Made available in DSpace on 2014-06-11T19:26:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-04-25Bitstream added on 2014-06-13T20:14:49Z : No. of bitstreams: 1 alberto_mc_me_rcla_prot.pdf: 5590132 bytes, checksum: 784e399b21f7830bb2111b5b49d2b78b (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A simulação numérica vem sendo largamente utilizada para avaliar condições de fluxo da água subterrânea, podendo subsidiar a previsão da migração de contaminantes. Neste trabalho, foi realizada simulação em regime de fluxo permanente de uma área adjacente ao rio Atibaia, no município de Paulínia, incluindo topo, encosta, várzea e leito do rio, como subsídio ao entendimento das condições hidrogeológicas locais. As grandes variações das propriedades hidráulicas se devem à complexa geologia da área dominada por depósitos glaciais, intrudidos por rochas basálticas. As ferramentas utilizadas para realização deste trabalho consistiram em técnicas convencionais de investigação de campo, como instalação de piezômetro, ensaios geofísicos, hidrogeológicos, petrofísicos e físico-químicos e, modelos matemáticos, a fim de subsidiar a caracterização hidrogeológica, e auxiliar o rearranjo da distribuição espacial das propriedades hidráulicas do meio físico. Os resultados mostraram eficiência da metodologia utilizada, para a caracterização hidrogeológica da área, conforme observado pela estreita relação entre modelo hidrogeológico conceitual inicial e o modelo final estabelecido pela simulação numérica. As mudanças nas propriedades hidráulicas mostraram compatibilidade com a variação litológica da área. A simulação foi realizada utilizando dois softwares, visual MODFLOW e FEFLOW, que apresentaram resultados similares após a calibração dos referidos modelos. / Numerical modeling has been widely used to evaluate groundwater flow and contaminant migration. In the present work, river-slope system adjacent to Atibaia River, Paulínia city, was simulated under steady-state conditions, accounting for upper and mid-slope, meadow and river bed, to help to understand local hydrogeological conditions. Great variability of hydraulic properties is due to the complex geology of the area, dominated by glacial depostis, intruded by basaltic igneous rocks. Tools used for this research consist of conventional field investigation techniques, such as piezometers construction, geophysical and hydrogeological essays, petrophysics and physical-chemical laboratory assessment and groundwater modeling to subsidize hydrogeological understanding, helping to refine spatial distribution of the hydraulic properties. These tools proved to be efficient because of the narrow relationship between initial conceptual hydrogeologic model, based on field data, and the model stabilished by numerical modeling. Changes in hydraulic properties due to model calibration process are compatible with the local lithological variation. The calibration was performed using two groundwater modeling softwares, visual MODFLOW and FEFLOW, showing similar results.

Orientador: Chang Hung Kiang / Banca: Edson Cesar Wendland / Banca: Gerson Cardoso da Silva Junior / Resumo: A simulação numérica vem sendo largamente utilizada para avaliar condições de fluxo da água subterrânea, podendo subsidiar a previsão da migração de contaminantes. Neste trabalho, foi realizada simulação em regime de fluxo permanente de uma área adjacente ao rio Atibaia, no município de Paulínia, incluindo topo, encosta, várzea e leito do rio, como subsídio ao entendimento das condições hidrogeológicas locais. As grandes variações das propriedades hidráulicas se devem à complexa geologia da área dominada por depósitos glaciais, intrudidos por rochas basálticas. As ferramentas utilizadas para realização deste trabalho consistiram em técnicas convencionais de investigação de campo, como instalação de piezômetro, ensaios geofísicos, hidrogeológicos, petrofísicos e físico-químicos e, modelos matemáticos, a fim de subsidiar a caracterização hidrogeológica, e auxiliar o rearranjo da distribuição espacial das propriedades hidráulicas do meio físico. Os resultados mostraram eficiência da metodologia utilizada, para a caracterização hidrogeológica da área, conforme observado pela estreita relação entre modelo hidrogeológico conceitual inicial e o modelo final estabelecido pela simulação numérica. As mudanças nas propriedades hidráulicas mostraram compatibilidade com a variação litológica da área. A simulação foi realizada utilizando dois softwares, visual MODFLOW e FEFLOW, que apresentaram resultados similares após a calibração dos referidos modelos. / Abstract: Numerical modeling has been widely used to evaluate groundwater flow and contaminant migration. In the present work, river-slope system adjacent to Atibaia River, Paulínia city, was simulated under steady-state conditions, accounting for upper and mid-slope, meadow and river bed, to help to understand local hydrogeological conditions. Great variability of hydraulic properties is due to the complex geology of the area, dominated by glacial depostis, intruded by basaltic igneous rocks. Tools used for this research consist of conventional field investigation techniques, such as piezometers construction, geophysical and hydrogeological essays, petrophysics and physical-chemical laboratory assessment and groundwater modeling to subsidize hydrogeological understanding, helping to refine spatial distribution of the hydraulic properties. These tools proved to be efficient because of the narrow relationship between initial conceptual hydrogeologic model, based on field data, and the model stabilished by numerical modeling. Changes in hydraulic properties due to model calibration process are compatible with the local lithological variation. The calibration was performed using two groundwater modeling softwares, visual MODFLOW and FEFLOW, showing similar results. / Mestre

