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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Etude de l'adhérence de revêtements poudre appliqués sur substrats composites à matrice polymère / Study of adhesion of powder coating apply on polymer matrix composite substrate

Lafabrier, Aurore 11 March 2014 (has links)
Sur de nombreuses pièces et structures, la peinture garantit une protection de surface et assure l'esthétique du produit final. Cependant, l'arrivée de nouvelles directives visant à réduire les sources de rejets majoritaires de Composés Organiques Volatiles (COV) incite les industriels à s'orienter vers des technologies alternatives aux peintures solvantées classiques, telles que les revêtements poudres. Dans le cas d'un substrat non-conducteur thermosensible, cette substitution implique de développer de nouvelles méthodes de mise en œuvre et d'en optimiser les paramètres.Ce travail de thèse vise à maîtriser l'adhérence et à comprendre les phénomènes d'adhésion de peintures poudre sur substrats composites à matrice organique, d'un point de vue physico-chimique. Notre travail s'est articulé autour d'une peinture poudre et de deux substrats composites dont l'un possède une matrice thermodurcissable (époxy) et l'autre une matrice thermoplastique (PEEK).Dans un premier temps, nous avons analysé l'influence des conditions de mise en œuvre sur l'interface substrat époxy/revêtement, afin de déterminer quel procédé favorise le plus l'adhérence entre la méthode "fond de moule" et l'application directe. Nous nous sommes, ensuite, intéressés à la durabilité de ces systèmes revêtus lors d'un vieillissement hygrothermique. Enfin, nous avons étudié l'effet des traitements plasmas atmosphérique et basse pression sur l'adhérence entre le revêtement poudre et le substrat à matrice PEEK. / On many products and structures, the painting ensures surface protection and provides aesthetic of final product. However, the new guidelines to reduce the main release's sources of Volatile Organic Compounds (VOCs) incite the industrials to use alternative to usual solvent-based paints such as powder coatings. In the case of non-conductive and heat-sensitive substrate, this substitution involves the development of new processes and the optimization of their parameters.This thesis is about controlling adhesion and understanding the adhesion of powder coatings on organic matrix composites substrates, on a physico-chemical point of view. Our work focus on a powder coating and two substrates, one containing thermosetting resin (epoxy) and the other a thermoplastic resin (PEEK) .As a first step, we analyzed the influence of the characteristic of the process on the epoxy substrate/coating interface to determine which one promotes the best adhesion between the "in mold-coating" and direct application. Then we studied the durability of these coated systems in a hydrothermal aging. Finally, we studied the effect of atmospheric plasma treatment and low pressure plasma treatment on the adhesion between powder coating and PEEK matrix substrate.
2

Design and control of a haptic device for minimally invasive surgery simulation / Conception et commande d'un dispositif à rendu haptique dans le cadre de la simulation de chirurgie minimalement invasive

