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  • 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.
11

Coincidência de aplicações em fibrados com base circulo e fibra garrafa de Klein. / Coincidence of maps on Klein bottle Fiiber bundles over the Ciircle.

Weslem Liberato Silva 03 March 2009 (has links)
Sejam K, a garrafa de Klein, e K M S^ um fibrado com base S^ e fibra K. Neste trabalho estudamos o seguinte problema: dadas aplicações f, g : M M que preservam fibra sobre S^, quando o par (f, g) pode ser deformado, por uma homotopia que preserva fibra sobre S^, a um par de aplicações (f^{\'} , g^{\'} ) livre de coincidência? / Let K be the Klein bottle and let K M S be a Klein bottle bundle over S 1 . In this work we study the following question: given a pair of fiber preserving maps over S^ , when can it be deformed by a fiberwise homotopy over S into a pair of coincidence free fiber preserving maps over S^, (f^{\'} , g^{\'} ) ?
12

Unhairing and Fiber bundle-opening of Cowhides using KCl and LiBr/[AMIm]Cl Assisted Neutral Protease for Leather Making

Liu, Hui, Zhang, Qian, Zhang, Yafei, Li, Xiumin, Tang, Keyong, Liu, Jie, Zheng, Xuejing, Pei, Ying 28 June 2019 (has links)
Content: Nowadays, tannery pollution is of great concern worldwide. The unhairing and fiber bundle-opening processes contribute the majority of the pollution by the use of sodium sulfide and calcium hydroxide, which were proposed to be replaced by neutral protease combined with (potassium chloride) KCl, (lithium bromide)LiBr/1-allyl-3-methylimidazolium chloride([AMIm]Cl) in the present work. Proper amount of KCl can speed up the unhairing with the grain not destroyed by the neutral protease. Four methods for unhairing and fiber bundle-opening were used as follows: 1. Two steps in different floats as KCl/neutral protease unhairing, followed by LiBr/[AMIm]Cl for fiber bundle-opening; 2. Two steps in different floats as neutral protease unhairing, followed by LiBr/[AMIm]Cl for fiber bundle-opening; 3. One step in the same float as neutral protease for unhairing firstly and then LiBr/[AMIm]Cl for fiber bundle-opening. 4. One step in the same float as neutral protease/KCl for unhairing firstly and then LiBr/[AMIm]Cl for fiber bundle-opening. It was found that using neutral protease/KCl solution for unhairing and LiBr/[AMIm]Cl solution for fiber bundle-opening is the best in fiber bundle-opening at the liming process. Besides, all the methods used here are better than the traditional liming processes (C) from viewpoints of unhairing and fiber bundleopening. Take-Away: 1. The addition of potassium chloride can improve the stability of neutral protease solution. 2. The catalytic efficiency of the enzyme was improved because of adding potassium chloride can enhance the contact rate of neutral protease with substrate. 3. Ionic liquids have less hydrolysis of collagen and larger dissolution of polysaccharides.
13

Effects of different salt-enzymes on opening up of collagen fiber bundles for leather making

Zhang, Yafei, Tang, Zhenye, Liu, Hui, Ferah, Cem Emre, Tang, Keyong 28 June 2019 (has links)
Content: Traditional leather industry involves mechanical, chemical and biological processes, and a lot of leather chemicals are widely used annually. In the beamhouse, especially in liming and re-liming, enormous pollution is usually released because of the traditional use of Na2S and lime. Many researchers have devoted to clean production for leather making. In this study, salt-enzyme liming process was studied in modern leather process to remove the inter-fibrillary matter. Three such salts as Na2SO4, NaCl, and MgCl2 were used with such enzymes as neutral protease and cellulase. The enzyme activity was evaluated by Folin Method. The opening up degree of collagen fiber bundles was observed by SEM and microscopic image of histological staining. The waste water was analyzed. The tannin absorptivity of the samples was evaluated by colorimetry. It was demonstrated that enzyme activity is not affected by salt, but it helps the action of enzymes on hides. Salt might accelerate the penetration of enzymes into the hide to promote the removal of inter-fibrillary and the opening up of collagen fiber bundles. The best fiber opening result was found by SEM at the MgCl2 content of more than 0.4 wt.% in liming. Microscopic observation by histological staining as well as waste water analysis indicated a good removing effect for the inter-fibrillary. This work may provide a cleaner leather making technology. Take-Away: 1.Salt-enzyme liming process was studied in modern leather process to remove the inter-fibrillary matter. 2.To provide theoretical guidance for the clean production of leather.
14

Simulation of Fatigue Performance & Creep Rupture of Glass-Reinforced Polymeric Composites for Infrastructure Applications