La modélisation numérique des écoulements de glace est indispensable pour prédire l’évolution des calottes polaires suite au réchauffement climatique. De récentes études ont souligné l’importance des modèles d’écoulement dits d’ordre supérieur voir même de Stokes au lieu de la traditionnelle approximation de couche mince dont les hypothèses ne sont pas valables dans certaines zones critiques mais à l’étendue limitée. Cependant, ces modèles d’ordre supérieur sont difficiles à utiliser à l’échelle d’un continent en raison de leurs temps de calculs prohibitifs. Ce travail de thèse propose une nouvelle technique qui permet de réduire les temps de calculs tout en maximisant la précision des modèles. Plusieurs modèles d’écoulement de glace de complexité variables ont été mis en place dans ISSM (Ice Sheet System Model), un code élément fini massivement parallèle développé par le Jet Propulsion Laboratory. L’analyse et la comparaison des différents modèles, à la fois sur des cas théoriques et réels, montrent que l’utilisation des modéles les plus complets est principalement nécessaire au voisinage de la zone d’échouage, transition entre les parties flottantes et posées de la glace, mais aussi que des modèles plus simples peuvent être utilisés sur la majeure partie des glaciers. Coupler différents modèles présente donc un avantage significatif en terme de temps de calcul mais aussi d’amélioration de la physique utilisées dans les modèles. Plusieurs méthodes de couplage de modèles existent et sont présentées dans ce manuscrit. Une nouvelle technique, dite de tuilage, particulièrement adaptée au couplage de modèles d’écoulement de glace est décrite ici : son principe repose sur la superposition et le raccordement de plusieurs modèles mécaniques. Une analyse mathématique est effectuée afin de définir les conditions d’utilisation de cette méthode de tuilage. Le traitement du couplage entre un modèle de Stokes et des modèles simplifiés, pour lesquels le calcul des vitesses horizontales et verticales est découplé, est ensuite présenté. Cette technique a été mise en place dans ISSM afin de pouvoir créer des modèles hybrides combinant plusieurs modèles d’écoulement de complexité variable. Après avoir été validée sur des cas synthétiques, cette technique est utilisée sur des glaciers réels comme Pine Island Glacier, dans l’Antarctique de l’Ouest, afin d’illustrer sa pertinence. Les modèles hybrides ont le potentiel d’améliorer la précision des résultats en combinant différents modèles mécaniques, utilisés chacun dans les zones où leurs approximations sont valides, tout en réduisant les temps de calcul et en étant compatibles avec les ressources informatiques actuelles. / Ice flow numerical models are essential for predicting the evolution of ice sheets in a warming climate. Recent research emphasizes the need for higher-order and even full-Stokes flow models instead of the traditional Shallow-Ice Approximation whose assumptions are not valid in certain critical but spatially limited areas. These higher-order models are however computationally intensive and difficult to use at the continental scale. The purpose of this work, therefore, is to develop a new technique that reduces the computational cost of ice flow models while maximizing their accuracy. To this end, several ice flow models of varying order of complexity have been implemented in the Ice Sheet System Model, a massively parallelized finite element software developed at the Jet Propulsion Laboratory. Analysis and comparison of model results on both synthetic and real geometries shows that sophisticated models are only needed in the grounding line area, transition between grounded and floating ice, whereas simpler models yield accurate results in most of the model domain. There is therefore a strong need for coupling such models in order to balance computational cost and physical accuracy. Several techniques and frameworks dedicated to model coupling already exist and are investigated. A new technique adapted to the specificities of ice flow models is developed: the Tiling method, a multi-model computation strategy based on the superposition and linking of different numerical models. A mathematical analysis of a mixed Tiling formulation is first performed to define the conditions of application. The treatment of the junction between full-Stokes and simpler models that decouple horizontal and vertical equation is then elaborated in order to rigorously combine all velocity components. This method is finally implemented in the Ice Sheet System Model to design hybrid models that combine several ice flow approximations of varying order of complexity. Following a validation on synthetic geometries, this method is applied to real cases, such as Pine Island Glacier, in West Antarctica, to illustrate its relevance. Hybrid models have the potential to significantly improve physical accuracy by combining models in their domain of validity, while preserving the computational cost and being compatible with the actual computational resources.

