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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.
1

Scale model seismicity : a detailed study of deformation localisation from laboratory acoustic emission data

Graham, Caroline C. January 2010 (has links)
Acoustic emissions (AE) can provide information relating to the internal state of a deforming rock sample during laboratory testing and have been utilised to quantify damage progression for time-dependent failure modeling. However, the underlying physical mechanisms that produce AE in different materials and their evolution during the process of damage localisation are not fully understood, particularly in porous media. In order to investigate the sources of laboratory acoustic emissions, a moment tensor inversion was applied to data from triaxial compression experiments on Aue granite and Clashach sandstone. The moment tensor inversion was verified for granite, by comparison with results obtained using a more simplistic source analysis technique. In the non-porous Aue granite, AE sources exhibited a predominantly tensile behaviour in the early stages of AE activity. However, shear sources become dominant in the vicinity of the peak stress. In contrast, during deformation of the Clashach sandstone, which has a significant pre-existing porosity, AE sources are dominated by a collapse signature and generally involve a notable shear component. AE that have a predominantly shear mechanism are also a major contributor to the microscale deformation imaged by the technique, and dominate during shear localisation. A combination of correlation analysis and source analysis was used to elucidate the temporal and spatial evolution of the AE source mechanisms involved in the localisation process, as well as during a temporary hiatus in the progression to failure. The results support the concept that the cascade to failure requires the simultaneous involvement of a range of micromechanical behaviours to maintain the progression of localised damage, and eventual formation of a fault. Localisation of collapse mechanisms was not observed until the final approach to failure. Finally, AE sources produced during brittle deformation of the Clashach sandstone were characterised in detail and compared to microstructural observations representing the integrated effect of all times up to the end of the test, and including smaller structures that may have been formed insufficiently dynamically to produce AE. Equivalent focal mechanisms for these events are presented and the relative proportions of their volumetric and shear components considered. The results indicate that AE sources display a wide spectrum of micromechanical behaviour that is consistent with microstructural observations, indicating that AE mechanisms are representative of ongoing deformation processes within the sandstone. It is argued that moment tensor inversion of acoustic emissions is a powerful tool for elucidating the micromechanical evolution of damage, during the brittle deformation of rock.
2

Alternative plate deformation phenomenon for squeeze film levitation

Almurshedi, Ahmed January 2018 (has links)
This thesis deals with a theoretical and an experimental exploration of squeeze film levitation (SFL) of light objects. The investigations aimed to find the important design parameters controlling this levitation mechanism and also to suggest an alternative way to implement SFL. The study, through computer modelling and experimental validation, focused on Poisson's contraction effect for generating SFL. A finite element model (ANSYS) was verified by experimental testing of five different plate designs. Each plate was subjected to a uniaxial plain stress by an arrangement of two hard piezoelectric actuators (PZT) bonded to the bottom of the plate and driven with DC or AC voltages. It was observed that pulsation of a dimple or crest shaped elastic deformation along the longitudinal axis in the central area of the plate was created because of Poisson's contraction. This Poisson's effect generated the squeeze-film between the plate and the levitated object. The separation distance between a floating lightweight object and the plate was analysed using computational fluid dynamics (ANSYS CFX) through creation of a modelling model for the air-film entrapped between the two interacting surfaces - a typical three-dimensional fluid-solid interaction system (FSI). Additionally, the levitation distance has been experimentally measured by a Laser Sensor. A satisfactory agreement has been found between model predictions and experimental results. Two levitation systems, one based on a horn transducer (Langevin type) and the other one in the form of a plain rectangular plate made of Aluminium and firmly fastened at both ends with a surface-mounted piezoelectric actuator, were compared in this thesis. Both devices were based on SFL mechanism. Evidently, the performances of both designs were greatly influenced by the design structure and in particular by the driving plate characteristics such as plate size and geometry as well as the driving boundary conditions. To this end, physical experiments were carried out and it was found that the device utilising horn-type transducer yields better levitation performance. Ultimately, the research explained the confusion between three approaches to non-contact levitation through literature review and also pointed out some essential parameters like piezoelectric actuators location, material of the driving structure, coupled-field between the actuators and the driving structure and the fluid-solid interface that was existed between the excited plate and the levitated object.
3