McBagonluri-Nuuri, David Fred 21 August 1998 (has links)
A simulation model which incorporates the statistical- and numerical-based Lattice Green Function Local Load Sharing Model and a Fracture Mechanics-based Residual Strength Model has been developed. The model simulates creep rupture by imposing a fixed load of constant stress on the composite over the simulation duration. Simulation of the fatigue of glass fiber-reinforced composites is achieved by replacing the constant stress parameter in the model with a sinusoidal wave function. Results from the creep rupture model using fused silica fiber parameters, compare well with S-2 glass/epoxy systems. Results using Mandell's postulate that fatigue failure in glass fiber-reinforced polymeric composites is a fiber-dominated mechanism, with a characteristic slope of 10 %UTS/decade are consistent with available experimental data. The slopes of fatigue curves for simulated composites for three frequencies namely: 2, 5 and 10 Hz are within 12-14 %UTS/decade compared with that of 10.6-13.0%UTS/decade for unidirectionl glass reinforced composites (epoxy and vinyl ester) obtained from Demers' [40] data. / Master of Science
15

Mr.

2015 February 1900 (has links)
Rotator cuff pathologies involving supraspinatus are a common cause of musculoskeletal morbidity and can lead to significant disability affecting the overall quality of life. Architectural parameters of the muscle directly influence its functional properties. Therefore, understanding of fiber bundle changes with surgery and different exercises can assist clinicians in planning better surgical and shoulder rehabilitative protocols. The first objective of this thesis was to systematically review human cadaveric studies of the normal supraspinatus architecture and highlight the key aspects that should be considered while performing studies of skeletal muscle architecture. The second objective was to understand the impact of surgical repair on the structural and functional recovery of the supraspinatus. The final objective was to provide a scientific rationale behind choosing an exercise to strengthen supraspinatus by investigating its muscle architecture. Study 1 systematically reviewed human cadaveric studies of the normal supraspinatus architecture. Results showed that the overall quality of majority of included is poor and there was a large range in the reported architectural values of the entire muscle. In conclusion, there were only a few studies providing the level of detail and quality suitable for advancing our understanding of shoulder biomechanics. Study 2 quantified and compared the fiber bundle architecture of the pathologic supraspinatus pre- and post-operatively at multiple time points. Results showed significant lengthening of fiber bundles after one month of surgery which then decreased significantly by 6 months of surgery. In contrast, an initial decrease followed by an increase in pennation angle overtime was found. The results suggest that the stretching applied to the tendon and muscle during repair could affect the length-tension relationship of the muscle, which in turn can compromise its function and may lead to inferior surgical outcomes. Study 3 compared the efficacy of three commonly prescribed supraspinatus strengthening exercises in the rehabilitation setting based on the architectural changes following resistance training. Results showed there was no change in FBL and increased strength after resistance training with prone horizontal abduction exercise. Findings suggest that prone horizontal abduction may be a more suitable exercise to strengthen supraspinatus.
16

Gradient Dependent Reconstruction from Scalar Data

Bhattacharya, Arindam January 2015 (has links)
No description available.
17

Roulement de variétés différentielles de dimensions quelconques / Rolling Manifolds of Arbitrary Dimensions

