• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 55
  • 22
  • 7
  • 6
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 131
  • 57
  • 45
  • 23
  • 19
  • 17
  • 16
  • 15
  • 15
  • 13
  • 12
  • 11
  • 9
  • 9
  • 8
  • 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.
81

Avaliação da viscosidade dinâmica de materiais implantáveis em pregas vocais: comparação entre camada superficial de fáscia temporal, camada profunda de fáscia temporal e gordura abdominal / Evaluation of dynamic viscosity of implantable materials into vocal folds: comparison among superficial layer of temporalis fascia, deep layer of temporalis fascia and abdominal fat

Wiikmann, Christian 25 February 2010 (has links)
OBJETIVO: Comparar a viscosidade dinâmica da camada superficial da fáscia temporal com a de outros tecidos biológicos tradicionalmente utilizados em implantes de pregas vocais para o tratamento de rigidez de pregas vocais. DESENHO DO ESTUDO: Experimental. MÉTODO: Amostras de camada superficial da fáscia temporal, camada profunda da fáscia temporal e gordura abdominal de 12 cadáveres são submetidas a medição de viscosidade dinâmica. RESUTADOS: A viscosidade dinâmica das diferentes amostras apresenta-se na seguinte ordem crescente: camada superficial da fáscia temporal, camada profunda da fáscia temporal e gordura abdominal. Observa-se diferença estatística na comparação entre todas as amostras. DISCUSSÃO: Quanto maior for a viscosidade da mucosa da prega vocal, maior é a pressão subglótica necessária para se iniciar a fonação. Dessa maneira, um bom material implantável em lâmina própria de prega vocal deve ter baixa viscosidade. Por esse parâmetro, a camada superficial da fáscia temporal é um material promissor para implantação em pregas vocais. CONCLUSÃO: A viscosidade dinâmica da camada superficial da fáscia temporal é menor que a da camada profunda da fáscia temporal e que a da gordura abdominal. / OBJECTIVE: To compare the dynamic viscosity of superficial layer of temporalis fascia with that of other biological tissues traditionally used for vocal fold implants to treat vocal fold rigidity. STUDY DESIGN: Experimental. METHOD: Measurement of dynamic viscosity of samples of superficial layer of temporalis fascia, deep layer of temporalis fascia and abdominal fat of 12 cadavers are performed. RESULTS: Dynamic viscosity values of the different samples are presented in the following increasing order: superficial layer of temporalis fascia, deep layer of temporalis fascia and abdominal fat. There is statistical difference among all the samples. CONCLUSION: Dynamic viscosity of superficial layer of temporalis fascia is lower than the ones of deep layer of temporalis fascia and abdominal fat.
82

Tectonic History and Present-Day Deformation in the Zagros Fold-Thrust Belt

Hessami, Khaled January 2002 (has links)
<p>This thesis uses various approaches such as observation of satellite images, field investigations, analogue modeling and GPS measurements to constrain deformation of the basement and sedimentary cover of the Zagros fold-thrust belt in time and space.</p><p>Focal mechanism solutions of most earthquakes indicate that deformation in the Zagros basement is due to shortening and thickening through numerous thrust faults. However, observations of strike-slip faulting recognized on satellite images imply that N-S trending faults in the Zagros, inherited from Pan-African basement, rotated about vertical axes to accommodate the convergence between Arabia and central Iran.</p><p>Field studies suggest that southwestward advance of the Zagros front has been recorded by syn-sedimentary structures. These structures indicate that deformation started as early as end Eocene in the northeast of the Simply Folded Zone and propagated progressively to the southwest. The deformation front drove the foreland basin to its present position along the Persian Gulf and Mesopotamia. </p><p>Scaled analogue models suggest that the seismicity due to orogenic shortening depends largely on the friction between the cover and its basement. Models show that fold-thrust belts with low tapers shortened above low friction ductile decollements involve several long-lived thrust faults generating low to moderate earthquakes over wide areas at the same time. By contrast, earthquakes with larger magnitudes are expected to occur along a few short-lived thrust ramps in fold-thrust belts with larger tapers shortened above high-friction decollments.</p><p>GPS-derived velocities across and along the Zagros suggest that only about one third (10 ± 3 mm/yr) of the current convergence between Arabia and Eurasia is accommodated within the Zagros by thickening to the east of the Kazerun Fault and thickening and lateral movement to the west. The remaining (21 ± 3 mm/yr) is transferred beyond the Zagros suture to central Iran and the northern Iranian mountains.</p>
83