Study on the thermomechanical properties and workability of Mg-based bulk metallic glasses

Chang, Yu-Chen 10 July 2008 (has links)
In the near couple years, the applications of amorphous alloys have attracted great attention due to their characteristics and future potential. This research is intended to synthesis a lighter Mg-based amorphous alloy as the imprinting materials for micro-electromechanical system (MEMS) with a high glass forming ability (GFA) and lower glass transition temperature (Tg). Also, the workability of the Mg-based metallic glasses is examined in terms of several viscous flow behaviors and parameters obtained from the thermomechanical analysis (TMA). The lighter Mg-based metallic glasses exhibit their superior glass forming ability, and can be cast into bulk metallic glasses (BMGs). Based on the thermal analysis of the Mg-Cu-Y glassy materials, the evaluation of the glass forming ability and thermal stability for searching the optimum alloy composition is conducted. By using Mg58Cu31Y11 amorphous alloy with the best composition as the micro-forming specimens, imprinting was made by hot pressing at 150oC with several applied compressive stresses to form the hexagonal micro-lens arrays. Finite element simulation using 3D Deform software is also applied to trace the microforming evolution, and to compare with the experimental observations. The results demonstrate that the imprinting is feasible and promising. On the other hand, the Mg-Cu-Gd BMGs with even better GFA than Mg-Cu-Y are explored in terms of their thermomechanical properties. Extension of this study is performed partially by Cu replacing by Ag or B for the improvement of maximum diameter and thermal stability. And the workability of these Mg-Cu-(Ag, B)-Gd metallic glasses, namely, Mg65Cu25-xAgxGd10 (x = 0, 3, 10 at %) and Mg65Cu22B3Gd10 is evaluated in terming of the thermomechanical parameters, viscous flow behavior, deformability, and the deformation model. It is found the fragility for viscous deformation would increase with the replacement of Ag or B, leading to the negative factors for the micro-forming and nano-imprinting practices. This conclusion is supported by the many extracted parameters. Thus, even the B-additive Mg based BMG has much higher hardness and Ag-additive Mg based BMG has the larger maximum rod diameter, they are more difficult to be formed, appearing as a negative factor in the micro-forming or nano-imprinting industry. The base Mg65Cu25Gd10 alloy stilly appears to be more promising than the Ag or B-containing alloys when the viscous forming is under consideration.
4

Rate Effects in Bulk Forming

Forster, James Allam 12 1900 (has links)
<p> One of the major industrial metalworking processes is extrusion and it is of technological importance to be able to estimate the loads and material flow characteristics within the deforming metal. Hot metals and superplastic materials are particularly sensitive to the speed of the operation al though it is difficult to col".sider this in an analysis of the problem. </p> <p> This thesis reviews the analytical techniques available to the engineer to determine the loads in bulk forming processes and examines the way in which rate effects have been accommodated. The upper bound method, which is an approximate analytical technique, is reviewed in detail. The concept of a tangential shear zone of constant shear strain rate is introduced and used to enable strain rate effects to be considered within the upper bound technique. The work rate across each discontinuity is shown to be a function of the material strain rate sensitivity, the shear zone width and the tangential veloc i ty change. </p> A number of tangential velocity fields are proposed for the side extrusion process. These are examined and compared by minimizing the work rate using a computer optimization technique. The optimum solution for a simple tangential velocity discontinuity field is shown to give load estimates which are within 10% of those given by the more exact slip-line field method. </p> <p> Experiments, performed by the author on the side extrusion of two materials, which have very different strain rate sensitivities, are reported in detail. A characteristic difference in the extrudate geometry for the two materials is identified and shown to be a result of the difference in the materials strain rate sensitivity index. The experimental extrusion pressures for the two materials at different ram velocities are compared with theoretical values derived using the theory developed earlier in the thesis; the correlation is good. </p> <p> The shape of the tangential discontinuity between a uniform translational and uniform rotational field is examined and shown to be a circular arc. A number of new tangential velocity discontinuity fields are presented for a variety of common metalworking processes. These fields comprise straight and circular discontinuities and represent a new type of "mixed" field which predicts the rotation of the extrudate. </p> / Thesis / Doctor of Philosophy (PhD)
5

