Dissertations / Theses on the topic 'Graphite Technique'
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Kandah, Munther. "Droplets generation mechanisms by graphite cathodes in the vacuum arc deposition technique." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69702.
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The most severe problem for the vacuum arc deposition (VAD) technique is the formation of micron-size particles on the films. These particles degrade the films' properties. The present work studied the generation mechanisms and characteristics of the droplets that are produced in the carbon films deposited by vacuum arc technique. To achieve a better control of the generation mechanism of these droplets, the effect of the arc current, arc duration time, cathode spot temperature and distance between cathode and substrate on the size and population of the micro-droplets are studied.The micro-droplets are in the range of 0.3 $ mu$m to 2 $ mu$m in diameter, and have a graphite structure. The most probable origin for these particles are the cathode. The size and population of these particles are directly proportional to the cathode spot temperature (i.e., to the arc current and/or arc duration time), and inversely proportional to the distance between the cathode and the substrate. The droplet production is mainly due to the heating effect.
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Ogden, Andrea L. "The development and evaluation of an alternative powder prepregging technique for use with larc-tpi/graphite composites." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10222009-125042/.
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Elmabrouk, Omar Mustafa. "An Investigation Of Compacted Graphite Cast Iron Production By Means Of Thermal Analysis Technique And Other Process Control Windows." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608096/index.pdf.
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ABSTRACT
AN INVESTIGATION OF COMPACTED GRAPHITE IRON PRODUCTION BY MEANS OF THERMAL ANALYSIS TECHNIQUE AND OTHER PROCESS CONTROL WINDOWS
El-mabrouk, Omar
PhD, Metallurgical and Material Engineering Department
Supervisor: Prof. Dr. Ali Kalkanli
January 2007, 123 pages
Compacted graphite irons have been proved valuable in many applications such as exhaust manifolds, hydraulic valves, and diesel engine blocks, the process of producing compacted graphite irons is not a straight forward process because of its narrow processing windows and its high sensitivity to the section thickness, treatment reaction time, pouring temperatures and charge composition.
In this thesis, compacted graphite was produced with minimum variations through all section thickness and the effect of Mg/S ratio, section thickness, and treatment agents on the graphite morphology, electrical resistivity property and fracture strength at high temperatures was investigated.
The range of Mg/S ratio and the section thickness was from 2/3 to 7/1 and 5 mm to 40 mm respectively. FeSiMg and FeSiMg cermish metal were used as a treatment agent.
Optical metallographic method was implemented to investigate the graphite
morphology change. For being a distinguishable characteristic for compacted graphite iron over ductile iron, thermal conductivity changes at high temperatures ranging from room temperature to 500 0C was examined by a suitable electrical setup in the manner of electrical conductivity changes by measuring the electrical resistance.
On the other hand, due to the higher values of mechanical properties of compacted graphite iron over those of gray iron, tensile strength was also examined by means of tensile test.
The relation between the compacted graphite shape and the alloy properties such as fracture strength and thermal conductivity was investigated. The most important controlling parameters to produce compacted graphite are Mg/S ratio and oxygen activity. The relation between these parameters with both fracture strength and thermal conductivity was established by means of multiple regression analysis technique.
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Chen, Zhichao. "Fabrication and research of 3D complex scaffolds for bone tissue engineering based on extrusion-deposition technique." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/27522.
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Fabrication of scaffold is the key for bone tissue engineering, which is commonly regarded as the most potential route for repairing bone defects. Previously, porous ceramic scaffolds were fabricated through a variety of traditional methods, like moulding and casting, but most of them cannot produce customised tissue-engineered scaffolds. Therefore, 3D printing methods are gaining more attention and are currently being explored and developed to make scaffolds with acceptable biocompatibility. With the considerable development of bone tissue engineering, the bioactivity of scaffolds is becoming increasingly demanded, which leads to new methods and techniques to produce highly biomimetic bone scaffolds. In this study, a new fabrication process to optimise the structures of scaffolds was developed, and intensive researches were performed on the porous scaffolds to confirm their advantages in biological performance. Specifically, by combination of motor assisted extrusion deposition and gas-foaming (graphite as the porogen) technique, hierarchically porous scaffolds with improved microstructures, i.e. multi-scaled pores from nanometre to millimetre (nm-μm-mm), was successfully developed. In this thesis, the optimal content of porogen for scaffolds was studied in terms of compressive strength and in-rod porosities. The most concerned physicochemical properties of scaffolds were carefully examined and the results revealed that such scaffolds exhibit excellent physicochemical properties owing to hierarchically porous structures. Due to additional in-rod micropores and increased specific surface area, along with better hydrophilicity, hierarchically porous scaffolds exerted complete superiority in biological activity, including promoting cellular proliferation of osteoblasts, adhesion and spreading status, as well as the ability to induce cellular differentiation.
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Rosie, Kathryn A. "A method for in situ SEM fracture studies of brittle materials using the double torsion technique : application to nuclear graphite." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11099.
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This work concerned the design and development of a miniature double torsion (DT) testing rig, for use inside the chamber of a scanning electron microscope, to perform in situ loading studies of brittle materials using the DT fracture mechanics specimen. The in situ performance of the system inside the SEM was highly satisfactory, while still providing free rotation of the attached stepper motor. Crack growth rates of down to 19nm/s were directly observed in PMMA specimens. It was concluded that the technique displayed merit in its ability to contribute to the knowledge base of slow cracking and damage development in brittle materials, with the advantage being that the gearing ratios of the current device resulted in slower specimen loading rates, which were more controlled, than reported previously.
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Omidvar, Hamid. "Films composites de nickel et de cuivre à base de graphite et PTFE, élaborés par la technique de dépôt chimique dynamique." Ecully, Ecole centrale de Lyon, 2006. http://bibli.ec-lyon.fr/exl-doc/TH_T2037_homidvar.pdf.
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Le procédé de dépôt chimique dynamique est une technique nouvelle qui consiste à métalliser un substrat en projetant simultanément par un aérosol, 2 phases aqueuses dispersées ; l’une contenant un réducteur l’autre un ou plusieurs sels métalliques. Le mélange de ces deux solutions forme un film liquide thermodynamiquement instable. La réaction d’oxydo réduction se déclenche alors à la surface du substrat. Des films de nickel-bore ou de cuivre sont ainsi réalisés, à température ambiante. Ce travail montre la faisabilité d’élaborer par cette technique, des films composites de NiB, NiBP et de cuivre incorporant des micro ou nano particules de graphite ou de PTFE. Les résultats présentés dans ce mémoire concernent d’une part, les caractéristiques d’élaboration (composition des solutions, cinétique de croissance est de 6µmh-1…) de films composites NiB avec graphite ou PTFE, de ternaire NiBP avec graphite ou PTFE, et des films de cuivre-graphite et cuivre-PTFE. D’autre part, nous présentons les résultats concernant les taux d’incorporation des particules dans les matrices métalliques et qui peuvent atteindre, pour le graphite et le PTFE, respectivement, en moyenne 12% et 24%. Ces films fonctionnels possèdent des coefficients de frottement de l’ordre de 0. 1. Avec des films minces de 2µm d’épaisseur, il est possible de réaliser pour les films composites NiB et NiBP, des lubrifiants solides et,dans le cas d’un film composite de cuivre, un film fonctionnel anti-usureThe technique of dynamic chemical plating is a new method which consists in direct metallization of a substrate. This technique is based on projection of a reducing agent and of a metal salts at the same time but separately onto a conductor or non-conductor substrate. Thus a very thin liquid film is formed and is adsorbed on the surface. This film, containing the active species, is also thermodynamically unstable which means that the oxidation-reduction reaction will occur spontaneously onto the substrate. The NiB and the Copper dynamic deposition were elaborated at room temperature. This work consists of the realization and caracterization of Ni and Cu composite coatings by this technique. This research outlines the development of the codeposition of micro or nano particles of graphite or PTFE in the NiB, NiBP and Cu matrix. The deposition rate under the optimum operating conditions is approximately 6 µmh-1, while the amount of the graphite and PTFE codeposited are about 12% and 24%, respectively. The coefficient of friction of these composites was determined by about 0. 1. With regard to the low coefficient of friction, it is possible to realize the thin films of NiB and NiBP composite with the thickness of 2µm for the applications of the solid lubricants on the one hand and the copper composite coating in order to the anti-wear functional films on the other hand
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Sabourdy, Claire. "Exploitation d'une technique d'analyse électrochimique, la voltampérométrie cyclique sur électrode à poudre de graphite, pour la détection de composés électroactifs normaux ou pathologiques dans les liquides biologiques." Paris 12, 1992. http://www.theses.fr/1992PA120032.
