The Earth's magnetic field is generated in its fluid outer core through dynamo action. In this process, convection and differential rotation of an electrically conducting fluid maintain the magnetic field against its ohmic decay. Using numerical models, we can investigate planetary dynamo processes and the importance of various core properties on the dynamo. In this thesis, I use numerical dynamo models in Earth-like geometry in order to understand the influence of inner core electrical conductivity and the choice of thermal and velocity boundary conditions on the resulting magnetic field. I demonstrate how an electrically conducting inner core can reduce the frequency of reversals and produce axial-dipolar dominated fields in our models. I also demonstrate that a strong planetary magnetic field intensity does not imply that the dynamo operates in the strong field regime as is usually presumed. Through a scaling law analysis, I find that irrespective of the choice of thermal or velocity boundary conditions, the available power determines the magnetic and velocity field characteristics like the field strength, polarity and morphology. Also, whether a dynamo model is in a dipolar, transitional or multipolar regime is dependent on the force balance in the model. I demonstrate that the Lorentz force is balanced by the Coriolis force in the dipolar dynamo regime models resulting in magnetostrophically balanced dynamos whereas the Lorentz force is balanced by the Inertial force (and not the Coriolis force) in the multipolar dynamo regime models resulting in a non-magnetostrophically balanced dynamo. The generation mechanism differs between the regimes and depends on the velocity boundary conditions. The zonal flows of the stress-free models are stronger than in the no-slip models, and bistability is more prominent when stress-free boundary conditions are used. A single scaling law may be feasible for all the models, but there does appear to be some variation for models with different thermal and velocity boundary conditions. The results presented in this thesis are not only applicable to the geodynamo, but will also aid in understanding the dynamos of other planets and exoplanets.

The Earth's magnetic field is generated in its fluid outer core through dynamo action. In this process, convection and differential rotation of an electrically conducting fluid maintain the magnetic field against its ohmic decay. Using numerical models, we can investigate planetary dynamo processes and the importance of various core properties on the dynamo. In this thesis, I use numerical dynamo models in Earth-like geometry in order to understand the influence of inner core electrical conductivity and the choice of thermal and velocity boundary conditions on the resulting magnetic field. I demonstrate how an electrically conducting inner core can reduce the frequency of reversals and produce axial-dipolar dominated fields in our models. I also demonstrate that a strong planetary magnetic field intensity does not imply that the dynamo operates in the strong field regime as is usually presumed. Through a scaling law analysis, I find that irrespective of the choice of thermal or velocity boundary conditions, the available power determines the magnetic and velocity field characteristics like the field strength, polarity and morphology. Also, whether a dynamo model is in a dipolar, transitional or multipolar regime is dependent on the force balance in the model. I demonstrate that the Lorentz force is balanced by the Coriolis force in the dipolar dynamo regime models resulting in magnetostrophically balanced dynamos whereas the Lorentz force is balanced by the Inertial force (and not the Coriolis force) in the multipolar dynamo regime models resulting in a non-magnetostrophically balanced dynamo. The generation mechanism differs between the regimes and depends on the velocity boundary conditions. The zonal flows of the stress-free models are stronger than in the no-slip models, and bistability is more prominent when stress-free boundary conditions are used. A single scaling law may be feasible for all the models, but there does appear to be some variation for models with different thermal and velocity boundary conditions. The results presented in this thesis are not only applicable to the geodynamo, but will also aid in understanding the dynamos of other planets and exoplanets.

