Made available in DSpace on 2016-04-27T17:13:02Z (GMT). No. of bitstreams: 1 Alessandra Nascimento.pdf: 1945223 bytes, checksum: f6950936e78897c5cfc27568b8cd6159 (MD5) Previous issue date: 2005-07-17 / Made available in DSpace on 2016-08-25T17:25:34Z (GMT). No. of bitstreams: 2 Alessandra Nascimento.pdf.jpg: 2104 bytes, checksum: c4715912a635b5fbde63d2a9b070733f (MD5) Alessandra Nascimento.pdf: 1945223 bytes, checksum: f6950936e78897c5cfc27568b8cd6159 (MD5) Previous issue date: 2005-07-17 / The objective of this study is to construct a trigonometrical table, on the basis of historical surveys of the works of Ptolomeu and other mathematicians of Old Greece, to investigate the appropriation of the meaning of the concepts of the trigonometrical reasons: sine, cosine and tangent, in the rectangular triangle, for students of first year Average education. We look for to answer to the research question: How to teach trigonometry in the rectangular triangle in significant way? E also decurrent questions: Which factors influence the acquisition of such knowledge? How to distanciar the use of Trigonometry in Average Education of mechanization? For in such a way we use the estimated theoreticians of Vygotsky in that if relates to the importance attributed to the social interaction, the language and the simbolizaction in the gradual domain of a conceptual field for the pupils, of the estimated theoreticians of Vergnaud, when dealing with the operations invariants: concept-in-action and theorem-in-action, of its conception, of conceptual field and concept, e also in the model presented for Parzysz for a theoretical picture of the education of geometry, where it detaches four stages of the development of the geometric thought. The results of the experimentation point with respect to an imbalance in Geometry and Algebra. The experimentation showed that despite this, an education of the Trigonometry of the generating rectangular triangle of motivations, including diversified activities, with problems situations, that stimulate thinking, the inquiry and carrying through, contributes so that the pupils construct the meaning of the trigonometrical reasons, besides favoring the argument and modifying some wrong conceptions / O objetivo deste estudo é construir uma tabela trigonométrica, com base em levantamentos históricos dos trabalhos de Ptolomeu e outros matemáticos da Grécia Antiga, para investigar a apropriação do significado dos conceitos das razões trigonométricas: seno, cosseno e tangente, no triângulo retângulo, por estudantes do 1o ano do Ensino Médio. Procuramos responder à questão de pesquisa: Como ensinar trigonometria no triângulo retângulo de maneira significativa? E também questões decorrentes: Quais fatores influenciam a aquisição de tal conhecimento? Como distanciar a utilização da Trigonometria no Ensino Médio da mecanização? Para tanto utilizamos os pressupostos teóricos de Vygotsky no que se refere à importância atribuída à interação social, à linguagem e à simbolização no progressivo domínio de um campo conceitual pelos alunos, dos pressupostos teóricos de Vergnaud, ao tratar dos invariantes operatórios: conceito-em-ação e teorema-em-ação, de sua concepção de campo conceitual e de conceito, e também no modelo apresentado por Parzysz para um quadro teórico do ensino da geometria, onde ele destaca quatro etapas do desenvolvimento do pensamento geométrico. Os resultados da experimentação apontam para uma defasagem em Geometria e em Álgebra. A experimentação mostrou que apesar disso, um ensino da Trigonometria do triângulo retângulo gerador de motivações, incluindo atividades diversificadas, com situações problematizadoras, que estimulem o pensar, a investigação e o realizar, contribui para que os alunos construam o significado das razões trigonométricas, além de favorecer a argumentação e modificar várias concepções errôneas