Les vibrations dans les sols constituent un problème environnemental de plus en plus important. Cette étude adresse plusieurs aspects des vibrations du sol. Les conditions locales du site et l'amplification des ondes sismiques représentent un sujet largement étudié en sismologie et en ingénierie sismique. Bien que la plupart des études soient consacrées à la sismologie d'ingénierie et à l'ingénierie sismique, des approches similaires pour la classification des sols et l'amplification du site n'ont pas encore été pleinement établies dans le domaine des vibrations urbaines.D'abord, une stratégie d’optimisation pour la méthode des couches absorbantes a été développée afin d'améliorer la précision des modèles par éléments finis. La conception de couches absorbantes simples en éléments finis par l'annulation de la partie réelle des ondes réfléchies dans le domaine du nombre complexe s'est révélée efficace lorsqu'elle est couplée à la réduction de la rigidité de la couche absorbante. Une réduction excessive de la rigidité ainsi que l'augmentation excessive du facteur de rigidité dans la matrice d'atténuation ont permis une grande réduction de la taille de la couche absorbante et par suite la conception d'une couche absorbante moins coûteuse.Ensuite, une partie importante du travail a été consacrée à la dérivation d'un nouvel ensemble de paramètres du type gradient de vitesse qui contrôle le transfert des vibrations à travers des sols multicouches. L'absence d'une approche compréhensive et bien structurée pour la prédiction et la classification des sites pour les problèmes de vibration laisse le problème large et compliqué. Différents sites ayant différentes propriétés mécaniques et géométriques ont été examinés à l'aide des éléments finis. Les réponses des sites ont été formulées dans des approches spectrales et temporelles simples. Les paramètres nouvellement dérivées ainsi que les lois spectrales servent de moyen de classification des sols multicouches pour les problèmes de vibrations et peuvent même être utilisées à des fins de conception.D’ailleurs, un outil d'intelligence artificielle pour prédire la réponse du sol en utilisant les paramètres précédemment dérivées associées aux propriétés géométriques de la couche de surface a été développé. L'outil des réseaux neurone a été utilisé pour analyser les effets paramétriques des paramètres de gradient de vitesse par rapport à la profondeur de la couche de surface. Des conclusions importantes ont été tirées de l'analyse concernant les propriétés mécaniques et géométriques des couches multiples et leurs effets variantes avec la distance de la source.Enfin, les enregistrements de sources multiples ont été étudiés en les comparants aux réponses spectrales des différents sites définis dans les sections précédentes. Le taux d'appariement entre le contenu spectral d'une source particulière et un site donné sert à évaluer l’aléa vibratoire causé par cette source au site correspondant. L'évaluation des risques de vibrations conduit à un lien de classification entre les sources d'une part et les sites caractérisés par des paramètres à gradient de vitesse d'autre part / Ground vibration is an increasingly important environmental problem. This study investigates multiple aspects of ground vibration. Local site conditions and the related amplification of seismic waves represent a widely studied topic in seismology and earthquake engineering. While most of the studies are dedicated to engineering seismology and earthquake engineering, similar approaches for soil classification and site amplification have not been yet fully established in the field of urban vibrations.First an improvement strategy for absorbing layer method was developed in order to enhance precision of the FEM models. The design of simple absorbing layers in FEM through the nullification of the real part of reflected waves in the complex number domain proved to be efficient when coupled with the stiffness reduction of the absorbing layer. Excessive reduction of the stiffness along with the excessive increase of the stiffness factor in the attenuation matrix enabled a large reduction in the size of the absorbing layer and therefore the design of an inexpensive absorbing layer.Afterwards an important part of the work was dedicated to the derivation of a new set of parameters of the velocity-gradient type that controls the vibration transfer through multilayered soil. The absence of a well-structured comprehensive approach for prediction and site classification for vibration problems leaves the problem broad and complicated. Different sites with different mechanical and geometrical properties were examined using FEM and their surface response was studied. Sites responses were formulated in simple time domain and spectral approaches. The newly derived proxies along with the spectral laws serve as a classification mean for multilayered soils in the vibration problem and may even be used for design purposes.An