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La voltammetrie cyclique sur electrode a poudre de graphite, ou micro-electrolyse capillaire repetitive, permet de reveler en une seule operation et sans separation prealable un nombre important de composes electroactifs, principalement aromatiques, excretes dans les liquides biologiques. Les traces obtenus se presentent sous la forme d'une succession de pics dont les potentiels et amplitudes sont caracteristiques de la composition du milieu analyse. L'etude du comportement electrochimique de plus de soixante composes phenoliques, indoliques, puriques ou pteridiniques d'interet biologique pris separement en milieu electrolytique de fond, completee par celle de l'effet d'ajouts doses de ces composes aux liquides biologiques consideres a permis d'affiner et de completer l'identification de la plupart des pics presents sur les traces voltamperometriques releves a partir d'echantillons d'urines reputees normales ou de liquide cephalo-rachidien. Des modifications des traces ainsi definis apparaissent lors de l'excretion de medicaments aromatiques varies, de leurs catabolites, ou de composes endogenes anormaux caracteristiques de certaines pathologies. La methode analytique a ete exploitee en cancerologie, pour le suivi de l'excretion urinaire de l'acide folinique et de son principal metabolite, l'acide 5-methyltetrahydrofolique, apres administration orale ou intraveineuse de la substance pharmaceutique. Elle a egalement permis la detection d'un compose endogene nephrotoxique, la 2,8-dihydroxyadenine, excrete massivement dans les urines d'un patient au cours d'une cure de chimiotherapie comportant des derives du platine. L'emploi de cette technique a egalement permis la mise en evidence d'un marqueur urinaire non encore identifie, commun aux demences degeneratives humaines (demence de type alzheimer, demence mixte et maladie de pick) et aux encephalopathies spongiformes humaines (maladie de creutzfeldt-jakob) et animales (tremblante du mouton et encephalopathie spongiforme bovine)
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Barabanova, Liudmyla. "Frictional Anisotropy of Graphene and Graphene Based Materials." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461941753.
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Glad, Xavier. "Synthèse et étude de la formation de pyramides et cônes de graphite par gravure en plasma radiofréquence argon/hydrogène." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0127/document.
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Le carbone présente de nombreuses formes allotropiques, dont le graphite, qui possède une large variété de formes géométriques d'intérêt pour l'industrie. Ce travail de thèse a permis la synthèse d'une nouvelle de ces formes: les pyramides hexagonales. Ces cristaux submicroniques sont créés à partir de substrats de graphite par gravure en plasma radiofréquence (rf) Ar/H2 basse pression. Pour comprendre la formation de ces nouveaux cristaux, la caractérisation des plasmas a été effectuée par sondes de Langmuir et absorption résonante laser afin de vérifier la température de surface et d'estimer les flux et énergies des ions. L'évolution temporelle de la gravure a été directement observée en microscopie électronique à balayage (MEB). La gravure chimique (Ar/H2) a formé des cônes de graphite à hélices dont les paramètres cristallins et une amorphisation de surface, due à l'hydrogène, ont été révélés par microscopie électronique en transmission (MET). La vitesse de gravure et l'état de surface montrent, en fonction du mélange, une zone de transition caractérisée par l'absence de structures. La gravure physique (Ar pur) conduit à la création des pyramides hexagonales de graphite. Un modèle de formation de ces cristaux a pu être proposé grâce à une bonne connaissance des différentes conditions plasma et des études poussées de microscopies électroniques sur plusieurs types de substrats. Les analyses MET haute résolution ont montré des boucles fermant les plans de bord du cristal et liées à sa formation. Nous avons également maîtrisé l'état de surface des substrats de graphite hautement orienté (HOPG) en créant une densité homogène de pyramides dont la taille peut être contrôléeCarbon occurs as many different allotropic forms. One in particular, graphite, exhibits a remarkable variety of geometrical configurations largely used in industrial applications. This work permitted the synthesis of a novel crystalline form: the hexagonal-pyramidal graphite hillocks. These submicronic structures are created from graphite substrates by low pressure Ar/H2 radiofrequency (rf) plasma etching. In order to understand the formation of these new crystals, plasma characterization has been carried out by Langmuir probes and laser absorption spectroscopy to check the surface temperature and estimate the ion fluxes and energies. Etching kinetics has been directly observed by scanning electron microscopy (SEM). Chemical etching processes in pure hydrogen resulted in the creation of helical graphite cones whose crystal parameters and surface amorphisation have been revealed by transmission electron microscopy (TEM). The etching rate and surface topography as function of the gas mixture show a transition where no structures are created. The physical etching in pure argon creates hexagonal-pyramidal graphite hillocks. A formation model of these crystals has been proposed owing to a good knowledge of the different plasma conditions and thorough electron microscopy studies on two kinds of substrates. High resolution MET analyses showed graphene loops closing the edges planes along the crystal facets and related to the structure’s formation. We also showed the texturing of the surface of highly ordered graphite (HOPG) by creating a high and homogeneous density of crystals whose size may be controlled
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Booyens, Johann Grebe. "The software ideated plate : towards designing a new relationship of integration between digital technology and the intaglio process." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1329.
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Dissertation submitted in partial fulfilment of the requirements for the degree
Master of Technology: Graphic Design in the Faculty of Informatics and Design at
the Cape Peninsula University of TechnologyThis study investigates the application and use of the latest graphic design software technologies to help plan and ideate the intaglio printmaking process. This is significant as intaglio is a 600 year old process which has evolved little, if any, in the last few hundred years although it was born from technology. Furthermore, the intaglio process relies on mental visualisation of the final artwork, making the real outcome and the planned outcome dissimilar. Students of intaglio printmaking are often surprised or disappointed by the printed result due to the lack of efficient planning. There are several ways in which software influences the creative process, including enhancing visualisation and communication, premature fixation, circumscribed thinking and bounded ideation. In this research, computer software is used as a simulator to facilitate the planning process in order to minimise the disconnect between visualisation and outcome, and serve as learning instrument. The use of digital computer technologies has been a highly debated issue in printmaking as there exists a rift between printmakers; those who embrace and explore new technologies and those who reject new methods in favour of traditional means. New technologies in printmaking offer exciting opportunities, both innovative and creative, but these new technologies are often seen as alternative or auxiliary methods of printmaking compared to traditional ways. Since these debates have been buried but not necessarily resolved, this study reinvigorates some of these perspectives and seeks a common middle ground. This study does not argue for, or against computer technology, but rather for a third paradigm: technology can coexist with intaglio without compromising the beauty and authenticity of hand processes. Computer technologies, therefore, serve as a facilitator to amplify the traditional intaglio hand process. However, the issue of discussion in this thesis is not hybrid printmaking but rather a hybrid mode of thinking in the printmaking discipline. This iterative design experiment consists of a written dissertation and intaglio printed artworks which inform and complement each other. The theoretical foundation of the art practice is found in the Bauhaus slogan: “Art and technology: a new unity”. Art and technology form the basis of the theory and the theme of entropy – the process of degeneration – is illustrated in the design artefacts. This theme shows process and illustrates the idea of a positive agent: the interference of computer in intaglio to instil new energy and value not only to keep it alive, but position it as an important skill necessary for growth in the knowledge-based economy. Furthermore, this study contributes to the scholarly discussion of design’s conceptual skills (ways of thinking) in order to enhance production capabilities (ways of making).
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PINNA, FEDERICO. "Study and Production of Special Targets for DCE Reactions with 0vbb-Decay Final States in the NUMEN Experiment." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2729322.
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Angelidis, Alexis, and n/a. "Shape modeling by swept space deformation." University of Otago. Department of Computer Science, 2006. http://adt.otago.ac.nz./public/adt-NZDU20060808.161349.