Guiatni, Mohamed 22 June 2009 (has links)
L'objectif principal de cette thèse est de développer une nouvelle interface pour la simulation des procédures de chirurgie mini-invasive. L'interface développée introduit les modalités visuelle, haptique et thermique pour les futures générations de simulateurs et de robots chirurgicaux. La particularité de cette recherche réside dans l'utilisation de la stimulation thermique dans une perspective d'application pour la chirurgie. Dans ce cadre, plusieurs modèles de transfert de chaleur ont été développés, implémentés et évalués pour des applications de téléprésence et de réalité virtuelle. Des sensations intéressantes ont été enregistrées, ce qui a une conséquence directe sur la capacité de distinguer entre des objets dans l'environnement et particulièrement dans le domaine médical où la sensation thermique est en corrélation avec la présence d'anomalies dans certaines maladies. Un nouveau dispositif haptique est conçu et réalisé en analysant les tâches chirurgicales en termes de dextérité, d'espace de travail, de force et de couple exigés. Nous avons tenu compte des exigences générales de conception mécaniques des interfaces haptiques à partir de ce qui a été établi dans la littérature de l'haptique. Le dispositif complet a été interfacé avec un logiciel de simulation en réalité virtuelle (SOFA). Nous avons intégré dans SOFA le module nécessaire pour la simulation thermique. L'intégration était réussie et un scénario de simulation réaliste avec le retour d'information visuel que thermique a été réalisé. Des résultats préliminaires utilisant la simulation complète sont présentés. / The main objective of this thesis focuses on the construction of a new interface for Minimally Invasive Surgery training. This interface incorporates novel broad band sensory modalities that include visual, haptic and thermal technology, into the evolution of the next generation of surgical robotic and surgical simulator. Our particular novelty in this research is in using of thermal stimulation in a MIS applied perspectives. Several thermal exchange models have been designed, implemented and evaluated for telepresence and virtual reality applications. Interesting sensations have been recorded which have a direct bearing on the ability to distinguish between objects in the surrounding environment and particularly in the medical field where temperature sensing correlates with anomalies in some know diseases. A new haptic device is designed and realized by analyzing surgical tasks in terms of required dexterity, workspace, force and torque. The mechanical design constraints have been considered with respect to the general requirements for haptic interface design from what has been well established in the haptics literature. The overall device has been interfaced with an open source VR simulator (SOFA). We added in SOFA the necessary software dealing with thermal simulation using built-in data structure and methods. The integration was successful and a realistic simulation scenario with both visual and thermal feedback was achieved. Preliminary results using the overall simulation are presented.
3

Molecular theory and simulation of oil-water contacts

January 2017 (has links)
acase@tulane.edu / The statistical mechanical theory of hydrophobic interactions was initiated decades ago for purely repulsive hydrophobic species, in fact, originally for hard-sphere solutes in liquid water. Systems which treat only repulsive solute-water interactions obviously differ from the real world situation. The issue of the changes to be expected from inclusion of realistic attractive solute-water interactions has been of specific interest also for decades. We consider the local molecular field (LMF) theory for the effects of solute attractive forces on hydrophobic interactions. The principal result of LMF theory is outlined, then tested by obtaining radial distribution functions (rdfs) for Ar atoms in water, with and without attractive interactions distinguished by the Weeks-Chandler-Andersen (WCA) separation. Change from purely repulsive atomic solute interactions to include realistic attractive interactions substantially diminishes the strength of hydrophobic bonds. Since attractions make a big contribution to hydrophobic interactions, Pratt-Chandler theory, which did not include attractions, should not be naively compared to computer simulation results with general physical interactions, including attractions. Lack of general appreciation of this point has lead to mistaken comparisons throughout the history of this subject. The rdfs permit evaluation of osmotic second virial coefficients B2. Those B2 are consistent with the conclusion that incorporation of attractive interactions leads to more positive (repulsive) values. In all cases here, B2 becomes more attractive with increasing temperature below T = 360K, the so-call inverse temperature behavior. In 2010, the Gulf of Mexico Macondo well (Deepwater Horizon) oil spill focused the attention of the world on water-oil phase equilibrium. In response to the disaster, chemical dispersants were applied to break oil slicks into droplets and thus to avoid large-scale fouling of beaches and to speed up biodegradation. Eventually the dispersant COREXIT 9500 was used predominantly in responding to this accident. The formulation of COREXIT dispersants is somewhat complicated and the various constituents (and their interactions) deserve exhaustive study. Here we focus on sorbitan monooleate (SPAN80), one important component of COREXIT 9500, and we investigate its behavior in oil-water-surfactant systems. Extensive all-atom molecular dynamics calculations on the water-squalane interface for nine different loadings with SPAN80, at T=300K, are analyzed for the surface tension equation of state, desorption free energy profiles as they depend on loading, and to evaluate escape times for absorbed SPAN80 into the bulk phases. These results suggest that loading only weakly affects accommodation of a SPAN80 molecule by this squalane-water interface. Specifically, the surface tension equation of state is simple from conditions of low loading (high tension) to high loading (lower tension) studied, and the desorption free energy profiles are weakly dependent on loading here. The perpendicular motion of the centroid of the SPAN80 head-group ring is well-described by a diffusional model near the minimum of the desorption free energy profile. Lateral diffusional motion is weakly dependent on loading. Escape times evaluated on the basis of a diffusional model and the desorption free energies are 0.07~s (into the squalane) and 300~h (into the water). The latter value is consistent with irreversible absorption observed by related experimental work. / 1 / Liang Tan
4