The significant generation of municipal solid waste (MSW) has become a controversial global issue. Pyrolysis and gasification technologies for treating rejects from solid waste disposal sites (SWDSs), for which over 50 % of MSW is attributed to combustible species, have attracted considerable attention. MSW is an alternative energy source that can partly replace fossil resources; there is an increasing awareness that global warming caused by the utilization of fossil resources is occurring. The goal of this thesis is to realize the efficient and rational utilization of MSW and decrease the harmful impact of pollutants, such as dioxin, HCl, and CO2, on the environment. To achieve this goal, some fundamental studies have been experimentally and numerically conducted to enhance the understanding of the properties of municipal solid waste thermal conversion. In this thesis, the pyrolysis behaviors of single pelletized recovered fuel were tested. A detailed comparison of the pyrolysis behaviors of typical recovered solid waste and biomass particles was conducted. A swelling phenomenon with a swelling ratio of approximately 1.6 was observed on the surface of pelletized recovered fuels. Subsequently, a particle model was constructed to describe the thermal conversion process for large recovered fuel particles that are composed of a high fraction of polyethylene (PE) and a comparable low fraction of cardboard. The results indicate that an understanding of the heat transfer mechanism in highly porous and molten structures and the selection of a heat transfer model are crucial for accurate prediction of the conversion process. MSW pyrolysis is a promising method for producing liquid products. With the exception of lignocellulosic materials, such as printing paper and cardboard, PE, polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) are the six main polymers in domestic waste in Europe. Characterization studies of the products obtained from these individual components, such as PE, PET, PVC, printing paper, and cardboard, have been conducted on a pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) system and a fixed-bed reactor. The possible pathways for the formation of the main primary/secondary products in rapid and conventional pyrolysis were also discussed. MSW steam gasification with CaO was performed in a batch-type fixed-bed gasifier to examine the effect of CaO addition on the heat transfer properties, pollutant removal, and devolatilization and char gasification behaviors in the presence of steam. A new carbon capture and recycle (CCR) system combined with an integrated municipal solid waste system was proposed. The foundation of the system is the development of a novel method to remediate CO2 using a high-temperature process of reforming CH4 and/or O2 and/or H2O without catalysts. Thermodynamic and experimental studies were performed. High temperatures significantly promoted the multi-reforming process while preventing the problem of catalyst deactivation. Potential improvements in the efficiency of the novel technology can be achieved by optimizing the reforming reactants. Landfill gas (LFG) and fuel gas from bio-waste treatment contain a considerable fraction of CH4, which may be a source of CH4 for this process. / <p>QC20141028</p>

Closed-loop ground source heat pumps (GSHPs) are used to transfer thermal energy between the subsurface and conditioned spaces for heating and cooling applications. A basic GSHP is composed of a ground heat exchanger (GHX), which is a closed loop of pipe buried in the shallow subsurface circulating a heat exchange fluid, connected to a heat pump. These systems offer an energy efficient alternative to conventional heating and cooling systems; however, installation costs are higher due to the additional cost associated with the GHX. By further developing our understanding of how these ground loops interact with the subsurface, it may possible to design them more intelligently, efficiently, and economically. To gain insight into the physical processes occurring between the GHX and the subsurface and to identify efficiencies and inefficiencies in GSHP design and operation, two main research goals were defined: comprehensive monitoring of a fully functioning GSHP and intensive simulation of these systems using computer models. A 6-ton GSHP was installed at a residence in Elora, ON. An array of 64 temperature sensors was installed on and surrounding the GHX and power consumption and temperature sensors were installed on the system inside the residence. The data collected were used to help characterize and understand the function of the system, provide motivation for further investigations, and assess the impact of the time of use billing scheme on GSHP operation costs. To simulate GSHPs, two computer models were utilized. A 3D finite element model was employed to analyse the effects of pipe configuration and pipe spacing on system performance. A unique, transient 1D finite difference heat conduction model was developed to simulate a single pipe in a U-tube shape with inter-pipe interactions and was benchmarked against a tested analytical solution. The model was used to compare quasi-steady state and transient simulation of GSHPs, identify system performance efficiencies through pump schedule optimization, and investigate the effect of pipe length on system performance. A comprehensive comparison of steady state and pulsed simulation concludes that it is possible to simulate transient operation using a steady state assumption for some cases. Optimal pipe configurations are identified for a range of soil thermal properties. Optimized pump schedules are identified and analysed for a specific heat pump and fluid circulation pump. Finally, the effect of pipe spacing and length on system performance is characterized. It was found that there are few design inefficiencies that could be easily addressed to improve general design practice.

In this thesis, the theory of three dimensional numerical modeling of transport and re-suspension of fine sediments is studied and a computer program is develped for simulation of the three dimensional suspended sediment transport. The computer program solves the three dimensional advection-diffusion equation simultaneously with a computer program prepared earlier for the simulation of three dimensional current systems. This computer program computes the velocity vectors, eddy viscosities and water surface elavations which are used as inputs by the program of fine sediment transport. The model is applied to Bay of Izmir for different wind conditions.