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In Computer Graphics, in the context of shape modeling on a computer, a common characteristic of popular techniques is the possibility for the artist to operate on a shape by modifying directly the shape�s mathematical description. But with the constant increase of computing power, it has become increasingly realistic and effective to insert interfaces between the artist and the mathematics describing the shape. While in the future, shape descriptions are likely to be replaced with new ones, this should not affect the development of new and existing shape interfaces. Space deformation is a family of techniques that permits describing an interface independently from the description. Our thesis is that while space deformation techniques are used for solving a wide range of problems in Computer Graphics, they are missing a framework for the specific task of interactive shape modeling. We propose such a framework called sweepers, together with a set of related techniques for shape modeling. In sweepers, we define simultaneous-tools deformation, volume-preserving deformation, topology-changing deformation and animated deformation. Our swept-fluid technique introduces the idea that a deformation can be described as a fluid. In fact, the sweepers framework is not restrained to shape modeling and is also used to define a new fluid animation technique. Since the motion of a fluid can be considered locally as rigid, we define a formalism for handling conveniently rigid transformations. To display shapes, we propose a mesh update algorithm, a point-based shape description and a discrete implicit surface, and we have performed preliminary tests with inverse-raytracing. Finally, our technique called spherical-springs can be used to attach a texture to our shapes.
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Penny, Sarah. "Inspection techniques for determining graphite core deterioration for nuclear applications." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/inspection-techniques-for-determining-graphite-core-deterioration-for-nuclear-applications(0c8e0d15-4e37-4d4e-acd5-f9cfb00bb1a9).html.
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Graphite bricks make up a significant part of the core of an Advanced Gas-cooled Reactor (AGR). The graphite moderates the neutrons vital to the continuation of the fission chain reaction and provides support and stability for the entire core. During operation, the graphite can be oxidised due to the extreme conditions inside the core and so undergo weight loss. Differential shrinkage caused by neutron interaction throughout the brick can also cause radial cracking to occur. The effects of the oxidation, weight loss and cracking reduce the ability of the graphite to function as a moderator. The effects also have the potential of reducing the structural integrity of the brick, causing movement and structural instability of the entire core. It is, therefore, vital to monitor the condition of the graphite bricks and to understand how the changes in the graphite's properties and structure may affect the safe operation of the reactor. This report firstly looks briefly at the effect of irradiation on the graphite brick; the mechanisms leading to weight loss and cracking. The report then considers various methods which can be used to inspect the deterioration of graphite blocks within the cores of AGRs deriving quantitative and qualitative information on density and crack profiling. These methods will be considered for use both on small samples trepanned from the core and in-situ blocks within the reactor core, requiring non-destructive techniques. The inspection methods considered in this report are: Electrical Impedance Tomography (EIT); Four point probes; Eddy Current Tomography; and Electromagnetic Inductance Tomography (EMT).There are two main contributions of this thesis. First, the development an EIT methodology using outward facing probes, which were best suited to the geometry of the graphite bricks within the AGR. Proof of principle was established using both modelling and laboratory testing. The second contribution is the development of commercial grade EMT equipment, which can be used on-site to determine the conductivity of trepanned samples. The method was successfully demonstrated in the laboratory; however, further development will be required for use on-site, due to the sampling speed required.
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Marchena, Martín-Francés Miriam. "Scalable techniques for graphene on glass." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/620627.
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The combination of unique properties -high electrical mobility, thermal conductivity, transparency and mechanical flexibility- make graphene promising for a wide variety of applications, including transparent electrodes, flexible displays, touch-screens and wearables. One of the main reasons that prevent its widespread use is the difficulty to maintain all of the previously mentioned properties when grown using industrial grade techniques. The most widely used technique for growing graphene on a large scale is Chemical Vapor Deposition (CVD), where graphene is, typically, first deposited on a Cu catalyst foil and then transferred to a target substrate using additional sacrificial materials (polymers). The transfer is time-consuming and can worsen the graphene properties and its quality. For instance, residues from transfer materials can alter the doping level. This thesis has investigated the direct growth, dry transfer and doping control of graphene on glass substrates, suggesting new methods and designs to improve the use of such substrates in devices, with a particular focus on optical applications where preserving the transparency is often required.
The thesis demonstrates direct growth of graphene on the desired target substrate using two techniques without any transfer step. In the first technique, graphene was grown on large patterned areas by using catalytic ultra-thin metal films (UTMFs) made of Ni, with thicknesses ranging from 5 to 50 nanometers. The dewetting of Ni UTMF when exposed to high growth temperatures allows graphene to deposit on the glass surface while the metal film is breaking and is retracted. In the second technique, graphene was grown on large areas covered by Cu nanoparticles, which can be arranged into different patterns and with surface densities. Tuning the Cu density by dip-coating and evaporation techniques and the possibility of etching the Cu afterwards allow the growth of flat graphene networks, but also of graphene assembled into three-dimensional shapes with high effective surface area, which opens up more potential applications.
CVD of graphene on Cu foil is a powerful growth technique, but its transfer is still a challenge. This thesis has demonstrated a successful dry transfer technique for graphene on glass substrates using interfacial polyimide layers, which is faster, easier and more scalable while preserving the electrical transport and optical properties.
The doping of graphene through the substrate surface or the additional top layers is not always easy to control. If not properly carried out, it can degrade the graphene properties, even when the previous growth and transfer steps have been successfully performed. This thesis has investigated a doping control post-processing technique, called “thermal poling” of glass, to induce the charge at the surface of the glass substrate and thus modify the electronic carrier density of graphene. The charge in the glass originates from the displacement of ions that become mobile at temperatures above 100ºC and when subjected to an electrical voltage of up to few kV. The corresponding stable and “frozen-in” electric field is responsible for the doping of graphene.
The results of this thesis widen the range of graphene applications where largescale
growth, practical transfer and doping control are required. At the same time, the thesis also opens new research avenues, especially to improve further the graphene quality when incorporated in devices.Esta tesis ha investigado el crecimiento directo, transferencia por vía seca y el control de dopaje del grafeno en vidrio, sugiriendo nuevos métodos y diseños para mejorar el uso de estos substratos en dispositivos, especialmente para aquellos con aplicaciones ópticas donde es necesaria una elevada transparencia. La tesis demuestra el crecimiento directo de grafeno en el substrato final deseado,usando para ello dos técnicas diferentes que evitan cualquier etapa de transferencia. En la primera técnica, el grafeno se ha crecido en áreas grandes y prediseñadas usando como catalizador láminas ultra-finas (UTMFs) de níquel con espesores comprendidos entre 5 y 50 nanómetros. Cuando estas láminas metálicas son expuestas a las temperaturas elevadas necesarias para crecer el grafeno ocurre el fenómeno de dewetting, en el cuál la lámina se rompe y el metal se retrae, lo que conlleva que el grafeno que ha crecido en el níquel se deposite en la superficie del vidrio. En la segunda técnica, el grafeno se ha crecido sobre nanopartículas de iv cobre que han sido depositadas previamente en vidrio con diferentes estructuras y densidad superficial. La variación de densidades obtenidas en las nanopartículas de cobre durante su deposición en vidrio, mediante técnicas de inmersión y evaporación,y la elliminación posterior del cobre permiten el crecimiento de grafeno en forma de red plana, pero también en estructuras tridimensionales con mayores áreas superficiales, lo que incrementa las posibles aplicaciones futuras. El crecimiento de grafeno mediante CVD en una lámina de cobre es la técnica más prometedora a nivel industrial, pero su transferencia desde el metal hasta el substrato final es aún cuestionable y supone un reto para lograr la completa implementación de esta tecnología. Esta tesis demuestra la capacidad de una técnica por vía seca y escalable a nivel industrial, para transferir grafeno de manera efectiva rápida y sencilla en substratos de vidrio, utilizando poliamida como material intermedio entre ambos y preservando las propiedades eléctricas y ópticas del grafeno. El dopaje de grafeno que se adquiere bien por la superficie del substrato final o por la contribución de capas depositadas encima, es difícil de controlar y puede conllevar a la degradación total de las propiedades elétricas del material, incluso cuando las etapas de síntesis y transferencias se han llevado a cabo de manera correcta. Esta tesis ha investigado la aplicación de una técnica para controlar el dopaje del grafeno a posteriori, es decir, una vez que ha sido depositado en el vidrio. Esta técnica se conoce como polarización térmica del vidrio y consiste en la inducción de una carga en la superficie del vidrio que provocará una modificación controlada del dopaje del grafeno. Esta carga superficial del vidrio se origina por el desplazamiento de iones provenientes de aditivos del vidrio, que comienzan a moverse a temperaturas superiores a 100ºC y cuando se aplica un voltaje externo de kV. Este proceso da lugar a un campo eléctrico muy estable, confinado y "congelado" dentro del vidrio a temperatura ambiente que será el responsable de la modificación del dopaje del grafeno. Los resultados de esta tesis amplían el rango de aplicaciones del grafeno donde es necesarios su crecimiento a gran escala, un método de transferencia efectivo y práctico y un control sobre su dopaje final. Del mismo modo, esta tesis también abre nuevas vías de desarrollo e investigación, especialmente para mejorar la calidad del grafeno cuándo éste es incorporado finalmente en dispositivos.
