In the present PhD work, three sophisticated models based on the "Engineering" modeling approach have been utilized to conveniently describe and thoroughly analyze details of Lightning events at the CN Tower. Both the CN Tower and the Lightning Channel are represented by a number of connected in series Transmission Line sections in order to account for the variations in the shape of the tower and for plasma processes that take place within the Lightning Channel. A sum of two Heidler functions is used to describe the "uncontaminated" Return Stroke current, which is injected at the attachment point between the CN Tower and the Lightning Channel. Reflections and refractions at all points of mismatched impedances are considered until their contribution becomes less than 1% of the originally injected current wave. In the proposed models, the problem with the current discontinuity at the Lightning Channel front, commonly taken care of by introducing a "turn-on" term when computing radiation fields, is uniquely treated by introducing reflected and transmitted components. For the first time, variable speed of propagation of the Return Stroke current front has been considered and its influence upon the predicted current distributions along the whole Lightning Channel path and upon the radiated distant fields analyzed. Furthermore, as another novelty, computation of the electromagnetic field is accomplished in Cartesian Coordinates. This fact permits to relax the requirement on the verticality of the Lightning Channel, normally imposed in Cylindrical Coordinates. Therefore, it becomes possible to study without difficulty the influence of a slanted Lightning Channel upon the surrounding electromagnetic field. Since the proposed sophisticated Five-Section Model has the capability to represent very closely the structure of the CN Tower and to emulate faithfully the shape of, as well as physical processes within the Lightning Channel, it is believed to have the potential of truthfully reproducing observed fields. The developed modeling approach can be easily adapted to study the anticipated radiated fields at tall structures even before construction.

Les Méditations cartésiennes exposent sommairement le rôle de la phénoménologie dans le projet de refondation des sciences. Husserl y discutera, à partir du doute cartésien, une sortie du scepticisme vers une fondation de la connaissance. Pour cela, deux choses devront être exposées : premièrement, le principe central à la subjectivité nommé « l’ego transcendantal » qui permettra de comprendre ce qui constitue l’essence de la subjectivité. Deuxièmement, la communauté intersubjective elle-même qui, une fois atteinte, permettra la constitution d’une connaissance certaine. Ce mémoire retracera le développement fait entre la première réduction, qui semble restreindre le phénoménologue à sa propre subjectivité, à celle de l’atteinte d’une communauté intersubjective. En exposant méthodiquement l’avancée de Husserl, nous montrerons comment une réelle intersubjectivité est développée, tout en soulevant certaines objections qui limitent la portée de cette entreprise, afin de parvenir à deux choses : premièrement, une remise en contexte d’un argument complexe se laissant trop souvent réduire à une lecture idéaliste au sens classique du terme; deuxièmement, que le corps joue un rôle central dans le projet husserlien et que ce sera sur celui-ci, pris en un sens spécifique, que s’édifiera la communauté existant entre les différentes monades. / Husserl’s Cartesian Meditations shows the role of phenomenology in the project of refoundation of sciences. Husserl exposed, starting from the Cartesian’s doubt, a solution to skepticism through an absolute foundation of knowledge. To do that, two things must be achieved: first, the main component of subjectivity, otherwise known as the “transcendental ego,” must be clarified to expose the essence of the subjectivity. Second, the intersubjective community, if properly constituted, should guarantee apodictic knowledge to phenomenology. This master’s thesis follows the development from the first reduction, which appears to refocus the phenomenologist’s gaze onto his own subjectivity, to the constitution of an intersubjective community. By showing methodically Husserl’s procedure, we will demonstrate how he develops a bona fide intersubjectivity, but also its epistemological limits. This examination will lead us to two things: first, the re-contextualization of what is a complex argument that is often reduced to a simple, classical idealism; second, the central role of the body, understood in a specific sense, in the Husserlian project, which should help to bridge the gap between what he called the different monads (subjects).