Tectonic History and Present-Day Deformation in the Zagros Fold-Thrust Belt

Hessami, Khaled January 2002 (has links)
This thesis uses various approaches such as observation of satellite images, field investigations, analogue modeling and GPS measurements to constrain deformation of the basement and sedimentary cover of the Zagros fold-thrust belt in time and space. Focal mechanism solutions of most earthquakes indicate that deformation in the Zagros basement is due to shortening and thickening through numerous thrust faults. However, observations of strike-slip faulting recognized on satellite images imply that N-S trending faults in the Zagros, inherited from Pan-African basement, rotated about vertical axes to accommodate the convergence between Arabia and central Iran. Field studies suggest that southwestward advance of the Zagros front has been recorded by syn-sedimentary structures. These structures indicate that deformation started as early as end Eocene in the northeast of the Simply Folded Zone and propagated progressively to the southwest. The deformation front drove the foreland basin to its present position along the Persian Gulf and Mesopotamia. Scaled analogue models suggest that the seismicity due to orogenic shortening depends largely on the friction between the cover and its basement. Models show that fold-thrust belts with low tapers shortened above low friction ductile decollements involve several long-lived thrust faults generating low to moderate earthquakes over wide areas at the same time. By contrast, earthquakes with larger magnitudes are expected to occur along a few short-lived thrust ramps in fold-thrust belts with larger tapers shortened above high-friction decollments. GPS-derived velocities across and along the Zagros suggest that only about one third (10 ± 3 mm/yr) of the current convergence between Arabia and Eurasia is accommodated within the Zagros by thickening to the east of the Kazerun Fault and thickening and lateral movement to the west. The remaining (21 ± 3 mm/yr) is transferred beyond the Zagros suture to central Iran and the northern Iranian mountains.
84

Η δομή του τεκτονικού καλύμματος των κυανοσχιστόλιθων στην ευρύτερη περιοχή Χάρτες - Άνδρου

Καπιζιώνης, Παναγιώτης 12 June 2015 (has links)
Μια τεκτονική και δομική ανάλυση του Κυκλαδικού καλύμματος των κυανοσχιστόλιθων [CBU] και μια επιπλέον προσέγγιση στην μεταμορφική και παραμορφωτική του εξέλιξη. Περιλαμβάνεται επίσης ένας νεότερος, πιο περιεκτικός γεωλογικός χάρτης. / A tectonic and structural analysis of the cyclades blueschist unit [CBU] and a further look into its metamorphic and deformational evolution. A new, more comprehensive geological map is also included.
85

Use of nanocellulose for security paper / Utilisation des nanocelluloses pour des papiers sécurité

