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Tool wear is a significant problem for manufacturing companies and represents a major challenge in their operations, but it is also a way they can gain a competitive advantage. To do this it is important to set up a standard procedure to develop high performing tooling. This thesis outlines how the Finite Element (FE) method can be used to understand and develop tool geometry. FE based simulation, as a numerical method, is a reliable method to assess the performance of a cutting tool before conducting machining tests based on the force and temperature profile predicted by the FE model. Defining a mathematical model which can be used as a built-in algorithm for tool wear prediction is very challenging and time consuming. Instead there is a possibility of using other factors such as stress distribution and temperature profile and correlate them to tool wear. In this research, the performance of different tool edge radius in cutting has been studied through experiments and in parallel Updated Lagrangian Models have been developed through ABAQUS/EXPLICIT for various cutting conditions, and experimental data was used to validate the data that has been generated from the finite element models. These models are very convenient to develop and capable of being applied for other types of material and cutting conditions. Thus, they represent an efficient way to reduce the amount of experiments needed to improve a tooling, the machining process, and thereby provide an effective way to increase the machining productivity of manufacturing companies. / Thesis / Master of Applied Science (MASc)

Cognitive-behavioral treatments are the most well-documented, and apparently most effective, treatments for childhood depression. Efforts to translate these findings to clinical practice are thwarted by the large number of strategies (and sessions) included in empirically supported treatment packages and a lack of guidance regarding differential selection of strategies. The aim of this study was to determine the impact of case formulation on the selection of individual treatments for childhood depression. Two hundred thirty-seven Ph.D.-level mental health professionals with knowledge of behavioral and/or cognitive behavioral theory and practice were recruited via e-mail to participate in this study. Candidates were asked to indicate the likelihood that they would select each of 9 cognitive-behavioral treatments based on one of twelve fictional vignettes. The vignettes were designed to represent children of ages 6, 10, and 14, and presenting with depression based on Cognitive Distortion, Social Skills Deficit, or Environmental Deficit etiologies. Three "Control" vignettes, in which the age of the child was varied but no case formulation was provided, were also included. Our results provide confirmation that case formulation is an important step in the treatment of childhood disorder. Participants successfully matched cognitive treatments to cognitive etiologies, social skills treatments to social skills deficit etiologies, and environmental treatments to environmental deficit etiologies of childhood depression. Differences in treatment selection were also noted with regard to age of the child being treated, in a manner consistent with developmental theory. Here, we have confirmed that the case formulation approach is useful in the differential selection of empirically supported cognitive-behavioral treatments for childhood depression. / Ph. D.

<p dir="ltr">Biologic drugs are a key defense against many health issues. In many cases, biologic drugs are not stable in the solution state and must be lyophilized. Lyophilization in the presence of excipients increases the stability of the drug by interactions with the excipients through hydrogen bonding, which will lower the local mobility of the drug. Key threats to stability include: inhomogeneity of the drug substance and excipients, high mobility, and crystallization. Solid-state nuclear magnetic resonance spectroscopy was used to identify crystallization, assess homogeneity, and measure the local mobility of lyophilized protein and mRNA/LNP systems. </p><p dir="ltr">The impact of disaccharide type and concentration on protein stability was explored. Human serum albumin (HSA) was lyophilized with disaccharides (sucrose and/or trehalose) in different relative concentrations, and solid-state nuclear magnetic resonance spectroscopy (ssNMR) ¹H T₁ and ¹H T_1rho relaxation times were measured to determine the homogeneity of the lyophilized systems on 20-50 and 1-3 nm domains, and measure local mobility with ¹H T₁ relaxation times. HSA/sucrose systems had longer ¹H T₁ relaxation times and were slightly more stable than trehalose systems in almost all cases shown. HSA/sucrose/trehalose systems have ¹H T₁ relaxation times between the HSA/sucrose and HSA/trehalose systems and did not result in a more stable system compared to binary systems. Phase separation was evident in a sample containing relative concentrations of 10% HSA and 90% trehalose, suggesting trehalose crystallization during lyophilization. Under these stability conditions, a ¹H T₁ relaxation time below 1.5 s correlated with an unstable sample, regardless of disaccharide(s) used.