artificial intelligence tool for predicting soil response using the previously derived proxies coupled with the geometrical properties of the surface layer was later developed. The neural networks tool was used to analyze the parametric effects of the velocity-gradient proxies versus that of the surface layer’s depth. Important conclusions were derived from the analysis regarding the mechanical and geometrical properties of multiple layers and their varying effects with distance from the source.Finally multiple sources recordings were studied through comparing them with the spectral responses of different sites defined in the previous sections. The rate of matching between the spectral content of a particular source and a given site serves as a mean to assess the vibration hazard caused by this source to the corresponding site. The vibration hazard assessment leads to a classification link between sources in one hand and sites characterized by velocity-gradient proxies on the other hand

The primary purpose of the current research was to implement a numerical model to investigate the interactions between the energy consumption in Heating, Ventilating, and Air Conditioning (HVAC) systems and occupants’ thermal comfort in commercial buildings. A numerical model was developed to perform a thermal analysis of a single zone and simultaneously investigate its occupants’ thermal sensations as a non-linear function of the thermal environmental (i.e. temperature, thermal radiation, humidity, and air speed) and personal factors (i.e. activity and clothing). The zone thermal analyses and thermal comfort calculations were carried out by applying the heat balance method and current thermal comfort standard (ASHRAE STANDARD 55-2004) respectively. The model was then validated and applied on a single generic zone, representing the perimeter office spaces of the Centre for Interactive Research on Sustainability (CIRS), to investigate the impacts of variation in occupants’ behaviors, building’s envelope, HVAC system, and climate on both energy consumption and thermal comfort. Regarding the large number of parameters involved, the initial summer and winter screening analyses were carried out to determine the measures that their impacts on the energy and/or thermal comfort were most significant. These analyses showed that, without any incremental cost, the energy consumption in both new and existing buildings may significantly be reduced with a broader range of setpoints, adaptive clothing for the occupants, and higher air exchange rate over the cooling season. The effects of these measures as well as their combination on the zone thermal performance were then studied in more detail with the whole year analyses. These analyses suggest that with the modest increase in the averaged occupants’ thermal dissatisfaction, the combination scenario can notably reduce the total annual energy consumption of the baseline zone. Considering the global warming and the life of a building, the impacts of climate change on the whole year modeling results were also investigated for the year 2050. According to these analyses, global warming reduced the energy consumption for both the baseline and combination scenario, thanks to the moderate and cold climate of Vancouver. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

En raison de leur utilisation accrue, de nombreux contaminants émergents, comme les antibiotiques de type quinolone sont retrouvés dans l’environnement. Leur devenir étant fortement contrôlé par leur interaction avec surfaces minérales, cette thèse a eu pour objectif de comprendre et prédire l’adsorption de quinolones sur des minéraux dans des conditions environnementales variées (pH, salinité, présence de cations et d’anions naturels, etc…) et de développer des modèles de transport réactif. Une approche innovante a alors été développée, combinant des données cinétiques et thermodynamiques, des mesures spectroscopiques in situ et de la modélisation de la complexation de surface. Cette thèse est divisée en deux sections. La première a eu pour but de déterminer les mécanismes de complexation de quinolones sur des oxydes de fer (goethite et magnétite) dans des conditions réduites et dans l’eau de mer. La stœchiométrie de la magnétite (Fe(II)/Fe(III)) s’est avéré être un facteur majeur de contrôle de l’adsorption de l’acide nalidixique (NA). Les effets compétitifs et coopératifs de différents ions présents dans l’eau de mer ont pu être prédits avec précision en réacteur fermé et en colonne (conditions de flux). La deuxième partie de la thèse s’est penchée sur les interactions entre goethite avec des ligands ubiquistes dans l’environnement, comme la matière organique naturelle (MON), et leur impact sur le transport de quinolones. L’adsorption de NA sur la goethite en présence et en l’absence de MON, ainsi que le fractionnement de la MON, ont été étudiés en colonne. Ces résultats pourraient permettre de mieux comprendre et prédire le