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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.
161

Monoclinic tm:klu(w04)2: a new crystal for efficient diode-pumped continuous-wave and q-switched lasers

Segura Sarmiento, Martha Yamile 27 April 2012 (has links)
El doble tungstato cristalino de potasio y lutecio con estructura monoclínica, KLu(WO4)2, se ha establecido como una nueva matriz laser de estado sólido para iones de Tm, Yb y Ho debido a (i) las altas secciones eficaces de absorción y emisión; (ii) la relativamente larga distancia entre iones Lu-Lu permitiendo altos niveles de concentración de iones activos sin perdidas significativas por fluorescencia; y (iii) el tiempo de vida suficientemente largo del nivel emisor de la transición láser asegurando un alto almacenamiento de energía. Estas características son explotadas en este trabajo usando Tm como ion activo para generar emisión láser a 1.94 µm. El máximo local de absorción del agua a esta longitud de onda hace a este laser interesante para aplicaciones medicas y atmosféricas. Cambio de polarización, operación en dos longitudes de onda, laser vibrónico, diseño láser de capa delgada Thin-disk, Q-conmutado pasivo y la interacción láser-tejido del láser de Tm:KLu(WO4)2 a 1.94 µm son demostrados en este trabajo. / Monoclinic potassium lutetium double tungstate KLu(WO4)2 is established as new laser host for Tm, Yb and Ho active ions due to (i) its very high values of absorption and emission cross sections (ii) its relatively large Lu-Lu distances allowing high ion concentration with minimum fluorescence quenching effects and (iii) the long lifetime of the upper laser level ensuring high energy storage. These characteristics are exploited in this work using Tm as active ion to generate laser emission at 1.94 µm. The local maximum of water absorption at this wavelength makes this laser interesting for medical and atmospheric applications. Polarization switching, dual-wavelength operation, vibronic laser, thin-disk laser design, passive Q-switching and the laser-tissue interaction of the 1.94 µm Tm:KLu(WO4)2 laser are demonstrated in this work
162

Dietary effects on cardiovascular disease risk biomarkers

Valls Zamora, Rosa Maria 09 October 2009 (has links)
La tesis consta de 4 proyectos: dos estudios de intervención, aleatorizados, paralelos y controlados, uno sobre los efectos de productos del cacao y otro sobre los de fibra soluble, Plantago ovata husk (Po-husk), sobre biomarcadores de enfermedad cardiovascular (ECV) en sujetos hipercolesterolémicos. El tercero es la identificación de compuestos fenólicos del aceite de oliva virgen (AOV) en plasma humano (en ayunas y en fase postprandial) y el cuarto, el desarrollo de una aplicación informática para implementar los criterios CONSORT.Los productos del cacao y Po-husk reducen las concentraciones plasmáticas de c-LDL y ejercen efectos beneficiosos sobre otros biomarcadores de ECV.Además se han detectado hasta 10 compuestos fenólicos del AOV, incluido el 3,4-DHPEA-EDA, en plasma humano postprandrial.Finalmente, la incorporación de productos del cacao o Po-husk o el AOV o su combinación a una dieta cardiosaludable se adecuará al perfil de biomarcadores de riesgo de ECV de cada paciente. / The thesis is based on 4 projects: 2 randomised, controlled, interventional studies, one of the cocoa cream products and the other of the soluble fibre (Plantago ovata husk (Po-husk) on biomarkers of CVD. Third, the virgin olive oil (VOO) phenolic compounds identification in fasting and postprandial human plasma, and fourth, designed a technology application to facilitate the implementation of criteria CONSORT statement.The cocoa cream products and Po-husk reduced in plasma LDL-c and also, had beneficial effects on other CVD biomarkers and risk factors.Also, had been detected until 10 phenolic compounds from VOO, including 3,4-DHPEA-EDA, in human postprandial plasma.Finally, applying cocoa products or Po-husk or VOO or in combination in a cardio-protective diet warrants consideration as individualised therapeutic measures based on the individual's CVD risk factor profile.
163