</p><p dir="ltr">The effect of mannitol on protein stability was studied. Human serum albumin was lyophilized in binary systems with mannitol, and in ternary systems with sucrose or trehalose and mannitol. The monomer content of the HSA was monitored over 36 weeks of storage at 50 C. The amount of mannitol in the system dictated the ability of mannitol to crystallize, and the polymorph that mannitol crystallized into. In HSA/mannitol systems, mannitol crystallization caused inhomogeneity of the matrix, determined by ¹H T_1rho relaxation times. Adding a disaccharide to the matrix, however, increased the homogeneity of the matrix. Addition of mannitol to a HSA/disaccharide matrix resulted in less stability at similar HSA:disaccharide ratios.</p><p dir="ltr">The impact of storage temperature on protein stability was investigated. Human serum albumin was lyophilized with sucrose or trehalose in histidine, phosphate, or citrate buffer. ¹H T₁ relaxation times were measured by ssNMR and were used to assess the homogeneity and mobility of the samples after zero, six, and twelve months at different temperatures. The mobility of the samples decreased after 6 and 12 months storage at elevated temperatures, consistent with structural relaxation of the amorphous disaccharide matrix. Formulations with sucrose had lower mobility and greater stability than formulations with trehalose.</p><p dir="ltr">The effect of an RF-assisted lyophilization method on homogeneity, mobility, stability, and moisture content was explored. This method, utilizing 18 GHz microwave frequency to accelerate the lyophilization cycle, resulted in equivalent or better stability for attenuated live virus or protein formulations, respectively. ssNMR showed comparable amounts of homogeneity in the formulations, however mobility of the samples produced by RF-assisted lyophilization was slightly higher.</p><p dir="ltr">A lyophilized mRNA/LNP formulation was prepared. Disaccharide type, disaccharide concentration, and freezing rate were found to alter critical quality attributes of the system. When mRNA/LNP formulations were stored at 4 C, solution formulations outperformed lyophilized formulations for at least 6 months. When mRNA/LNP formulations were stored at room temperature, solution formulations were superior for the first three months, however lyophilized formulations outperformed solution formulations after 6 months, with less growth in particle size and less loss of encapsulation efficiency. ssNMR was used to assess the interactions between the formulation components.</p>

Within computer science education, goal-oriented feedback motivates beginners to be engaged in learning programming. As the number of students increases, it is challenging for teaching assistants to cater to all the doubts of students and provide goals. This problem is addressed by intelligent visual feedback which guides beginners formulate effective goals to resolve all the errors they would incur while solving a programming assignment. Most current automated feedback mechanisms provide feedback without categorization, prioritization, or goal formulation in mind. Students may overlook important issues, and high priority issues might be hidden among other issues. Also, beginners are not well equipped in formulating goals to resolve the issues provided in the feedback. In this research, we address the problem of providing an effective, intelligent goal-oriented feedback to student's code to resolve all the issues in their code while ensuring that the code is well tested. The goal-oriented feedback would eventually implicitly navigate the students to write a logically correct solution. The code feedback is summarized into four categories in the descending order of priority: Coding, Student's Testing, Behavior, and Style. Each category is further classified into subcategories, and a simple visual summary of the student's code is also provided. Each of the above-mentioned categories has detailed feedback on each error in that category to provide a better understanding of the errors. We also offer enhanced error messages and diagnosis of errors to make the feedback very useful. This intelligent feedback has been integrated into Web-CAT, an open-source automated grading tool developed at Virginia Tech that is widely used by many universities. A user survey was collected after the students have utilized this feedback for a couple of programming assignments and we obtained promising results to claim that our intelligent feedback is effective. / Master of Science / Within computer science education, goal-oriented feedback motivates beginners to be engaged in learning programming. As the number of students increases, it is challenging for teaching assistants to cater to all the doubts of students and provide goals. This problem is addressed by intelligent visual feedback which guides beginners formulate effective goals to resolve all the issues they would incur while programming. Most current automated feedback mechanisms provide feedback without categorization, prioritization, or goal formulation in mind. Students may overlook important issues, and high priority issues might be hidden among other issues. Also, beginners are not well equipped in formulating goals to resolve the issues provided in the feedback. In this research, we address the problem of providing an effective, intelligent goal-oriented feedback to student’s code to resolve all the issues in their code. The goal-oriented feedback would eventually implicitly navigate the students to write a logically correct solution. The code feedback is modularized smartly to guide students to understand the issues easily. A simple visual summary of the student’s code is also provided to help students obtain an overview of the issues in their code. We also offer detailed feedback on each error along with enhanced error messages and diagnosis of errors to make the feedback very effective.