Desmaisons, Johanna 14 September 2018 (has links)
L’originalité de ce travail est d’étudier la contribution des nanocelluloses pour limiter deux défauts courant dans les papiers sécurités: le froissage et les “cornes”, où plis qui se manifestent dans les angles des papiers. Ces défauts sont principalement causés par une manipulation quotidienne de ces papiers à haute valeur ajoutée, et sont responsables d’une perte en qualité visuelle et mécanique ainsi que de troubles économiques. Les nanocellulose peuvent être divisées en deux différentes familles de matériaux : les nanofibrilles de celluloses (NFCs) et les nanocristaux de cellulose (NCCs). Les NFCs sont longues et flexibles et peuvent facilement s’enchevêtrer pour former un réseau cohésif maintenu par de nombreuses liaisons hydrogènes. Les NCCs sont des matériaux petits et rigides, et leurs impressionantes propriétés mécaniques font d’eux des candidats intéressants pour être utilisés en renfort de polymère. Dans cette étude, deux stratégies sont proposées pour incorporer ces deux types de nanocellulose dans la fabrication du papier sécurité. Premièrement, il est question d’introduire une couche de NFCs à l’intérieur du papier afin d’augmenter la résistance de ce papier au froissage. Ensuite, il est question d’imprégner ce papier avec de l’alcool polyvinylique renforcé par des NCCs afin d’augmenter la résistance aux cornes. Enfin, ces approches sont testées à l’échelle pilote et industrielle. / The original feature of this work is the use of nanocellulose for limiting two security paper defects: corner folds, also called “dog-ears”, and crumpling. These defects, caused principally by daily handling of these high added value documents, are responsible for a decrease of paper visual and mechanical quality and constitute an economic loss. Nanocellulose can be divided into two different families: cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). CNFs are long and flexible materials with the ability to entangle and form a network strongly maintained by hydrogen bonds. CNCs are short and rigid materials whose outstanding mechanical properties make them good candidates for reinforcement in a polymer matrix. In this study, two strategies are proposed to incorporate these two kinds of nanocellulose in the security paper process. First, it is question to introduce a CNF layer within the paper substrate in order to increase the paper crumpling resistance. Then, it is question to impregnate the paper with CNCs-reinforced polyvinyl alcohol (PVOH) in order to increase the dog-ears resistance. Finally, these approaches are tested at pilot and industrial scales.
86

Observation, modélisation et simulation des vibrations des maquettes de plis vocaux : applications à des configurations pathologiques / Observation, modelling and simulation of the vibrations of a vocal folds replica with applications to pathological configurations

Hermant, Nicolas 09 October 2014 (has links)
Les travaux de cette thèse portent sur la compréhension des phénomènes physiques sous-jacents à la production normale ou pathologique de la voix. Certaines formes de pathologies pouvant concerner des affections structurelles des cordes vocales (polypes, paralysie, ...) et altérer de façon plus ou moins conséquente la mise en vibration des cordes vocales. Une partie de ces travaux porte ainsi sur l'observation expérimentale de la production de parole pathologique, grâce notamment à la mise au point d'une maquette auto-oscillante de cordes vocales artificielles. Celle-ci reprend la structure de latex remplie d'eau sous pressions des maquettes déjà développées au Gipsa-lab mais permet une plus grande indépendance des paramètres de contrôle. Un accent particulier des manipulations expérimentales est également porté sur la caractérisation mécanique des structures vibrantes, dont la connaissance est indispensable à la reproductibilité et la répétabilité des mesures ultérieures sur la maquette, ainsi qu'à l'analyse des résultats expérimentaux avec couplage aéroacoustique et la validation de modèles numériques associés.D'un côté, un calcul du comportement vibratoire des maquettes basée sur une méthode éléments finis a été mise oeuvre. Le modèle numérique développé utilise ainsi une formulation du couplage hydro-élastique entre le latex et l'eau qui constituent les maquettes et offre la possibilité de prendre en compte les grandes déformations et les pré-contraintes liées au gonflement du latex soumis à une forte pression d'eau. Finalement, un modèle d'écoulement glottique couplé à un modèle mécanique distribué de type "masse-raideur" a été utilisé et étendu pour simuler des comportements pathologiques tels que des asymétries (entre les deux cordes vocales et au sein d'une corde) ou la présence d'une masse ajoutée (kyste, polype). Un procédure d'optimisation de ce modèle sur une configuration expérimentale de référence permet alors de comparer les calculs aux observations des seuils d'oscillation sur les maquettes en présence d'une masse ajoutée. / My PhD work has focused on understanding physical phenomena related to speech production in healthy and pathological conditions. Some pathologies affect the structure of the vocal folds which could lead to a more or less substantial alteration of their vibrations. Part of this work is experimental modeling of speech production applied to pathologies, with the development of a self-oscillating vocal fold replica. This replica is made of water-filled latex, such as have already been developed at Gipsa-lab, but it allows a larger independence within its control parameters and it can be used to reproduce pathological conditions. A particular interest is brought to mechanical characterization of these vibrating structures. This characterization is of primary importance when it comes to repeatability and reproducibility of measurements, as for the analysis of experimental results with aeroacoustic coupling and the validation and improvements of corresponding numerical models.Simulations of the vocal fold vibrating behavior based on the finite element method have been developed. The model uses a formulation of the hydro-elastic coupling between the latex and the water which the replica is made of. It also offers the possibility to take into account the large deformations and the prestress within the latex induced by water pressure. Another numerical approach is made using a theoretical laryngeal flow model coupled with a distributed mass-spring model and a set of resonators. Calculations of the dynamical system stability offer the possibility for comparisons with the experimental setup through a finite set of parameters. This model is adapted to simulate pathological conditions such as asymmetries and the presence of growths (cysts, polyps). Finally, an optimization calculation of this model on an experimental reference configuration of the replica allows us to compare the calculations with the measurements on this replica with the presence of a polyp.
87

