• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 135
  • 64
  • 58
  • 45
  • 18
  • 12
  • 9
  • 9
  • 8
  • 5
  • 3
  • 3
  • 3
  • 3
  • 2
  • Tagged with
  • 405
  • 128
  • 110
  • 60
  • 47
  • 39
  • 38
  • 30
  • 28
  • 27
  • 26
  • 26
  • 25
  • 25
  • 24
  • 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.
311

Modélisation dynamique et suivi de tumeur dans le volume rénal / Dynamic modeling and tumor tracking for the kidney

Leonardi, Valentin 13 November 2014 (has links)
Ce travail de thèse porte sur la modélisation dynamique 3D du rein et le suivi d’une tumeur de cet organe. Il s’inscrit dans le projet KiTT (Kidney Tumor Tracking) qui regroupe des chercheurs issus de plusieurs domaines : la modélisation géométrique, la radiologie et l’urologie. Le cadre de cette thèse suit une tendance de mini-invasivité des gestes chirurgicaux observée ces dernières années (HIFU, coelioscopie). Sa finalité est d’aboutir à un nouveau protocole de destruction de tumeurs rénales totalement non-invasif, par la diffusion d’agents physiques (ondes d’ultrasons) à travers la peau et focalisés sur la tumeur. Devant le mouvement et la déformation que le rein présente au cours du cycle respiratoire, la problématique de ces travaux de recherche est de connaître en permanence la position de la tumeur afin d’ajuster à moyen terme la diffusion des ondes en conséquence. / This Ph.D. thesis deals with the 3D dynamic modeling of the kidney and tracking a tumor of this organ. It is in line with the KiTT project (Kidney Tumor Tracking) which gathers researchers from different fileds: geometric modeling, radiology and urology. This work arised from the tendency of nowadays surgical gestures to be less and less invasive (HIFU, coelioscopy). Its goal is to result in a totally non-invasive protocol of kidney tumors eradication by transmitting ultrasound waves through the skin without breaking in it. As the kidney presents motions and deformations during the breathing phase, the main issue is to know the kidney and tumor positions at any time in order to adjust the waves accordingly.
312

