Mechanical ventilation (MV) is a system that partially or fully assists patients whose respiratory system fails to achieve a gas exchange function. However, MV can cause a ventilator-associated lung injury (VALI) or even contribute to a multiple organ dysfunction syndrome (MODS) in acute respiratory distress syndrome (ARDS) patients. Despite advances in today technologies, mortality rates for ARDS patient are still high. A better understanding of the interactions between airflow from mechanical ventilator and the airway could provide useful information used to develop a better strategy to ventilate patients. The mechanisms, which mechanical ventilation induces airway inflammation, are complex processes and cover a wide range of spatial scales. The multiscale model of the airway have been developed combining the computational models at organ, tissue, and cellular levels. A model at the organ level was used to study behaviors of the airway during mechanical ventilation. Strain distributions in each layer of the airway were investigated using a model at the tissue level. The cellular inflammatory responses during mechanical ventilation were investigated through the cellular automata (CA) model incorporating all biophysical processes during inflammatory responses. The multiscale modeling framework started by obtaining airway displacements from the organ-level model. They were then transferred to the tissue-level model for determining the strain distributions in each airway layer. The strain levels in each layer were then transferred to the cellular-level model for inflammatory responses due to strain levels. The ratio of the number of damage cells to healthy cells was obtained through the cellular-level model. This ratio, in turn, modulated changes in the Young’s modulus of elasticity at the tissue and organ levels. The simulation results showed that high tidal volume (1400 cc) during mechanical ventilation can cause tissue injury due to high concentration of activated immune cells and low tidal volume during mechanical ventilation (700 cc) can prevent tissue injury during mechanical ventilation and can mitigate tissue injury from the high tidal volume ventilation. The multiscale model developed in this research could provide useful information about how mechanical ventilation contributes to airway inflammation so that a better strategy to ventilate patients can be developed.

Quartzite samples taken in the east part of Krkonoše-Jizera Massif belong to metasedimentary cover of paraautochtonous unit. Rocks underwent a polyphase deformation which established a strong shape preffered orientation (SPO) of quartz grains. In folded quartz veins, deformation overprint mechanisms and microstructure, CPO and SPO relations were studied. For determination of crystal preffered orientations (CPO) the method of computer integrated polarization microscopy (CIP) was used. Microstructural analysis was focused on grain sizes, aspect ratios, long axis orientations and their relation to the deformation overprint grade. Results implies that dominant mechanism of quartz grain recrystallization is grain boundary migration. Folds were created by simple shear in microscale. The deformation overprint grade is strongest in the top of the fold hinge, where grains achieve highest aspect ratios and sizes. In the lower parts of the fold hinge the original CPO is preserved in small grains and SPO has similar orientation to original CPO. During folding CPO and SPO rotated with shear direction in dependance on deformation overprint grade.