O papel das estruturas litológicas e tectônicas na evolução da rede hidrográfica da Região Serrana do Espírito Santo: o caso da bacia hidrográfica do Rio Benevente / The role of lithological and tectonic structures in the evolution of the river system in the mountainous region of the Espírito Santo: the case of river basin Benevente

Roberto José Hezer Moreira Vervloet 06 August 2014 (has links)
O papel da litologia e da organização tectônica Proterozóica para entendimento da gênese do relevo, em termos de erosão diferencial, tem sido relativamente negligenciado nos últimos decênios em favor de linhas de explicação baseadas nas mudanças paleoclimáticas, tectônica moderna, e geoquímica de superfície. Fato que tem permitido a formação de modelos explicativos fechados sobre a gênese e dinâmica do relevo. Entretanto, em áreas de embasamento cristalino a organização tectônica e a diversidade composicional químico-mineralógica das rochas auxilia fortemente o entendimento do papel da erosão diferencial, na explicação da diversidade de compartimentos geomórficos. A organização tectônica das rochas, através de sistemas de falhas e dobras de fundo (estudados na década de 1950 por Francis Ruellan), tem papel fundamental no entendimento dos processos de erosão diferencial responsável pela diversidade de compartimentos geomórficos. Neste sentido, este trabalho procura provar, através do método da Associação e Indeterminação Geomorfológica de Leopold e Langbein (1970), que a Região Serrana do Espírito Santo, e, em especial, a da bacia hidrográfica do Rio Benevente é resultante da erosão diferencial sobre rochas de rica diversidade químico-mineralógica, organizada por meio de dobras de fundo e sistemas de falhas transcorrentes conjugadas. Para realização desta investigação foi elaborado uma proposta de cartografia hidrogeomorfológica para pesquisa de bacias hidrográficas, estudando-se a evolução dos perfis fluviais longitudinais, perfis morfogeológicos, estruturas tectônicas e composição químico-mineralógica das unidades litológicas associado a compartimentação morfológica do relevo. Tudo fundamentado no método escolhido. O que certamente parece ser uma coisa óbvia, no entanto, evidencia a atuação de um verdadeiro sistema de dissecação fluvial, associado ao rebaixamento de níveis de base (knickzonas) que evoluem conforme o mergulho da foliação metamórfica dos flancos das dobras e da zona de dano associado às falhas. A conclusão que se chega é a de que o relevo da bacia do Rio Benevente, e por sua vez da Região Serrana do Estado, configura-se como compartimentos geomórficos residuais resultantes da evolução de knickzonas fluviais associadas à organização tectônica das dobras de fundo responsáveis pela gênese de níveis diferenciais de resistência litológica e de distribuição espacial das falhas e fraturas. A composição das unidades litológicas também influencia, fortemente, a compartimentação do relevo, estando o nível de convexização dos relevos e a dissecação na forte dependência do grau de participação dos minerais do grupo dos plagioclásios, anfibólios e piroxênios na constituição litológica das litoestruturas / The role of lithology and Proterozoic tectonic organization for understanding the genesis of relief in terms of differential erosion, has been relatively neglected in recent decades in boon of lines of explanation based on paleoclimatic changes, modern tectonics, and geochemistry. This fact has allowed the formation of \"closed\" on the genesis and dynamics of relief explanatory models. However, in sites of crystalline basement tectonics organization and compositional diversity chemical-mineralogical Rocks strongly supports the understanding of the role of differential erosion, in explaining the diversity of geomorphic compartments. The tectonic organization of the rocks through system failure and bottom folds (studied in the 1950s by Francis Ruellan) plays a fundamental role in understanding the processes of differential erosion responsible for the diversity of geomorphic compartments. In this sense, this work seeks to prove, by the method of the