la zone intertidale, caractéristique du forçage de la marée. Nousavons également étudié les variations de la géométrie de cette lentille et du temps de résidencesous l’influence de différents paramètres, tel que la pente de la plage, la conductivité hydraulique,l’amplitude de la marée et le coefficient de dispersion. Une deuxième version du modèle décrit la dégradation de la matière organique, l’évolution des concentrations en oxygène, en nitrates,en phosphates. Ainsi nous disposons de la répartition spatio-temporelle des concentra- tions deces différentes espèces chimiques dans le sédiment. Aujourd’hui les problèmes environnementauxs’avèrent fondamentaux pour notre société et la compréhension des interactions sédiments-océanen est une étape essentielle. Ce modèle nous permet de mieux percevoir le rôle joué par la ma-rée et de quantifier les processus qu’elle induit dans les sédiments variablement saturés des plagessableuses. Ce modèle participe de façon significative à la compréhension des processus biogéochi-miques se déroulant dans ces environnements particulièrement complexes et permet la structurationdes campagnes de mesure. / For a better understanding of the complexity of the biogeochemical processes in coastal re-gion, a 2D model has been developed. This model couples hydrodynamic forcing generated bythe tide and the transport-reaction processes of biogeochemical species. Di- scharge of the tideinto the variably-saturated porous media is modelled by Richards equation. Some numerical me-thods are required for solving this kind of complex problem, as Streamline Upwind Petrov Galerkin(SUPG) method and shock capturing method. The highly dynamical site of the Truc-Vert beach hasbeen chosen as reference field, mainly because of avalaible biogeochemical and hydrodynamicalstudies. The input parameters of the model come from these field data (ANR PROTIDAL and MO-BISEA projects) and from the bibliography. The validation of the model was made in regards oftwo case studies from published hydrodynamic simu- lations under tidal forcing and from avaliabletransport-reaction solutions. A first version of the model has been declined to describe silicic acidevolution into porous media under tidal forcing. The flux of the silicic acid to the ocean and theresidence time of silicic acid into permeable sandy sediments were estimated. After some days, weobserve the formation of a lens of low silicic acid concen- tration in the upper part of the intertidalzone. This lens is the main imprint of the tidal forcing. We studied also variations of the lens geo-metry and the residence time under influence of model parameters, such as the beach slope, the tideamplitude and the dispersion coefficient. A second version of the model describes the organic mat-ter degradation , and simulates the concentrations of oxygen, nitrates and phosphates. The modelreproduces the spatial (2D) and temporal distribution of the concentration of these different che-mical species into the sediment. Nowadays environmental problems are fondamental for our societyand the understanding of the sediment-ocean interactions is a crucial step. The new model allowsus a better understanding of the tidal impact on biogeochemical processes in permeable sediments and offers a quantitative approach on biogeochemical processes that occur into variably-saturatedsandy sediments. The model also offers a useful tool to optimize sampling strategy for field studies.
67

Joseph Smith—History: From Dictation to Canon

Bennett, Russ Kay 09 June 2012 (has links) (PDF)
This thesis seeks to answer the question of how Joseph Smith—History found in The Pearl of Great Price developed into a part of the canon of The Church of Jesus Christ of Latter-day Saints. When the prophet Joseph Smith first dictated the text to his scribes it seems he had not intended for the work to become scripture, but simply to follow the Lord's divine mandate to keep a record. Additionally he provided the purpose in his document to "disabuse the public mind, and put all inquirers after truth in possession of the facts, as they transpired." The format he proposed for the Manuscript History illustrates how it was originally not purposed for scripture. The compiling of that history took the efforts of many men and women and spanned the length of almost twenty years to complete. Joseph Smith had begun the dictation to his scribe George Robinson in 1838, but it was unfinished. Joseph later began the dictation anew to his scribe James Mulholland, first having the man rewrite what he had told to Robinson and then picking up the dictation from there. While the prophet had started and stopped histories before, this particular dictation began the enduring effort. The Manuscript History was developed from the original 59 pages that were scribed by Mulholland. By the efforts of other scribes, but mostly Willard Richards, the history was completed. The official statement of Brigham Young and Orson Pratt upon its completion said nothing of extracting portions for canon. But Mulholland's work seemed destined for a different purpose than the rest of the Manuscript History. It was printed serially in the Times and Seasons, and a few apostles seemed to catch a vision of what the manuscript could do for potential converts and members of the Church. Orson Pratt was especially a proponent of communicating certain key events as illustrated in his missionary tract "Remarkable Visions." A later apostle, Franklin D. Richards, would see the benefit of using the official history to distribute the history of the restoration of the Church to others. He extracted portions from Mulholland's text that covered certain main events in Joseph's life and printed them in his missionary tract The Pearl of Great Price. This pamphlet would eventually be canonized by The Church of Jesus Christ of Latter-day Saints in 1880. Joseph Smith-History's inclusion in the reclamation of revelation that occurred in 1880 was deserved. This is evidenced by examining the process of canonization and the guiding principles of canonization employed by the Church of Jesus Christ of Latter-day Saints. It was canonized at the same time as many other revelations and at a General Conference saturated with many important events. Consequently it is difficult to gauge the reaction to its inclusion in canon, except in how it has been used since its canonization. After its inclusion into scripture the text has become a foundational piece of literature for the Church. The impact the text has had can be seen in the culture, missionary work, and doctrine of the Church. The focus of this thesis is to map the text's journey from birth to canonization.
