The prevalence of cardiovascular disease (CVD) has increased dramatically due in part to the increased rates of obesity in North America. Atherosclerosis, the most prevalent type of CVD, is a progressive disease characterized by the build-up of plaque within the arteries. The plaque development leads to the narrowing of arteries, referred to as stenosis, and restricts crucial blood flow to the organs of the body. This condition is often treated by the implantation of a stent, a wire mesh scaffold device placed in the region of an atherosclerotic plaque after balloon angioplasty. The stent was developed to improve the clinical outcome of angioplasty procedures by mitigating the effects of elastic recoil by the vessel wall and maintaining vessel patency after angioplasty. Since the introduction of stents as a treatment option over a decade ago, in-stent restenosis (ISR) has been an iatrogenic outcome and remains an unsolved limitation of the interventional treatment device, resulting in stent failure and additional surgical procedures to restore blood flow. Many improvements have been made in stent design in order to reduce the likelihood of ISR, but none have eliminated the problem. Endothelial cells lining vessel walls transduce local hemodynamic loading in the stent vicinity, such as wall shear stress magnitude (WSS), into biochemical signals that lead to the progression of ISR. Hence, resolving the hemodynamics in the vicinity of the stent is crucial to reducing the rates of stent failure. The objective of the study is to address the problem of ISR by clearly elucidating the flow physics induced by stent implantation, accounting in particular for vessel curvature, by first considering idealized stent models, then progressing to an actual stent model. Stent designs are typically based upon data originating solely from studies of flow in straight vessels, which, once optimized for this configuration, may lead to suboptimal performance when placed in tortuous vessels. Previous stent studies have almost categorically neglected the effects of curvature on the flow physics, despite the fact that even extremely mild curvature changes the axial WSSM distribution within the vessel and induces the development of secondary flows, which alters the advection of chemicals released into the lumen. Using computational fluid dynamics (CFD) techniques, this study seeks to (i) determine the impact of stent strut amplitude and frequency on primary and secondary flow structures; (ii) determine the significance of the stent strut shape in the size of the stagnation zone; (iii) evaluate flow behavior in the transition region from smooth walled to stented vessel; and (iv) examine the collection of these effects in a full stent model geometry in a curved tube. This study takes a systematic approach, dissecting the impact of the stent first into simplified foundational components, then investigating each component and finally synthesizing the components into a full stent model with the long-term goal of optimizing stent design to reduce the rate of restenosis. As well, the study findings can aid in understanding the signal transduction mechanisms of the endothelial cells, which play a role in the development of ISR, and reduce the cardiovascular disease mortality rate by improving the clinical outcome of treatment procedures. Further, the study findings contribute to the fundamental understanding of flow in curved pipes with wall protrusions, the impact of the choice of the constitutive model of the fluid, and the hemodynamic environment in the vicinity of the stent.

The purpose of this thesis is to present a definition and some properties of a curved arc in a plane and to present a definition and some properties of the Jordan curve.

This thesis describes how to evaluate a first-order approximation of the vibration induced on a beam that is vertically curved and experiences a moving load of non-constant velocity. The curved beam is applicable in the example of a roller coaster. The present research in the field does not consider a curved beam nor can similar research be applied to such a beam. The complexity of the vibration of a curved beam lies primarily in the description of the variable magnitude of the moving load applied. Furthermore, this motion is also variable. This thesis will present how this beam will displace in response to the moving load. The model presented can be easily manipulated as it considers most variables to be functions of time or space. The model will be compared to existing research on linear beams to ensure the unique response of a curved beam.

No description available.

It is well known that the standard canonical uncertainty relation does not apply to the angular variable ? and its conjugate LZ. That is, the relation ? ø ? L Z > h/2 is false. The break down of the result has to do with difference in topology between the line and the circle. It is thus desirable to generalize the standard uncertainty relation topologically and find satisfactory results for the non-Euclidean spaces. This problem is intimately related to the issue of finding a consistent definition for quantum mechanics on "curved spaces". Just as the Heisenberg uncertainty relation was pivotal in understanding the basic structure of standard quantum mechanics, a solution to this problem should shine some light onto the proper conduct of quantum mechanics on general topological spaces. In this study we explore in detail how the standard uncertainty relation may breakdown. We also address the importance of topological considerations in quantum mechanics in general - we shall show how a change in topological character can change the nature of the quantum mechanics for a system and how the consideration of the topology of a system can greatly organize the solution of a problem and in some cases even be necessary for a. full understanding of the problem. We then discuss the derivation of satisfactory uncertainty relations for the compact, homogeneous spaces of the circle, the n-torus and the n-sphere. Finally, we draw out any implications to the issue of properly defining quantum mechanics on the non- Euclidean spaces.