Association and Indeterminacy Geomorphological Leopold and Langbein (1970), the mountainous region of the Espírito Santo, and in special the river basin Benevente is the result of differential erosion of rocks rich chemical-mineralogical diversity, organized by folds background and strike-slip fault systems combined. To carry out this research hydrogeomorphological a proposed mapping is designed to survey watershed studying the evolution of longitudinal river profiles, profiles morphogeologicals, tectonic structures and chemical-mineralogical composition of rock units associated with morphological partitioning of relief. All based on the method chosen. This certainly seems like an obvious thing, however, highlights the work of a true system of river dissection, associated with the lowering of baseline levels (knickzones) that evolve according to the metamorphic foliation dipping flanks of the folds and the damage zone associated with the fault. The conclusion reached is that the relief Benevente River basin, and in turn the mountainous region of the state, appears as residual geomorphic compartments resulting from the evolution of river knickzonas associated with the organization of tectonic folds background responsible for the genesis of differential levels of lithologic resistance and spatial distribution of faults and fractures. The composition of the lithological units also influences strongly the partitioning of relief, being the level of reliefs and round dissecting the strong dependence of the degree of participation of the group of the minerals plagioclase amphibole and pyroxene in the lithological constitution of lithostructurals
88

Avaliação da viscosidade dinâmica de materiais implantáveis em pregas vocais: comparação entre camada superficial de fáscia temporal, camada profunda de fáscia temporal e gordura abdominal / Evaluation of dynamic viscosity of implantable materials into vocal folds: comparison among superficial layer of temporalis fascia, deep layer of temporalis fascia and abdominal fat

Christian Wiikmann 25 February 2010 (has links)
OBJETIVO: Comparar a viscosidade dinâmica da camada superficial da fáscia temporal com a de outros tecidos biológicos tradicionalmente utilizados em implantes de pregas vocais para o tratamento de rigidez de pregas vocais. DESENHO DO ESTUDO: Experimental. MÉTODO: Amostras de camada superficial da fáscia temporal, camada profunda da fáscia temporal e gordura abdominal de 12 cadáveres são submetidas a medição de viscosidade dinâmica. RESUTADOS: A viscosidade dinâmica das diferentes amostras apresenta-se na seguinte ordem crescente: camada superficial da fáscia temporal, camada profunda da fáscia temporal e gordura abdominal. Observa-se diferença estatística na comparação entre todas as amostras. DISCUSSÃO: Quanto maior for a viscosidade da mucosa da prega vocal, maior é a pressão subglótica necessária para se iniciar a fonação. Dessa maneira, um bom material implantável em lâmina própria de prega vocal deve ter baixa viscosidade. Por esse parâmetro, a camada superficial da fáscia temporal é um material promissor para implantação em pregas vocais. CONCLUSÃO: A viscosidade dinâmica da camada superficial da fáscia temporal é menor que a da camada profunda da fáscia temporal e que a da gordura abdominal. / OBJECTIVE: To compare the dynamic viscosity of superficial layer of temporalis fascia with that of other biological tissues traditionally used for vocal fold implants to treat vocal fold rigidity. STUDY DESIGN: Experimental. METHOD: Measurement of dynamic viscosity of samples of superficial layer of temporalis fascia, deep layer of temporalis fascia and abdominal fat of 12 cadavers are performed. RESULTS: Dynamic viscosity values of the different samples are presented in the following increasing order: superficial layer of temporalis fascia, deep layer of temporalis fascia and abdominal fat. There is statistical difference among all the samples. CONCLUSION: Dynamic viscosity of superficial layer of temporalis fascia is lower than the ones of deep layer of temporalis fascia and abdominal fat.
89