Cette thèse propose une étude du débat entre Descartes et Pierre Bourdin par la reconstruction historique des évènements et par une analyse des concepts qui ressortent de la controverse. Née autour de questions concernant la dioptrique et soulevée par la publication du Discours et des Essais (1637), et en particulier après la soutenance par Charles Potier de trois thèses contre la Dioptrique en 1640, la controverse passe à la fin de 1641 sur le plan métaphysique avec la rédaction par Bourdin d’une Dissertatio qui sera incluse dans la deuxième édition des Méditations (1642) avec l’Épitre au Père Dinet. L’intervention du Père Dinet, précisément, sera décisive pour la résolution de la dispute, qui coïncide avec la publication des Principia Philosophiæ (1644), dont des copies destinées aux jésuites seront distribuées à Paris par Bourdin. Le premier chapitre est consacré aux thèmes de la critique de la Dioptrique à partir du contexte scientifique de Bourdin, en incluant les thèses de certains de ses élèves et trois manuscrits. Dans le deuxième, j’identifie par l’analyse des Objectiones et Responsiones VII un développement essentiel de la critique de Bourdin. De la méthode du doute, où les commentateurs voient généralement l’essentiel de la critique de Bourdin, dépend selon lui la faiblesse de la théorie de la distinction entre l’âme et le corps. Dans le troisième chapitre, par l’analyse de l’Épitre au Père Dinet, je reconstruis la fin de la controverse et les dynamiques qui la lient à la publication des Principia. La transcription d’une Optique, présente dans un des trois manuscrits, conclut la thèse. / This study looks at the controversy between Descartes and Pierre Bourdin, providing a historical reconstruction and analysing the concepts in their debate. The dispute arose after the publication of Discours and Essais (1637) and, particularly, when Charles Potier defended three theses against the Dioptric in 1640. The dispute evolved from the scientific to the metaphysic plane with Bourdin’s redaction of a Dissertatio, which was included in the second edition of Meditations (1642) as the Seventh Set of Objections with Replies and, together with the Letter to Father Dinet, form an Appendix to Meditations. Dinet’s intervention made possible a reconciliation between Descartes and Bourdin, which coincided with the publication of Principia (1644). The first chapter is dedicated to the themes of the critic to the optic starting from Bourdin’s scientific context, using the theses of the students of the Jesuit College and the contents of three manuscripts. In the second chapter, with the analysis of Objections VII, Bourdin’s critic, which is usually considered to have its focus on the method and, precisely, on doubt, undergoes a crucial development concerning the Cartesian demonstration of real distinction. Bourdin identifies the weakness of the theory of real distinction based on the doubt. This chapter also scrutinizes a lecture of Descartes’ answer that underlines points of tension between Meditations and Answers. The third chapter, analysing Letter to Father Dinet, reconstructs the end of controversy and the dynamic that links it to the publication of Principia. A transcription of an Optic from one of three manuscripts concludes the dissertation.

Apesar do grau relativamente alto de maturidade existente na área de pesquisa de aprendizado supervisionado em lote, na qual são utilizados dados originários de problemas estacionários, muitas aplicações reais lidam com fluxos de dados cujas distribuições de probabilidade se alteram com o tempo, ocasionando mudanças de conceito. Diversas pesquisas vêm sendo realizadas nos últimos anos com o objetivo de criar modelos precisos mesmo na presença de mudanças de conceito. A maioria delas, no entanto, assume que tão logo um evento seja classificado pelo algoritmo de aprendizado, seu rótulo verdadeiro se torna conhecido. Este trabalho explora as situações complementares, com revisão dos trabalhos mais importantes publicados e análise do impacto de atraso na disponibilidade dos rótulos verdadeiros ou sua não disponibilização. Ainda, propõe um novo algoritmo que reduz drasticamente a complexidade de aplicação do teste de hipótese não-paramétrico Kolmogorov-Smirnov, tornado eficiente seu uso em algoritmos que analisem fluxos de dados. A exemplo, mostramos sua potencial aplicação em um método de detecção de mudança de conceito não-supervisionado que, em conjunto com técnicas de Aprendizado Ativo e Aprendizado por Transferência, reduz a necessidade de rótulos verdadeiros para manter boa performance de um classificador ao longo do tempo, mesmo com a ocorrência de mudanças de conceito. / Despite the relatively maturity of batch-mode supervised learning research, in which the data typifies stationary problems, many real world applications deal with data streams whose statistical distribution changes over time, causing what is known as concept drift. A large body of research has been done in the last years, with the objective of creating new models that are accurate even in the presence of concept drifts. However, most of them assume that, once the classification algorithm labels an event, its actual label become readily available. This work explores the complementary situations, with a review of the most important published works and an analysis over the impact of delayed true labeling, including no true label availability at all. Furthermore, this work proposes a new algorithm that heavily reduces the complexity of applying Kolmogorov- Smirnov non-parametric hypotheis test, turning it into an uselful tool for analysis on data streams. As an instantiation of its usefulness, we present an unsupervised drift-detection method that, along with Active Learning and Transfer Learning approaches, decreases the number of true labels that are required to keep good classification performance over time, even in the presence of concept drifts.