One of the exciting aspects of cosmology is to understand the period of `cosmic inflation' that powered the epoch of the Big Bang. Inflation has been very successful in explaining several puzzles of the standard big bang scenario. But the most important success of inflation is that it can explain the temperature fluctuations of cosmic microwave background and the large scale structures of the universe. Despite its great success, the details of the physics of inflation are still unknown. A large number of models of inflation successfully explain all the observations making it remarkably hard to distinguish between different models. We explore the possibility of differentiating between different inflationary models by studying two-point and three-point functions of primordial fluctuations produced during inflation. First, we explore possible constraints on the inflationary equation state by considering current measurements of the power spectrum. Next, we explore the possibility of a single field slow-roll inflationary model with general initial state for primordial fluctuations. The two-point and three-point functions of primordial fluctuations are generally computed assuming that the fluctuations are initially in the Bunch-Davies state. However, we show that the constraints on the initial state from observed power spectrum and local bispectrum are relatively weak and for slow-roll inflation a large number of initial states are consistent with the current observations. As the precision of the observations is increasing significantly, we may learn more about the initial state of the fluctuations in the near future. Finally, we explore the consistency relations for the three-point functions, in the squeezed limit, of scalar and tensor perturbations in single-field inflation that in principle can be used to differentiate between single-field and multi-field inflation models. However, for slow-roll inflation, we find that it is possible to violate some of the consistency relations for initial states that are related to the Bunch-Davies state by Bogoliubov transformations and we identify the reason for the violation. Then we discuss the observational implications of this violation. / text

No description available.

In this thesis we examine 360 degree curvilinear displays and their potential for the display of 3D information. We present two systems: a spherical display prototype and a cylindrical display. Our spherical display prototype used the lack of set user position and natural visibility constraints of a spherical display to create a 3D display system that treated the sphere as a volumetric display through the use of 360 degree motion parallax and stereoscopy. We evaluated these properties by examining how our use of stereoscopy and 360 degree motion parallax, might aid in the preservation of basic body orientation cues and in pose estimation tasks in a telepresence application with our final cylindrical display. Results suggest the combined presence of 360 degree motion parallax and stereoscopic cues within our cylindrical display significantly improved the accuracy with which participants were able to assess gaze and hand pointing cues, and to instruct others on 3D body poses. The inclusion of 360 degree motion parallax and stereoscopic cues also led to significant increases in the sense of social presence and telepresence reported by participants. / Thesis (Master, Computing) -- Queen's University, 2013-01-29 14:14:33.822

