• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 20
  • 9
  • 5
  • 4
  • 4
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 54
  • 12
  • 8
  • 8
  • 7
  • 7
  • 7
  • 6
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Estudo da viscoelasticidade linear e não linear de misturas de PP/PA-6 compatibilizadas ou não. / Study of lineal and non lineal viscoelastic behavior of PP/PA-6 polymer blends compatibilized or no.

Guillermo Palmer Martín 15 December 2006 (has links)
Neste trabalho estudou-se o comportamento reológico e morfológico da mistura polimérica imiscível de polipropileno e poliamida. Como resultado deste estudo obtiveram-se valores de tensão interfacial entre 10mN/m e 13mN/m. A tensão interfacial diminuiu em até 87% quando a mistura é compatibilizada com polipropileno maleado. A análise morfológica no regime de viscoelasticidade linear quando avaliada uma morfologia de emulsão de poliamida em polipropileno revelou diâmetro médio da fase dispersa entre 1,5µm e 20µm. O diâmetro das gotas da fase dispersa diminuiu com a adição de polipropileno maleado chegando a reduções de até 98%, mantendo-se constante a concentração da fase dispersa. No regime de viscoelasticidade não linear foram testados modelos para avaliar o comportamento da mistura em fluxos de cisalhamento e extensão, sendo que somente para os fluxos de extensão foi obtida boa correlação dos resultados experimentais com as previsões teóricas. / Rheological and morphological behaviour of polypropylene and polyamide polymer blend was studied. The values of interfacial tension were obtained between 10mN/m and 13mN/m. The interfacial tension decreased in 87% for compatibilized blend. Morphology analysis for linear viscoelastic regime shows dispersed drop diameter between 1,5µm and 20µm. The diameter of the drops decreased with the addition of maleic polypropylene reducing until 98%, keeping constant the concentration of the disperse phase. In non linear viscoelastic regime different models were tested to evaluate the behavior of the blends in shear and elongacional flows. However, only the elongacional flow results were acquired with theoretical - experimental corroboration.
52

O juízo como subordinação intensional e a Analítica Transcendental da Crítica da Razão Pura

Godoy, Evandro C. January 2014 (has links)
Interpretações com diferentes nuances têm sido oferecidas para a concepção de juízo enunciada na Crítica da Razão Pura, mas, grosso modo, pode-se classificálas sob duas linhas gerais, a interpretação analítica e a interpretação a partir de Port-Royal. Ambas as linhas interpretativas, entretanto, se identificam na tese de que no juízo são também subordinadas representações singulares. Esta concepção, designada de interpretação extensional do juízo, leva de modo geral a uma leitura pouco caridosa da obra. A finalidade deste texto é propor e esboçar a defesa de outro modo de conceber o juízo pautado pelas seguintes teses: i) intuições e conceitos não se relacionam no ou pelo juízo; ii) a relação extensional não é suficiente para a determinação de qual conceito é superior ou inferior (gênero ou espécie) e iii) a relação que estabelece a série intensional do conceito determina a hierarquia superior/inferior e por isto é a relação de maior relevância cognitiva. Fazendo frente à concepção extensional, a proposta aqui defendida é designada de interpretação intensional e demanda que a distinção entre intuições e conceitos seja levada às últimas consequências. A potência elucidativa e a conformidade com o texto desta abordagem do juízo mostram-se pela possibilidade de compatibilização das diferentes partes da Analítica transcendental, mesmo aquelas que a literatura secundária tende a descartar ou atribuir pouco significado. Na esteira da elaboração desta compatibilização, após a apresentação e defesa da concepção intensional do juízo, o texto trata em sequência da Dedução metafísica, da Dedução transcendental, do Esquematismo e dos Princípios, procurando ressaltar a interconexão e articulação destas partes, que é calcada na mediação da relação entre os produtos do entendimento e da sensibilidade pela imaginação. Assim, apesar de partir da concepção de juízo, o objetivo do texto é buscar uma leitura da obra magna de Kant que prioriza a consistência. A compatibilização da concepção de juízo com as partes mais relevantes da Analítica – principalmente para o que pesa para o problema da possibilidade de juízos sintéticos a priori – é uma conquista considerável, mas este estudo representa passos, que embora sejam fundamentais, são apenas iniciais na compreensão do idealismo transcendental. / Interpretations with different nuances have been offered for the conception of judgment set out in the Critique of Pure Reason, but, roughly speaking, one can classify them under two broad lines, named, analytic interpretation and interpretation from Port-Royal. However, both lines identify itself under the thesis that in judgments are also subordinate singular representations. This conception, designated here extensional interpretation of judgment, commonly leads to an uncharitable reading of the work. The objective of this text is to propose and outline the defense of another conception of judgment, guided by the following theses: i) intuitions and concepts do not relate in or by means of judgment, ii) the extensional relation is not sufficient to determine which concept is higher or lower (genus or species) and iii) the relation which establishes the intensional series of concept is that one which determines the higher/lower hierarchy and that is the relationship of more cognitive relevance. Contrasting to extensional conception, the proposal advocated here is named of intensional interpretation and demands to take the distinction between intuitions and concepts until its ultimate consequences. The explanatory power and accordance with text of this approach of judgment shows itself by reconciling different parts of the Transcendental Analytic, even those that secondary literature tends to dismiss or assign little significance. In the development of this compatibility, after the presentation and defense of intensional conception of judgment, the text addresses sequentially the Metaphysical Deduction, the Transcendental Deduction, the Schematism and the Principles, seeking to emphasize the linkage and interconnection of these parts, which is modeled on mediation of imagination in the relationship between the products of understanding and sensibility. Therefore, although starting from the conception of judgment, the purpose of the text is to seek a reading of Kant's greatest work that prioritizes consistency. Presenting the compatibility of conception of judgment with the most relevant parts of Analytic – mainly for the concern of the possibility of synthetic a priori judgments – is a considerable achievement, but this study represents steps that, although fundamentals, are just initials to the understanding of transcendental idealism.
53