Made available in DSpace on 2015-03-04T20:06:51Z (GMT). No. of bitstreams: 0 Previous issue date: 16 / Nenhuma / A dissertação tem por objetivo problematizar como professoras de uma escola estadual do município de Esteio, situado na região metropolitana da capital do Estado do Rio Grande do Sul, descrevem a aprendizagem da matemática escolar e, em particular, o raciocínio lógico de seus alunos. Os aportes teóricos vinculam-se ao pensamento pós-estruturalista, especialmente a algumas formulações do filósofo Michel Foucault e a ideias presentes na obra Discurso do Método, de René Descartes, principalmente aquelas ligadas à ordenação do pensamento. O material de pesquisa está constituído por documentos avaliativos da escola, em especial por 58 pareceres descritivos elaborados por cinco professoras dos anos iniciais do Ensino Fundamental da instituição estudada, e por entrevistas que com elas foram realizadas. As entrevistas foram gravadas e posteriormente transcritas. A análise do material de pesquisa possibilitou: mostrar as ressonâncias das ideias cartesianas como condutoras das condutas dos sujeitos escolares na contem / This dissertation aims at problematizing how teachers from a state school in Esteio, a town located in the metropolitan region surrounding the capital of Rio Grande do Sul, describe the learning of school mathematics, particularly their students’ logical reasoning. The theoretical bases of this investigation have been linked to the poststructuralist thought, following some formulations of Michel Foucault, and ideas from Discourse on Method, by René Descartes, mainly those linked to thought ordering. Evaluation documents of the school studied, especially 58 descriptive evaluations written by five teachers of elementary school, as well as interviews with these teachers have constituted the research material. The interviews were recorded and later transcribed. The analysis of the research material has allowed for: showing the resonances of Cartesian ideas as conducting the conducts of school subjects in contemporaneity; reflecting upon relationships between Mathematics as a foundation of reasoning and its ma

Digital Clay represents a new type of 3-D human-computer interface device that enables tactile and haptic interactions. The Digital Clay kinematics structure is computer controlled and can be commanded to acquire a wide variety of desired shapes (shape display), or be deformed by the user in a manner similar to that of real clay (shape editing). The design of the structure went through various modifications where we finally settled on a crust matrix of spherical joint unit cells. After designing the kinematics structure, the next step is predicting the deformation of the crust matrix based upon a handful of inputs. One possible solution for predicting the shape outcome is considering minimizing the potential energy of the system. In this thesis two methods will be introduced. The first method will be an abstract model of the crust where the energy is calculated from a simplified model with one type of angular springs. The second method is the actual manufacturable crust model with two types of angular springs. From the implementation of these two methods, the output will be center-points of the unit cells. From the center-points, one can also calculate the joint angles within each unit cell.

In the thesis work, a code to solve the two dimensional compressible Euler equations for external flows around arbitrary geometries have been developed. A Cartesianmesh generator is incorporated to the solver. Hence the pre-processing can be performed together with the solution within a single code. The code is written in the C++ programming language and its object oriented capabilities have been exploited to save memory in the data structure developed. The Cartesian mesh is formed by dividing squares successively into its four quadrants. The main advantage of using this type of a mesh is the ability to generate meshes around geometries of arbitrary complexity quickly and to adapt the mesh easily based on the solution. The main disadvantage of this method is that the treatment of the cells that are cut by the geometry. For the solution procedure Roe&rsquo / s method as well as flux vector splitting methods are used for the flux evaluation. The flux vector splitting schemes used are van Leer, AUSM, AUSMD and AUSMV methods. Time discretization is performed using a multi-stage method. To increase the accuracy least squares reconstruction is employed. The code is validated by performing calculations around a NACA0012 airfoil profile. The effect of reconstruction is demonstrated by plotting the pressure coefficient on the airfoil. The distribution obtained using reconstruction is very close to the experimental one while there is a considerable deviation for the case without reconstruction. Also the shock capturing capabilities of different methods have been investigated. In addition the performance of each method is analyzed for flow around an NLR 7301 airfoil with a flap.