A trajectória da prevançao às drogas no Brasil: do proibicionismo à reduçao de danos e seus reflexos nas políticas locais

Silva Trad, Sergio do Nascimento 20 December 2010 (has links)
RESUMEN La investigación analizó el control y la regulación del uso de drogas en el Brasil – donde se confrontan los modelos de abstinencia y de Reducción de Daños - y sus implicaciones para las políticas y prácticas locales. El marco teórico apoyase en el enfoque socio-cultural del fenómeno de las drogas a partir de Oriol Romaní, Howard Becker, Norbert Elias e Roger Chartier. La metodología articuló la investigación histórica, basada en análisis documental, y el estudio etnográfico en tres instituciones de asistencia as drogas en Salvador y espacios complementares (barrios populares, eventos científicos). Los resultados apuntan contradicciones en la actual política nacional de drogas. Los servicios especializados incorporan progresivamente el modelo de la Reducción de Daños. Sin embargo, el ideal de la abstinencia persiste fuertemente en el imaginario social brasileño y se refleja en las conductas de la policía, y ciertamente, en las dificultades de financiación de los servicios. / A investigação analisou o controle e a regulação do uso de drogas no Brasil – confrontando os modelos de abstinência e de Redução de Danos - e suas implicações para as políticas e práticas locais. O marco teórico apóia-se no enfoque sócio-cultural do fenômeno das drogas a partir de Oriol Romaní, Howard Becker, Norbert Elias e Roger Chartier. A metodologia articulou a investigação histórica, baseada na análise documental, e estudo etnográfico em três instituições de assistência às drogas em Salvador e espaços complementares (bairros populares, eventos científicos). Os resultados apontam contradições na atual política nacional de drogas. Os serviços especializados incorporam progressivamente o modelo de Redução de Danos. Entretanto, o ideal da abstinência persiste fortemente no imaginário social brasileiro e se reflete nas condutas da policia, e certamente, nas dificuldades de financiamento dos serviços.
164

MULTIVARIATE CHARACTERIZATION OF LIGNOCELLULOSIC BIOMASS AND GRAFT MODIFICATION OF NATURAL POLYMERS

KRASZNAI, DANIEL 29 February 2012 (has links)
The plant cell wall contains significant quantities of renewable polymers in the form of cellulose, hemicellulose, and lignin. These three renewable polymers have the potential to complement or replace synthetic polymers in a variety of applications. Rapidly determining the quantities of these polysaccharides in lignocellulosic biomass is important yet difficult since plant biomass is recalcitrant and highly variable in composition. Part of this contribution outlines a novel compositional analysis protocol using infrared spectroscopy and multivariate regression techniques that is rapid and inexpensive. Multivariate regression models based on calibration mixtures can be used to discern between populations of lignocellulosic biomass or to predict cellulose, hemicellulose, and lignin quantities. Thus, the compositional analysis step can be expedited so that other processes, like fractionation of the lignocellulose polymers, can be tuned accordingly to maximize the value of the final product. Hybrid materials were also generated using a variety of polymerization techniques and post-polymerization modifications. A novel controlled/living radical polymerization initiator was synthesized (2-bromo-2-methylpropane hydrazide) containing a hydrazide functionality that was covalently linked to the reducing-end of dextran. Despite the rapid coupling of the hydrazide- based initiator to the reducing-end of dextran, the instability of the alkyl bromide bond resulted in several unsuccessful attempts at Cu(0)-mediated controlled/living radical polymerization. Recommendations were given to improve the stability of this compound; however, an alternative approach to synthesizing hybrid copolymers was also investigated in parallel. Hyperbranched polymers were synthesized using commercially available vinyl and divinyl monomers in the presence of a cobalt(II) complex that enabled control over the size, architecture, and mol% of pendant vinyl groups amenable to post-polymerization modification. Modifying the ratio of divinyl monomer to cobalt(II) complex provided a series of hyperbranched polymers with variable morphology and mol% pendant vinyl groups. The pendant vinyl bonds were subsequently converted to amines via thiol additions with cysteamine. These amine functionalized hyperbranched polymers were then used in a subsequent reductive amination reaction with the reducing-end of dextran to produce the amphiphilic core-shell copolymer poly(methyl methacrylate-co-ethylene glycol dimethacrylate)-b-dextran. These amphiphilic copolymers mimicked the colloidal behaviour of conventional block copolymer micelles without requiring difficult syntheses or tedious self-assembly steps. / Thesis (Master, Chemical Engineering) -- Queen's University, 2012-02-28 11:20:01.568
165