The Mars climate has been explored using two reanalysis datasets based on combining spacecraft observations of temperature and dust with the UK version of the LMD Mars GCM. The semiannual oscillation (SAO) of zonal-mean zonal wind was studied using the existing Mars Analysis Correction Data Assimilation reanalysis during Mars Years (MYs) 24-27. The SAO of zonal-mean zonal wind was shown to exist and extend over a wide range of latitudes. The dynamical driving processes of the SAO in the tropics were investigated, and the forcing due to meridional advection appeared to be the main contributor to the SAO. The study also highlighted some phenomena associated with perturbations of the global circulation during the MY 25 global dust storm (GDS). The meridional advection term was shown to be weaker in the first half of GDS year MY 25 than in the following year, but the forcing due to meridional advection and westward thermal tides both appeared to intensify during the MY 25 GDS. The capabilities of the Mars data assimilation system were also extended in this thesis, 1) to represent dynamic dust lifting and dust transport during the assimilation and 2) to assimilate measurements of the dust vertical distribution. The updated reanalysis was then used to study several major dust events during MY28-29. It proved able to reproduce a southward-moving regional dust storm without the overwhelming assistance of the assimilation. Dust devil lifting was found to at least partly provide the initial pattern of dust of this moving dust storm. The cold anomaly of the cooling zone beneath this dust storm could be as large as &Tilde; 2 K similar to the magnitude of what was found during the MY 25 GDS. Using the reanalysis, the life cycle of the planet-encircling global dust storm in MY28 was also studied. The Noachis dust storm that occurred just before the MY 28 GDS was found to be the joint result of a travelling Chryse storm, enhanced by dust lifting along its path and local dust lifting in Noachis itself. The adiabatic heating associated with the north polar warming that occurred during MY 28 GDS was up to &Tilde; 3 times as large as that found during the non-GDS year MY 29. The wind stress dust lifting was shown to in strong correlation with the global average dust loadings, and significantly decreased when the GDS decayed.

Goal of this paper is defining Hoek - Brown failure criterion for samples of granodiorite from possible site of Czech deep geological repository - Brezovy potok. Paper includes triaxial testing, defining HB failure criterion for intact rock, rock massif and evaluation of available data. Other methods for defining parameters of HB failure criterion (eg. GSI and mi) are also explored. Comparisons for all parameters and data are given. Paper is concluded with simple numerical model, using results from laboratory testing and literature review.

O trabalho apresentado tem como finalidade analisar os sistemas de ancoragem utilizados na fabricação de End Fittings (EF), através de ensaios de dois sistemas de ancoragem alternativos aos utilizados atualmente na indústria. Além disso, é apresentado o desenvolvimento de um modelo de elementos finitos (MEF) que permite a reprodução do comportamento durante o processo de pullout da ancoragem com melhor desempenho. A caracterização dos materiais envolvidos no sistema de ancoragem foi necessária para o desenvolvimento do modelo numérico. Desta forma, o modelo numérico conta com as propriedades elásticas e plásticas dos materiais, fator que influencia o comportamento do sistema assim como os valores de carga necessários para o arrancamento. A comparação das ancoragens propostas foi realizada a partir dos valores de força obtidos por meio de um teste de arrancamento, chamado de pullout. Para isto, arames da armadura de tração de uma linha flowline de 2,5 polegadas foram conformados de acordo à geometria das ancoragens propostas e embebidas em resina epóxi tentando, desta forma, representar de forma simplificada parte do sistema de ancoragem utilizado nos EF. O desempenho das ancoragens foi analisado a partir das curvas de força em função do deslocamento, nas quais se analisou a força máxima de pullout (força máxima de arrancamento), o deslocamento para força máxima de pullout e o valor de rigidez do sistema. Finalmente depois de selecionada a ancoragem com melhor desempenho, os valores experimentais foram comparados com os valores obtidos do modelo numérico, mostrando uma boa aproximação com valores de erro relativo para a força máxima de pullout e rigidez de -1% e 8%, respectivamente. Por fim, propõe-se como trabalho futuro a continuação nos estudos experimentais de pullout com o objetivo de aprofundar o conhecimento sobre os parâmetros que mais influenciam nestes sistemas, através da utilização de novas geometrias e materiais, assim como a normalização do processo de preparação e ensaio das amostras. / The work aims to analyze the anchoring systems used in manufacturing of flexible pipe End Fittings (EF) through the tests of two alternative anchoring systems different of the currently used in the industry. In addition, it is presented the development of a finite element model (MEF) that allows to reproduce the behavior during the pullout process of the anchoring system with the better performance. The characterization of the materials involved in the anchoring system was necessary for the development of the numerical model. In this way, the numerical model include the elastic and plastic properties of materials, factor that influence the behavior of the system as well as the force values needed for the pullout. The comparison of the proposed anchoring systems was performed from the force values obtained through a pullout test. For this, the armor wires of a flowline flexible pipe with a bore of 2.5-inch were conformed according the geometry of the anchoring systems proposed and then were fixed in epoxy resin, trying in this way to represent a simplified form of the anchoring system used in EF. The performance of the anchoring systems was analyzed from the force-displacement curves. The maximum pullout force, the offset for maximum strength of pullout and the stiffness value of the system were used for the analysis. Finally, after selected the anchoring system with better performance, the experimental values were compared with the values obtained from the numerical model. The results showed a good approximation, with a relative error for the maximum pullout force and stiffness of -1% and 8% respectively. As proposal for future works, the author proposes to continue with the experimental studies of pullout in order to enhance the knowledge about the influential parameters in these systems, through the use of new geometries and materials, as well as the standardization of the test samples preparation.