Les matériaux composites connaissent un intérêt croissant dans la majorité des secteurs de l’industrie en raison de leur faible poids propre et de leurs propriétés physico-chimiques intéressantes. Cependant, l’utilisation de ces matériaux a nécessité de conduire en parallèle des réflexions sur leur assemblage avec d’autres matériaux qui a donné naissance au développement de la technologie d’assemblage par collage structural. Cette technique qui permet de pouvoir assembler des matériaux de nature différente en limitant par exemple l’augmentation du poids propre de la structure n’est pas encore totalement maîtrisée. Pour cela, des développements sur la qualification des efforts d’adhésion ou sur la compréhension de la durabilité sont encore nécessaires. Cette thèse aborde la problématique de l’optimisation des assemblages collés et vise en particulier à étudier de manière plus précise l’utilisation de la courbure afin d’optimiser le transfert des efforts au sein du joint de colle. Deux types de colle, présentant l’une un comportement élastique fragile et l’autre un comportement élastoplastique ont été étudiés dans ce travail sur les différents volets analytique, numérique, et, expérimental. Il s’est avéré que la plasticité de l’adhésif semble améliorer la capacité de résistance du joint collé et sera alors un paramètre essentiel dans leur optimisation. Une étude de la géométrie courbe des joints collés acier/composite a été ensuite menée et il ressort de cette étude que cette géométrie est efficace pour augmenter la résistance d'un joint collé à la rupture. De plus, afin d’approfondir les connaissances sur le comportement mécanique du joint collé courbe, et en absence d’étude bibliographique suffisante sur ce type de collage, nous avons ensuite eu recours à la modélisation par la méthode des zones cohésives pour pouvoir aussi valider l’atout de la géométrie courbe par rapport à la géométrie plane. Ce travail s’est enfin intéressé à la durabilité mécanique de cette solution en abordant la thématique de la fatigue ; même si des investigations supplémentaires seront nécessaires, nous avons d’ores et déjà constaté que l’optimisation du joint par l’utilisation d’une colle élastoplastique et une géométrie courbe permet d’améliorer le comportement en fatigue de l’assemblage collé / Composite materials are gaining increasing interest in most of the industry sectors due to their low self-weight and their interesting physico-chemical properties. However, the use of these materials called for parallel reflections on their assembly with other materials which gave rise to the development of the structural bonding technology. This technique which allows to assemble materials of different natures by limiting, for example, the increase in the self-weight of the structure, is not fully mastered yet. For this purpose, further development on the qualification of the adhesion forces or on the understanding of durability are still necessary. This thesis addresses the problem of the optimization of adhesive bonded joints and aims in particular to study, more precisely, the use of the curvature in order to optimize the transfer of forces within the bonded joint. Two types of adhesive, one exhibiting a fragile elastic behavior and the other an elastoplastic behavior, have been studied in this work on the various analytical, numerical, and experimental aspects. We presumed that the plasticity of the adhesive appears to improve the strength of the bonded joints and; hence, shall be considered as an essential parameter in their optimization. A study of the curved geometry of the steel / composite bonded joints was then carried out, where it emerged that this geometry was effective in increasing the strength of the bonded joint and its ultimate capacity. Moreover, in order to extend the knowledge on the mechanical behavior of the curved bonded joints, and in the absence of sufficient bibliographical references on this type of bonding, we then resorted to the modeling by using the cohesive zone method to also validate the advantage of the curved geometry with respect to the plane geometry. This work finally focuses on the mechanical durability of this solution by addressing the fatigue thematic; even if additional investigations are needed, we have already found that the optimization of the joint by the use of an elastoplastic adhesive, and a curved geometry can improve the fatigue behavior of the adhesive bonded joints

Parmi les outils les plus classiques de l'Analyse Multivariée, les Composantes Principales sont aussi un des plus anciens puisqu'elles furent introduites il y a plus d'un siècle par Pearson (1901) et redécouvertes ensuite par Hotelling (1933). Aujourd'hui, cette méthode est abondamment utilisée en Sciences Sociales, en Economie, en Biologie et en Géographie pour ne citer que quelques disciplines. Elle a pour but de réduire de façon optimale (dans un certain sens) le nombre de variables contenues dans un jeu de données. A ce jour, les méthodes d'inférence utilisées en Analyse en Composantes Principales par les praticiens sont généralement fondées sur l'hypothèse de normalité des observations. Hypothèse qui peut, dans bien des situations, être remise en question. Le but de ce travail est de construire des procédures de test pour l'Analyse en Composantes Principales qui soient valides sous une famille plus importante de lois de probabilité, la famille des lois elliptiques. Pour ce faire, nous utilisons la méthodologie de Le Cam combinée au principe d'invariance. Ce dernier stipule que si une hypothèse nulle reste invariante sous l'action d'un groupe de transformations, alors, il faut se restreindre à des statistiques de test également invariantes sous l'action de ce groupe. Toutes les hypothèses nulles associées aux problèmes considérés dans ce travail sont invariantes sous l'action d'un groupe de transformations appellées monotones radiales. L'invariant maximal associé à ce groupe est le vecteur des signes multivariés et des rangs des distances de Mahalanobis entre les observations et l'origine. Les paramètres d'intérêt en Analyse en composantes Principales sont les vecteurs propres et valeurs propres de matrices définies positives. Ce qui implique que l'espace des paramètres n'est pas linéaire. Nous développons donc une manière d'obtenir des procédures optimales pour des suite d'experiences locales courbées. Les statistiques de test introduites sont optimales au sens de Le Cam et mesurables en l'invariant maximal décrit ci-dessus. Les procédures de test basées sur ces statistiques possèdent de nombreuses propriétés attractives: elles sont valides sous la famille des lois elliptiques, elles sont efficaces sous une densité spécifiée et possèdent de très bonnes efficacités asymptotiques relatives par rapport à leurs concurrentes. En particulier, lorsqu'elles sont basées sur des scores Gaussiens, elles sont aussi efficaces que les procédures Gaussiennes habituelles et sont bien plus efficaces que ces dernières si l'hypothèse de normalité des observations n'est pas remplie.