An End-to-End Solution for Complex Open Educational Resources

Mohamed Nour, Morwan 01 November 2012 (has links)
Open access and open resources have gained much attention from the world in the last few years. The interest in sharing information freely by the use of the World Wide Web has grown rapidly in many different fields. Now, information is available in many different data forms because of the continuous evolution in technology. The main objective of this thesis is to provide content creators and educators with a solution that simplifies the process of depositing into digital repositories. We created a desktop tool named ORchiD, Open educational Resources Depositor, to achieve this goal. The tool encompasses educational metadata and content packaging standards to create packages while conforming to a deposit protocol to ingest resources to repositories. A test repository was installed and adapted to handle Open Educational Resources. The solution proposed is centered on the front-end application which handles the complex objects on the user desktop. The desktop application allows the user to select and describe his/her resource(s) then creates the package and forwards it to the specified repository using the deposit protocol. The solution is proved to be simple for users but also in need of further improvements specifically in association to the metadata standard presented to user.
166

Problèmes de plongements en géométrie symplectique

Opshtein, Emmanuel 03 July 2014 (has links) (PDF)
Ce mémoire concerne les phénomènes de rigidité/flexibilité liés aux plongements et leurs applications en topologie symplectique. Les deux grands thèmes abordés sont les plongements symplectiques équidimensionnels en dimension 4 et la géometrie symplectique C^0.
167

Optimización térmica y energética de la doble fachada acristalada con ventilación mecánica en clima mediterráneo