De la pratique à la théorie : analyse de la traduction de El juguete rabioso de Roberto Arlt par Antoine Berman

Villarroel, Marina 12 1900 (has links)
« Il va sans dire que c’est l’expérience du traduire qui constitue le centre de gravité de mon rapport général à la traduction. Je ne suis traductologue que parce que je suis, primordialement, traducteur » (Berman 2001, p. 16). La théorie de la traduction d’Antoine Berman serait donc enracinée dans sa pratique. Bien que son nom soit devenu incontournable en traductologie et que ses idées aient suscité de nombreux débats, peu de chercheurs ont étudié le lien entre la théorie et la pratique de ce traductologue. Le présent mémoire tente de combler cette lacune. Au moyen d’une analyse de la traduction de El juguete rabioso de Roberto Arlt faite par les époux Berman, il explore comment la pratique et la théorie de la traduction d’Antoine Berman se sont nourries l’une de l’autre. Le premier chapitre retrace le parcours d’Antoine Berman : son travail de traducteur, ses influences, sa théorie de la traduction, l’impact de celle-ci et les critiques qui lui ont été adressées. Dans le chapitre deux, nous découvrons Roberto Arlt et son œuvre afin de bien cerner les enjeux de sa traduction. Le chapitre trois analyse, selon la méthode bermanienne, la traduction française de ce roman publiée pour la première fois en 1984. Deux éléments du texte sont mis en relief : la diversité de registres discursifs, dont les sociolectes argentins, et la richesse lexicale qui en découle. En conclusion, l’étude montre que Le jouet enragé est marqué par une certaine inhibition et une rigidité sans doute inhérentes à toute traduction-introduction. Trop attachée aux normes, cette première version restitue timidement la diversité narrative de l’original. Ainsi, on peut supposer que les préceptes de Berman, et plus exactement sa liste de « tendances déformantes » (Berman 1999) reflètent, en partie, et avant tout, les limites et les difficultés qu’il a pu rencontrer dans l’exercice de sa pratique. / “Needless to say my experience of translating constitutes the core of my general relationship with translation. I am a translation studies’ theorist because primarily I am a translator” (Berman…p. 16, my translation). Antoine Berman’s translation theory is rooted in his practice. Even though his name is irreversibly linked to the field of translation studies and his ideas have caused numerous debates, few researchers have studied the relation between his theory and practice. This thesis attempts to fill that gap through an analysis of the French translation of Roberto Arlt’s El juguete rabioso by Isabelle and Antoine Berman. It explores how Antoine Berman’s translation practice and theory feed from each other. The first chapter recounts the development of Antoine Berman: his work as a translator, his influences, his theory of translation and its impact, as well as the criticism addressed towards it. In chapter 2, we discover Roberto Arlt and his work in order to fully understand the problematic points of its translation. Following Antoine Berman’s method, chapter 3 analyses the only French translation of El juguete rabioso published in 1984. It concentrates on two particular elements of the text: the diverse discursive registers, including the use of Argentine sociolects, and their lexical richness. In conclusion, the study shows that Le jouet enragé carries the flaws (défectivité) inherent in any introductory translation. Too attached to linguistic conventions, this first version timidly recreates the arrative diversity of the original. Thus, it could be suggested that Antoine Berman’s theories, and more specifically his list of “deforming tendencies”, reflect in part, and, above all, the limits and difficulties that he encountered in the exercise of his practice.
6

Uma tradução comentada da obra The unfortunate traveller: or, the life of Jack Wilton, de Thomas Nashe / An annotated translation of The unfortunate traveller: or, the life of Jack Wilton, by Thomas Nashe