La compréhension de la relation structure-propriété est un élément indispensable pour la conception et l'amélioration des matériaux, notamment ceux utilisés dans le domaine de l'emballage alimentaire. Afin de contribuer à la compréhension des phénomènes de transport dans le polylactide (PLA), les travaux de ce mémoire se sont portés sur la modulation de la microstructure du PLA en lien avec ses propriétés barrière aux gaz (oxygène, hélium) et aux composés organiques (esters éthyliques, sondes fluorescentes). La microstructure a été modulée i) par l'ajout de plastifiant (ATBC, PEG), ii) par la cristallisation selon trois procédés, le traitement thermique, la cristallisation induite par des composés organiques et le biétirage. Ces approches ont permis, respectivement, de faire varier le pourcentage de phase amorphe par rapport à la phase cristalline, la fraction de volume libre au sein de la phase amorphe, et la structure cristalline. L'augmentation de la cristallinité par recuit à partir du vitreux n'a pas conduit à une diminution systématique et importante des coefficients de transport des molécules de gaz (oxygène, hélium). Deux hypothèses principales ont ainsi été formulées pour expliquer ce comportement : la dédensification de la phase amorphe et la présence d'une phase amorphe mobile et d'une phase rigide. L'influence du biétirage sur les propriétés barrière aux gaz a été très limitée même au plus fort ratio d'étirage (4×4). Néanmoins cette technique a l'avantage de pouvoir réaliser des morphologies différentes.L'étude des coefficients de transport par plusieurs méthodes (sorption, perméation, diffusion par contact solide/solide) a mis en évidence la loi d'échelle ( ) dans le cas des molécules fluorescentes et a permis une première estimation du coefficient alpha. Une approche par Résonance Paramagnétique Electronique a permis de mettre en évidence des séparations de phase des systèmes plastifiés par ATBC et PEG. Cette méthode pourrait constituer un des moyens de sonder les hétérogénéités locales et les changements microstructuraux liés à l'interaction de molécules perméantes et de la matrice polymère, lors du transport. / The understanding of the relationship between structure and properties is fundamental for materials conception and improvement, in particular for those used in food packaging industry. To contribute to the understanding of the transport phenomena in polylactide (PLA), this study was focused on the adjustment of PLA microstructure modulation related to its gas (oxygen, helium) and organic compounds (ethyl esters, fluorescent molecules) barrier properties. The microstructure was modulated i) by adding plasticizers (ATBC, PEG), ii) by crystallizing according to 3 processes, thermal treatment, organic compounds induced crystallization and biaxially orientation. These approaches, respectively enabled to vary, the ratio of amorphous phase and crystalline phase, free volume fraction into amorphous phase and the crystalline structure. The increase in crystallinity degree, by annealing from cold state, did not result in a systematic and significant decrease of the gas molecules transport coefficient (oxygen, helium). Two main hypotheses were formulated to explain this behaviour: de-densification of amorphous phase and the presence of a mobile and a rigid amorphous phase. The influence of biaxially orientation on gas barrier properties was strongly limited even at the highest stretching ratio (4×4). Nevertheless several morphologies can be formed thanks to this technique.The transport coefficient study by several methods (sorption, permeation and diffusion by solid/solid contact) highlighted a scale law with the fluorescent molecules and allowed to a first estimation of the α coefficient. Thanks to Electronic Spin Resonance approach, phase separation of plasticized systems by ATBC and PEG were highlighted. This method could be one of the means to probe the local heterogeneities and the micro-structural changes related to the interaction of permeating molecules and polymer matrix during transport.