Web-based feedback system: the life cycle management as continuous maintenance of apartment facility information

Jeong, Jin Su 30 October 2006 (has links)
This research investigates the feasibility of web technology as a means of delivering facility information for better support of facility operations and maintenance. This study proposes a web-based feedback system as a pragmatic solution to the limitations of current facility management (FM) processes, increasing the efficiency of these processes via web technology. In practice, work orders and records are often misplaced, resulting in reduced efficiencies, redundancies, and time-consuming, costly tasks. This problem may be overcome by use of a system that stores information digitally and provides a web-based interface. The interface could allow operations personnel to create documentation, share and monitor work orders, provide feedback for service online, and facilitate communication between facility teams. The benefit for a FM department is that it can receive feedback on performance, which would improve the quality of service and build a record of practical experiences. In this research, the software was tested using two types of prototype testing: first, system testing to evaluate functionality, usability and capability; and second, a post-task questionnaire survey was conducted to test and review the concept, interface, and usability of the system. Facility Management Industry Advisor Council (FMIAC) members answered the questionnaires after using the system posted on the web. By using web-based feedback system, a facility web site can be created and maintained easily through a standard web browser. The questionnaires from the FMIAC members were analyzed to test research questions. The tests show that the software aids facilities managers in maintaining living documents of their facilities.
5

Web-based feedback system: the life cycle management as continuous maintenance of apartment facility information

Jeong, Jin Su 30 October 2006 (has links)
This research investigates the feasibility of web technology as a means of delivering facility information for better support of facility operations and maintenance. This study proposes a web-based feedback system as a pragmatic solution to the limitations of current facility management (FM) processes, increasing the efficiency of these processes via web technology. In practice, work orders and records are often misplaced, resulting in reduced efficiencies, redundancies, and time-consuming, costly tasks. This problem may be overcome by use of a system that stores information digitally and provides a web-based interface. The interface could allow operations personnel to create documentation, share and monitor work orders, provide feedback for service online, and facilitate communication between facility teams. The benefit for a FM department is that it can receive feedback on performance, which would improve the quality of service and build a record of practical experiences. In this research, the software was tested using two types of prototype testing: first, system testing to evaluate functionality, usability and capability; and second, a post-task questionnaire survey was conducted to test and review the concept, interface, and usability of the system. Facility Management Industry Advisor Council (FMIAC) members answered the questionnaires after using the system posted on the web. By using web-based feedback system, a facility web site can be created and maintained easily through a standard web browser. The questionnaires from the FMIAC members were analyzed to test research questions. The tests show that the software aids facilities managers in maintaining living documents of their facilities.
6

Organic Board Games with Tangible Tiles: interaction methods for small hexagonal tiles

Rooke, Michael 27 April 2009 (has links)
The keyboard and mouse have dominated human-computer interaction for over twenty years. Much effort has been made to break away from this paradigm by creating novel interaction systems and techniques. This thesis presents a system with small hexagonally shaped cardboard tiles called Organic Board Games, along with methods of interaction for these tiles. Tiles are used as a means for controlling and interfacing with abstract objects in a computer system. Particular attention is given to controlling games with the tiles, as some of the original motivation for the system was from the board game Settlers of Catan. The many design considerations for Organic Board Games are discussed; prototype implementations that were constructed are presented and critiqued, and observations are made regarding these systems' applicability to interface design. Several proposals are presented for the system's evaluation and development beyond the example implementations. / Thesis (Master, Computing) -- Queen's University, 2009-04-25 13:23:44.451
7

The design of an economical, high speed interface between the cirrus computer and the Chemical Engineering Process control laboratory.