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-07-06T13:51:44Z No. of bitstreams: 1 THICIANY MATSUDO IWANO - DISSERTAÇÃO PPGMAT 2005..pdf: 3751075 bytes, checksum: 2aaae3fdd115cd9f6f4b653f522d94c8 (MD5) / Made available in DSpace on 2018-07-06T13:51:44Z (GMT). No. of bitstreams: 1 THICIANY MATSUDO IWANO - DISSERTAÇÃO PPGMAT 2005..pdf: 3751075 bytes, checksum: 2aaae3fdd115cd9f6f4b653f522d94c8 (MD5) Previous issue date: 2005-10 / Neste trabalho apresentamos um estudo das principais técnicas de geração de malhas poligonais, a partir de superfícies descritas matematicamente por funções implícitas,isto é, superfícies definidas pelo conjunto S = f−1(0) = {X ∈ R3 | f(X) = 0}, onde f : R3 → R e f é, pelo menos, de classe C2. Mostramos um método para obter as curvaturas gaussiana e média dessas superfícies a partir do vetor ∇f para cada ponto de S. Abordamos questões como a preservação de características geométricas e topológicas do objeto gráfico. Dentre os métodos estudados, ressaltamos o algoritmo Marching Triangles, que gera uma malha a partir de um ponto arbitrário p sobre a superfície S e um referencial local, usando a abordagem do avanço de frentes. Em sua implementação, usamos o raio de curvatura, calculado a partir da curvatura normal máxima absoluta da superfície em cada ponto p pertencente a S, para adaptar o comprimento das arestas da malha triangular à geometria local da superfície S / In this work we present a study about the main techniques of surfaces meshes generation, described by implicit functions, that is, surfaces defined by the set S = f−1(0) = {X ∈ R3 | f(X) = 0}, where f : R3 → R and f is, at least, C2. We discuss aspects involving his preservation of graphic object’s geometry and topology. As special method we cite the Marching Triangles that generates a mesh starting from an arbitrary point p on surface S and a local referencial, using advancing fronts approach. In our implementation, we use the radius of curvature, calculated from surface’s absolute maximum normal curvature in each point p in S and the triangular mesh, to adapt the edges length of the mesh to the local geometry.

This thesis deals with the evaluation of swirl turbine measurement, which the length of the turbine blades was gradually reduced. The subject of the effect was influence of the length of the blades, especially the measured efficiency of the turbine, and the character assessment of the flow at the inlet and outlet of the impeller. The measured data were analysed using the computing workbook with macro support, which can be used to evaluate other measurements of similar character. The different behaviour of the turbine depending on the length of the blades of the impeller was shown in the characteristics of the turbine and velocity triangles. For the variant with the best efficiency achieved was constructed QH diagram used in the design of turbine parameters for a particular location.

Present graphic requires a lot of optimizations of rendering techniques and mathematical calculations. It is caused by increased requirements of scene's visualization. One of scene's optimizing techniques is the Level of detail. This thesis is focused on methods used by LOD in OpenSceneGraph and OpenGL library. Next it will be described how to choose the right level of detail in a scene. Later it will be explained how to simplify 3D models. These techniques will be implemented in converting tool and demonstrating application. Methods for simplify 3D models will be tested for their speed and quality.

The main focus of the Master thesis is the analysis of design parameters for observation triangles of vehicles, pedestrian and cyclists of the ČSN 73 6110 standard. The thesis consists of two main chapters, which are Problem analysis and Major analysis. The first chapter sheds light on some of the most commonly used technical terms on issues related to this work. The second chapter presents evaluation and possible adjustments and optimizations that can result to improved observation conditions in selected areas. The conclusion summarizes the knowledge achieved during processing the thesis.

Considering that geometry is taught according to certain principles that do not encourage creativity, I have decided to employ the mixed methods philosophical framework applying the concurrent transformative design in the form of an exploratory case study. The case study to (i) explore and design a model that influences learning using polygon pieces and mathematics dictionary in the teaching and learning of geometry to grade 8 learners; (ii) investigate if the measurement of angles and sides of polygons using polygon pieces assisted by mathematics dictionary promote learners’ comprehension of geometry and (iii) investigate how mathematics teachers should use polygon pieces along with mathematics dictionary to teach properties of triangles in order to promote learners’ conceptual understanding. Drawing from my research findings a model has been developed from the use of polygon pieces and mathematics dictionary. The model use of mathematics dictionary in teaching and learning geometry is to develop learners’ mathematics vocabulary and terminology proficiency. Polygon pieces are to enhance the comprehension of geometric concepts. The quantitative data emerged from marked scripts of the diagnostic and post-intervention tests, the daily reflective tests and intervention activities were analysed as percentages and presented in line and bar graphs. Qualitative data obtained from observation notes and transcribed interviews were analysed in three forms: thematically, constant comparison and keywords in context. These findings support other research regarding the importance of using physical manipulatives with mathematics dictionary in teaching and learning geometry. They align with other findings that stress that manipulatives are critical facilitating tools for the development of mathematics concepts. The investigations led into the designing of a teaching model for the topic under study for the benefit of the mathematics community in the teaching and learning of geometry, focusing on properties of triangles. The model developed during this study adds to the relatively sparse teaching models but growing theoretical foundation of the field of mathematics. / Mathematics Education / Ph. D. (Mathematics Education)