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Gou, Hongmei. "Digital forensic techniques for graphic data." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7361.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Zakaria, Khalid Hj. "The joy of graphics." Virtual Press, 1987. http://liblink.bsu.edu/uhtbin/catkey/543774.
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In the environmental design professions, many students and practitioners lack confidence in visual communication skills, especially in the case of quick perspective sketching. For many, sketching as a beneficial design tool is not fully learned or appreciated.This study explores sketching fundamentals and a teaching technique to promote perspective sketching as an effective design tool. Experimental workshops were conducted with various beginning environmental design students in three universities. Students responded to a post-workshop questionnaire which attempted to solicit feedback about the demonstrated sketching technique as to whether the technique 1) increased their ability, 2) increased their confidence, 3) increased their enjoyment, and 4) increased their willingness to pursue sketching in the future. Students were also evaluated on the degree of improvement according to simplicity, clarity and proper perspective setting of their sketches.The results suggested that the workshop, teaching methods and sketching techniques were successful. Students showed marked improvement and indicated in the questionnaire that they enjoyed the experience and were pleased with their new skills. They also indicated a positive feeling about the teaching methods and the sketching techniques.Department of Landscape Architecture
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González, García Francisco. "Continuity and interpolation techniques for computer graphics." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/117143.
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In Computer Graphics applications, it is a common practice to texture 3D models to apply material properties to them. Then, once the models are textured, they are deformed to create new poses that can be more appropriate for the needs of a certain scene and finally, those models are visualized with a rendering algorithm. Many of those approaches suffer from continuity problems that dumper interpolation procedures. Thus, in this thesis we present three algorithms that address continuity in key areas of Computer Graphics: Continuity Mapping in texturing, *Cages in mesh deformation and I-Render in visualizationEn aplicacions orientades als gràfics per ordinador existeix una pràctica molt comuna d'associar informació de materials a objectes 3D mitjançant l'aplicació de textures. Una vegada els models estan texturats, solen deformar-se per tal de crear noves postures, les quals poden ser més adients per a les necessitats d'una determinada escena. Finalment, els models 3D es visualitzen mitjançant l'ajuda d'un algorisme de visualització. Molts dels mètodes de texturat, deformació i visualització existents pateixen problemes de continuïtat que dificulten la posterior aplicació de tècniques d'interpolació. Així doncs, en aquesta tesis doctoral presentem una sèrie d’algorismes que aporten continuïtat en àrees estratègiques i importants en els gràfics per ordinador: Continuity Mapping en el texturat de malles 3D, *Cages per a la deformació suau i continua de malles i I-Render en el camp de la visualització interactiva
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Lim, Hong Lip. "Rendering techniques in three-dimensional computer graphics." Phd thesis, Faculty of Engineering, 1993. http://hdl.handle.net/2123/5674.
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Burden, Adrian Paul. "Electron microscopy techniques to further the understanding of conductive polymer composites." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337609.
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Mehri, Dehnavi Maryam. "Krylov subspace techniques on graphic processing units." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114424.
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Computations related to many scientific and engineering problems spend most of their time in solving large, sparse linear systems. Improving the performance of these solvers on modern parallel architecture enables scientists to simulate large accurate models and manipulate massive amounts of data in reasonable time frames. Krylov subspace methods (KSM) are iterative techniques used to solve large sparse systems. The main time consuming kernels in KSMs are sparse matrix vector multiplication (SpMV), vector operations (dot products and vector sums) and preconditioner manipulation. This work presents techniques and algorithms to accelerate some of these kernels on a recent generation of parallel architecture called manycore processors. The performance of the proposed optimizations are tested on graphic processing units (GPUs) and compared to previous work. The SpMV kernel is accelerated on GPUs and speedups of up to 3.3 times are achieved compared to previous GPU implementations of the algorithm. The conjugate gradient iterative solver is accelerated on NVIDIA graphic cards and a 12.9 fold speedup is achieved compared to optimized implementation of the kernel on multicore CPUs. The sparse approximate inverse preconditioner is accelerated on GPUs and used to enhance the convergence rate of the BiCGStab iterative solver. The preconditioner is generated on NVIDIA GTX480 in the same time as it takes 16 AMD 252 Opteron processors to generate the same preconditioner.Communicating data between levels of a memory hierarchy and processors is time consuming and costly in KSMs. Communication-avoiding (CA) Krylov solvers take k steps of a KSM for the same communication cost as one step to reduce the communication overhead in standard KSMs. The matrix powers kernel in communication-avoiding Krylov solvers is accelerated on NVIDIA GPUs and speedups of up to 5.7 are achieved for the tested problems compared to the standard implementation of k SpMV kernels.Les calculs liés à de nombreux problèmes scientifiques et techniques demandent qu'on consacre beaucoup de temps à la résolution de grands systèmes linéaires creux. Améliorer la performance de ces résolveurs sur l'architecture paralléle moderne permet aux scientifiques de simuler de grands modèles précis et de manipuler une quantité massive de données dans des délais raisonnables. Les méthodes sous-espaces Krylov (KSM) sont des techniques itératives utilisées pour résoudre de grands systèmes creux. Les noyaux principaux qui demandent beaucoup de temps dans les KSMs sont la multiplication matrice-vecteur creuse (SpMV), les opérations sur les vecteurs (produits scalaires et sommes vectorielles) et la manipulation de préconditionneur. Ce travail présente les techniques et les algorithmes pour accélérer certains de ces noyaux sur une génération récente d'architecture parallèle appelée processeurs multicoeurs. La performance des optimisations proposées est testée sur des processeurs graphiques (GPU) et comparée aux travaux antérieurs.Le noyau SpMV est accéléré sur les processeurs graphiques et des accélérations jusqu'à 3.3 fois plus rapides sont atteintes par rapport aux implémentations de l'algorithme des processeurs graphiques précédents. Le gradient conjugué du résolveur itératif est accéléré sur des cartes graphiques NVIDIA et une accélération 12.9 fois plus rapide est réalisée par rapport à l'implémentation optimisée du noyau sur des processeurs multicœurs. Le préconditionneur approximatif inverse creux est accéléré sur les processeurs graphiques et utilisé pour améliorer le taux de convergence du résolveur itératif BiCGStab. Le préconditionneur est généré sur un NVIDIA GTX480 pour la même durée nécessaire à 16 processeurs AMD Opteron 252 pour générer le même préconditionneur.La communication de données entre les niveaux d'une hiérarchie de mémoire et des processeurs est longue et coûteuse en KSMs. Les résolveurs sans communication (communication-avoiding ou CA) de Krylov n'utilisent qu'un nombre k d'étapes d'une méthode de sous-espace de Krylov (KSM) pour un coût de communication équivalent comme une étape qui permet de réduire les frais généraux des communications dans les KSMs standards. Le noyau des pouvoirs de matrice dans les résolveurs de Krylov sans communication est accéléré sur les processeurs graphiques NVIDIA et des accélérations jusqu'à 5.7 plus rapides sont atteintes pour les problèmes testés par rapport à l'implémentation standard de k des noyaux SpMV.
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Nowak, A. K. "Applications of computer graphics techniques to zeolite chemistry." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380003.
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Chalmers, Matthew J. "Realism and design techniques for multiprocessor graphics systems." Thesis, University of East Anglia, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253537.
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Wagner, Philipp. "Modélisation du graphène avec les techniques ab initio." Nantes, 2013. http://www.theses.fr/2013NANT2011.