Les procédés de mise en forme de tôles minces sont très largement répandus dans l’industrie. Néanmoins, l’utilisation de ces procédés est limitée par le niveau de formabilité du matériau formé, notamment dans le cas des alliages d’aluminium. Afin d’améliorer ces limites de formabilité, des procédés de mise en forme à chaud peuvent être envisagés. L’objectif de cette thèse est d’étudier à l’aide d’approches expérimentale et numérique l’effet de la température et de la vitesse de déformation sur la formabilité des tôles en alliage d’aluminium AA5086 et de proposer une modélisation capable de prédire ces effets. Une campagne d’essais a été réalisée sur ce matériau à partir d’un essai d’emboutissage de type Marciniak. Des courbes limites de formage (CLF) ont été établies sur une plage de température allant de l’ambiant jusqu’à 200°C et pour des vitesses de déformation allant du quasi-statique à 2s-1. Des effets, positif de la température et négatif de la vitesse de déformation sur la formabilité ont été mis en évidence. La prise en compte des effets de la température et de la vitesse de déformation dans les modèles prédictifs des CLF, qu’ils soient analytiques ou numériques, est à ce jour très limitée. Dans ce travail, un modèle numérique prédictif basé sur la simulation par éléments finis du modèle géométrique de Marciniak et Kuczynski (M-K) est proposé. Les déformations limites obtenues avec de ce modèle sont très sensibles à la description du comportement thermo-viscoplastique du matériau et à la calibration du défaut géométrique pilotant l’apparition de la striction dans le modèle M-K. Des essais de traction uniaxiale réalisés dans les mêmes conditions opératoires que les essais de mise en forme de Marciniak ont permis d’identifier des lois d’écrouissage de nature très différentes (rigidifiante, saturante ou mixte). Ces lois conduisent à des prédictions très différentes de la formabilité du matériau pour une valeur donnée du défaut géométrique du modèle EF M-K. Différentes stratégies de calibration de la taille de ce défaut initial ont été envisagées. L’utilisation du point expérimental de la CLF correspondant à des conditions de déformation plane permet de calibrer de manière satisfaisante la valeur de ce défaut. Cette procédure de calibration a été appliquée pour l’ensemble des lois identifiées. Les lois de nature rigidifiante de type Ludwick se sont montrées les plus effficaces alors que les lois saturante de type Voce se sont avérées incapables de prédire la formabilité du matériau pour certaines conditions opératoires. Finalement, il est démontré qu’une valeur constante du défaut géométrique ne peut être retenue pour l’ensemble des conditions opératoires étudiées même si le modèle M-K s’est avéré assez efficace pour représenter l’effet de la température plutôt que celui de la vitesse de déformation. / Sheet metal forming processes are widely used in industry. Nevertheless, the use of these processes is limited by the formability of the considered material, in particular in the case of the aluminium alloys. To improve the formability, warm forming processes can be considered. The objective of this work is to study by means of both experimental and numerical approaches, the effects of temperature and strain rate on the formability of AA5086 aluminium alloy sheets and to propose a modeling suitable to predict these effects. Experimental tests have been carried out on this material by means of the Marciniak stamping experimental device. Forming limit curves (FLCs) have been established on a temperature range going from ambient temperature to 200°C and on a strain rate range going from quasi-static up to 2s-1. A positive effect of the temperature and a negative effect of the strain rate on the formability limits were highlighted. To date, very few predictive models of the FLCs taking into account temperature and strain rate effects are proposed in the literature. In this work, in order to predict the experimental temperature and strain rate sensitivities, a predictive model based on the finite element simulation of the Marciniak and Kuczynski (M-K) geometrical model is proposed. The limit strains obtained with this model are very sensitive to the description of the thermo-viscoplastic behaviour modeling and to the calibration of the initial geometrical imperfection controlling the onset of the necking. Thanks to tensile tests carried out for the same operating conditions that those of Marciniak forming tests, several types (power law, saturation and mixed) of hardening laws have been identified. These hardening laws have been implemented in theFE M-K model to obtain numerical limit strains. Very different formability limits have been observed for a given value of the geometrical defect. Several strategies for the calibration of this initial imperfection size have been tested. The use of the experimental point of the FLC0 corresponding to plane strain condition allows a good calibration of the initial imperfection value. This calibration procedure was carried out for all hardening laws. It is shown that the power law type models such as Ludwick law are more efficient while saturation laws such as Voce law are unable to predict the material formability for some conditions. Finally, it is shown that a constant value of the geometrical defect cannot be used to the whole operating conditions studied even if FE M-K model is shown to be efficient to represent the temperature effect rather than strain rate one.