Retournement, flexion, étirement : particules dans les écoulements laminaires et chaotiques / Tumbling, bending, stretching : particles in laminar and chaotic flows

Plan, Emmanuel Lance Christopher VI Medillo 15 June 2017 (has links)
Les particules soumises à un écoulement peuvent manifester des orientations préférées et une variété de déformations en fonction de leur géométrie et élasticité et du champ de vitesse de l'écoulement. A l’inverse, les flux peuvent être modifiés lorsque les contraintes des particules sont non négligeables. Cette thèse présente des résultats théoriques et numériques sur cette relation bilatérale en deux parties. La Ière partie commence par une analyse de stabilité et des simulations numériques qui montrent une particule brownienne semi-flexible dans un écoulement élongationnel effectuant un retournement, un phénomène associé aux flux de cisaillement. Le Chap. 2 étend les outils analytiques dédiés aux modèles simples ou aux flux indépendante du temps pour les modèles perle-barre-bond généraux dans les flux aléatoires. En partant des résultats des chapitres précédents, Le Chap. 3 aboutit à l'étude d'un degré de liberté lagrangien inexploré dans un écoulement turbulent : la flexion. Une particule semi-flexible courbe différemment dans les flux aléatoires bidimensionnels et tridimensionnels. La IIème partie concerne la turbulence élastique, un régime chaotique créé dans un écoulement de faibles forces inertielles par l'ajout de polymères élastiques. Le Chap. 4 estime le nombre de degrés de liberté d'une solution de ce régime via la dimension Lyapunov de l'attracteur du modèle Oldroyd-B bidimensionnel, un modèle connu de reproduire la turbulence élastique dans les simulations numériques. Le Chap. 5 pose des questions sur la nécessité d'élasticité pour produire un régime chaotique et conclut qu'une solution de polymère de barres peut créer un régime comparable à la turbulence élastique. / Particles, when subjected into a flow, may display preferred orientations and a variety of deformations depending on their geometry and elasticity and the flow velocity field. Flows can conversely be modified when the particle stresses are sufficiently large. This thesis presents theoretical and numerical results on this two-way relationship between particles and flows in two parts. Part I starts with a stability analysis and numerical simulations that show a simple semiflexible Brownian particle in an extensional flow undergo tumbling, a phenomenon normally associated to shear flows. Chapter 2 extends analytical tools available only for elementary polymer models or for steady flows to general bead-rod-spring models in random flows. By building on the results from the previous chapters, Chap. 3 culminates with the study of an unexplored Lagrangian degree of freedom in a turbulent flow: bending. A semiflexible particle is shown to display different bending behaviours in two- and three-dimensional random flows. This prediction is confirmed via direct numerical simulations of the particle in a turbulent flow. Part II concerns “elastic turbulence", a chaotic regime created in a flow with low inertial forces by the addition of elastic polymers. Chapter 4 provides an estimate for the number of degrees of freedom of a solution of this chaotic system via the Lyapunov dimension of the attractor of the two-dimensional Oldroyd-B model, a model known to reproduce elastic turbulence in numerical simulations. Chapter 5 questions the necessity of elasticity in producing a chaotic regime and concludes that a rodlike polymer solution can create a regime similar to elastic turbulence.
54

二軸押出機を用いたナノコンポジットの分散混合に関する研究 / ニジク オシダシキ オ モチイタ ナノコンポジット ノ ブンサン コンゴウ ニカンスル ケンキュウ

松本 紘宜, Koki Matsumoto 22 March 2018 (has links)
博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

Page generated in 0.0582 seconds