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Le travail de cette thèse porte sur l'étude du matériau graphène et de nanostructures dérivées, par modélisation ab initio. L'influence des terminaisons chimiques des bords du feuillet graphène (armchair, zigzag et Klein, en considérant aussi des reconstructions possible) a été étudiée. En l'absence de terminaisons, une nouvelle configuration stable «repliée» a été identifiée; qui correspond à la création de structure nanotube le long des bords du feuillet. Une étude des bords hydrogénés a été effectuée, qui montrait des nouvelles configurations de bords Klein reconstruites énergétiquement favorable. En outre, les bords hydrogénés joueront un rôle clef dans les processus de croissance du graphène, et d'éventuels modèles de croissance adaptés via l'addition des dimères de carbone sont proposés. Des terminaisons plus complexes sur des nanorubans de graphène de type armchair de 4 à 25 Å de largeur ont été modélisées également, par exemple impliquant -OH (hydroxyle). L'influence sur la structure et les propriétés électronique, chimique et mécaniques des nanorubans a été étudiée. Cette partie a conduit à rediscuter la notion de module de Young de nanofeuillets (graphène, BN, MoS2, MoTe2 etc. ). Notamment ce travail propose une définition de «volume à prendre en compte» sur la base d'une densité électronique moyenne. Cette nouvelle approche offre un cadre transférable sous-jacent pour calculer le module de Young, et donc de pouvoir extrapoler correctement les valeurs entre le graphène, des nanotubes de carbone et du graphite. Le concept a aussi été étendu à des polymères organiquesIn this thesis graphene and related nanostructures were studied, using density functional ab initio modelling techniques. The influence of different edge terminations has been investigated for typical pristine graphene edges (armchair, zigzag and Klein) and several reconstructed edge configurations. For unterminated graphene edges a new stable folded back edge has been identified, creating a nanotube along the graphene edge. A systematic study of hydrogenated edges was performed, and new favourable reconstructed Klein edge configurations were found. Furthermore hydrogenated edges are expected to play an important role for graphene growth processes, and thus possible adapted growth models via carbon dimer addition are proposed. Next more complex edge functionalisations such as hydroxylated (-OH) edges were studied, in particular modelling thin 4 - 25 Å wide armchair graphene nanoribbons. Notably the influence on structural, electronic, chemical and mechanical properties has been investigated. This promises new routes towards controlled design of specific nanoribbon properties. Finally the in-plane Young’s modulus of various nanosheets (including graphene, BN, MoS2, MoTe2 etc. ) were calculated. In this context a new geometry independent volume definition for nanoobjects has been developed, based on the average electron density. This new approach offers a transferable underlying framework to calculate the Young’s modulus, and thus values correctly extrapolate for example between graphene, carbon nanotubes and bulk graphite. The concept was further extended to organic polymers
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Mélançon, Alain. "Penser l'éducation artistique et technique pour pratiquer le design graphique historique de la formation en design graphique au Québec avant 1970." Mémoire, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/2646.
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Cette analyse chronologique permet de revoir la séquence des événements qui façonnent les programmes de formation et qui décrivent les tensions constantes entre la pratique artistique, la technique et la communication qui sont au coeur de la formation et de la pratique du design graphique. Dans un premier temps, cette recherche propose d'évaluer les caractéristiques de la formation en art publicitaire dans les écoles des Beaux-Arts et les écoles techniques du Québec depuis le début du xxe siècle. Ensuite, l'étude des rapports Parent et Rioux démontre que les bouleversements amenés par la Révolution tranquille transforment littéralement l'éducation artistique et technique par la création de nouvelles institutions. Enfin, à la lumière du développement des études collégiales et universitaires qui débutent a partir de 1969, comment évolue la profession et la formation en design graphique dans ce contexte?Cette contribution constitue une première analyse systématique sur l'historique de la formation en design graphique au Québec. Elle offre une vue d'ensemble sur les programmes et les discours d'institutions et de professionnels qui ont marqué l'histoire du design graphique au Québec.
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Choudhury, Prasun. "Carbonaceous nanomaterials and composites green techniques for organic synthesis." Thesis, University of North Bengal, 2020. http://ir.nbu.ac.in/handle/123456789/4336.
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Brenner, Kevin A. "Benchmarking and chemical doping techniques for nanoscale graphene interconnects." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47581.
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The interconnect fabric that provides electrical connectivity to active devices is an essential component to modern semiconductor chips. As the dimensions of these devices are scaled to improve performance and keep pace with Moore's Law, the local Cu interconnects must scale in parallel. Intrinsic material properties of Cu result in spiking electrical resistivity with scaling and present a looming bottleneck to chip performance. In this thesis, we introduce graphene as a replacement material to Cu interconnects in support of future chip scaling. In particular we focus on experimentally establishing fundamental mechanisms of chemically doping graphene via the basal plane and edge passivation, with broad contributions that extend beyond the focus of local interconnects.
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Belkhiter, Nadir. "Transducteur d'affichage de documents techniques décrits en LRDM(texte, graphique, fac-similé)." Lyon 1, 1985. http://www.theses.fr/1985LYO19006.
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Ce projet réalisé en collaboration avec le CNET a eu pour objet la description et l'archivage de documents techniques. En effet, devant les problèmes sans cesse accrus que pose la maintenance des produits industriels et publics, le CNET nous a chargé de définir et concevoir un langage qui permettrait la représentation unifiée d'une documentation technique. Celle-ci est caractérisée par un volume important et un contenu informationnel de nature composite (rapports issus de systèmes de traitement de texte, plans et schémas électroniques provenant de systèmes de C. A. O, textes manuscrits numérisés par la technique du fac-similé,. . . ). Cette unification dans la représentation devait être ensuite démontrée à travers une réalisation logicielle expérimentale. Une première version du langage LRDM permettant une représentation homogène de texte, graphique et fac-similé est totalement spécifiée et un prototype (Transducteur d'Affichage) expérimental et opérationnel en démontre la faisabilité. Celui-ci est composé de deux modules complémentaires : - un analyseur/codeur écrit en LET (Langage d’Écriture des Transducteurs) et permettant l'analyse (syntaxique et sémantique) ainsi que le codage en vue de l'archivage de descriptions sources L. R. D. H, - un Interprète d'Affichage écrit en PASCAL qui permet la consultation de documents préalablement analysés et codés par le premier module. Dans sa version actuelle le prototype autorise une consultation séquentielle ou directe sur deux types de terminaux (écran graphique couleur Tektronix 4105 d'une part, et table traçante couleur Tektronix 4662 d'autre part).
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Hougs, Roland Borch. "Practical and efficient techniques for irradiance estimation in difficult lighting conditions." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268483.
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Huang, Ben. "Removing Textured Artifacts from Digital Photos Using Spatial Frequency Filtering." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/148.
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An abstract of the thesis of Ben Huang for the Master of Science in Electric and Computer Science presented [August 12nd, 2010]. Title: Removing textured artifacts from digital photos by using spatial frequency filtering Virtually all image processing is now done with digital images. These images, captured with digital cameras, can be readily processed with various types of editing software to serve a multitude of personal and commercial purposes. But not all images are directly captured and even of those that are directly captured many are not of sufficiently high quality. Digital images are also acquired by scanning old paper images. The result is often a digital image of poor quality. Textured artifacts on some old paper pictures were designed to help protect pictures from discoloration. However, after scanning, these textured artifacts exhibit annoying textured noise in the digital image, highly degrading the visual definition of images on electronic screens. This kind of image noise is academically called global periodic noise. It is in a spurious and repetitive pattern that exists consistently throughout the image. There does not appear to be any commercial graphic software with a tool box to directly resolve this global periodic noise. Even Photoshop, considered to be the most powerful and authoritative graphic software, does not have an effective function to reduce textured noise. This thesis addresses this problem by proposing the use of an alternative graphic filter to what is currently available. To achieve the best image quality in photographic editing, spatial frequency domain filtering is utilized instead of spatial domain filtering. In frequency domain images, the consistent periodicity of the textured noise leads to well defined spikes in the frequency transform of the noisy image. When the noise spikes are at a sufficient distance from the image spectrum, they can be removed by reducing their frequency amplitudes. The filtered spectrum may then yield a noise reduced image through inverse frequency transforming. This thesis proposes a method to reduce periodic noise in the spatial frequency domain; summarizes the difference between DFT and DCT, FFT and fast DCT in image processing applications; uses fast DCT as the frequency transform to solve the problem in order to improve both computational load and filtered image quality; and develops software that can be implemented as a plug in for large graphic software to remove textured artifacts from digital images.
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Blanke, William John. "Multiresolution techniques on a parallel multidisplay multiresolution image compositing system." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035942.
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Arbelot, Benoit. "Transferts d'apparence en espace image basés sur des propriétés texturelles." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAM018/document.
