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The performance of nonstructural components in critical infrastructure, such as nuclear power plants (NPPs), has been primarily based on experience and historical data. This topic has been attracting increased interest from researchers following the Fukushima Daiichi nuclear disaster in 2011. This disaster demonstrated the importance of using batteries in NPPs as an auxiliary power system, where such systems can provide the necessary power to mitigate the risk of serious accidents. However, little research has been conducted on such nonstructural components to evaluate their performance following the post- Fukushima safety requirements, recommended by several nuclear regulators worldwide [e.g., Nuclear Regulatory Commission (NRC), and Nuclear Safety Commission (NSC)]. To address this research gap, this dissertation investigates the lateral performance of an auxiliary battery power system (ABPS) similar to those currently existing/operational in NPPs in Canada. The ABPS was experimentally tested under displacement-controlled quasi-static cyclic fully-reversed loading that simulates lateral seismic demands. Due to the presence of sliding batteries, the ABPS was then tested dynamically under increased ground motion levels on a shake table. The experimental results demonstrated that the design guidelines and fragility curves currently assigned to battery rack systems in the FEMA P58 prestandards do not encompass all possible failure mechanisms. A 3D numerical model was also developed using OpenSees software. The model was validated using the experimental results. The model results showed that the lateral performance of ABPS with different configurations (i.e. different lengths, tiers, and seismic categories) is influenced by the capacity of the L-shaped connection between the side rails and the end rail. However, the model was not able to predict all the damage states from the dynamic experimental tests, since the rocking/sliding/impact behavior of the batteries is a highly complex nonlinear problem by nature and beyond the scope of this study. The model presented is limited to the assessment of the lateral performance of different ABPS statically. This dissertation demonstrated the difference between the observed behavior of laboratory-controlled lateral performance tests of ABPSs operational/existing in NPPs and the behavior of ABPSs found in the literature that relied on limited historical and experience data. Finally, this dissertation laid the foundations for the need to further investigate the behavior of other safety-related components in NPPs and assess their compliance with new post-Fukushima design requirements. / Thesis / Doctor of Philosophy (PhD)

Ce travail s'inscrit dans le cadre du projet SIMED fédérant les activités de modélisation à l'échelle méditerranéenne, et plus globalement dans le programme MERMEX qui vise à étudier les cycles biogéochimiques en mer Méditerranée et leurs évolutions futures. L'étape préliminaire a été de coupler la plateforme de modélisation hydrodynamique (NEMO) à celle de modélisation biogéochimique mécaniste (Eco3M), afin de réaliser une simulation (2000-2012) utilisant les sorties hydrodynamiques de la configuration NEMO-MED12 pour forcer le modèle biogéochimique Eco3M-MED. Les nombreuses comparaisons menées dans cette thèse (chlorophylle, sels nutritifs, production primaire, etc.) ont aidé à s'assurer de la capacité du modèle à reproduire les principales caractéristiques biogéochimiques de la Méditerranée. Ce travail a permis de généraliser le rôle majeur joué par le carbone organique dissous dans la pompe biologique à l'échelle de la mer Méditerranée. Les résultats montrent que la production de carbone organique particulaire est restreinte aux régions de forte dynamique physique, tandis que l'accumulation de carbone organique dissous dans les eaux de surface est commune à la plupart des régions du bassin. Ce dernier processus s'est avéré dépendant des contenus cellulaires du phytoplancton et des bactéries hétérotrophes. Finalement d'après le modèle, la fraction dissoute du carbone organique contribuerait à hauteur d'environ 64 % à l'exportation dans le bassin Ouest, et de 90 % dans le bassin Est. Le bassin Est -en dépit de sa plus forte oligotrophie- s'avère participer à près de 60 % à l'exportation de carbone organique en mer Méditerranée. / This work is part of the SIMED project which is dedicated to basin-scale modeling of the Mediterranean Sea. It also belongs to the MERMEX program which aims at studying biogeochemical cycles in the Mediterranean Sea and their evolution. The first step of this work was to couple the hydrodynamic modeling platform (NEMO) to the mechanistic biogeochemical modeling platform (Eco3M). We ran a simulation (2000-2012) using the hydrodynamic outputs from NEMO-MED12 configuration to force the biogeochamical model Eco3M-MED. The model evaluation was conducted using numerous field measurements (chlorophyll, nutrients, primary production, etc.). The simulation strengthens and extends to the whole basin the prominent role of dissolved organic carbon in the biological carbon pump in the whole Mediterranean Sea. A comprehensive analysis of organic carbon (particulate and dissolved) production processes production was performed. Results reveal that particulate organic carbon production is restricted to the highly dynamic areas, whereas dissolved organic carbon accumulation in the surface layers is a common process in much areas of the basin. This latter process appeared to dependant on the cellular contents of phytoplancton and heterotrophic bacteria, themselved being controled by low phosphate availability. Finally, the dissolved organic carbon contribution to carbon export is around 64 % in the Western basin, and up to 90 % in the Eastern basin. When taking into account the dissolved fraction, total organic carbon export in the Eastern basin -despite its higher oligotrophy- exceeds the one in the Western basin (60% against 40 %).