Cette étude porte sur l'émulsification en continu du bitume à l'aide de mélangeurs statiques de type SMX, dans le domaine des émulsions concentrées, voire très concentrées. Ce travail suit une approche intégrant trois types de paramètres : procédé, formulation physico-chimique et composition, avec pour objectif ultime la maîtrise de la taille de gouttes. Il a été montré qu'une combinaison de fortes teneurs en bitume et de hautes températures d'émulsification favorisent l'obtention de très petites tailles de gouttes (diamètre médian inférieur ou égal à 1 µm). Cette observation contraste avec l'émulsification à forte teneur en phase dispersée en procédé discontinu. Ces résultats mettent en évidence une compétition entre les aspects énergétiques de l'émulsification et la formulation physico-chimique. Il a été mis en évidence, que lors de l'émulsification en continu à des fractions massiques en bitume supérieures à 90 %, la taille des gouttes n'est pas une fonction de l'énergie fournie mais que ce sont les paramètres de formulation qui contrôlent l'émulsification. Le suivi de la cinétique de l'émulsification et de la morphologie de l'émulsion au cours du processus d'émulsification a montré que le mécanisme d'émulsification à très fortes concentrations en bitume (90 % massique) passe par une étape d'inversion de phases catastrophique, suivie d'un affinage de l'émulsion dû aux effets de cisaillement et d'élongation lors de la phase finale de mélange. Une méthodologie basée sur une analogie de Poiseulle pour la mesure en ligne de la viscosité de procédé a été développée, permettant l'évaluation in-line du comportement rhéologique d'un fluide à travers des mesures de débit et de perte de charge / This work focuses on the continuous emulsification process (using SMX static mixers) of bitumen for concentrated and highly concentrated emulsions. This work uses an approach that integrates the process, the physic-chemical formulation and composition parameters, with the main objective of controlling the drop size of the emulsions. It was shown that the emulsification carried out at high bitumen concentrations and high temperatures favours the production of emulsions with very small droplets sizes (mean diameter ? 1 mm). This is in contrast with emulsification process in batch mode, in the same concentration and temperature conditions. These results demonstrate the competition between energy and physic-chemical formulation aspects. It was also revealed that when continuous emulsification is carried out at 90 % wt. of bitumen, droplet sizes are not a function of the energy provided and, hence, the emulsification process is controlled by the formulation parameters. Morphological analyzes, coupled with kinetics of emulsification obtained by in-situ monitoring of the viscosity, allowed the description of the mechanisms occurring during the emulsification at high internal phase ratio. It was possible to identify two principal steps in the mechanism: a catastrophic phase inversion followed by a droplet reduction by agitation, the largest size reduction being achieved thanks to the effects of shear and elongation in the static mixer. An inline process viscosity measurement methodology was developed. This methodology, based on a Poiseuille analogy, allows the evaluation of the rheological behavior of a fluid through flow rate and pressure drop measurements

Les principaux enjeux de la fabrication de pièces en matériaux composites (coût, temps de fabrication, performances,...) sont intimement liés aux moyens de mise en oeuvre, principalement les autoclaves; qui engendrent non seulement des coûts très élevés en termes d'installation et d'entretien, mais limitent également les cadences de production à cause de la longueur des cycles. Afin de réduire cette dépendance, des procédés de fabrication hors autoclave ont été envisagés (Quickstep, Roctool, VARTM, VBO...) entrainant par conséquent des modifications dans la conception des matériaux destinés à ces procédés (cinétique, rhéologie, façon dont sont imprégnées les fibres...). Afin de limiter les changements en termes de procédé de fabrication, de matières premières, de produits d'environnement et de conditions de mise en oeuvre, c'est sur le procédé Vacuum Bag Only que porte cette étude. Plusieurs développement de semi-produits ces dernières années ont permis d'augmenter la robustesse de ce procédé de fabrication, palliant ainsi à cette absence de pression externe durant la cuisson en étuve. Il reste toutefois à démontrer la viabilité de ces produits par rapport à leur mise en oeuvre, à comprendre les mécanismes d'extraction de l'air et à estimer les propriétés mécaniques atteignables par rapport à leur équivalent autoclave. / The main issues concerning composite part manufacturing (cost, manufacturing time, mechanical performances, etc.) are closely linked to the means of curing, mainly autoclaves; which do not only generate very high installation and maintenance costs, but also limit production rates because of the length of the cycles. In order to reduce this dependence, non-autoclave manufacturing processes have been envisaged (Quickstep, Roctool, VARTM, VBO ...) therefore leading to modifications in the design of the materials intended for these processes (including kinetics, rheology, fiber impregnation methods). In order to limit the changes in terms of manufacturing process, raw materials, environment products and implementation conditions, this study is based on the Vacuum Bag Only process. Several semi-product developments in recent years have made it possible to increase the robustness of this manufacturing process, thereby overcoming the lack of external pressure during an oven cure. However, the viability of these products in relation to their implementation still needs to be demonstrated, as well as the understanding of the air removal mechanisms and the estimation of the achievable mechanical properties compared to their autoclave counterpart.