O reparo em dutos defeituosos é previsto por normas e literatura, porém existe grande espaço para definição dos parâmetros ideais para aplicação prática e avaliação do desempenho destes reparos em fadiga. O presente trabalho tem por objetivo a definição dos parâmetros ideais para aplicação de reparos eficientes do tipo dupla calha sem solda circunferencial e com carregamento externo em escala real em dutos com defeitos de mossa com cava. O reparo é baseado na instalação de duas calhas concêntricas ao duto a ser reparado, preenchendo-se o defeito com resina e aplicando carga de compressão através de atuadores hidráulicos com correntes a fim de induzir tensões compressivas na região do defeito e, por fim, as calhas são unidas longitudinalmente pelo processo de soldagem. Para este trabalho, foi realizada uma modelagem numérica utilizando o método de elementos finitos de modo a simular a reprodução do defeito, ensaios de fadiga sem reparo, parâmetros para aplicação do reparo, ensaios de fadiga com reparo e, por fim, ensaio hidrostático. O procedimento proposto foi a reprodução do defeito, primeiramente o duto foi deformado com uma esfera metálica, de modo a formar uma mossa de profundidade igual a 6 % do diâmetro externo e, em seguida, a cava foi usinada com a utilização de um disco abrasivo. Após a produção do defeito, três amostras foram ensaiadas em fadiga, de modo a produzir uma amostra de referência sem reparo a ser comparada com os corpos de prova com reparo. O reparo dupla calha foi aplicado em duas amostras com defeito, sendo essas então submetidas a ensaios de fadiga. Esses ensaios indicaram que ambas as amostras resistiram a um número de ciclos correspondentes a 100 anos de vida em serviço. Por fim, as amostras reparadas após o ensaio de fadiga foram submetidas a ensaios hidrostáticos até a ruptura, a fim de avaliar a vida remanescente. Ambos os dutos romperam fora da região reparada, com uma pressão 2,1 %, menor que a pressão calculada analiticamente. Como principal resultado, foram obtidos parâmetros ideais para aplicação do reparo dupla calha em dutos com defeito tipo mossa com cava. Os resultados experimentais mostram convergência em relação aos dados do modelo numérico, provando que a modelagem por elementos finitos pode ser uma ferramenta útil no desenvolvimento deste tipo de trabalho. / Defective duct repairs are envisaged by norms and by the literature, yet there is enough space left to define ideal parameters for practical application and performance evaluation of these fatigue repairs. This work’s objective is to define the ideal parameters for the application of efficient repairs in double spouts without circumferential welding and real scale external loading in ducts with dent and gouge defects. The repair is based on the installation of two concentric spouts in the duct, filling the defect with resin and applying compression loading through hydraulic actuators with currents to induce compressive stresses in the defective area. Afterwards, the spouts are united lengthwise through the process of welding. To develop this work, we conducted a numerical modelling by using the finite element method to simulate the reproduction of the defect, as well as fatigue tests with no repairs, parameters for the application of repairs, fatigue tests with repairs, and finally a hydrostatic test. The proposed procedure was the reproduction of the defect. At first the duct was deformed with a metallic sphere, to form a dent whose depth was equal to 6 % of the external diameter and, subsequently, the gouge was machined with the help of an abrasive disk. Following the production of a defect, three samples were tested in fatigue to produce a reference sample without repair which would be compared to the samples with repairs. The double spout repair was applied in two samples with defects, which were then subjected to fatigue tests. These tests showed that both samples resisted to a number of cycles corresponding to a 100-year use lifespan. At last, the samples repaired after fatigue tests were subjected to hydrostatic tests until rupture, in order to evaluate their remaining lifespan. Both ducts ruptured outside of the repaired region, with a stress rate of 2.1 %, lower than the stress calculated analytically. The main result of this study was obtaining ideal parameters for the application of double spout repair in ducts with dents and gouge defects. The experimental results show convergence in relation to the numerical model data, proving that finite element modelling can be a useful tool when conducting this kind of work.