<p>This thesis presents predictive models for important variables concerning eutrophication effects in lakes. The keystone is a dynamic phosphorus model based on ordinary differential equations. By calculating mass fluxes of phosphorus into, within and out from a lake, the concentrations of different forms of phosphorus in different compartments of the lake are estimated.</p><p>The dynamic phosphorus model is critically tested and several improvements are presented, including two new compartments for colloidal phosphorus, a sub-model for suspended particulate matter (SPM) and new algorithms for lake outflow, water mixing, diffusion, water content and organic content of accumulation sediments are implemented. Predictions with the new version show good agreement against empirical data in five tested lakes.</p><p>The sub-model for SPM uses the same driving variables as the basic phosphorus model, so the inclusion of this model as a sub-model does not require any additional variables. The model for SPM may also be used as a separate model giving monthly predictions of suspended particulate matter in two water compartments and one compartment with SPM available for resuspension in ET-sediments.</p><p>Empirical data from Lake Erken (Sweden) and Lake Balaton (Hungary) are used to evaluate the variability in settling velocity of SPM. It is found that the variability is substantial and may be accounted for by using a dimensionless moderator for SPM concentration. Empirical data from accumulation area sediments in Lake Erken are used to develop a model for the dynamics of phosphorus sedimentation, burial and diffusion in the sediments. The model is shown to provide reasonable monthly predictions of four functional forms of phosphorus at different sediment depths.</p><p>Simulations with the lake phosphorus model using two different climate scenarios indicate that lakes may respond very differently to climate change depending on their physical character. Lake Erken, with a water retention time of 7 years, appears to be much more sensitive than two basins of Lake Mälaren (Sweden) with substantially shorter retention times. The implication would be that in eutrophic lakes with long water retention times, eutrophication problems may become serious if the future becomes warmer. This will be important in contexts of lake management when remedial measures against lake eutrophication have to be taken.</p>

This thesis presents predictive models for important variables concerning eutrophication effects in lakes. The keystone is a dynamic phosphorus model based on ordinary differential equations. By calculating mass fluxes of phosphorus into, within and out from a lake, the concentrations of different forms of phosphorus in different compartments of the lake are estimated. The dynamic phosphorus model is critically tested and several improvements are presented, including two new compartments for colloidal phosphorus, a sub-model for suspended particulate matter (SPM) and new algorithms for lake outflow, water mixing, diffusion, water content and organic content of accumulation sediments are implemented. Predictions with the new version show good agreement against empirical data in five tested lakes. The sub-model for SPM uses the same driving variables as the basic phosphorus model, so the inclusion of this model as a sub-model does not require any additional variables. The model for SPM may also be used as a separate model giving monthly predictions of suspended particulate matter in two water compartments and one compartment with SPM available for resuspension in ET-sediments. Empirical data from Lake Erken (Sweden) and Lake Balaton (Hungary) are used to evaluate the variability in settling velocity of SPM. It is found that the variability is substantial and may be accounted for by using a dimensionless moderator for SPM concentration. Empirical data from accumulation area sediments in Lake Erken are used to develop a model for the dynamics of phosphorus sedimentation, burial and diffusion in the sediments. The model is shown to provide reasonable monthly predictions of four functional forms of phosphorus at different sediment depths. Simulations with the lake phosphorus model using two different climate scenarios indicate that lakes may respond very differently to climate change depending on their physical character. Lake Erken, with a water retention time of 7 years, appears to be much more sensitive than two basins of Lake Mälaren (Sweden) with substantially shorter retention times. The implication would be that in eutrophic lakes with long water retention times, eutrophication problems may become serious if the future becomes warmer. This will be important in contexts of lake management when remedial measures against lake eutrophication have to be taken.