Dans le cadre d’une collaboration avec la société PHYTOREM, nous avons élaboré un prototype de distribution autorégulé afin d’épandre des Eaux Usées après un simple dégrillage et via la Phytorémédiation (dépollution par les plantes).La première approche du projet de thèse a été de comprendre les comportements rhéologiques des effluents, mis à disposition par Phytorem, et mécaniques du matériau élastomère de type EPDM. Nous avons exposé les différentes façons de retrouver leurs propriétés rhéologiques et mécaniques par le biais de divers tests de rhéométrie, concernant les effluents, et de traction uni-, bi- et équibi-axiale, pour la partie matériau. Ceci nous a permis d’obtenir d’une part, la viscosité de nos effluents, et d’autre part, la loi de comportement la mieux adaptée à notre matériau.La deuxième et dernière approche porte sur les interactions entre un fluide et une membrane hyperélastique ayant pour fonction de réguler un écoulement. Le comportement de la membrane contrainte par la pression a été simulé sous Abaqus. Ces résultats ont permis de modéliser l’écoulement (code CFD commercial) lorsque la membrane est déformée et de déterminer numériquement la loi débit/pression du dispositif. Ces développements numériques s’appuient sur la méthode des éléments finis et un couplage partitionné simple en une étape pour une première approche entre le fluide, la membrane et la structure. Les modèles numériques sont validés expérimentalement. Ces travaux participent à l’élaboration d’un prototype de distributeur auto-régulé. / In collaboration with PHYTOREM, we have developed a prototype of self-regulated drip emitter to spread the Wastewater after a simple screening using phytoremediation (remediation by plants).The first approach of the thesis project was to understand the rheological behaviour of waste provided by PHYTOREM, and mechanical properties behaviour of EPDM elastomer type. We have explained the different ways to find their rheological and mechanical properties through various rheometry tests on waste, and tension uni-, biand equibi-axiale, for the material part. This allowed us to obtain first, the viscosity of our waste, and secondly, the behaviour law of best suited to our material.The second and final approach focuses on the interactions between a fluid and a hyperelastic membrane whose function is to regulate flow. The membrane behaviour under pressure stress was simulated using Abaqus. These results were used to model the flow (commercial CFD) when the membrane is distorted and to determine numerically its flow versus pressure law. These developments are relying on numerical finite element method and partitionned into a single coupling step for a first approach between fluid, membrane and structure. The numerical models are validated experimentally. This work contributes to the development of a prototype of self-regulated drip emitter.

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The objectives of this research are to measure residual stress in both unblasted and sandblasted mild steel specimens by using three different techniques: X-ray diffraction (XRD), strain-gage hole drilling (SGHD), and electronic speckle pattern interferometry (ESPI) hole drilling, and to validate the new ESPI hole drilling method by comparing its measurement results to those produced by the SGHD method. Both the XRD and SGHD methods were selected because they are accurate and well-verified approaches for residual stress measurements. The ESPI hole drilling technique is a new technology developed based on the SGHD technique, without the use of strain gage. This technique is incorporated into a new product referred to as the PRISM system, manufactured by Hytec, Incorporated, in Los Alamos, New Mexico. Each method samples a different volume of material at different depths into the surface. XRD method is especially different compared to the other two methods, since XRD only measures stresses at a depth very close to the surface (virtually zero depth). For this reason, no direct comparisons can be made between XRD and SGHD, as well as between XRD and ESPI hole drilling. Therefore, direct comparisons can only be made between SGHD and ESPI hole drilling methods.

During this thesis work a coupled thermo-mechanical finite element model (FEM) was builtto simulate hot rolling in the blooming mill at Sandvik Materials Technology (SMT) inSandviken. The blooming mill is the first in a long line of processes that continuously or ingotcast ingots are subjected to before becoming finished products. The aim of this thesis work was twofold. The first was to create a parameterized finiteelement (FE) model of the blooming mill. The commercial FE software package MSCMarc/Mentat was used to create this model and the programing language Python was used toparameterize it. Second, two different pass schedules (A and B) were studied and comparedusing the model. The two pass series were evaluated with focus on their ability to healcentreline porosity, i.e. to close voids in the centre of the ingot. This evaluation was made by studying the hydrostatic stress (σm), the von Mises stress (σeq)and the plastic strain (εp) in the centre of the ingot. From these parameters the stress triaxiality(Tx) and the hydrostatic integration parameter (Gm) were calculated for each pass in bothseries using two different transportation times (30 and 150 s) from the furnace. The relationbetween Gm and an analytical parameter (Δ) was also studied. This parameter is the ratiobetween the mean height of the ingot and the contact length between the rolls and the ingot,which is useful as a rule of thumb to determine the homogeneity or penetration of strain for aspecific pass. The pass series designed with fewer passes (B), many with greater reduction, was shown toachieve better void closure theoretically. It was also shown that a temperature gradient, whichis the result of a longer holding time between the furnace and the blooming mill leads toimproved void closure.