Characterisation and performance of fibre-reinforced composite restorations

Al-Haddad, Ala'A. January 2015 (has links)
In the modern era of metal-free minimally-invasive dentistry, there is a growing tendency toward using metal-free restorative alternatives that provide not only excellent aesthetics but also enable superior durability. Fibre-reinforced composite (FRC) is one cost-effective alternative that fulfils the requirements of aesthetics and durability, and offers favourable physico-mechanical properties. Many FRC applications are well-documented in the literature, such as crowns and fixed partial dentures (FPD); however, their clinical implementation is still limited, owing to the lack of significant knowledge about their longevity, deterioration signs, optimum design and overall performance. This in-vitro research aimed to address these uncertainties by investigating the performance of FRC restorations, and the influence of fibre reinforcement on particular physcio-mechanical properties, including surface hardness, edge-strength, shear bond strength, fatigue and wear resistance. Basic testing models were used to investigate the effect of incorporating differently-oriented FRCs on the surface hardness, edge-strength and shear bond strength of particulate-reinforced composite (PRC). The results revealed that the incorporation of FRC significantly enhanced surface hardness (by 12 - 19 %) and edge-strength (by 27 -75 %). However, this incorporation significantly reduced the shear bond strength (SBS) between PRC and other restorative materials, including lithium disilicate ceramic (10.9±3.1 MPa) and Co-Cr metal alloy (12.8±2.3 MPa), compared to the control (15.2±3.6 MPa, 15.0±3.7 MPa). The orientation of FRC was also found to affect the efficiency of reinforcement as bidirectional FRCs exhibited significantly higher hardness (76.8±1.2 VHN), edge-strength (67.7±8.2 N) and SBS (14.1±3.9 MPa) values than unidirectional FRCs (72.4±1.2 VHN, 56.8±5.9 N, 9.8±2.3 MPa).Clinically-relevant testing models, employing accelerated aging techniques, were performed to investigate the fatigue and wear behaviours of anatomically-shaped FRC restorations in-vitro. Direct inlay-retained FRC-FPDs with two framework designs, were tested for their fatigue behaviour and load-bearing capacity. Type-I design (with an additional bidirectional FRC layer incorporated perpendicular to the loading direction) yielded significantly higher fatigue resistance (1144.0±270.9 N) and load-bearing capacity (1598.6±361.8) than Type-II design (with a woven FRC embedded around the pontic core) (716.6±72.1 N, 1125.8±278.2 N, respectively). However, Type-19II design exhibited fewer delamination failures. Both framework design and dynamic fatigue were found to have a significant influence (p < 0.05) on the load-bearing capacity of FRC-FPDs. Additionally, the in-vitro fatigue and wear behaviours of FRC crowns, fabricated conventionally from bidirectional FRC and indirect PRC (Sinfony), were compared with those made of two CAD/CAM alternatives, namely Lava Zirconia (LZ) and Lava Ultimate (LU). A chewing simulator was employed to induce some fatigue wear in crowns, while an intraoral 3D scanner was used to quantify the resultant morphological changes. The results showed that FRC crowns had significantly lower mean cumulative wear (233.9±100.4 μm) than LU crowns (348.2±52.0 μm), but higher than LZ crowns (16.4±1.5 μm). The mean load bearing-capacity after fatigue simulation was also the highest for LZ crowns (1997.8±260.2 N) compared with FRC (1386.5±258.4 N) and LU crowns (756.5±290.9 N).Accordingly, the incorporation of FRC in resin-composite restorations is advocated since it increases surface hardness and marginal integrity, improves fatigue and wear behaviours, and enhances load-bearing capacity and overall performance.
313

Datorstödda mättekniker i fält av sprickor i limträbalkar

Vorobyev, Alexey January 2012 (has links)
Cracks in wood are considered to be one of the major problems for products, which have been made from this material. Crack detection and its propagation methods should be revised and improved with application of modern techniques. Nowadays new measuring techniques like digital camera image processing, and 3-D laser scanning are available. This work describes computer aided in-field methods for registration cracks in wood, its propagation, and tracing dimensional stability of glued laminated beams. The benefits of different methods for supervision of wooden element as well as its limitations are discussed. / <p>Validerat; 20120608 (anonymous)</p>
314

Développement des instruments de mesures des profiles transversaux et d'emittance pour l'accélérateur linéaire LINAC4 au CERN / Development of beam transverse profile and emittance monitors for the CERN LINAC4