Mayer, Karina Gusen 06 August 2015 (has links)
Esta dissertação apresenta uma tradução comentada de parte do livro The Unfortunate Traveller: or, The Life of Jack Wilton, escrito por Thomas Nashe em 1594 e discute os desafios de traduzir pela primeira vez para o português esse romance picaresco escrito durante o período elisabetano. As alterações estruturais, lexicais e semânticas ocorridas na língua inglesa durante esses anos e as diferenças culturais entre a Inglaterra do século XVI e o Brasil da atualidade são algumas das dificuldades enfrentadas no processo tradutório dessa obra. O primeiro capítulo apresentará uma leitura crítica da obra, do autor e uma contextualização do romance picaresco. No segundo capítulo haverá uma explanação das duas teorias de tradução usadas nesta dissertação: as tendências deformadoras propostas por Antoine Berman (1985), que propõem identificar as variações encontradas nas traduções em relação ao texto original; e o modelo descritivo das Modalidades de Tradução elaboradas pelo Prof. Dr. Francis H. Aubert (1998, 2006), derivado do modelo pedagógico dos procedimentos técnicos da tradução (Vinay & Darbelnet, 1958, 1977). No terceiro capítulo usaremos essas duas teorias como ferramentas para análise das escolhas tradutórias adotadas e suas implicações na escrita do texto na língua de chegada. O quarto capítulo trará a tradução de 50% do livro ao lado do texto original em inglês com notas e comentários no rodapé. / This work presents an annotated translation of a part of the book The Unfortunate Traveller: or, The Life of Jack Wilton, written by Thomas Nashe in 1594 and discusses the challenges of translating for the first time into Portuguese this picaresque novel written during the Elizabethan period. Structural, lexical and semantic changes in the English language over the years and the cultural differences between the sixteenth-century England and contemporary Brazil are some of the difficulties in the translation process of this work. The first chapter will present a critical reading of the work and the author. In the second chapter there will be an explanation of the two translation theories used in this dissertation: the comparative method of deforming tendencies proposed by Antoine Berman (1985), which proposes to identify the variations found in translations from the original text. And the second, the The translation modalities descriptive model developed by Francis H. Aubert (1998, 2006), derived from the pedagogical model of the technical procedures of translation (Vinay & Darbelnet, 1958, 1977). In the third chapter these two theories will be used as tools to analyze the translation choices and its implications in writing the text in the target language. The fourth chapter will bring the translation of 50% of the book side by side with the original text in English with notes and comments in footnotes.
7

Étude traductologique des figures de la répétition sous le prisme de l'approche littérale : le Bourgeois Gentilhomme de Molière en anglais / Translatological study of the figures of repetition through the prism of the literal approach : molière's Le Bourgeois Gentilhomme in English

Ksouri, Imen 16 December 2014 (has links)
La présente étude porte sur la manière dont est abordée la répétition dans la traduction anglaise du Bourgeois gentilhomme de Molière (1670), pièce de théâtre où la répétition lexicale et syntaxique foisonne. Pour ce faire, nous faisons une analyse contrastive de neuf versions anglaises de la pièce que nous comparons à l’original ainsi que les unes aux autres. Cette analyse qui prend comme fil conducteur la théorie de Berman aussi bien d’un point de vue théorique (la traduction de la lettre) que pratique (la critique des traductions et les tendances déformantes) nous permet de dégager les grandes tendances de chacune des traductions et, de ce fait, d’approfondir et de nuancer la réflexion sur la traduction littérale, en remettant en perspective la littéralité comme la solution la plus adéquate pour le traitement de phénomènes relevant de la forme dans un discours, tels que la répétition. / This study examines the treatment of repetition in the English translations of Moliere’s play Le Bourgeois gentilhomme, a text where lexical and syntactic repetitions abound. This research is conducted by way of a contrastive analysis of nine English versions of the play that we compare to the original and to each other. Based on Berman’s principles both from a theoretical point of view (the translation of the letter) and a practical one (evaluation of translation and deforming tendencies), this analysis allows us to identify the general patterns of each translation, and thereby, deepen and nuance thinking about literal translation while reasserting the status of literalism as the most adequate solution for the handling of phenomena pertaining to the form of a given text or discourse, such as repetition.
8