Fluid-structure interaction (FSI) is an important physical phenomenon in many applications and across various disciplines including aerospace, civil and bio-engineering. In civil engineering, applications include the design of wind turbines, pipelines, suspension bridges and offshore platforms. Ocean structures such as drilling risers, mooring lines, cables, undersea piping and tension-leg platforms can be subject to strong ocean currents, and such structures may suffer from Vortex-Induced Vibrations (VIV's), where vortex shedding of the flow interacts with the structural properties, leading to large amplitude vibrations in both in-line and cross-flow directions. Over the past years, many experimental and numerical studies have been conducted to comprehend the underlying physical mechanisms. However, to date there is still limited understanding of the effect of oscillatory interactions between fluid flow and structural behavior though such interactions can cause large deformations. This research proposes a mathematical framework to accurately predict FSI for elastically supported rigid structures. The numerical method developed solves the Navier-Stokes (NS) equations for the fluid and the Equation of Motion (EOM) for the structure. The proposed method employs Finite Differences (FD) on Cartesian grids together with an improved, efficient and oscillation-free Immersed Boundary Method (IBM), the accuracy of which is verified for several test cases of increasing complexity. A variety of two and three dimensional FSI simulations are performed to demonstrate the accuracy and applicability of the method. In particular, forced and a free vibration of a rigid cylinder including Vortex-Induced Vibration (VIV) of an elastically supported cylinder are presented and compared with reference simulations and experiments. Then, the interference between two cylinders in tandem arrangement at two different spacing is investigated. In terms of VIV, three different scenarios were studied for each cylinder arrangement to compare resonance regime to a single cylinder. Finally, the IBM is implemented into a three-dimensional Large-Eddy Simulation (LES) method and two high Reynolds number (Re) flows are studied for a stationary and transversely oscillating cylinder. The robustness, accuracy and applicability of the method for high Re number flow is demonstrated by comparing the turbulence statistics of the two cases and discussing differences in the mean and instantaneous flows.

Convex cycles play a role e.g. in the context of product graphs. We introduce convex cycle bases and describe a polynomial-time algorithm that recognizes whether a given graph has a convex cycle basis and provides an explicit construction in the positive case. Relations between convex cycles bases and other types of cycles bases are discussed. In particular we show that if G has a unique minimal cycle bases, this basis is convex. Furthermore, we characterize a class of graphs with convex cycles bases that includes partial cubes and hence median graphs. (authors' abstract) / Series: Research Report Series / Department of Statistics and Mathematics

In the present PhD work, three sophisticated models based on the "Engineering" modeling approach have been utilized to conveniently describe and thoroughly analyze details of Lightning events at the CN Tower. Both the CN Tower and the Lightning Channel are represented by a number of connected in series Transmission Line sections in order to account for the variations in the shape of the tower and for plasma processes that take place within the Lightning Channel. A sum of two Heidler functions is used to describe the "uncontaminated" Return Stroke current, which is injected at the attachment point between the CN Tower and the Lightning Channel. Reflections and refractions at all points of mismatched impedances are considered until their contribution becomes less than 1% of the originally injected current wave. In the proposed models, the problem with the current discontinuity at the Lightning Channel front, commonly taken care of by introducing a "turn-on" term when computing radiation fields, is uniquely treated by introducing reflected and transmitted components. For the first time, variable speed of propagation of the Return Stroke current front has been considered and its influence upon the predicted current distributions along the whole Lightning Channel path and upon the radiated distant fields analyzed. Furthermore, as another novelty, computation of the electromagnetic field is accomplished in Cartesian Coordinates. This fact permits to relax the requirement on the verticality of the Lightning Channel, normally imposed in Cylindrical Coordinates. Therefore, it becomes possible to study without difficulty the influence of a slanted Lightning Channel upon the surrounding electromagnetic field. Since the proposed sophisticated Five-Section Model has the capability to represent very closely the structure of the CN Tower and to emulate faithfully the shape of, as well as physical processes within the Lightning Channel, it is believed to have the potential of truthfully reproducing observed fields. The developed modeling approach can be easily adapted to study the anticipated radiated fields at tall structures even before construction.