In a quest to design novel deployable structures, flexible polyhedra provide interesting insights. This work follows the discovery of flexible polyhedra and aims to make flexible polyhedra more useful. The dissertation describes how flexible polyhedra can be made. The flexible polyhedra first considered in this dissertation have a rotational degree of freedom. The range of this rotational movement is measured and maximised in this work by numerical maximisation. All polyhedra are established computationally: an iterative solution method is used to find vertex coordinates; several clash detecting methods are described to define whether each rotational position of a flexible polyhedron is physically possible; then a range of motion is defined between occurrences of clashes at the two ends; finally, an optimisation tool is used to maximise the range of motion. By using these tools, the range of motion of two types of simplest flexible polyhedra are maximised. The first type is a series of flexible polyhedra generalised from the Steffen flexible polyhedron. The range of motion of this type is improved to double that of Steffen’s original, from 27° to 59°. Another type of flexible polyhedron is expanded from a model provided by Tachi. Based on the understanding of Steffen’s flexible polyhedron, optimisation parameters are carefully given. This new type has achieved a wider range of motion, so now the range of motion of flexible polyhedron is tripled to 80°. After enlarging the range of motion of the degree of freedom in the 1-dof systems, the dissertation found multiple degrees of freedom in one polyhedron. The multiple mechanisms can be even repetitive, so that an n-dof polyhedron is found. A polyhedron of two degrees of freedom is first presented. Then, a unit cell for any number of mechanisms is found. As a repetitive structure, a 3-dof polyhedron is presented. Finally, this work presents the possibility of configuring a flexible polyhedral torus and a closed polyhedral surface that is able to flex without the need to stop.

Euclidean Geometry is a challenging topic for most of the learners in the secondary schools. A qualitative case study explores the reasoning skills of ninth graders in the proving of congruent triangles in their natural environment. A class of thirty-two learners was conveniently selected to participate in the classroom observations. Two groups of six learners each were purposefully selected from the same class of thirty-two learners to participate in focus group interviews. The teaching documents were analysed. The Van Hiele’s levels of geometric thinking were used to reflect on the reasoning skills of the learners. The findings show that the majority of the learners operated at level 2 of Van Hiele’s geometric thinking. The use of visual aids in the teaching of geometry is important. About 30% of the learners were still operating at level 1 of Van Hiele theory. The analysed books showed that investigation help learners to discover the intended knowledge on their own. Learners need quality experience in order to move from a lower to a higher level of Van Hiele’s geometry thinking levels. The study brings about unique findings which may not be generalised. The results can only provide an insight into the reasoning skills of ninth graders in proving of congruent triangles. I recommend that future researchers should focus on proving of congruent triangles with a bigger sample of learners from different environmental settings. / Mathematics Education / M. Ed. (Mathematics Education)

Als Stand der Technik sind einfache, kreisförmige Verrundungen zur Reduktion von Kerbspannungen an Querschnittsübergängen bekannt, für die aus Tabellenwerken / Diagrammen in der Literatur die Formzahl einfach abgelesen werden kann. Die Effizienz der Spannungsreduktion solcher Lösungen ist jedoch sehr begrenzt. Ziel der Arbeit ist es daher, dem Konstrukteur bzw. Berechnungsingenieur ein Verfahren in die Hand zu geben, mit dem er für Standardquerschnittsübergänge und Standardlastfälle "Nicht-Kreiskerben" ohne teure und zeitaufwendige FEM-Analyse einfach durch Nutzung geeigneter Formzahldiagramme auslegen kann. Dabei sind sogar Formzahlen von nahezu eins möglich, d.h., in der "Kerbe" bleibt praktisch nur noch die Nennspannung übrig. Die Präsentation ist zweitgeteilt: Im ersten Teil werden die Arbeitsmethoden bzw. Softwarefunktionen und verwendeten Softwarewerkzeuge vorgestellt: Dies sind die Programme Creo Parametric als vollparametrisches CAD-Werkzeug und Creo Simulate als p-FEM-Programm der Parametric Technology Coprporation (PTC). Der zweite Teil der Präsentation beschreibt den Gültigkeitsbereich sowie die untersuchten Kerbgeometrien: Die einfache kreisförmige Verrundung als Stand der Technik, die Zwei-Radien-Kerbe, die Baud-Kurve, die Methode der Zugdreiecke nach Claus Mattheck, die elliptische Kerbe sowie die konische Rundung als generalisierte elliptische Kerbe. Es wird kurz eine Bibliothek vorgestellt, mit der solche Kerben einfach ausgelegt werden können, d.h. Ihre exakte Geometrie festgelegt sowie die zugehörige Formzahl αk bestimmt werden kann. / Circular (one-radius) fillets are known as state-of-the-art for reducing notch stresses at cross section transitions. The stress concentration factor Kt of such geometries can be read out from diagrams/tables given in the literature. However, the efficiency of stress reduction of circular notches is very limited. The goal of the work therefor is to present a method for the designer/analyst how to design non-circular notches/fillets just by using suitable Kt-diagrams without time-consuming and expensive FEM analyses. Kt-numbers of nearly one are possible, that means in the "notch" just the nominal stress appears and no stress concentration takes place. The presentation has two parts: Part one describes the working methods and software functions as well as software tools: Creo Parametric as fully-parametric CAD program and Creo Simulate as embedded p-FEM-tool from Parametric Technology Corporation (PTC) have been used. The second part describes the range of validity and the examined notch geometries: The one-radius fillet as state-of-the-art, the two-radii filet, the Baud-curve, the method of tensile triangles from Claus Mattheck, the standard elliptical fillet and the conical round as generalized elliptical fillet. A notch layout library is shortly presented that allows to design such fillets, that means exactly determine the notch geometry and the related stress concentration factor Kt.