Cuerva Contreras, Eva 04 November 2013 (has links)
El diseño de edificios siguiendo criterios de sostenibilidad y eficiencia energética se ha convertido en un imperativo en los países desarrollados, sobre todo a raíz de la Directiva europea 2010/31/UE sobre Eficiencia Energética en los Edificios, cuyo objetivo para el año 2019 es el de conseguir zero-emission buildings, es decir, edificios cuyo impacto sobre el entorno sea casi nulo, al ser autosuficientes energéticamente y no emitir gases de efecto invernadero. En respuesta a esta corriente, la Doble Fachada Acristalada (DFA) representa una alternativa constructiva que, aplicada en entornos mediterráneos, supone una posible estrategia de diseño energéticamente eficiente para mejorar el comportamiento de las tradicionales fachadas de vidrio de uso tan extendido en los edificios de oficinas y comerciales de las grandes ciudades. El estudio de la implantación de la DFA y su comportamiento ha sido un tema tratado extensamente en la última década. No obstante, la literatura disponible está muy restringida a casos de regiones de clima frío y templado de Europa y América del Norte, contexto en el cual pueden encontrarse casos de aplicación eficiente a nivel energético. Sin embargo, las experiencias de aplicación de DFA en zonas de clima mediterráneo arrojan posibles problemas de funcionamiento, sobre todo durante la estación cálida, debido al sobrecalentamiento de la entrepiel causado por la elevada radiación solar característica de este tipo de clima. Este fenómeno ocasiona que sea necesario un coste energético extra para obtener unas condiciones de confort adecuadas en el interior del edificio. El estudio de la DFA requiere de una investigación exhaustiva de los fenómenos de transferencia de calor y fluidodinámicos involucrados. Para realizar un análisis apropiado de estos fenómenos, y gracias a la mejora de la potencia de cálculo de los ordenadores en los últimos años, han aparecido métodos que permiten abordar el problema de analizar el comportamiento de la DFA a través de la definición de modelos matemáticos que simplifican el modelo real. En esta línea, el uso de programas de simulación térmica zonal y multizonal, así como la utilización de programas de dinámica de fluidos computacional (CFD), se han destacado como herramientas útiles a la hora de modelizar los fenómenos fluidodinámicos y de transferencia de calor asociados a la DFA. El objetivo general de esta tesis se centra en la optimización del comportamiento térmico y energético de una doble fachada acristalada con ventilación forzada (DFAV) horizontal y configuración constructiva fija, para su aplicación en edificios de oficinas localizados en zonas de clima mediterráneo. Dicha optimización, que se ha llevado a cabo mediante el software de simulación térmica zonal TAS, pretende resolver los posibles problemas de sobrecalentamiento en el interior del edificio generados cuando se aplica esta tipología de fachada en climas de alta radiación solar. En el modelo analizado, la ventilación de la entrepiel de la fachada –que es la encargada de la evacuación del exceso de calor de la misma–, se supone a cargo de un sistema de recirculación del aire de climatización expulsado del edificio. Este sistema puede ser complementado, en caso de requerirse una mayor extracción de calor, por un equipo auxiliar que mediante la impulsión de aire exterior permita aumentar el caudal de aire a través de la entrepiel. Por otro lado, se ha utilizado un modelo analítico simplificado –desarrollado a partir de las ecuaciones fundamentales de transferencia de calor–, que se ha evaluado en diversos puntos característicos del dominio para comprobar la exactitud de los resultados obtenidos a través de las simulaciones realizadas. Se ha concluido que, para estimar la efectividad de la DFAV a la hora de disminuir la demanda energética del edificio, este modelo matemático simplificado –que utiliza coeficientes de transmisión de calor combinados medios– puede considerarse válido. Además, las diferencias obtenidas con el modelo simulado son lo suficientemente reducidas para considerar que –a falta de un modelo experimental sobre el que validar los resultados obtenidos– dicho desarrollo matemático permite afirmar la bondad de los resultados obtenidos en el modelo de simulación. Respecto al proceso de optimización de la DFAV se ha concluido que, para una oficina de características estándar, la fachada es el elemento clave que define el comportamiento termoenergético del edificio, de manera que su correcto diseño es fundamental para conseguir minimizar su consumo energético y alcanzar las mejores condiciones de confort térmico interior posibles. Así, en edificios con fachadas altamente vidriadas situados en entornos de elevada radiación solar como el mediterráneo, la utilización de vidrios que limiten las ganancias solares en el interior del edificio es básica para el control de la demanda de climatización del mismo. Contrariamente, el comportamiento del edificio empeora al sustituir el vidrio interior transparente por uno bajo emisivo, lo que prueba que, en ocasiones, la utilización de un vidrio de mayor calidad no supone un beneficio claro en cuanto a la disminución de la demanda del edificio en el cuál se instala. Además, se comprueba que la utilización de la DFAV frente al muro cortina tradicional permite mejorar las condiciones de demanda de climatización y de confort térmico alcanzadas en un edificio como el analizado. Por último, se ha concluido que la aplicación de una estrategia de ventilación mixta a caudal variable en función de las necesidades de climatización de los espacios ocupados supone una mejora notable a nivel de reducción de la demanda de climatización global del edificio, aunque únicamente respecto al caso de DFA sin ventilar. Las mejoras respecto a los casos con la doble fachada ventilada con un caudal elevado de aire exterior son