Mortada, Amina 18 November 2014 (has links)
Nous étudions dans cette thèse le roulement sans glissement et sans pivotement de deux variétés lisses M et Ṁ l'une sur l'autre de dimensions et n et ṅ respectivement. L'objectif principal est de chercher des conditions nécessaires et suffisantes de la commandabilité du système commandé défini par le roulement. Dans le premier chapitre, on présente les motivations et le plan de la thèse ainsi les notations utilisées le long des chapitres. Dans le deuxième chapitre, on caractérise l'espace d'état du roulement quand M et Ṁ sont des variétés Riemanniennes lorsque n n'est pas nécessairement égal à ṅ et du développement quand M et Ṁ sont des variétés affines munies des connexions affines avec n = ṅ Ainsi, on donne les relèvements et les distributions correspondant aux deux notions précédentes. Le troisième chapitre contient quelques résultats de la commandabilité du système de roulement des variétés Riemanniennes. Plus précisément, on présente les conditions nécessaires de la non-commandabilité du roulement d'une variété Riemannienne 3-dimensionnelle sur une autre 2-dimensionnelle.Le chapitre 4 porte sur le roulement d'une variété Riemannienne de dimension 2 sur une autre de dimension 3. On trouve que la dimension d'une orbite non-ouverte quelconque de l'espace d'état appartient à {2,5,6,7}. Les aspects géométriques de deux variétés sont liés principalement avec le fait que la variété de dimension 3 contient une sous-variété totalement géodésique de dimension 2.Dans le dernier chapitre, on introduit et étudie un concept d'holonomie horizontale associé à un triplet (M,∇,Δ ) avec M variété différentielle connexe, ∇ connection affine complète sur M et Δ distribution complètement commandable. Si H^∇est le groupe d'holonomie associé à Ṁ on considère alors son sous-groupe obtenu uniquement en considérant le transport ∇- parallèle par rapport aux lacets dans M tangents à la distribution Δ On le note H_Δ^∇et on l’appelle groupe d'holonomie horizontal. On prouve que le groupe d'holonomie horizontal H_Δ^∇ est un sous-groupe de Lie de GL(n). Puis, on démontre par un exemple que la fermeture du groupe d'holonomie horizontal restreint (H_Δ^∇ )^0 n'est pas nécessairement égal à H_Δ^∇. A cette fin, on utilise le modèle du roulement avec M un groupe de Carnot homogène munie d'une connexion de Levi-Civita associée à une métrique Riemannienne sur l'espace Euclidien R^n munie de la connexion Euclidienne. / In this thesis, we study the rolling motion without spinning nor slipping of a smooth manifolds M and Ṁ against another of dimensions n and ṅ respectively. The purpose is to find the necessary and sufficient conditions for the controllability issue of the system of rolling. We start by a French review of the principal results of the thesis is included in the introduction. In Chapter 1, we present the motivations of the subject thesis, the structure of the contents and the notations used along the manuscript. The second chapter contain a characterization of the state space of rolling manifolds when M and Ṁ are Riemannian manifolds with n and ṅ are not necessarily equal and of the development of manifolds when M and Ṁ are affine manifolds of dimension n = ṅ equipped with affine connections. We also state the definitions of the lifts and the distributions with respect to the previous notions. The controllability results of the rolling system of Riemannian manifolds is included in Chapter 3. We give all the necessary conditions of the non-controllability of rolling of 3-dimensional Riemannian manifold against 2-dimensional Riemannian manifold. Chapter 4 deals with the rolling of a 2-dimensional Riemannian manifold against a 3-dimensional Riemannian manifold. We prove that the dimension of an arbitrary non-open orbit of the state space belongs to {2,5,6,7}. The geometrical aspects of the two manifolds depend on the existence of a 2-dimensional totally geodesic submanifold in the 3-dimensional manifold. The last chapter introduces and addresses the issue of horizontal holonomy associated to a triple (M,∇,Δ) with M smooth connected manifold, ∇ complete affine connection M and Δ completely controlable distribution over M. If H_Δ^∇. denotes the holonomy group associated with (M,∇) one considers its subgroup obtained by considering only the ∇- parallel transport with respect to loops of M tangent to the distribution Δ This subgroup is denoted by H_Δ^∇ and we call it horizontal holonomy group. We prove that the horizontal holonomy group H_Δ^∇ is a Lie subgroup of GL(n). Then, we show by means of an example that the closure of a restricted horizontal holonomy group on a Riemannian manifold is not necessarily equal to the holonomy group of the Riemannian manifold. To this end, we use the rolling problem of M taken as a step 2 homogeneous Carnot group equipped with the Levi-Civita connection associated to a Riemannian metric onto the Euclidean space R^n equipped with the Euclidean connection.
18

Sobre (H,G)-coincidências de aplicações com domínio em espaços com ações de grupos finitos / About (H,G)-coincidence for maps of spaces with finite group actions

Souza, Bruno Caldeira Carlotti de [UNESP] 23 February 2017 (has links)
Submitted by Bruno Caldeira Carlotti de Souza null (brunoccarlotti@gmail.com) on 2017-03-02T01:45:21Z No. of bitstreams: 1 Dissertação - Bruno C. C. de Souza.pdf: 1030573 bytes, checksum: e3dd1e43953565236359b6d10831067c (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-07T18:32:31Z (GMT) No. of bitstreams: 1 souza_bcc_me_sjrp.pdf: 1030573 bytes, checksum: e3dd1e43953565236359b6d10831067c (MD5) / Made available in DSpace on 2017-03-07T18:32:31Z (GMT). No. of bitstreams: 1 souza_bcc_me_sjrp.pdf: 1030573 bytes, checksum: e3dd1e43953565236359b6d10831067c (MD5) Previous issue date: 2017-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo principal deste trabalho é apresentar detalhadamente um estudo sobre um critério, que aparece na referência Coincidence for maps of spaces with finite group action de D. L. Gonçalves, J. Jaworowski, P. L. Q. Pergher e A. Volovikov, para a existência de (H,G)-coincidências de aplicações cujo contradomínio é um CW-complexo finito Y de dimensão k e cujo domínio é um espaço X paracompacto, Hausdorff, conexo e localmente conexo por caminhos e munido de uma G-ação livre, de modo que exista um inteiro m tal que os grupos i-dimensionais de homologia de X sejam triviais nas dimensões 0<i<m e a cohomologia (m+1)-dimensional de G não seja trivial. Para a realização deste estudo foram necessários alguns resultados da teoria de cohomologia de grupos finitos, com ênfase em grupos de cohomologia periódica segundo a teoria de cohomologia de Tate, alguns resultados da teoria de fibrados e algumas noções da teoria de sequências espectrais cohomológicas. / The mais objective of this work is to present in detail a study about a criterion, which appears in the reference Coincidence for maps of spaces with finite group actions by D. L. Gonçalves, J. Jaworowski, P. L. Q. Pergher and A. Volovikov, for existence of (H,G)-coincidences of maps into a finite CW-complex Y with dimension k and whose domain is a paracompact, Hausdorff, connected and locally pathconnected space X with a free action of G, in a way that there exists an integer m such that the ith-homology group of X is trivial for 0<i<m and the (m+1)th-cohomology group of G is nontrivial. For the study of this criterion were needed some results of the theory of cohomology of finite groups, with emphasis on groups with periodic cohomology according to Tate cohomology theory, some results of the theory of fiber bundles and some notions of the theory of cohomological spectral sequences.
19