Made available in DSpace on 2014-12-17T14:08:52Z (GMT). No. of bitstreams: 1 JulioCSN_DISSERT.pdf: 2712130 bytes, checksum: ee800f3d5f68d01d1d955c026ae1891b (MD5) Previous issue date: 2013-02-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The multiphase flow occurrence in the oil and gas industry is common throughout fluid path, production, transportation and refining. The multiphase flow is defined as flow simultaneously composed of two or more phases with different properties and immiscible. An important computational tool for the design, planning and optimization production systems is multiphase flow simulation in pipelines and porous media, usually made by multiphase flow commercial simulators. The main purpose of the multiphase flow simulators is predicting pressure and temperature at any point at the production system. This work proposes the development of a multiphase flow simulator able to predict the dynamic pressure and temperature gradient in vertical, directional and horizontal wells. The prediction of pressure and temperature profiles was made by numerical integration using marching algorithm with empirical correlations and mechanistic model to predict pressure gradient. The development of this tool involved set of routines implemented through software programming Embarcadero C++ Builder? 2010 version, which allowed the creation of executable file compatible with Microsoft Windows? operating systems. The simulator validation was conduct by computational experiments and comparison the results with the PIPESIM?. In general, the developed simulator achieved excellent results compared with those obtained by PIPESIM and can be used as a tool to assist production systems development / Na ind?stria do petr?leo a ocorr?ncia de escoamento multif?sico ? comum em todo o percurso dos fluidos, durante a produ??o, transporte e refino. O escoamento multif?sico ? definido como o escoamento simult?neo composto por duas ou mais fases com propriedades diferentes e imisc?veis. Uma importante ferramenta computacional para o dimensionamento, planejamento e otimiza??o de sistemas de produ??o ? a simula??o de escoamento multif?sico em dutos e meios porosos, normalmente, feita por simuladores comerciais. O objetivo b?sico desses simuladores ? prever a press?o e temperatura em diferentes pontos do sistema de produ??o. Este trabalho prop?e o desenvolvimento de um simulador de escoamento multif?sico em po?os verticais, direcionais e horizontais, capaz de determinar o gradiente din?mico de press?o e temperatura. A determina??o dos perfis de press?o e de temperatura foi feita por meio de integra??o num?rica utilizando o algoritmo de marcha com correla??es emp?ricas e modelo mecanicista para determinar o gradiente de press?o. O desenvolvimento do simulador envolveu o conjunto de rotinas implementadas atrav?s do software de programa??o Embarcadero C++ Builder? vers?o 2010, que permitiu a cria??o de arquivo execut?vel compat?vel com os sistemas operacionais da Microsoft Windows?. A valida??o do simulador foi conduzida por experimentos computacionais e compara??o dos resultados com o simulador de uso comercial PIPESIM?. De modo geral, o simulador desenvolvido alcan?ou excelentes resultados quando comparado com os obtidos pelo PIPESIM, podendo ser utilizado como ferramenta para auxiliar no desenvolvimento de sistemas de produ??o

Le champ électrique d'une puissance suffisante peut provoquer une augmentation de conductivité et perméabilité de la membrane cellulaire. L'effet est connu comme l'électroporation, attribuée à la création de voies aqueuses dans la membrane. Quantifier le transport de la matière dans le cadre d'électroporation est un objectif important. Comprendre ces processus a des ramifications dans l’extraction du jus ou l’extraction sélective des composés de cellules végétales, l'amélioration de l'administration de médicaments, et des solutions aux défis environnementaux. Il y a un manque de modèles qui pourraient être utilisés pour modéliser le transport de la matière dans les structures complexes (tissus biologiques) par rapport à l'électroporation. Cette thèse présente une description mathématique théorique (un modèle) pour étudier le transport de la matière et le transfert de la chaleur dans tissu traité par l’électroporation. Le modèle a été développé en utilisant les lois de conservation et de transport et permet le couplage des effets de l'électroporation sur la membrane des cellules individuelles au transport de la matière ou la chaleur dans le tissu. Une solution analytique a été trouvée par une simplification, mais le modèle peut être étendu avec des dépendances fonctionnelles supplémentaires et résolu numériquement. La thèse comprend cinq articles sur l'électroporation dans l'industrie alimentaire, la création de modèle pour le problème de diffusion, la traduction du modèle au problème lié à l’expression de jus, validation du modèle, ainsi que des suggestions pour une élaboration future du modèle. Un chapitre supplémentaire est dédié au transfert de la chaleur dans tissu. / An electric field of sufficient strength can cause an increase of conductivity and permeability of cell membrane. Effect is known as electroporation and is attributed to creation of aqueous pathways in the membrane. Quantifying mass transport in connection with electroporation of biological tissues is an important goal. The ability to fully comprehend transport processes has ramifications in improved juice extraction and improved selective extraction of compounds from plant cells, improved drug delivery, and solutions to environmental challenges. While electroporation is intensively investigated, there is a lack of models that can be used to model mass transport in complex structures such as biological tissues with relation to electroporation. This thesis presents an attempt at constructing a theoretical mathematical description – a model, for studying mass (and heat) transfer in electroporated tissue. The model was developed employing conservation and transport laws and enables coupling effects of electroporation to the membrane of individual cells with the resulting mass transport or heat transfer in tissue. An analytical solution has been found though the model can be extended with additional dependencies to account for the phenomenon of electroporation, and solved numerically. Thesis comprises five peer-reviewed papers describing electroporation in the food industry, model creation for the problem of diffusion, translation of the model to the mathematically-related case of juice expression, model validation, as well as suggestions for possible future development, extension, and generalization. An additional chapter is dedicated to transfer of heat in tissue.