Als Stand der Technik sind einfache, kreisförmige Verrundungen zur Reduktion von Kerbspannungen an Querschnittsübergängen bekannt, für die aus Tabellenwerken / Diagrammen in der Literatur die Formzahl einfach abgelesen werden kann. Die Effizienz der Spannungsreduktion solcher Lösungen ist jedoch sehr begrenzt. Ziel der Arbeit ist es daher, dem Konstrukteur bzw. Berechnungsingenieur ein Verfahren in die Hand zu geben, mit dem er für Standardquerschnittsübergänge und Standardlastfälle "Nicht-Kreiskerben" ohne teure und zeitaufwendige FEM-Analyse einfach durch Nutzung geeigneter Formzahldiagramme auslegen kann. Dabei sind sogar Formzahlen von nahezu eins möglich, d.h., in der "Kerbe" bleibt praktisch nur noch die Nennspannung übrig. Die Präsentation ist zweitgeteilt: Im ersten Teil werden die Arbeitsmethoden bzw. Softwarefunktionen und verwendeten Softwarewerkzeuge vorgestellt: Dies sind die Programme Creo Parametric als vollparametrisches CAD-Werkzeug und Creo Simulate als p-FEM-Programm der Parametric Technology Coprporation (PTC). Der zweite Teil der Präsentation beschreibt den Gültigkeitsbereich sowie die untersuchten Kerbgeometrien: Die einfache kreisförmige Verrundung als Stand der Technik, die Zwei-Radien-Kerbe, die Baud-Kurve, die Methode der Zugdreiecke nach Claus Mattheck, die elliptische Kerbe sowie die konische Rundung als generalisierte elliptische Kerbe. Es wird kurz eine Bibliothek vorgestellt, mit der solche Kerben einfach ausgelegt werden können, d.h. Ihre exakte Geometrie festgelegt sowie die zugehörige Formzahl αk bestimmt werden kann. / Circular (one-radius) fillets are known as state-of-the-art for reducing notch stresses at cross section transitions. The stress concentration factor Kt of such geometries can be read out from diagrams/tables given in the literature. However, the efficiency of stress reduction of circular notches is very limited. The goal of the work therefor is to present a method for the designer/analyst how to design non-circular notches/fillets just by using suitable Kt-diagrams without time-consuming and expensive FEM analyses. Kt-numbers of nearly one are possible, that means in the "notch" just the nominal stress appears and no stress concentration takes place. The presentation has two parts: Part one describes the working methods and software functions as well as software tools: Creo Parametric as fully-parametric CAD program and Creo Simulate as embedded p-FEM-tool from Parametric Technology Corporation (PTC) have been used. The second part describes the range of validity and the examined notch geometries: The one-radius fillet as state-of-the-art, the two-radii filet, the Baud-curve, the method of tensile triangles from Claus Mattheck, the standard elliptical fillet and the conical round as generalized elliptical fillet. A notch layout library is shortly presented that allows to design such fillets, that means exactly determine the notch geometry and the related stress concentration factor Kt.