devenir des quinolones dans l’environnement. / Due to their extensive use, many emerging contaminants, such as quinolone antibiotics, are released to the environment. Because their environmental fate is largely controlled by their interaction with mineral surfaces, such as iron oxides, this thesis aimed to assess quinolones adsorption onto minerals under environmental relevant conditions (pH, ionic strength, presence of ubiquitous cations and anions, etc.) and develop reactive transport models. To address these issues, an innovative approach combining kinetic and thermodynamic data, in situ spectroscopic measurements and surface complexation modeling, was proposed. This thesis manuscript consists of two parts. The first part investigated the binding mechanisms of quinolones onto iron oxides (goethite and magnetite) under reducing or seawater conditions. Considerable impact of the magnetite stoichiometry (Fe(II)/Fe(III)) on its sorption capability towards nalidixic acid has been demonstrated. Competitive and synergetic effects of different seawater ions on quinolone adsorption to goethite were accurately predicted under static and water saturated flow-through conditions. The second part investigated the interactions of goethite with naturally occurring ligands such as natural organic matter (NOM) and their impacts on the mobility/transport of quinolones. Interactions of NOM and goethite and effects on the surface hydrophilicity were first investigated. Then, nalidixic acid adsorption to goethite and to NOM-covered goethite and NOM fractionation were examined under flow-through conditions. These results may have important implications for assessment and prediction of the fate of quinolones antibiotics in the environment.

L’évaluation de la vascularisation tumorale par l’échographie de contraste ultrasonore a montré son intérêt pour déterminer l’efficacité des traitements anti-angiogéniques. Malgré tout, cette technique suscite de nombreux questionnements concernant la sensibilité des méthodes de quantification du signal ultrasonore. Pour répondre à cette problématique, il a été question dans cette thèse de développer la première modélisation numérique de l’écoulement du sang et des agents de contraste dans des réseaux vasculaires pour étudier les méthodes de quantification du signal ultrasonore et leurs sensibilités par rapport à des variations de volume du réseau tumoral et des vitesses du sang. Une première étape de la thèse a consisté à valider, par une comparaison expérimentale, les hypothèses faites pour la modélisation numérique et principalement la prise en compte du sang comme un fluide Newtonien homogène. La modélisation numérique a permis de mettre en évidence les paramètres les plus sensibles aux modifications du débit vasculaire tumorale que sont l’aire sous la courbe, le rehaussement maximal et la pente de la courbe de rehaussement du signal dans le cadre de la méthode semi-quantitative. Lorsqu’il s’agit de suivre les variations du volume vasculaire tumoral, il apparait que la méthode quantitative par deconvolution de la fonction artérielle est plus sensible. Les méthodes de quantification ont également été étudiées par le biais d’une étude in vivo sur 44 souris. Cette approche numérique de l’écoulement des agents de contraste est prometteuse et peut permettre à terme une évaluation plus large des autres méthodes de quantification développées à ce jour pour l’échographie de contraste. / Evaluation of tumor vascularization by dynamic contrast-enhanced ultrasonography showed interest for the assessment of the effectiveness of anti-angiogenic treatments. Nevertheless, this technique raises many questions about the sensitivity of quantification methods of the ultrasound signal. To address this issue, this thesis focused on the development of the first digital modeling of blood flow and contrast agents in vascular networks to study the methods of quantification of the ultrasound signal and theirs sensitivity according to variations of tumor network volume and blood velocity. A first step of the thesis was to validate by an experimental comparison, the assumptions of the digital modeling and mainly the taking into account of the blood as a homogeneous Newtonian fluid. Digital modeling allowed to highlight parameters sensitive to the modification of the blood flow which are in the case of the semi-quantitative method the area under the enhancement curve, the maximum of the enhancement curve and the slope of the enhancement curve. When it comes to follow variations of the tumor vascular volume, it appears that the quantitative method by deconvolution of the arterial function is more sensitive. The quantification methods have also been investigated throught an in vivo study of 44 mice. This digital approach of the flow of the contrast agents is promising and may eventually enable a more extensive evaluation of other quantification methods developed in dynamic contrast-enhanced ultrasonography to date.

