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.

Both primary and secondary liver cancers are common and the majority of patients are not eligible for surgical resection or a liver transplant, which are considered the only hope of cure. Mortality rates are high and there is a need for alternative treatment options. New forms of local treatment work best on small tumours; large ones, however, remain difficult to treat. Hyperthermia involves heating tumours to 40??-44?? C. The aim is to heat the entire tumour without damaging the surrounding normal tissue. Treating deep seated tumours is technically challenging. Ferromagnetic embolisation hyperthermia (FEH) is a novel method of treating liver tumours. Magnetic microspheres are infused into the hepatic artery and lodge primarily in the tumour periphery. An applied alternating-current magnetic field causes the microspheres to heat. Animal experiments have shown that this is a promising technique. There is a need for modelling of FEH prior to commencement of clinical trials. Analytical and numerical models of tumour heating during FEH treatment are presented here. The models help predict the temperature distributions that are likely to arise during treatment and give insight into the factors affecting tumour and liver heating. The models incorporate temperature-dependent thermal properties and blood perfusion rates of the tissues and a heterogeneous clustering of microspheres in the tumour periphery. Simulations show that the poorly perfused tumours heat preferentially while the liver is effectively cooled by blood flow from the portal vein. A peripheral distribution of heat sources produces a more even temperature field throughout the tumour, compared to a heat source that is centred within the tumour core. Large tumours reach higher temperatures and have higher heating rates, supporting experimental findings. Using temperature-dependent, rather than constant, values for thermal conductivities and blood perfusion rates results in higher temperatures within the tumour. The uneven clustering of microspheres in the tumour periphery leads to a more heterogeneous temperature distribution in the core, but it has less of an effect on the wellperfused liver. The results show that FEH has the potential to effectively treat liver tumours and the technique merits further investigation.

Forests play an important role in mitigating climate change by removing carbon dioxide (CO2) from the atmosphere via photosynthesis and storing it in plant tissues and soil organic matter (SOM). Plant roots are a major conduit for transporting recently fixed CO2 belowground, where carbon (C) remains in SOM or returns to the atmosphere via respiration of soil microbes. Compared to aboveground plant processes related to the C cycle, there is little understanding of how belowground plant-C allocation to roots, symbiotic root fungi and secretions into the soil influence the gain or loss of C from the soil. Further, the uncertainty in the timing and amount of root growth that occurs in forests is a barrier to understanding how root activity responds to global change and feeds back to the C cycle. Therefore, the objective of my research is to quantify the timing and magnitude of C allocation to roots and soil via data compilation, field studies and modeling across broad spatial scales. Using data compilation at the global scale, I show that root and shoot phenology are often asynchronous and that evergreen trees commonly have later root growth compared to deciduous trees using meta-analysis across four biomes. At the plot scale, field studies in a mid-latitude forest demonstrate that deciduous stands allocate more C belowground earlier in the growing season compared to a conifer stand. The difference in phenology between stands can be attributed to the timing of root growth. At the root scale, zymographic analysis demonstrates that microbial extracellular enzyme activity is concentrated near the surface of roots and that the rhizosphere can extend well beyond 2 mm from the root surface. Finally, I developed a new model of microbial physiology and extracellular enzyme activity to assess how climate change may affect plant - microbe interactions and soil organic matter decomposition. I show that increases in temperature and the quantity of C inputs substantially alter decomposition. Collectively, these results demonstrate the importance of belowground allocation to the C cycle of terrestrial ecosystems.

A chevron is a U-shaped rock structure constructed for improving navigation conditions by diverting majority of flow towards main channel. The objective of this study is to improve understanding of how chevrons affect channel flow. For this study, a two-dimensional numerical hydrodynamic model of a two-km-long reach of the Mississippi River was developed; three chevrons have been constructed in the modeled reach. The model was calibrated by adjusting Manning's n to match predicted and observed water surface elevations (WSELs). The model was validated using measured WSEL and velocity data from two events: a low-flow discharge (4,500 m3/s) and high-flow discharge (14,000 m3/s). At reach scale the model performed well in predicting WSELs. Average difference between model prediction and observed WSEL was 0.23 m in low-flow condition and 0.05 in high flow condition. Root mean square of errors (RMSEs) and mean absolute errors (MAEs) were used to measure the degree of agreement between predicted and measured velocities. At the reach scale there was reasonable agreement between predicted and observed velocities (RMSE = 0.416 m/s and 0.425 m/s, respectively, for low-flow and high-flow conditions). Local differences between predicted and observed velocities were up to 1.5 m/s; this is attributed to uncertainties in the velocity measurements. The model's sensitivity of to changes in Manning's n, eddy viscosity and bathymetry were also analyzed. The sensitivity analysis showed that there are specific areas (e.g., near the banks of the river) which are sensitive to changes in Manning's n. This indicates that spatial distribution of Manning's n is required to increase the accuracy in the model's predictions of velocity. Model was found to be stable in a specific range of eddy viscosity values. Eddy viscosity had little effect on velocity predictions but was important for model stability (i.e., the model was stable only for a range of eddy viscosity values). Reach scale changes in bathymetry had minor impacts on RMSE and MAE. However, local changes in channel bathymetry resulted in differences in velocity predictions as much as ±0.4 m/s.

This thesis is directed towards the comparison of active and passive bolts systems to reveal which system shows the most favorable behavior for improved performance, safety and cost. This was achieved through the incorporation of new technologies, field data, numerical modeling and established theories in ground control analysis. All in all, a better understanding of the quasi-static behavior of underground coal mine roofs has been attained. Over the summer of 2010, the Department of Mining and Mineral Resource Engineering at Southern Illinois University Carbondale, in conjunction with Andy Hyett of YieldPoint Inc., Peabody and the National Institute of Occupational Safety and Health (NIOSH), installed over one hundred and seventy instrumented extensometers, closure meters, shear-meters, passive rebar roof bolts, tension rebar roof bolts, and double lock rebar roof bolts at three coal mines. Two of the three coal mines were room-and-pillar mines and the other a longwall mine. Data was routinely collected over a nine-month period to analyze shearing, dilation, and axial bolt loading occurring within the rock mass, and entry closure occurring between the excavation hanging-wall and foot-wall. Based on bolt loadings, shear, axial behavior and statistical analysis, initial results indicate that active roof bolts do not show superior performance for the added cost. Active bolts seem to show no difference from passive bolts in the initial loading phase either, indicating that tension bleed-off is a concern soon after installation; however, this observation was not captured, as the data loggers were not intrinsically safe. Considering the modeling results, the trends in axial loading seem to be calibrated but the magnitudes are not. Computer modeling also shows the potential to accurately model in situ bolt performance; however, challenges remain in obtaining a good match between numerical modeling and field observations.

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