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Les techniques de manipulation de l'apparence d'une image sont très utilisées dans de nombreux domaines comme la photographie, la biologie, l'astronomie ou le spectacle vivant. L'apparence d'une image dépend de ses couleurs et textures, mais aussi des informations 3D perçues comme les formes, les matériaux et l'éclairage. Ces caractéristiques créent aussi une atmosphère et une émotion spécifique à l'image, qui fait aussi partie de son apparence. Le but des techniques de manipulation en espace image est de modifier les couleurs et les textures pour modifier les formes, matériaux et illumination perçus, et de là éventuellement modifier l'atmosphère de l'image.Les méthodes de transfert d'apparence sont une classe spécifique de techniques de manipulation visant à rendre le processus plus intuitif en calculant automatiquement la modification à apporter à l'image. Pour ce faire, elles se basent sur une image supplémentaire fournie par l'utilisateur et représentant l'apparence désirée.Dans cette thèse, nous étudions le transfert d'apparence en espace image basé sur des propriétés texturelles. Les textures étant une partie intégrante de l'apparence, guider les transferts d'apparence par de l'information texturelle est une option attrayante. Nous présentons d'abord une technique de filtrage de descripteurs de texture pour mieux préserver les structures de l'image et les transitions entre textures. Nous utilisons ensuite ce filtrage couplé à différents descripteurs de texture pour effectuer un transfert de couleur, une colorisation et un transfert de texture localement, guidés par la textureImage-space appearance manipulation techniques are widely used in various domains such as photography, biology, astronomy or performing arts. An image appearance depends on the image colors and texture, but also the perceived 3D informations such as shapes, materials and illumination. These characteristics also create a specific look and feel for the image, which is also part of the image appearance. The goal of image-space manipulation techniques is to modify colors and textures as a mean to alter perceived shapes, illumination, materials, and from this possibly alter the image look and feel.Appearance transfer methods are a specific type of manipulation techniques aiming to make the process more intuitive by automatically computing the image modification. In order to do so, they use an additional user-provided image depicting the desired appearance.In this thesis, we study image-space appearance transfer based on textural properties. Since textures are an integral part of the image appearance, guiding appearance transfers with textural information is an attractive approach. We first present a texture descriptor filtering framework to better preserve image edges and texture transitions in the texture analysis. We then use this framework coupled with different texture descriptors in order to apply local texture guided color transfer, colorization and texture transfer
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Whited, Brian Scott. "Tangent-ball techniques for shape processing." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31670.
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Thesis (Ph.D)--Computing, Georgia Institute of Technology, 2010.Committee Chair: Jarek Rossignac; Committee Member: Greg Slabaugh; Committee Member: Greg Turk; Committee Member: Karen Liu; Committee Member: Maryann Simmons. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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McDaid, John P. Jr. "Improved Groundstation Consoles Using New Visualization Techniques and Graphics Technology." International Foundation for Telemetering, 1994. http://hdl.handle.net/10150/611670.
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International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThe advance from alphanumeric terminals to displays using new graphics technologies like the X Window System and Microsoft Windows has in many cases failed to tap the full potential of these technologies. Many common telemetry tasks continue to use similar user interfaces based on tabular real-time data displays and menus. This paper will demonstrate the application of new techniques which, when used with emerging graphics technologies, will maximize the effectiveness of telemetry ground station consoles. Advances in visualization and animation have greatly enhanced the information content of current displays and significantly improved their ease of use.
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Лютий, Тарас Володимирович, Тарас Владимирович Лютый, Taras Volodymyrovych Liutyi, Олександр Юрійович Поляков, Александр Юрьевич Поляков, Oleksandr Yuriiovych Poliakov, S. Denisov, and P. Hanggi. "Technique of the Fast Ferrofluids Simulation." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35341.
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We present a highly-parallel implementation of the Langevin simulation method for modeling ferrofluids
on Graphical Processor Units (GPU). Our method is based on the Barnes-Hut algorithm. As a benchmark
we use the straightforward 'all-to-all interaction' algorithm. The obtained results are in good agreement
with known theoretical model. With the proposed method we were able to follow the evolution of a
system of one million interacting particles over long time-scales, the task hitherto is out of reach with the
standard, CPU-based numerical schemes.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35341
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Spicer, Richard. "Application of graphical techniques in archaeology and their implications on methodology." Thesis, Staffordshire University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293949.
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Czirbesz, J. C. "An investigation into the techniques used in real time 3D graphics." Thesis, University of Bath, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375336.
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Choi, Yi-king. "Computer visualization techniques in surgical planning for pedicle screw insertion /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B22956475.
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Andrysco, Nathan. "A user study contrasting 2D unsteady vector field visualization techniques." Connect to this title online, 2005. http://hdl.handle.net/1811/300.
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Senior Honor's Thesis (Computer and Information Science)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains viii, 27 p.; also includes graphics (some col.). Includes bibliographical references (p. 27). Available online via Ohio State University's Knowledge Bank.
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Chang, Jian. "Physically based mesh-free deformation framework and techniques for computer graphics." Thesis, Bournemouth University, 2006. http://eprints.bournemouth.ac.uk/3495/.
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In this thesis, we introduce a mesh-free deformation framework. Four different applications are presented based on it. Among them, a technique of mesh-free deformations and a technique ofreusable deformations are to model the deformations in two different ways, while the hyper-twist and the force mapping are applied to other graphic purposes related to deformations.Existing physicanv-based deformation techniques, such as the finite element method and the massspring systems, require the deformed object to be properly meshed. The proposed mesh-free deformations are constructed with unconnected points and no mesh is required in the computation.This process strict~1' follows the principles of classic mechanics and a deformation is defined as a combination of fundamental solutions. Because no mesh is involved, deforming a complex shape is as straightforw'ard as deforming a simple one and the trade-off between efficiency and accuracy is easy to achieve by redistributing the points concerned. Experiments show that this method is fast and offers similar accuracy to the finite element methods.Reducing both computational cost and amount of unnecessary human intervention remains a pressing issue in the animation production. To provide a faster and more user-friendly tool, we extend the above mesh-free deformations technique and develop another technique. A key feature is thereusability of deformations. Existing deformations can be simply extracted and reapplied physicallyusing the 'copy' and 'paste' operations. it relieves the modelling efforts. In this way, the visual realism is combined with the modelling efficiency and the user-friendliness for animators.The mesh-free deformation framework is capable to describe the deformations in an infinite body which is in line with the distortion of a 3D space. The twist of an infinite body, hyper-twist, is investigated to show how a 3D space and the object embedded can be radically deformed. Abstract shapes with aesthetic effects can be created in this process as well as their animations. Following the idea of mesh-free computation, we apply forces on a surface to create the fine details of the surface. A force map records the applied forces and their distributions. We call this technique force mapping, which can be used for surface modeling, compression, reconstruction and editing. As an alternative to displacement mapping, force mapping benefits from the fact that the physical property, force, is integrated into a geometric surface explicitly.
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Almisbahi, Hind. "Analysing graphene vibrations via molecular dynamics simulations and dimension reduction techniques." Thesis, University of Surrey, 2019. http://epubs.surrey.ac.uk/850063/.
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Graphene was first isolated in the lab in 2003 and this work was first published in 2004 by a research team at The University of Manchester. Since that date, graphene research has exploded due to its special properties. Phonons and molecular dynamic simulation provide valuable tools to study the molecular systems under different structure forms. They are helpful to study graphene ribbons and defects. On the other hand, many machine learning techniques were extensively used to analyse the enormous amounts of data resulted from the molecular simulations. As such, this thesis aimed to use one of the machine learning techniques to study phonons of graphene with single vacancy defect and graphene armchair nanoribbons. PCA can be used to transform the atomic velocities into orthogonal eigenvectors such that each eigenvector represents one of the phonon modes of graphene. This is helpful to visualize the atomic motion of a specific phonon mode. To provide orthogonal eigenvectors, PCA needs the data to be of gaussian distribution. The atomic velocities resulted from the molecular simulations follow gaussian distribution at the equilibrium state. Hence, the assumption of gaussian distribution needed by PCA is achieved. However, only some of the phonon modes can be calculated from the atomic velocities in their real space. Most of the phonon modes are calculated after transforming the atomic velocities to a reciprocal space (k space) using spatial Fourier transform. The k space atomic velocities are not following gaussian distribution. This thesis introduced a novel method to use PCA to isolate and visualize the phonon modes extracted from the k space velocities. To prove the feasibility of using PCA to isolate k space phonons, we conducted classical molecular simulations of graphene with different structures. The effect of single vacancy defect on graphene phonons was studied in comparison to the perfect graphene. In addition, the effect of the armchair ribbon width on graphene phonon modes was investigated. The results of the conducted molecular simulations were used with PCA to visualize some of the phonon modes of pristine graphene and armchair nanoribbons of graphene. We used PCA to present the evolution of the atomic motion of specific k space phonon modes of armchair ribbons: the first overtone of TA phonon mode and the highest overtone of TO phonon mode. The presented motions showed that the breathing like mode is a transition state between two opposite atomic motions of TA mode. In the method we introduced using PCA, we used the eigenvectors with the lowest eigenvalues to study the Fourier transformed atomic velocities. This method rotated the k space atomic velocities into the eigenvectors with the lowest eigenvalues which helped to isolate and visualize the k space phonon modes.