The concept of reinforcement was developed in late 20th century and since then till the recent past there are many works carried out on the effect of fibers in imparting strength and stiffness to the soil. Experimental investigations on fiber reinforced soils showed an increase in shear strength and reduction in post peak loss of strength due to the reinforcement. Analytical/mechanistic models are developed to predict the stress-strain response of fiber reinforced soil (under discrete framework, energy dissipation methods, force equilibrium methods etc). Numerical investigations are also carried out, and it was observed that the presence of random reinforcing material in soils make the stress concentration diffuse more and restrict the shear band formation. Soil properties vary from point to point at micro level and influence stress mobilization. Hence, there is a need to carry out probabilistic analysis to capture the effects of uncertainties and variability in soil and their influence on stress-strain evolution. In the present thesis an attempt has been made to propose a mechanistic model that predicts the stress-strain response of fiber reinforced soil and also considers the effect of anisotropy of fibers. A stochastic/probabilistic model is developed that predicts the stochastic stress-strain response of fiber reinforced soil. In addition, probabilistic analysis is carried out to observe the effect of number of fibers across the shear plane in imparting shear resistance to soil. The mechanistic model and stochastic models are validated with reference to the experimental results of consolidated undrained (CU) triaxial tests on coir fiber reinforced red soil for different fiber contents. The entire thesis is divided into six chapters. Chapter-wise description is given below. Chapter one presents a general introduction to the works carried out on fiber reinforced soils and also the investigations carried out on probabilistic methodologies that takes into account the soil variability. Thus, the chapter gives an outline of the models developed under mechanistic and probabilistic frameworks in the thesis. The objectives and organization of the thesis are also presented. Chapter two presents a detailed review of literature on the role of fibers in fiber reinforced soil. The details of experimental investigations carried out and models developed are explained briefly. Also, the literature pertaining to the role of variability in soil on its engineering behavior is presented. Based on the literature presented in this chapter, concluding remarks are made. Chapter three presents the details of a new mechanistic model developed based on modified Cam-clay model. This model considers the effect of fiber content and also the effect of anisotropy due to fibers. The predictions from the mechanistic model are compared with the experimental results. Under anisotropic condition, as angles of inclination of fiber vary from 0° to 90° with the bedding plane, it is observed that the strength increment in the reinforced soil is not as significant as that observed in isotropic case. Horizontal fibers turn out to be most effective since they are subjected to maximum extension thereby inducing tensile resistance which in turn contributes for strength increase in fiber reinforced soil. Chapter four presents a new approach to predict the stochastic stress-strain response of soil. Non-homogeneous Markov chain (multi-level homogeneous Markov chain) modeling is used in the prediction of stochastic response of soil. The statistical variations in the basic variables are taken into account by considering the response quantities (viz. stress at a given strain or settlement at a given load level) as random. A bi-level Homogeneous Markov chain predicts the stochastic stress-strain response efficiently. The predicted results are in good agreement with the experimental results. An illustration of this model is done to predict the stochastic load-settlement response of cohesionless soil. A simple tri-level homogeneous Markov chain model is proposed to predict settlements of soil at a given load for an isolated square footing subjected to axial compression. A parametric study on the effect of correlation coefficient on the prediction of settlements is performed. Chapter five presents the results of probabilistic analysis carried out to determine the effect of number of fibers across the shear plane in improving the shear strength of soil. It is observed that as the percentage of fibers in the specimen increases, the probability of failure of specimen under the same stress condition reduces and thus the reliability of the fiber reinforced soil system increases. In Chapter six, a summary of the important conclusions from the various studies reported in the dissertation are presented.

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