Path Optimization Of Flapping Airfoils Based On Unsteady Viscous Flow Solutions

Kaya, Mustafa 01 February 2008 (has links) (PDF)
The flapping path of a single airfoil and dual airfoils in a biplane configuration is optimized for maximum thrust and/or propulsive efficiency. Unsteady, low speed viscous flows are computed using a Navier-Stokes solver in a parallel computing environment. A gradient based algorithm and Response Surface Methodology (RSM) are employed for optimization. The evaluation of gradient vector components and the design of experiments for RSM, which require unsteady solutions, are also carried out in parallel. Parallel computations are performed using Parallel Virtual Machine (PVM) library. First, a single airfoil undergoing a combined sinusoidal or non-sinusoidal pitching and plunging motion is studied. The non-sinusoidal flapping motion is described using an elliptic curve or Non-Uniform Rational B-Splines (NURBS). It is shown that the thrust generation may significantly be increased in comparison to the sinusoidal flapping motion. For a high thrust, the airfoil stays at high effective angle of attack values during the upstroke and the downstroke, and the effective pitching occurs at minimum and maximum plunge positions. Secondly, the optimization of sinusoidal and non-sinusoidal flapping paths of dual airfoils is considered. Moving and deforming overset grids are used for computations. The deforming overset grids remove the restrictions on the flapping motion, and improve the optimization results obtained earlier. At low flapping frequencies, an airfoil in a biplane configuration produces more thrust than a single airfoil. Yet, at high frequencies the airfoil in biplane configuration produces less thrust at a significantly lower efficiency than the single airfoil.
9

De la pratique à la théorie : analyse de la traduction de El juguete rabioso de Roberto Arlt par Antoine Berman

Villarroel, Marina 12 1900 (has links)
« Il va sans dire que c’est l’expérience du traduire qui constitue le centre de gravité de mon rapport général à la traduction. Je ne suis traductologue que parce que je suis, primordialement, traducteur » (Berman 2001, p. 16). La théorie de la traduction d’Antoine Berman serait donc enracinée dans sa pratique. Bien que son nom soit devenu incontournable en traductologie et que ses idées aient suscité de nombreux débats, peu de chercheurs ont étudié le lien entre la théorie et la pratique de ce traductologue. Le présent mémoire tente de combler cette lacune. Au moyen d’une analyse de la traduction de El juguete rabioso de Roberto Arlt faite par les époux Berman, il explore comment la pratique et la théorie de la traduction d’Antoine Berman se sont nourries l’une de l’autre. Le premier chapitre retrace le parcours d’Antoine Berman : son travail de traducteur, ses influences, sa théorie de la traduction, l’impact de celle-ci et les critiques qui lui ont été adressées. Dans le chapitre deux, nous découvrons Roberto Arlt et son œuvre afin de bien cerner les enjeux de sa traduction. Le chapitre trois analyse, selon la méthode bermanienne, la traduction française de ce roman publiée pour la première fois en 1984. Deux éléments du texte sont mis en relief : la diversité de registres discursifs, dont les sociolectes argentins, et la richesse lexicale qui en découle. En conclusion, l’étude montre que Le jouet enragé est marqué par une certaine inhibition et une rigidité sans doute inhérentes à toute traduction-introduction. Trop attachée aux normes, cette première version restitue timidement la diversité narrative de l’original. Ainsi, on peut supposer que les préceptes de Berman, et plus exactement sa liste de « tendances déformantes » (Berman 1999) reflètent, en partie, et avant tout, les limites et les difficultés qu’il a pu rencontrer dans l’exercice de sa pratique. / “Needless to say my experience of translating constitutes the core of my general relationship with translation. I am a translation studies’ theorist because primarily I am a translator” (Berman…p. 16, my translation). Antoine Berman’s translation theory is rooted in his practice. Even though his name is irreversibly linked to the field of translation studies and his ideas have caused numerous debates, few researchers have studied the relation between his theory and practice. This thesis attempts to fill that gap through an analysis of the French translation of Roberto Arlt’s El juguete rabioso by Isabelle and Antoine Berman. It explores how Antoine Berman’s translation practice and theory feed from each other. The first chapter recounts the development of Antoine Berman: his work as a translator, his influences, his theory of translation and its impact, as well as the criticism addressed towards it. In chapter 2, we discover Roberto Arlt and his work in order to fully understand the problematic points of its translation. Following Antoine Berman’s method, chapter 3 analyses the only French translation of El juguete rabioso published in 1984. It concentrates on two particular elements of the text: the diverse discursive registers, including the use of Argentine sociolects, and their lexical richness. In conclusion, the study shows that Le jouet enragé carries the flaws (défectivité) inherent in any introductory translation. Too attached to linguistic conventions, this first version timidly recreates the arrative diversity of the original. Thus, it could be suggested that Antoine Berman’s theories, and more specifically his list of “deforming tendencies”, reflect in part, and, above all, the limits and difficulties that he encountered in the exercise of his practice.
10