Cheymol, Benjamin 15 December 2011 (has links)
Dans les prochaines années, le complexe d'accélérateur du CERN va subir une profonde mise a jour dont le but est une augmentation de la luminosité du LHC. Le projet LIU ( LHC Injectors Upgrade) coordonne les mises a jour des différentes parties de la chaine d'injection. Le projet LINAC4 s'inscrit dans ce cadre et sera la première étape de la mise à jour. Cette thèse présente les différentes études conduites lors du développement de l'instrumentation nécessaire à la mesure du faisceau. Ce travail est limité aux instruments permettant la mesure des profils transverses (taille et emittance). La thèse se divise en quatre parties. La première partie, composée des trois premiers chapitres, est vue comme une partie d'introduction où il sera présenté le projet LINAC4 ainsi que les différents aperçus théoriques nécessaires à la conception de types d'instruments requis. Le chapitre 2 décrit brièvement la dynamique des faisceaux dans un accélérateur et présente également des rappels théoriques sur l'effet de charge d'espace induit par le faisceau. Le chapitre 3 est un rappel sur les interactions entre particules et matière. La seconde partie, comprenant les chapitres 4 a 6, décrit les différentes études menées lors de la conception des SEM grid, wire scanner et emittance mètre. Le lecteur trouvera dans cette partie une description des instruments mentionnés et qui seront déployés lors de la phase de test et pendant la phase d'opération du LINAC4. Le chapitre 4 s'attarde sur les effet de charge thermique induite sur les fils des SEM grid et wire beam scanner par le faisceau et leur conséquence sur la survit de ces fils. Le LINAC4 va produire un faisceau intense d'ion H-, avec une taille de faisceau de l'ordre du millimètre, cette densité de particule va, à basse énergie, induire un grand dépôt d'énergie dans la matière. La hausse de température qui en résulte peut dépasser les limites thermomécaniques des matériaux usuels employés pour ce type de mesure. Cette étude permet de déterminer le matériau idéal pour le fil et d'imposer certaines restrictions sur l'utilisation des différents moniteurs de profils. Au sein de ce chapitre il est aussi présente une estimation des signaux obtenus pour des géométries et des matériaux de fils différents. Les chapitres 5 et 6 sont une études de l'emittance mètre a moyenne énergie du LINAC4 (3 et 12 MeV), le système employé est un système dit "Slit & grid", ou une fente permet de sélectionner une faible partie du faisceau, le reste étant absorbé, le profil du faisceau non perturbé est mesuré par une grille. Le chapitre 5 présente une étude sur les erreurs systématiques des mesures d'emittance dû a la diffusion multiple et a l'effet de charge d'espace du faisceau, ces deux phénomènes constituant les principales erreurs conduisant à une mauvaise reconstruction de l'emittance mesurée. Le chapitre 6 quant a lui est dédié à l'étude mécanique de la fente de l'emittance mètre. Comme pour les fils des moniteurs de profils, la charge thermique sur la partie supportant la slit est importante. Ce chapitre décrit les études effectuées pour le choix des matériaux et de la géométrie des pièces mécaniques. La troisième partie de la thèse, qui se résume au chapitre 7, est consacrée aux différents résultats expérimentaux obtenus dans la phase de test de la source de particule du LINAC4 ainsi que ceux obtenus lors d'une visite d'étude à SNS. Une partie de se chapitre décrira la mise au point de l'instrumentation aux banc test de la source, une autre présente l'effet de la diffusion multiple sur les mesures d'emittance à SNS et propose une mise a jour de l'instrument. Le chapitre 8 constitue la dernière partie de cette thèse. Dans ce dernier chapitre, le lecteur pourra lire une étude préliminaire sur l'utilisation d'un faisceau laser pour la mesure d'emittance et de profil aux hautes énergies du linac. / LINAC4 is part of the CERN Large Hadron Collider injector chain upgrade (LIU) and will accelerate H− ions from 45 keV to 160 MeV, it will be the first step of the upgrade with the replacement of LINAC2 in 2018. In order to measure beam profiles along the LINAC, several SEM grid and wire beam scanner (WS) monitors will be installed between the RF cavities from 50 MeV to 160 MeV. This thesis covers all monitor design aspects intended to cope with the required specifications. In particular, the overall measurement robustness, accuracy and sensitivity must be satisfied for different commissioning and operational scenarios. The physics mechanisms generating the wire signals and the wire resistance to beam induced thermal loads have been considered in order to determine the most appropriate monitor design in terms of wire material and dimensions. In addition, for the commissioning phase, a movable diagnostics test bench will be used to adjust the machine parameters during different stages of installation. One of the main instruments on this movable bench is a transverse emittance meter. This thesis presents the different studies done for the mechanical design of the slit and for the estimation of the systematical error on the measurement due to space charge and multiple scattering. To complete this section, the first results of the commissioning of the LINAC4 ions source and LEBT are presented, together with results form emittance measurement taken at the Spallation Neutron Source in Oak Ridge (Tennessee, USA). This last part of the thesis presents different studies done for a beam profiles and emittance measurements with a laser wire, with a large input from the SNS beam diagnostic group.
315

Expanding the Definition of Liminality: Speculative Fiction as an Exploration of New Boundaries