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Ben, Salk Soukaina. "Graphène et matériaux 2D : techniques de transfert, fabrication d'hétérostructures et applications." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1I031.
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L’excellente mobilité du graphène en fait un matériau de choix pour les applications radiofréquence. Cependant, cette mobilité est limitée expérimentalement par les défauts structuraux et environnants introduits par la croissance du matériau sur substrat métallique, la méthode de transfert sur un support hôte, l’interaction du graphène avec le substrat hôte sur lequel il est transféré et par les procédés de fabrication des composants. Cette thèse, cofinancée par la Région Hauts-de-France, a pour objectif de remédier à ces problèmes afin de rendre le graphène pratiquement insensible à son environnement. Elle est constituée de deux grandes parties : (i) Le transfert par exfoliation électrochimique (transfert humide) des monocristaux de graphène millimétriques (~5mm) synthétisés par CVD ainsi que leur caractérisation physique et électrique ; cette étude est réalisée dans le cadre d’un programme d’échange entre l’IEMN et l’Université d’Irvine en Californie (Programme PUF-Partner University Funding-portant sur le développement de l’électronique flexible). (ii) La fabrication et la caractérisation d’hétérostructures hBN/Graphène/hBN par transfert sec de matériaux exfoliés. Bien que la méthode CVD (Chemical Vapor Deposition) ait permis récemment l’obtention de larges monocristaux de graphène ayant une très haute qualité sur cuivre ; le transfert vers un substrat SiO2 introduit généralement des défauts et des contaminations dans le graphène résultant en des dispositifs de basses performances. Une première partie du travail mené dans cette thèse a permis de développer et mettre au point au sein du laboratoire un système de transfert fiable du graphène CVD. La méthode utilisée est basée sur une approche d’exfoliation électrochimique exploitant l’effet des bulles générées à l’interface graphène/Cu. L’optimisation de cette approche nous a permis de transférer des cristaux de graphène en préservant leur qualité. Enfin, la caractérisation électrique de dispositifs fabriqués sur des cristaux de graphène a permis d’obtenir une résistance de contact relativement basse attestant de la bonne qualité du graphène transféré. Afin de limiter l’interaction du graphène avec son environnement et ainsi préserver sa haute mobilité, l’encapsulation par du nitrure de bore hexagonale hBN permet de satisfaire ce besoin. La croissance de grandes surfaces du hBN étant toujours un grand défi scientifique, l’exfoliation mécanique est une approche de synthèse nécessaire pour la réalisation de ces héterotructures de type Van der Waals. La seconde partie du travail mené dans cette thèse a permis de développer (de la conception à la réalisation) et de mettre en place au sein du laboratoire une plateforme de nano manipulation « Stamping Set-up » dédiée à l’empilement des matériaux 2D ainsi que le développement d’un procédé d’encapsulation du graphène par transfert sec. Différents échantillons ont été fabriqués avec succès en utilisant du graphène monocouche et bicouche. Les caractérisations morphologiques et structurelles ont permis de montrer que le graphène après encapsulation présente de très faibles valeurs de dopage et de variations de contraintes à l’échelle nanométrique. Ce qui promet des valeurs de mobilité élevées. Ces travaux fournissent une voie vers l’obtention de graphène de grande qualité qui constitue une brique essentielle pour le développement de dispositifs électroniques à base d’hétérostructures de matériaux 2DThe high theoretical mobility of graphene makes it an excellent material for radio frequency applications. However, this mobility is limited by structural defects introduced by material growth techniques, the transfer method from metallic substrates to hosting semiconductor substrates, the fabrication processes of devices as well as the interaction of graphene with hosting substrate. This thesis aims to address these issues in order to make graphene practically insensitive to its environment. There are mainly two parts involved in this work: (i) Transfer by electrochemical exfoliation (wet transfer) of millimetre size single domains of graphene (~ 5mm) synthesized by CVD as well as their physical and electrical characterization; this study is part of an exchange program between the IEMN and the University of Irvine-California (PUF-Partner University Funding Program-on the development of flexible electronics). (ii) Fabrication and characterization of hBN/Graphene/hBN heterostructures by dry transfer of exfoliated materials. Although the CVD (Chemical Vapor Deposition) method made it possible to obtain large single crystals of graphene on copper; the mandatory transfer to SiO2 substrate generally introduces defects and contaminations in graphene resulting in low performance devices. A reliable transfer system for CVD graphene is developed and optimized for cleanroom use. The method used is based on an electrochemical exfoliation approach known as Bubble transfer. By optimizing this approach, we were able to transfer graphene single domains without structural defects. Finally, the electrical characterization of devices based on the transferred graphene crystal made it possible to obtain a relatively low contact resistance owing to the good quality of the transferred graphene. In order to limit the interaction of graphene with its environment and thus preserve its high mobility, encapsulation with hexagonal boron nitride hBN makes it possible to satisfy this need. The fabrication of these Van der Waals heterostructures is performed using mechanically exfoliated materials because the growth of large areas hBN is still considered a great scientific challenge. An experimental nano-manipulation platform “Stamping set-up” dedicated to the stacking of 2D materials is developed (from design to realization) as well as a process for graphene encapsulation by dry transfer. Different samples have been successfully fabricated using monolayer and bilayer graphene. Morphological and structural characterizations have shown that graphene after encapsulation shows very low doping values and uniform strain at the nanometre scale; which promises high mobility values. This work paves the way towards obtaining high quality graphene which is an important part for the development of electronic devices based on heterostructures of 2D materials
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Romero, Michael. "Volume ray casting techniques and applications using general purpose computations on graphics processing units /." Online version of thesis, 2009. http://hdl.handle.net/1850/10760.
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Thesis (M.S.)--Rochester Institute of Technology, 2009.Typescript. Accompanying CD-R contains the source code and related files for compilation and execution of the volume renderer developed in the thesis. Includes bibliographical references (leaves 110-112).
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Holländer, Matthias. "Synthèse géométrique temps réel." Thesis, Paris, ENST, 2013. http://www.theses.fr/2013ENST0009/document.
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La géométrie numérique en temps réel est un domaîne de recherches émergent en informatique graphique.Pour pouvoir générer des images photo-réalistes de haute définition,beaucoup d'applications requièrent des méthodes souvent prohibitives financièrementet relativement lentes.Parmi ces applications, on peut citer la pré-visualisation d'architectures, la réalisation de films d'animation,la création de publicités ou d'effets spéciaux pour les films dits réalistes.Dans ces cas, il est souvent nécessaire d'utiliser conjointement beaucoup d'ordinateurs possédanteux-mêmes plusieurs unités graphiques (Graphics Processing Units - GPUs).Cependant, certaines applications dites temps-réel ne peuvent s'accomoder de telles techniques, car elles requièrentde pouvoir générer plus de 30 images par seconde pour offrir un confort d'utilisationet une intéraction avec des mondes virtuels 3D riches et réalistes.L'idée principale de cette thèse est d'utiliser la synthèse de géométrie,la géométrie numérique et l'analyse géométrique pourrépondre à des problèmes classiques en informatique graphique,telle que la génération de surfaces de subdivision, l'illumination globaleou encore l'anti-aliasing dans des contextes d'intéraction temps-réel.Nous présentons de nouveaux algorithmes adaptés aux architectures matérielles courantes pour atteindre ce butEal-time geometry synthesis is an emerging topic in computer graphics.Today's interactive 3D applications have to face a variety of challengesto fulfill the consumer's request for more realism and high quality images.Often, visual effects and quality known from offline-rendered feature films or special effects in movie productions are the ultimate goal but hard to achieve in real time.This thesis offers real-time solutions by exploiting the Graphics Processing Unit (GPU)and efficient geometry processing.In particular, a variety of topics related to classical fields in computer graphics such assubdivision surfaces, global illumination and anti-aliasing are discussedand new approaches and techniques are presented
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Chaudhary, Gautam. "RZSweep a new volume-rendering technique for uniform rectilinear datasets /." Master's thesis, Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-04012003-141739.