This three-paper dissertation tests whether General Strain Theory (GST) can be helpful in explaining the relationship between strains experienced by refugee youth and youth’s anti-social behaviors such as delinquency and radicalization to violence and what factors mediate the relationship between strain and crime. Additionally, it uses mixed methods combining community meaning-making with quantitative research methods to provide multiple lenses to the issue of youth and negative outcomes. The first chapter presents the context in which Somali refugee youth experiences should be examined as well as relevant literature. The second chapter examines if GST can help us understand the experiences of Somali youth and delinquencies. It examines if three strains (procedural injustice, teacher punishment, and family conflict) are significantly related to crimes against people among this population and if this relationship is mediated by mental health symptoms and marginalization. The results show that both procedural justice and teacher punishment were able to predict crimes against people but the relationship between procedural injustice and crimes against people was fully mediated by mental health symptoms and by marginalization while the relationship between teacher mistreatment and crime remained significant even when mental health symptoms and marginalization were added to the equation. Surprisingly, while the family conflict was highly correlated with both marginalization and mental health symptoms, it was not significantly related to crimes against people. The third chapter applies GST to radicalization to violence among Somali youth. It examines whether three strains (procedural injustice, teacher punishment, and family conflict) predict youth radicalization to violence and whether this relationship is mediated by individual-level factors such as mental health, marginalization and gang attitudes. The analysis shows that only procedural injustice is significantly related to radicalization to violence and that both marginalization and gang attitudes fully mediated the relationship while mental health partially mediated it. The final chapter uses Interpretive Phenomenological Analysis (IPA) to examine community meaning making around youth radicalization. Qualitative interview results show that community members were able to identify important structural, cultural and individual level factors that led to youth radicalization and that many of the factors that they identified such as police and teacher mistreatment and gang presence where similar to the findings in the quantitative research.

Student Number: 9811822T - MSc Dissertation - School of Computational and Applied Mathematics - Faculty of Science / This dissertation reviews population dynamic type models of viral infection and introduces some new models to describe strain competition and the infected cell lifecycle. Laboratory data from a recent clinical trial, tracking drug resistant virus in patients given a short course of monotherapy is comprehensively analysed, paying particular attention to reproducibility. A Bayesian framework is introduced, which facilitates the inference of model parameters from the clinical data. It appears that the rapid emergence of resistance is a challenge to popular unstructured models of viral infection, and this challenge is partly addressed. In particular, it appears that minimal ordinary differential equations, with their implicit exponential lifetime (constant hazard) distributions in all compartments, lack the short transient timescales observed clinically. Directions for future work, both in terms of obtaining more informative data, and developing more systematic approaches to model building, are identified.

New stricter environmental legislation requires lower emissions and fuel consumption of automotive engines. Therefore the fuel efficiency must be increased but this leads to higher loads in the engine. As for the exhaust system it is affected by higher thermomechanical loads. Until today the turbo manifold has been nitrocarburized in order to increase the wear resistance in slip joints with other exhaust components. The problem is that there is no knowledge of how the nitrocarburizing affects the thermomechanical properties of the material. The purpose of this thesis work is to examine the difference in thermomechanical properties with and without nitrocarburizing on the three different ductile irons High Silicon, SiMo51 and SiMo1000 intended for exhaust components. Thermo-mechanical fatigue (TMF) experiments were performed on test rods to evaluate difference in number of cycles to failure. In each cycle the test-rod was affected by a combination of mechanical loads and thermal loads resembling those found on exhaust components. Light optical microscopy, scanning electron microscopy and x-ray radiography were used to examine microcracks and damage mechanisms of the materials. It was found that the nitrocarburizing did not affect the number of cycles to failure in any large extent. Further, it was also found that SiMo1000 on average has the longest lifetime followed by SiMo51 and High Silicon. Although, the difference is small for many loadings and taking a 95% confidence band into account the curves overlap for many loading cases.