Adaptation to climate change requires a careful evaluation of the infrastructure performance under extreme events in a changing climate. Earthen levees are critical infrastructure systems, which play a vital role to the country’s safety, environment, and economic security. The main objective of this study is to quantitatively assess the integrity of earthen levees subject to extreme precipitation and flooding under a changing climate. A multi-disciplinary modeling framework is developed and applied to two earthen levees, Elkhorn and Sherman Island levees, in California. Patterns of extreme precipitation and flooding are obtained for the study areas under current and future climate. A nonstationary framework is employed, which accounts for climate change-induced changes in statistics of future extreme precipitation. The precipitation and flooding data are then applied as hydraulic loads in a set of fully coupled stresslow finite element simulations to determine the factory of safety (FOS) and probability of failure (Pf) of the levees for different scenarios. The Pf values are used to develop fragility curves, which can provide valuable tools for risk assessments. The modeling framework is used to study three distinct yet interrelated problems. The first problem assesses the performance of the Elkhorn levee using historical and projected future precipitation patterns. The results show that Pf increases 3%-12% under the projected extreme precipitation compared to the baseline scenario. The second problem involves quantifying the effects of changes in future streamflow on the fragility behavior of the Elkhorn levee considering multiple modes of failure. For the cases examined, incorporating future floods leads to up to 23% reduction in FOS and 95% increase in Pf. The third problem assesses the fragility behavior of the Sherman Island levee under compound flooding (induced by coastal, fluvial and pluvial processes), an overlooked aspect in the majority of the existing flood hazard analyses. Results show that considering compound flooding leads to 22% and 30% reductions in FOS for 2- and 50-year recurrence intervals, respectively. Using the projected future pluvial flooding increases Pf by 13%. Findings of this research suggest that risk assessments based on historical records can significantly underestimate the levee’s Pf in a changing climate.

In metal cutting applications, development of coatings to reduce friction between tool and chip and also enhance wear resistance of the tool is an important objective. The effectiveness of such coatings is ultimately evaluated through metal cutting trials; however, bench-scale tests can play a role in predicting some aspects of a candidate coating’s performance. This dissertation further develops the concept of an on-axis rotation pin-on-disc tribometer for the evaluation of friction coefficient between tool and work material pairs under temperature and stress conditions similar to those experienced between tool and chip in metal cutting. Firstly, the characteristics of the imprint formed by the spherical-tipped pin in the disc during tribometer tests are studied. Specific focus is given to the growth of the imprint during the rotating stage of the test; the severity of pile-up of work material around the periphery of the imprint; different zones of contact at the imprint surface; and evidence of (or lack thereof) of bulk shear in the surrounding work material below the surface of the disc. The importance of estimating the actual temperature at the pin-disc interface (inaccessible for direct measurement) is also raised. Evidence is presented that suggests the pin-disc interface is higher for tests involving coatings with higher electrical resistivity, despite exhibiting similar temperatures 2 mm above the interface (accessible for direct measurement). A numerical model is developed in an effort to estimate the pin-disc interface during stationary specimen tests for specific pin and disc materials under controlled conditions. An empirical relationship is also established to express the variation of electrical resistivity with temperature for cemented tungsten carbide (6% cobalt content). Finally, coefficient of friction results for coated and uncoated cemented carbide pins in contact with AISI 1045 steel discs are related to short duration turning trials involving the same material pairs. Coatings exhibiting low friction coefficient result in appreciably lower cutting forces, reduced built-up edge intensity and more tightly curled chips. The possibility that the low thermal conductivity of such coatings could be producing similar effects by forcing more heat into the chips is also explored. / Dissertation / Doctor of Philosophy (PhD) / This dissertation further develops the concept of a pin-on-disc apparatus for evaluating the friction coefficient between materials under temperature and stress conditions similar to those experienced in metal cutting. Firstly, characteristics of the imprint formed by the pin in the disc during tests with the apparatus are studied. Specific focus is given to the growth of the imprint during the rotating stage of the test and different zones of contact at the imprint surface. Secondly, the importance of estimating the actual temperature at the pin-disc interface, inaccessible for direct measurement, is raised and a numerical model developed to aid in its estimation. Finally, coefficient of friction results generated on the apparatus are correlated to the magnitude of forces measured and other observations made during metal cutting trials involving the same material pairs.