Lacy, Dianna C 20 December 2019 (has links)
Speculative fiction allows an expanded view of literature and so allows scholars to explore new boundaries in the way words and ideas work. In the titular character of The Last Unicorn by Peter S. Beagle, the reader sees an expansion of self through liminality while A Scanner Darkly by Philip K. Dick explores its collapse. In order to portray each of these the character examined must move though one seems to move upward and the other downward. This idea of movement is only part of what expands the idea of liminality past the traditional idea of a doorway to create a hallway that the character might traverse on the way from place to place. This is not a redefinition of the term but a revision, a change in the way that we look at the concept as we accept and explore newer genres.
316

Breaking Down the Reflex-Machine in Three Works by Philip K. Dick

Gaarn-Larsen, Sara January 2018 (has links)
This thesis expands upon Philip K. Dick’s philosophy surrounding ‘androidization’, a process of degradation leading to the devolution of individuals into what he termed as ‘reflex-machines’. Often used interchangeably with Dick’s reference to the human-android, existing criticism has applied the ‘reflex-machine’ label broadly to characters throughout his work. This thesis aims to clarify the implications of such a state through a close reading of his three works, The Three Stigmata of Palmer Eldritch, A Maze of Death, and A Scanner Darkly while detailing the processes that comprise the androidization which produces it. In doing so, it proposes that androidization is made up of a series of stages. This distinction is vital for understanding what Dick suggests for the potential recovery of the individual from the state of a reflex-machine and his hope for humanity at large. Split into two parts, this essay first examines the production of the reflex-machine with the support of theories by Louis Althusser, Max Horkheimer and Theodor Adorno, Michel Foucault, and Jean Baudrillard. It then considers the solutions that Dick proposes for the individual undergoing androidization by referencing theories by Carl Jung, as well as Gilles Deleuze and Felix Guattari.
317

Tuhost ramene průmyslového robotu / Stiffness of Industrial Robot Arm

Vogel, Jan January 2017 (has links)
Stiffness analysis of an arm of an industrial robot with linear kinematics during a drilling operation. For solving this problem are used optical scanners. Finding the optimal cutting force for drilling by criterions: minimal deformation of robots arms and, at the same time, the emerging vibration from the cutting process is also minimal.
318

Pozemní laserové skenování / Terrestrial laser scanning

Endlicherová, Lucie January 2015 (has links)
This diploma thesis is focused on determine the characteristics of accuracy of the terrestrial laser scanner FARO Focus 3D S120. It is validated the recommended distance between the objects (targets and spheres) and the terrestrial scanner. Next it is tested accuracy of the Cartesian coordinates X, Y, Z measured by laser scanning with resolution 1/2. At the end it is investigated the accuracy of the area determination in X coordinate gained by the scanning of a smooth slightly curved surface.
319

Analýza přesnosti laserového skenování / Analysis of an accuracy of laser scanning

Vacová, Dominika January 2017 (has links)
The main goal of this master thesis is processing a point cloud with respect of possibilities of a registration clouds based on reference objects or on objects in general. This thesis studies transformations to the reference coordinate system S –JTSK. The first part of this thesis describes a theoretical background of the laser scanning and its use. A practical part shows the results and the evaluation of whole research.
320

Tvorba 3D modelu budovy s využitím laserového skenování / Creation of 3D model of building using laser scanning

Sabo, Stanislav January 2016 (has links)
The aim of this thesis is to scan the part of the interior and exterior of the Faculty of Electrical Engineering and Communication building using the FARO Focus3D X 130 scanner, and the creation of a 3D model in the WGS 84 system. Subsequently, methods, status and utilization research of this technology and point cloud processing software is provided. The collected data are processed in the SCENE. Three-dimensional model is designed using the Pointfuse and Microstation V8i programs. In the end, the registration accuracy of the scans and the resulting 3D model accuracy are evaluated.

Page generated in 0.0383 seconds