A structural study of Witteberg group rocks (Cape supergroup) in the Cape fold belt, Steytlerville district, Eastern Cape

Brunsdon, Gideon January 2006 (has links)
A structural study of Witteberg Group Rocks was conducted along the Soutkloof River, approximately 14 km east of Steytlerville, Eastern Cape Province of South Africa. Here a north to south geotraverse was studied in an attempt at unravelling the structural geology of the rocks belonging to the Upper Devonian to Lower Carboniferous Witteberg Group (Upper Cape Supergroup). These rocks are mostly arenaceous and include quartzite, sandstone, siltstone and shale which have been folded, faulted and metamorphosed. Thrust, normal and strike-slip faulting occur in the area. Shallow south-dipping low-angle thrust fault planes are displaced by steep south-dipping thrust planes and subordinate north-dipping backthrusts. Displacement along thrust planes is predominantly northwards. Steeply dipping thrust fault planes are often reactivated as east-west striking normal faults. Strike-slip faulting postdates all observed structural features and displaces normal and thrust fault planes. Open to tight folds are present and are mostly northvergent and often steepened or truncated by steep south-dipping thrust fault planes. South-vergent folds are related to backthrusting and post-fold faulting. The study has revealed that the current geological map and the local stratigraphy were compiled without recognising major structural features such as thrust, normal and strike-slip faulting and their (the map and currently accepted stratigraphy) validity are therefore questioned. The presence of extensive faulting suggests that the conventional stratigraphic interpretation of the Witteberg Group should be revised.
90

A study of the structural geology of the Witteberg Group and lowermost Karoo Supergroup, Darlington Dam, Jansenville District, Eastern Cape

Goossens, Angelique Emily Maria January 2003 (has links)
A number of outcrops of the Witteberg Group and lowermost Karoo Supergroup rocks were studied in the area south of the Darlington Dam, Jansenville District, with the aim of documenting structural characteristics of the area. All lithologies are folded with fold styles varying from gentle to near isoclinal (based on interlimb angle). Fold axes are either sub-horizontal or plunging at gentle to moderate angles whereas axial planes dip gently to vertically (predominantly steep to sub-vertical). Folds verge predominantly towards the north but where southward verging they are associated with faulting or strongly folded areas. Folds plunge gently to the east-southeast and west-northwest. The area consists of a large anticlinorium with both first and second order folds occurring. Eastwest striking faults occur in the study area and are classified as normal, reverse and thrust faults. A study of the joint sets shows that there are four dominant joint directions, namely 18o, 33o, 97o and 107o (in order from least to most important). An interpretation of the tectonic history is presented in which the relationships between faults and folds show that faults formed during and after folding. Folding, and reverse and thrust faulting, occurred during the compressional events that formed the Cape Fold Belt, whereas the normal faults formed during the relaxation of these compressional forces or during the break-up of Gondwana.

Page generated in 0.0433 seconds