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Implementing and Evaluating Variable Soil Thickness in the Community Land Model, Version 4.5 (CLM4.5)

Brunke, Michael A., Broxton, Patrick, Pelletier, Jon, Gochis, David, Hazenberg, Pieter, Lawrence, David M., Leung, L. Ruby, Niu, Guo-Yue, Troch, Peter A., Zeng, Xubin 05 1900 (has links)
One of the recognized weaknesses of land surface models as used in weather and climate models is the assumption of constant soil thickness because of the lack of global estimates of bedrock depth. Using a 30-arc-s global dataset for the thickness of relatively porous, unconsolidated sediments over bedrock, spatial variation in soil thickness is included here in version 4.5 of the Community Land Model (CLM4.5). The number of soil layers for each grid cell is determined from the average soil depth for each 0.9 degrees latitude x 1.25 degrees longitude grid cell. The greatest changes in the simulation with variable soil thickness are to baseflow, with the annual minimum generally occurring earlier. Smaller changes are seen in latent heat flux and surface runoff primarily as a result of an increase in the annual cycle amplitude. These changes are related to soil moisture changes that are most substantial in locations with shallow bedrock. Total water storage (TWS) anomalies are not strongly affected over most river basins since most basins contain mostly deep soils, but TWS anomalies are substantially different for a river basin with more mountainous terrain. Additionally, the annual cycle in soil temperature is partially affected by including realistic soil thicknesses resulting from changes in the vertical profile of heat capacity and thermal conductivity. However, the largest changes to soil temperature are introduced by the soil moisture changes in the variable soil thickness simulation. This implementation of variable soil thickness represents a step forward in land surface model development.
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The role of industries in providing basic life-skills education to unskilled black employees in the Empangeni/Richards Bay industrial areas

Ncube, Thenjiwe Patricia 04 1900 (has links)
Thesis (MPhil)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Historically, the majority of South Africans were denied access to free, compulsory and general education (National Multi-Plan, 1997:1). This means that many citizens did not have access to that educational foundation necessary for further learning, quality employment opportunities or even full and active social and political participation. Various arguments throughout this study imply that the South African education system presented unequal educational opportunities for most of its people. In this case, Black Education failed to produce people with the necessary skills for our economy. To compensate these people, the opportunities for education should be created everywhere in schools, sports clubs, NGOs and more importantly, in workplaces because education is the key for survival. Due to the need for economic growth and the need for skilled workers, large numbers of adults should be provided with extensive adult education. In other words, industries should become educational centres where employees could be equipped with numeracy and literacy programmes which would improve production and basic life-skills necessary to meet the demands of the economy at large. The study sought to find out "what role the two industries play in providing basic life-skills education to unskilled Black employees in the Empangeni/Richards Bay industrial areas". This was an empirical survey involving the target population of unskilled Black employees and facilitators of the adult education programmes of the lllovo Sugar Milling and Spoornet industries. In this study two different types of questionnaires were designed and used to ascertain the respondents' disposition towards adult education programmes. In each industry one questionnaire was administered to the unskilled Black employees and another to the facilitators of adult education progarmnes. The research sample comprised of seven unskilled Black employees from lllovo, twentyfive unskilled Black employees from Spoomet, two facilitators from Illovo and another two facilitators from Spoornet industries. The data collected from the sample attempted to answer the following research questions: ./ What basic day-to- day life-skills are needed by unskilled Black employees in the industries? ./ How effective are these programmes to unskilled Black employees in the industries? ./ How accessible are these programmes to unskilled Black employees? These questions necessitated a literature study and an empirical survey as research tools. It has emerged from the study that adult education is seen as an agent for social change and instrument for social development. The study seeks to assess the extent to which these programmes: .:. Fulfil the day-to-day basic needs of unskilled Black employees, in for example, financial management or identifying and using sources