Excessive release of nitrogen (e.g., ammonia and organic nitrogen) into natural water systems can cause serious environmental problems such as algal blooms and eutrophication in lakes and rivers, threating the aquatic life and ecosystem balance. Membrane aerated biofilm reactor (MABR) and anaerobic ammonia oxidation (Anammox) are new technologies for wastewater treatment with an emphasis on energy-efficient nitrification and denitrification. Microplastic (MP) is an emerging contaminant in wastewater and sludge treatment that has a negative effect on the environment and public health. For these relatively new technologies and contaminants, mathematical models can enhance our understanding of the removal mechanisms, such as reaction kinetics and mass transport. In this study, mathematical models were developed and utilized to simulate the removal of nitrogen and MP in biological reactions in wastewater treatment processes. Firstly, a comprehensive MABR model was developed and calibrated using a pilot-scale MABR operation data to estimate the important process parameters where it was found that biofilm thickness, liquid film thickness and C/N ratio are key parameters on nitrification and denitrification. Secondly, a mathematical model for Anammox process was developed and calibrated using previous experimental results to simulate the wastewater treatment using Anammox process, reflecting the importance of dissolved oxygen on the nitrogen removal using Anammox bacteria. Thirdly, a granule-based Anammox mathematical model was built and calibrated using other simulation results from previous Anammox studies, showing the significance of operational conditions (e.g., granule diameter and dissolved oxygen) on the success of Anammox enrichment process. Fourthly, an enzyme kinetic mathematical model was constructed and calibrated with lab-scale experiments to simulate the MP reduction using hydrolytic enzymes under various experimental conditions where it was found that anaerobic digesters can be an innovative solution for MP removal during the wastewater treatment processes. Based on the main findings in this study, it can be concluded that mathematical models calibrated with various experimental results are efficient tools for determining the important operational parameters on the nitrogen and MP removal and helping in the design and operation of large-scale removal applications. / Thesis / Doctor of Philosophy (PhD) / Nitrogen and microplastic (MP) are serious contaminants in wastewater that can cause critical environmental and public health problems. Nitrogen can cause algal blooms, threatening the aquatic ecosystem while MP can be ingested by the biota (e.g., fish and seabirds), causing serious damage in the food chain. Nitrogen removal in the conventional biological wastewater treatment is relatively expensive, requiring high energy cost and large footprint for the wastewater treatment facilities. MP removal is also difficult in the conventional wastewater and sludge treatment processes. Therefore, new technologies, including membrane aerated biofilm reactor (MABR), anaerobic ammonia oxidation (Anammox) and hydrolytic enzymes processes, are implemented to improve the nitrogen and MP removal with a reduced energy and resources consumption in wastewater and sludge treatment processes. Numerical models are considered as an efficient tool for better understanding of these novel technologies and the competitive biological reaction in these technologies coupled with accurate estimation of process rates of the reactions. In this thesis, different numerical models were developed and calibrated to estimate the important model parameters, assess the effect of operational conditions on the removal mechanisms and determine the dominant parameters on the removal of nitrogen and MP in the wastewater treatment processes. These numerical models can be used for better understanding of the removal mechanisms of nitrogen and MP, helping in the design and operation of removal systems and addressing novel technologies in large-scale nitrogen and MP removal applications.