Modélisation dynamique des systèmes non-holonomes intermittents : application à la bicyclette / Dynamic modelling of intermittent non-holonomic systems : application to the bicycle

Mauny, Johan Raphaël 14 December 2018 (has links)
Cette thèse traite de la modélisation dynamique des systèmes non-holonomes intermittents et de son application à la bicyclette 3D de Whipple. Pour cela, nous nous sommes appuyés sur un ensemble d'outils en mécanique géométrique (réduction Lagrangienne et projection dans le noyau des contraintes cinématiques essentiellement). Dans un premier temps, nous avons traité le cas de la bicyclette persistante. En définissant l'espace des configurations du vélo comme un fibré principal de groupe structural SE(3), nous avons obtenu un modèle des points de contact et des contraintes exempt de toute non-linéarité associée à un paramétrage de type coordonnées généralisées. Cette formulation nous a permis d'obtenir le noyau des contraintes sous une forme symbolique sans singularité. Nous avons alors produit un modèle symbolique de la dynamique de la bicyclette persistante en utilisant la méthode de réduction par projection de sa dynamique libre dans le sous espace de ses vitesses admissibles. Cette approche étend le cadre général mis au point ces dernières années pour la locomotion bio-inspirée. Profitant de la structure de SE(3), un modèle de la bicyclette intermittente a été proposé dans le cadre d'une approche événementielle. L'adoption du modèle physique de l'impact plastique, nous a permis d'étendre la méthode de réduction par projection au cas intermittent. Nous avons alors comparé notre approche "réduite" à l'approche classiquement utilisée et avons montré qu'elles partageaient une interprétation géométrique commune. Ces outils ont finalement été appliqués à la simulation de la bicyclette intermittente afin d'illustrer la richesse de sa dynamique. / This thesis deals with the dynamic modelling of intermittent non-holonomic systems andits application to the Whipple 3D bicycle. To that end, we relied on a set of tools in geometric mechanics (mainly Lagrangian reduction and the projection in the kernel of the kinematic constraints). In the first instance, we have addressed the case of the bicycle subjected to persistent contacts. By defining the space of the bicycle configurations as a principal fibre bundle with SE(3) as structural group, we obtained a model of the contact points and of the constraints free of any non-linearities associated with a generalized coordinate type configuration. This formulation allowed us to obtain the kernel of the constraints in a symbolic form without singularity. We then produced a symbolic model of the dynamics ofthe bicycle subjected to persistent contacts using the projection reduction method of its free dynamics in the subspace of its permissible speeds. This approach extends the general framework developed in recent years for bio-inspired locomotion. Taking advantage of the structure of SE(3), a model of the intermittent bicycle was proposed as part of an event-driven approach. Moreover, the adoption ofthe physical model of plastic impact has allowed us to extend the projection reduction method to the intermittent case. We then compared our "reduced" approach to the conventional approach and showed that they shared a common geometric interpretation. These tools were finally applied to the simulation of the intermittent bicycle to illustrate its rich dynamics.
20

Effect of twist, fineness, loading rate and length on tensile behavior of multifilament yarn

Rypl, Rostislav, Vořechovský, Miroslav, Sköck-Hartmann, Britta, Chudoba, Rostislav, Gries, Thomas 03 June 2009 (has links) (PDF)
The idea underlying the present study was to apply twisting in order to introduce different levels of transverse pressure. The modified structure affected both the bonding level and the evolution of the damage in the yarn. In order to isolate this effect in a broader context, additional parameters were included in the experiment design, namely effects of loading rate, specimen length and filament diameter (directly linked to the fineness of the yarn). These factors have been studied in various contexts by several authors. Some related studies on involved factors will be briefly reviewed.

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