of informatiom like directories and maps . •:. Fulfil the literacy and numeracy needs of unskilled Black employees, in for example, appending signatures, reading newspapers and bank forms . •:. Cultivate good habits in the workplace such as punctuality, time management, safety precautions and proper procedures. The findings reveal that adult education programmes in industries were valuable and useful to employees as they were able to transfer the skills acquired from the programme to the real world situation. These life-skills included counting money, writing names and letters, appending signatures, reading newspapers and safety precautions signs, understanding road signs and making telephone calls. The researcher concludes with a number of recommendations including the following: ~ Each industry should establish a building named a 'college' or 'centre' within its premises where adult education programmes will be presented. ~ Each industry should have its own policy documents regarding the provision of worker life-skills education. ~ All workers have a right to paid education and training leave. This means that skilled, semi-skilled and unskilled workers should be entitled to four or six weeks of paid leave per year for further education throughout their working life. / AFRIKAANSE OPSOMMING: As gevolg van die historiese en politieke ontwikkeling in Suid-Afrika is die meerderheid van die bevolking toegang tot vrye, verpligte en algemene onderwys ontsê (National Multi- Plan, 1997: 1). Dit het tot gevolg gehad dat die meerderheid van die bevolking dus ook nie toegang gehad het tot verdere onderwys en gevolglik ook nie tot goeie werksgeleenthede en dus deelname aan die maatskaplike en politieke lewe ontneem is. In hierdie navorsing word minderwaardige onderwysgeleenthede wat aan die meeste swart mense gegee is uitgewys. Dit het tot gevolg gehad dat swart onderwys nie die opgeleide menslike hulpbronne kon lewer wat die ekonomie nodig gehad het nie. Ekonomiese groei is afhanklik van opgeleide menslike hulpbronne en om dit moontlik te maak behoort onderwysgeleenthede in groot getalle vir volwassenes geskep te word. Daarom behoort skoolfasiliteite, sportklubs, nie-regeringsorganisasies en die werkplek benut te word om onderwys aan die ongeletterde volwassene te gee. Dit impliseer dat nywerhede geleenthede vir geletterdheids- en syfervaardigheidsprogramme vir hulle werkers behoort te skep sodat hulle toegerus kan word met basiese lewensvaardighede en sodoende hulle lewenskwaliteit en produktiwiteit verhoog kan word. Met die navorsing is gepoog om vas te stel watter rol nywerhede in die Empangeni- /Richardsbaai-gebied speel in die verskaffing van onderwys in basiese lewensvaardighede aan hulle ongeskoolde swart werkers. Twee verskillende vraelyste en onderhoude is gebruik om data in te samel by 'n steekproef van die ongeskoolde swart werkers en die fasiliteerders van onderwysprogramme aan volwassenes by Illovo Suikermeule en Spoornet. Daar is gepoog om die respondente se houdings ten opsigte van onderwysprogramme aan volwassenes in dié twee nywerhede vas te stel. Die navorsinsteekproef het sewe ongeskoolde swart werkers en twee fasiliteerders van Illovo Suikermeule en vyf-en-twintig ongeskoolde swart werkers en twee fasiliteerders van Spoornet ingesluit. Met behulp van die ingesamelde data van die steekproef is gepoog om die volgende vrae te beantwoord: - Watter basiese lewensvaardighede benodig die ongeskoolde swart werkers in hierdie twee nywerhede? - Watter onderwysprogramme vir volwassenes is deur die twee nywerhede daargestelom in die onderwysbehoeftes in basiese lewensvaardighede van die ongeskoolde swart werkers te voorsien? Hoe toeganklik is hierdie programme vir die ongeskoolde swart werkers? Hoe effektief is die programme vir ongeskoolde swart werkers in die twee nywerhede? Om die vrae te probeer beantwoord was dit noodsaaklik om 'n literatuurstudie te doen, 'n vraelysopname te onderneem en onderhoude te voer. Die doelstellings met die navorsing was om te bepaal in watter mate die onderwysprogramme vir volwassenes in die twee nywerhede: voorsien in die daaglikse behoeftes van ongeskoolde swart werkers byvoorbeeld om hulle finansies te bestuur en om inligtingsbronne soos gidse en kaarte te identifiseer en te gebruik; voorsien in die geletterdheids - en syfervaardigheidsbehoeftes van ongeskoolde swart werkers soos die gebruik van 'n handtekening, die lees van koerante en die invul van bankvorms; lei tot 'n bewuswording en 'n besef van die belangrikheid van onderwys aan ongeskoolde swart werkers; ongeskoolde swart werkers voorberei om akademiese ondersteuning, soos byvoorbeeld hulpverlening met skoolwerk, aan hulle kinders te voorsien; 'n bewuswording skep van die maatskaplike, politieke, kulturele en ekonomiese verband waarin ongeskoolde swart werkers hulle bevind. Dit sluit die verskaffing van onderwys in basiese lewensvaardighede met betrekking tot vigs, gesinsbeplanning en kiesersopvoeding in; en die aankweek van goeie gewoontes in die werksituasie soos stiptelikheid. tydsbestuur, die toepassing van