Dunne, Lawrence John. January 1969 (has links) (PDF)
Thesis (Master of Applied Science) -- University of Adelaide, Faculty of Engineering, 1971.
8

Apport de l'humour dans les interventions d'agents pour soutenir le télé-apprentissage

Hudon, Martin January 2001 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
9

Influência da ciclagem térmica e mecânica em água na resistência ao cisalhamento da união infraestrutura/porcelana de cobertura de diferentes sistemas totalmente cerâmicos / Shear bond strength of all-ceramics core/veneer interface and its susceptibility to thermal and mechanical cycling

Vidotti, Hugo Alberto 23 May 2011 (has links)
Este estudo avaliou a influência da ciclagem térmica e mecânica, aliadas, na resistência ao cisalhamento da interface entre porcelana de cobertura e infraestruturas de diferentes sistemas totalmente. Também foi realizada a caracterização das interfaces por meio de análise de espectroscopia por energia dispersiva de Raios X (EDS). Foram testados sistemas totalmente cerâmicos a base de dissilicato de lítio (DL), zircônia tetragonal estabilizada por ítrio recoberta por estratificação (ZC) e por injeção (ZI) e alumina infiltrada por vidro (AI). Um grupo metalocerâmico a base de liga de CoCr foi testado como grupo controle. Vinte espécimes circulares de 6mm de diâmetro de cada sistema foram submetidos ao teste de resistência ao cisalhamento em máquina de ensaios mecânicos, sendo que metade destes (n=10) sofreram os procedimentos de ciclagem térmica e mecânica antes da realização dos testes. Os resultados foram analisados através do teste ANOVA a dois critérios (p<0,05) e utilizou-se teste de Tukey (p<0,05) para as comparações múltiplas. Análise das fratura foi realizada através de estereomicroscópio e MEV. A análise de EDS foi realizada ao longo da interface infraestrutura/porcelana de cobertura em um espécime de cada sistema seccionado longitudinalmente. As ciclagens térmica e mecânica aliadas não influenciaram na resistência ao cisalhamento dos sistemas testados. Houve, contudo, diferença estatística entre os sistemas testados. O grupo CoCr apresentou os maiores valores (34,72 ± 7,05 Mpa), seguido dos grupos DL (27,07 ± 5,28), ZI (23,58 ± 2,71), ZC (22,46 ± 2,08) e AI (18,15 ± 1,99). Os modos de fratura foram predominantemente adesivos para o grupo CoCr, coesivos na infraestrura para o grupo DL, coesivo na porcelana de cobertura para os grupos ZC e ZI, e mistos para o grupo AI. As análises de EDS mostraram haver uma zona de interação para todos os sistemas testados. Deste modo, é possível sugerir, através das análises de fratura e de EDS, que haja uma união química entre a porcelana de cobertura e infraestrutura nos diferentes sistemas testados e que as variações de resistência ao cisalhamento estão relacionadas a fatores intrínsecos ou na capacidade de molhamento da porcelana de cobertura. / The objective of this study was to evaluate the influence of thermal and mechanical cycling on the shear bond strength of different all-ceramic cores and veneering porcelain interfaces. It was also to characterize chemically the interfaces by energy dispersive spectroscopy (EDS). The allceramic systems tested were lithium dissilicate (DL), zirconia veneered by layering technic (ZC) or pressing technic (ZI) and glass infiltrated alumina (AI). A CoCr group was used as control. Twenty cylindrical specimens for each system were subjected to shear bond strength in a universal testing machine with a 0.5 mm/min crosshead speed. Half of the specimens (n=10) were thermal and mechanical cycled before shear bond strength was carried out. Mean shear bond strength (MPa) were analyzed with a 2-way analysis of variance and the Tukey test. Failures were classified with tereomicroscope and scanning electron microscope (SEM) analysis. In an addition, energy dispersive X-ray spectroscopy (EDS) analysis was performed from core/veneer interfaces. Thermal and mechanical cycling did not influence statistically on the shear bond strength for the systems evaluated. However, there was a statically significant difference between the systems evaluated. Control group (CoCr) presented the highest values (34,72 ± 7,05 Mpa), followed by DL (27,07 ± 5,28), ZI (23,58 ± 2,71), ZC (22,46 ± 2,08) e AI (18,15 ± 1,99). Thermal and mechanical cycling did not influence statistically on the shear bond strength for the systems evaluated. Failure modes were predominantly adhesive for CoCr group, cohesive in the core for DL, cohesive in veneer for groups ZC and ZI and mixed for AI. EDS analysis showed a interaction zone for all systems evaluated. Thus, it is possible to suggest, trough EDS analysis, that there is a chemical bond between core and veneer materials and that the shear bond strength variations can be related to intrinsic factors within veneering porcelain or to its wetting capacity.
10