Lajes nervuradas modeladas computacionalmente são geralmente analisadas por metodologias simplificadas, tanto para a geometria da seção (convertendo em lajes maciças ou grelhas) como para as propriedades mecânicas dos materiais (regime elástico-linear). Estes estudos teóricos apresentam grandes diferenças quando comparados com ensaios experimentais, mesmo para baixos níveis de carregamento. Isto se deve principalmente pela não consideração da excentricidade entre os eixos da nervura e da capa, como também à simplificação do comportamento mecânico do concreto à tração. Modelos numéricos chamados realísticos consideram o efeito da excentricidade entre os eixos da capa e nervura da seção transversal. Pode-se, ainda, introduzir a não-linearidade física do concreto armado nestes modelos, obtendo resultados mais próximos do real. O objetivo deste trabalho é estabelecer um modelo numérico realístico, para a seção típica de laje nervurada, atendendo às indicações descritas acima. Para a consideração da excentricidade entre os eixos da capa e nervura empregam-se elementos de casca, em posição horizontal para a capa e vertical para a nervura. A não-linearidade física do concreto à tração é representada através do modelo de fissuração distribuída proposto por D’AVILA (2003). Para as análises não-lineares empregou-se o programa computacional de elementos finitos SAP2000 versão 16, onde os elementos de casca permitem discretizar o concreto armado em camadas, ao longo da espessura. Um bom desempenho do modelo numérico proposto foi verificado pela validação deste a partir de modelos experimentais, assim como da análise numérica de outros autores. Realizaram-se, por último, análises de algumas lajes nervuradas com solicitações de carregamentos excessivos, a fim de prever seus desempenhos frente a estados limites de flexão. Os resultados obtidos nestas análises mostraram, também, um bom desempenho do modelo proposto. / Waffle slab structures simulated by computational models are generally analyzed by simplified methods, both for section geometry (converting into solid slabs) and the material mechanical properties (linear elastic regime). The results obtained by such theoretical studies show large differences when compared to experimental tests, even at low loading levels. This is mainly due to non-consideration of the eccentricity between the rib and cover axes and simplification of the concrete tensile strength mechanical behavior. The so called realistic numerical models consider the effect of eccentricity between the axes of hood and ribs of the cross section. One may also introduce physical nonlinearity of reinforced concrete in these models, obtaining results closer to real. The objective of this work is to establish a realistic numerical model for the typical section of a waffle slab, considering the physical nonlinearity of concrete and its collaboration between cracks, by the smeared crack model proposed by D' AVILA (2003). The computational finite element program SAP2000 version 16 is used for the non-linear analysis. The shell element discretization enabled the heterogeneous characteristics of reinforced concrete to be considered through layers along the thickness. The numerical model was validated based on the analysis of experimentally tested slabs. Finally, some waffle slabs were numerically analyzed under a uniformly distributed and incrementally growing load. The proposed model was able to predict their overall behavior and some local aspects could also be observed.