Cette thèse a pour but de proposer une formulation EF adaptée à la modélisation de l'usinage à grande vitesse en pointe d'outil. La simulation doit pouvoir détecter les phénomènes extrêmement localisés qui peuvent apparaître, avec des temps de calcul raisonnables. L'implémentation est réalisée à l'aide de la librairie EF CimLib, offrant un remailleur adaptatif robuste non structuré et permettant le calcul massivement parallèle. Le travail se décompose en deux parties. La première consiste à développer, implémenter et valider une formulation de type explicite non sensibles au locking volumique, permettant l'utilisation d'algorithmes de remaillage non structurés robustes. Deux formulations sont comparées en dynamique rapide: une semi-explicite, basée sur des éléments tétraédriques mixtes avec stabilisation bulle et une explicite, basée sur des éléments tétraédriques linéaires modifiés. La seconde partie consiste à appliquer la formulation explicite, retenue pour son efficacité, au cas particulier de l'usinage à grande vitesse. Une résolution thermique est implémentée et couplée à la mécanique. Des simulations thermomécaniques de coupe orthogonales 2D de Ti6Al4V sont réalisées. Les résultats obtenus sont en très bonne adéquation avec la littérature, et permettent d'importants gains de temps de calcul. L'initiation et la propagation de la bande de cisaillement dans le copeau peuvent être analysés précisément. Un algorithme de R-Adaptation surfacique a été ajouté afin d'étendre ces résultats en 3D. On peut alors se rapprocher de la réalité industrielle du procédé sans perdre en précision.

Le développement d’une couche limite turbulente sur des structures entraîne des vibrations et des nuisances sonores. Celles-ci sont estimées par des calculs vibro-acoustiques qui nécessitent le spectre de pression pariétale turbulente en fréquence-nombre d’onde. Ce spectre est généralement calculé via des modèles empiriques. Or ces modèles ont un domaine de validité très restreint et ne sont pas adaptés pour des écoulements complexes, avec notamment des gradients de pression. Dans ces travaux, une méthode est proposée pour calculer les corrélations spatio-temporelles de pression pariétale à partir d’une solution sous forme intégrale de l’équation de Poisson. Le spectre de pression est obtenu à partir de la transformation de Fourier de ces corrélations. L’expression retenue pour ces dernières fait intervenir les dérivées d’une fonction de Green ainsi que les champs de la vitesse moyenne et des tensions de Reynolds qui sont obtenus par simulation RANS. Elle fait aussi intervenir des coefficients de corrélation de vitesse spatio-temporelle qui doivent être modélisés. Pour cela, un nouveau modèle de coefficient de corrélation spatiale a été développé : l’Extended Anisotropic Model. Le calcul des corrélations et du spectre de pression est réalisé en utilisant une méthode numérique basée sur une stratégie d’échantillonnage adaptatif combinée à du krigeage. Elle permet de réduire le nombre de valeurs de corrélation de pression nécessaires pour obtenir le spectre de pression pariétale et donc de réduire le temps de calcul. La méthode est appliquée à des écoulements de couche limite turbulente sur une plaque plane et sur un profil NACA-0012 avec un gradient de pression adverse. / Turbulent boundary layer flows over structures induce vibrations and noise. The latter are estimated by vibro-acoustic studies which require the wavenumber-frequency turbulent wall-pressure spectrum. This spectrum is generally computed via empirical models. However, these models have a very narrow domain of validity and are not adapted for complex flows, in particular with pressure gradients. In this work, a method is proposed to compute space-time wall-pressure correlations from an integral solution of the Poisson equation. The pressure spectrum is obtained by the Fourier transform of these correlations. The expression retained for the pressure correlations involves the derivatives of a Green function as well as the mean velocity field and the Reynolds stresses which are obtained by RANS solutions. It also involves space-time velocity correlation coefficients that have to be modelled. To achieve this, a new model was developed for the spatial correlation coefficients: the Extended Anisotropic Model. To compute the wall-pressure correlations and spectrum, a numerical method based on a self adaptive sampling strategy combined with Kriging is used. It reduces the number of pressure correlation values required to compute the wall-pressure spectrum and thus reduces the computation time. The method is applied to turbulent boundary layer flows over a flat plate and over a NACA-0012 profile with an adverse pressure gradient.