Mecanismo de condução elétrica na interface do &#945;-Ag2WO4 e do &#945;-Ag2-xWO4 com nanopartículas de Ag na superfície / Electrical conduction mechanism at the interface of &alpha;-Ag2WO4 e do &alpha;-Ag2-xWO4 with Ag nanoparticles on the surface.

Gollino, Felipe 03 August 2015 (has links)
O projeto tem como proposito estudar o comportamento elétrico da microestrutura e interface de tungstato de prata e do tungstato de prata com nanoparticulas de prata focando em uma possível aplicação como dispositivo eletrônico. Os rods de &alpha;-Ag2WO4 foram sintetizadas utilizando o método hidrotermal assistido por microondas e posteriormente submetidas a um feixe de elétrons fazendo com que os íons de prata Ag+, dentro do bulk do cristal, sejam reduzidos e migrem para a superfície do material crescendo as partículas metálicas. A nucleação desses filamentos podem ser visualizado ao vivo e in situ acompanhando as imagens de MEV-FEG da matrix do material. A fase do material, posições atômicas e o entendimento da distrorção da rede foi confirmada pela difratometria de raio-X com o refinamento Rietveld. O material foi caracterizado, estruturalmente, pelas técnicas de espectroscopia Raman e infravermelho, na qual consegue entender quais são as ligações a curto alcance que os átomos estão fazendo. Foi estudado o seu comportamento eletrônico e espectroscópico, por medidas de espectroscopia de UV-Vis-NIR determinando o valor de bandgap do material. Por meio das medidas de XPS foi possível comparar o a pureza e o o grau de oxidação da superfície. E finalmente, foram realizadas medidas de espectroscopia de impedância e condutividade elétrica em regime DC do material não-irradiado e irradiado para com o feixe de elétrons para se entender o mecanismo de condução elétrica. Pelas curvas de impedância, é possível perceber que as amostras irradiadas possuem uma resistência maior causada pelos defeitos gerados dentro da estrutura dificultando a mobilidade dentro do cristal. Foi possível notar pelas medidas elétricas, que a formação dessa superfície com o nanoparticulas altera o o contato entre os cristais do material, apresenta um desvio da linearidade, essa a fase no contorno estaria permitindo a migração dos portadores de carga nos limites dos cristais de tungstato. / This project have to aim study the electrical conduction behavior of silver tungsten and silver tungsten with Ag nanoparticles microstructures and interface on focus in a possible application in electronic device. The rods of &alpha;-Ag2WO4 were synthetized using a microwave assisted method and then target by a electron beam, making the Ag+ ions inside of the crystal, reduce and go out to surface material as nanoparticles of Ag0 metallic. This growth can be view in situ by MEV-FEG. The phase of material, atomic position and structure distortion was confirmed by DRX pattern with Rietveld refinement. The material was structural characterized for Raman and infrared spectroscopy, which could be understood what bonds at short range the atoms was doing. The electronic behavior was study by UV-Vis-NIR spectroscopy for determine the bandgap. XPS measurements were performed to compare the purity of the surface and the degree of oxidation. Finally, the samples non-irradiated and irradiated were characterized electrical with impedance spectroscopy and electrical conductivity in DC to understand the electrical conduction mechanism. For the impedance curves, it was possible to notice that the samples irradiated have a higher resistance caused by the bulk defects difficult the mobility inside de crystal. Can be observed by electrical measures, that the formation of this surface with nanoparticles modify the contact between the crystal, showing a leak of linearity, this phase in the boundary could allow the migration of the charge transport.

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