veiligheidsmaatreëls in die gebruik van korrekte procedures tot gevolg het. Die bevindinge van die navorsing dui daarop dat onderwysprogramme aan volwassenes in die nywerhede waardevol en nuttig vir die ongeskoolde swart werkers is aangesien dit hulle in staat stelom die vaardighede wat hulle aangeleer het na die werklike alledaagse lewenssituasie oor te dra. Hierdie vaardighede sluit onder andere in die tel van geld, die skryf van hulle name en briewe, die gebruik van 'n handtekening vir die ondertekening van dokumente, die lees van koerante en kennisgewings i.v.m. veiligheidsmaatreëls, die verstaan van padtekens en die maak van telefoonoproepe. Dit blyk ook uit die navorsing dat onderwysprogramme aan volwassenes as 'n werktuig van maatskaplike ontwikkeling beskou word. Die aanbevelings wat op grond van die bevindinge van die navorsing gemaak word, sluit onder andere die volgende in: Nywerhede wat groot getalle ongeskoolde swart werkers in diens het, behoort 'n beleid ten opsigte van onderwysprogramme in basiese lewensvaardighede aan werkers te hê. Elke nywerheid behoort fisiese fasiliteite vir die aanbieding van onderwysprogramme aan volwassenes op die perseel te hê. Hierdie fisiese fasiliteit kan 'n "kollege" of ,,s»entrum genoem wor d. Alle werkers behoort die reg te hê op vier tot ses weke betaalde onderwys-en opleidingsverlof per jaar.
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Dual-Scale Modeling of Two-Phase Fluid Transport in Fibrous Porous Media

Ashari, Alireza 23 November 2010 (has links)
The primary objective of this research is to develop a mathematical framework that could be used to model or predict the rate of fluid absorption and release in fibrous sheets made up of solid or porous fibers. In the first step, a two-scale two-phase modeling methodology is developed for studying fluid release from saturated/unsaturated thin fibrous media made up of solid fibers when brought in contact with a moving solid surface. Our macroscale model is based on the Richards’ equation for two-phase fluid transport in porous media. The required constitutive relationships, capillary pressure and relative permeability as functions of the medium’s saturation, are obtained through microscale modeling. Here, a mass convection boundary condition is considered to model the fluid transport at the boundary in contact with the target surface. The mass convection coefficient plays a significant role in determining the release rate of fluid. Moreover the release rate depends on the properties of the fluid, fibrous sheet, the target surface as well as the speed of the relative motion, and remains to be determined experimentally. Obtaining functional relationships for relative permeability and capillary pressure is only possible through experimentation or expensive microscale simulations, and needs to be repeated for different media having different fiber diameters, thicknesses, or porosities. In this concern, we conducted series of 3-D microscale simulations in order to investigate the effect of the aforementioned parameters on the relative permeability and capillary pressure of fibrous porous sheets. The results of our parameter study are utilized to develop general expressions for kr(S) and Pc(S). Furthermore, these general expressions can be easily included in macroscale fluid transport equations to predict the rate of fluid release from partially saturated fibrous sheets in a time and cost-effective manner. Moreover, the ability of the model has been extended to simulate the radial spreading of liquids in thin fibrous sheets. By simulating different fibrous sheets with identical parameters but different in-plane fiber orientations has revealed that the rate of fluid spread increases with increasing the in-plane alignment of the fibers. Additionally, we have developed a semi-analytical modeling approach that can be used to predict the fluid absorption and release characteristics of multi-layered composite fabric made up of porous (swelling) and soild (non-swelling) fibrous sheets. The sheets capillary pressure and relative permeability are obtained via a combination of numerical simulations and experiment. In particular, the capillary pressure for swelling media is obtained via height rise experiments. The relative permeability expressions are obtained from the analytical expressions previously developed with the 3-D microscale simulations, which are also in agreement with experimental correlations from the literature. To extend the ability of the model, we have developed a diffusion-controlled boundary treatment to simulate fluid release from partially-saturated fabrics onto surfaces with different hydrophilicy. Using a custom made test rig, experimental data is obtained for the release of liquid from partially saturated PET and Rayon nonwoven sheets at different speeds, and on two different surfaces. It is demonstrated that the new semi-empirical model redeveloped in this work can predict the rate of fluid release from wet nonwoven sheets as a function of time.

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