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Ashraf, Muhammad. "Catégorisation de graphiques par les enseignants et les élèves." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENH018/document.
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Les graphiques ont pris de plus en plus d'importance dans le matériel pédagogique, les manuels scolaires ou encore les programmes informatiques. Malgré la coexistence de différents types de graphiques ou de genres graphiques, jusqu'à maintenant, les recherches sur l'apprentissage ont seulement pris en compte la distinction entre le texte et l'image. Cette thèse vise à éclaircir ce qui, dans la recherche sur l'apprentissage, semble être une catégorie globale et indivisible : les représentations visuelles. Nous nous sommes concentrées sur ce que pensent des enseignants et des étudiants de Master concernant différents types de représentations visuelles et leurs fonctions présumées dans l'enseignement et l'apprentissage. A l'heure actuelle, la recherche sur les graphiques est principalement axée sur la compréhension des élèves. Il existe très peu de recherches sur la compréhension des graphiques par les enseignants. En outre, la dimension de la formation des enseignants aux graphiques est, elle aussi, relativement ignorée. La thèse se présente en deux parties : une recherche théorique suivie d'une recherche empirique. La première partie du travail examine la littérature relative aux représentations graphiques dans l'histoire, dans les programmes scolaires à travers le monde ainsi que leur utilisation dans l'enseignement et l'apprentissage. Elle expose également les classifications des différents types de graphiques. La seconde partie de la thèse prend appui sur trois enquêtes menées auprès d'enseignants en activité et d'étudiants de Master en formation. La première investigue la compréhension des graphiques d'enseignants en activité en France et au Pakistan. Les deux autres ont été conduites auprès de futurs enseignants, en utilisant la méthode du tri de carte, afin d'identifier leurs compétences relatives à la catégorisation des différents types de graphiques.En conclusion, il semble que les programmes de formation des enseignants manquent d'un enseignement à la compréhension graphique. Même en géographie, pourtant considérée comme la discipline des graphiques et de leur enseignement, nous constatons que les enseignants sont peu familiers avec de nombreux genres graphiques. Dans l'ensemble, les graphiques génériques (camemberts, histogrammes, cartes et tableaux, etc.) ont été facilement identifiés par les enseignants alors que la classification des graphiques hybrides s'est révélée plus difficile pour la plupart d'entre euxVisualizations have gained more importance in pedagogical material, in text books and in computer programs. Despite the co-existence of many different types of visualizations or graphical genres, learning research only has taken into account the distinction between text and pictures. This thesis aims at unpacking what, at least in learning research, seems to be one single holistic indivisible category of visualizations. We focused on teachers' and Masters students' thoughts on the existence of different types of visualizations and their presumed function in teaching and learning. Research on graphical representations is mainly focused on students' comprehension of graphical representations. However, there is very little research in extend of teachers' comprehension of graphical representations. In addition, the aspect of teacher training of graphical representations is also relatively ignored. There are two main parts in this thesis: theoretical and empirical. In theoretical part, we presented the literature on the existence of graphical representations in worldwide curricula. Remarkable works of cartographers who played important rule for the advancement of graphic representations in context of teaching and learning. And finally, classification of different genres of graphical representations was also exhibited. Empirical part on the other hand, based on three studies conducted with in-service teachers and Masters students' about their comprehension of graphical genres. First study was conducted with in-service teachers from France and Pakistan to investigate their basic understanding of graphical representations. Second and third study explores the Masters' students' categorization of graphical representations. In conclusion, it seems that the teacher training programs lack the training of graphic comprehension. Even in the domain of geography which is considered the major domain about graphics and graphic education, teachers were observed unfamiliar with many graphic genres. Overall, Generic graphical representations (i.e. line graph, pie charts, bar charts, maps and tables etc.) were identified more comfortably. However, classification of hybrid graphical representations (i.e. combination of map and bar graph or other hybrid graphics) was slightly difficult for the participants
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Bardsley, Tim. "The design and evaluation of an autostereoscopic computer graphics display." Thesis, De Montfort University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390980.
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Gachet-Delaborde, Mireille. "Formes et sens de l'univers graphique en maternelle : études de cas et enjeux didactiques." Thesis, Metz, 2009. http://www.theses.fr/2009METZ031L/document.
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L’enjeu de la recherche est d’analyser les usages scolaires des objets écrits que conçoivent et réalisent les enseignants de dernière année de maternelle pour familiariser les élèves au « monde de l’écrit ». Les formes les plus fréquentes peuvent être collectives telles que des affiches, des listes d’élèves, des séries de mots utilisés dans des activités ritualisées, ou individuelles telles que des étiquettes comportant diverses unités de la langue : lettre, syllabe, mot, groupe de mots. L’analyse des supports écrits intègre leur description et le relevé des schèmes langagiers et gestuels qu’ils permettent. Globalement, une surface écrite comprend des signes alphabétiques qui renvoient au langage et une organisation spatiale qui recourt à des techniques visuelles muettes. Les éléments de l’organisation spatiale sont des constituants signifiants de l’écrit dont J. Goody (1979) a étudié la capacité heuristique. Nous montrons que l’école maternelle fait un grand usage des objets écrits pour enseigner et pour organiser la vie de la classe. Nous constatons que des élèves ont des difficultés de lecture dues à une naturalisation (Chevallard : 1982) chez les enseignants des techniques visuelles muettes. Les enseignants présupposent que les savoirs utiles pour lire ne concernent que les signes alphabétiques et négligent d’expliquer ce qui concerne la surface où s’organise l’écrit. Nous préconisons un apprentissage dirigé des procédés muets qui veille à les nommer et à en observer les fonctionsThe purpose of this research is the analysis of the use, at school, of the written items conceived by teachers in the last year of kindergarten (children aged 4 to 5) in order to familiarise children with « the world of writing ». The most common form can be collective ones, such as posters, lists of pupils’ names, of series of words used in ritualized activities, or individual ones, such as tags reading various units of language: letter, syllable, word, group of words. Analysing written material means describing it and to taking down the schemes of body language that they give. On the whole, a written surface is composed of alphabetical signs related to language, and a spatial organization using silent visual techniques. The elements of the spatial organization are meaningful constituents of writing, whose heuristic capacity was studied by J. Goody (1979). We will show that, in kindergarten, many written items are used to teaching and organize the class life. We can establish that pupils have reading difficulties due to the naturalization (Chevallard : 1982) by their teachers of the silent visual techniques. Teachers assume that the useful knowledge pupils need to learn to read is related to the alphabetical signs only ; as a consequence, they do not explain how writing is spatially organized. We recommend a guided learning process of those silent practices, which would be named and whose functions would be clearly explained
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Choi, Yi-king, and 蔡綺瓊. "Computer visualization techniques in surgical planning for pedicle screw insertion." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224234.
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Au, Kin Chung. "Differential techniques for scalable and interactive mesh editing /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CSED%202007%20AU.
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Bigonnet, Bruno. "Holonomie et graphe de certains feuilletages avec singularites." Toulouse 3, 1986. http://www.theses.fr/1986TOU30165.
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On considere des feuilletages avec singularites au sens de sussmann et stefan, tels qu'ils s'introduisent en theorie du controle et en geometrie symplectique: la dimension des feuilles croit au voisinage des feuilles singulieres. On sait que, dans le cas regulier, les graphes des relations d'equivalence regulieres locales definies par les plaques se recollent en un groupoide differentiable, qui est le groupoide d'holonomie d'ehresmann, ou le "graphe" de winkelnkemper-connes, et qui determine le revetement d'holonomie de chaque feuille. On etend ici cette notion a certains feuilletages singuliers, notamment ceux pour lesquels les sauts de dimension ne depassent pas l'unite. Ceci determine, pour les feuilles singulieres, un revetement d'holonomie qui peut etre plus fin que celui de l'holonomie topologique. Il est la base d'un "fibre principal d'holonomie", que l'on peut voir comme un eclatement de la feuille singuliere. La construction utilise la notion de "quasi-graphoide" ou de "convecteur", qui generalise, par une condition de monomorphisme, la notion de graphe d'equivalence reguliere. On observera que le fibre d'holonomie peut etre non trivial pour une feuille singuliere simplement connexe.