Uma tradução comentada da obra The unfortunate traveller: or, the life of Jack Wilton, de Thomas Nashe / An annotated translation of The unfortunate traveller: or, the life of Jack Wilton, by Thomas Nashe

Karina Gusen Mayer 06 August 2015 (has links)
Esta dissertação apresenta uma tradução comentada de parte do livro The Unfortunate Traveller: or, The Life of Jack Wilton, escrito por Thomas Nashe em 1594 e discute os desafios de traduzir pela primeira vez para o português esse romance picaresco escrito durante o período elisabetano. As alterações estruturais, lexicais e semânticas ocorridas na língua inglesa durante esses anos e as diferenças culturais entre a Inglaterra do século XVI e o Brasil da atualidade são algumas das dificuldades enfrentadas no processo tradutório dessa obra. O primeiro capítulo apresentará uma leitura crítica da obra, do autor e uma contextualização do romance picaresco. No segundo capítulo haverá uma explanação das duas teorias de tradução usadas nesta dissertação: as tendências deformadoras propostas por Antoine Berman (1985), que propõem identificar as variações encontradas nas traduções em relação ao texto original; e o modelo descritivo das Modalidades de Tradução elaboradas pelo Prof. Dr. Francis H. Aubert (1998, 2006), derivado do modelo pedagógico dos procedimentos técnicos da tradução (Vinay & Darbelnet, 1958, 1977). No terceiro capítulo usaremos essas duas teorias como ferramentas para análise das escolhas tradutórias adotadas e suas implicações na escrita do texto na língua de chegada. O quarto capítulo trará a tradução de 50% do livro ao lado do texto original em inglês com notas e comentários no rodapé. / This work presents an annotated translation of a part of the book The Unfortunate Traveller: or, The Life of Jack Wilton, written by Thomas Nashe in 1594 and discusses the challenges of translating for the first time into Portuguese this picaresque novel written during the Elizabethan period. Structural, lexical and semantic changes in the English language over the years and the cultural differences between the sixteenth-century England and contemporary Brazil are some of the difficulties in the translation process of this work. The first chapter will present a critical reading of the work and the author. In the second chapter there will be an explanation of the two translation theories used in this dissertation: the comparative method of deforming tendencies proposed by Antoine Berman (1985), which proposes to identify the variations found in translations from the original text. And the second, the The translation modalities descriptive model developed by Francis H. Aubert (1998, 2006), derived from the pedagogical model of the technical procedures of translation (Vinay & Darbelnet, 1958, 1977). In the third chapter these two theories will be used as tools to analyze the translation choices and its implications in writing the text in the target language. The fourth chapter will bring the translation of 50% of the book side by side with the original text in English with notes and comments in footnotes.

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