escasas. Así pues, la decisión de emplear un tipo u otro de ventilación de la entrepiel de la DFAV vendrá determinada por el análisis de coste de implantación contra la disminución de la demanda de climatización asociada a cada sistema. Las reducciones de la demanda de climatización obtenidas parecen descartar la instalación del sistema de recirculación de aire interior para ventilar la DFAV, al obtenerse escasas mejoras respecto a un sistema de ventilación con aportación de aire todo exterior. / The building design in base of sustainability and energy efficiency criteria has become an imperative in developed countries, especially since the application of the European Directive 2010/31/EU on Energy Efficiency in Buildings, whose goal for 2019 is the achievement of zero-emission buildings, buildings with almost zero impact on the environment. In response to this trend, Double Glazed Facade (DGF) represents a constructive alternative that can improve the performance of traditional glass facades commonly used in commercial and offices buildings located in large cities. The study of the DGF has been largely restricted to cases of cold and temperate climate regions in Europe and North America. In this context, many energy efficient applications can be found. However, the DGF application experiences in Mediterranean climate have shown potential performance problems, due to the facade overheating caused by high solar radiation characteristic of this type of weather. This phenomenon is responsible of the need of an extra energy cost for adequate comfort conditions inside the building. The study of the DGF requires an intensive investigation of heat transfer phenomena involved. For a proper analysis of these phenomena, some methods which analyze the DFA behavior through mathematical models which simplify the real model can be used. In this line, the use of thermal simulation zonal programs and the use of computational fluid dynamics have emerged as useful tools when modeling physical phenomena associated to the DFA. The main objective of this thesis focuses on the optimization of the thermal and energy performance of a double skin facade with an horizontal forced ventilation scheme, and with a fixed structural design, for its application in office buildings located in areas with a Mediterranean climate. This optimization has been carried out with the thermal simulation software TAS. The facade ventilation of the analyzed model ¿which is res pons ible for the removal of the heat accumulated in the space between the two skins is generated by a system which recirculates the air expelled from the building. This system can be supplemented with an auxiliary system which drives outside air for increasing the air flow through the facade cavity. On the other hand, a symplified analytical model developed from the fundamental equations of heat transfer has been used to check the accuracy of the results obtained through simulations. It has been concluded that such mathematical model allows us to affirm the goodness of the results obtained in the simulation model. Furthermore, it can be considered valid to estimate the effectiveness of DGF to decrease the energy demand of the building. Regarding the DFAV optimization process, it has been concluded that, for an standard office building, the facade is the key element that defines the thermal behavior of the building. So, its correct design is essential for minimizing energy consumption and for achieving indoor thermal comfort conditions. It is found that the use of DGF against traditional curtain wall can reduce the cooling demand and improve the thermal comfort in a building like the one analyzed. Moreover, it has been concluded that the application of variable flow hybrid ventilation causes a notable improvement to reduce overall cooling demand of the building when comparing with the unventilated DGF case. The analysis of the HVAC reductions seems to advise against the installation of an air recirculation system to ventilate the DGF cavity, because of the little improvement obtained over the use of a ventilation system only with exterior air supply. So the final decision to use a certain type of cavity ventilation will be determined by the analysis of implementation cost against the HVAC demand reduction for each system.
168

Exact Results in Five-Dimensional Gauge Theories : On Supersymmetry, Localization and Matrix Models

Nedelin, Anton January 2015 (has links)
Gauge theories are one of the corner stones of modern theoretical physics. They describe the nature of all fundamental interactions and have been applied in multiple branches of physics. The most challenging problem of gauge theories, which has not been solved yet, is their strong coupling dynamics. A class of gauge theories that admits simplifications allowing to deal with the strong coupling regime are supersymmetric ones. For example, recently proposed method of supersymmetric localization allows to reduce expectation values of supersymmetric observables, expressed through the path integral, to finite-dimensional matrix integral. The last one is usually easier to deal with compared to the original infinite-dimensional integral. This thesis deals with the matrix models obtained from the localization of different 5D gauge theories. The focus of our study is N=1 super Yang-Mills theory with different matter content as well as N=1 Chern-Simons-Matter theory with adjoint hypermultiplets. Both theories are considered on the five-spheres. We make use of the saddle-point approximation of the matrix integrals, obtained from localization, to evaluate expectation values of different observables in these theories. This approximation corresponds to the large-N limit of the localized gauge theory. We derive <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?N%5E%7B3%7D" /> behavior for the free energy of 5D N=1* super Yang-Mills theory at strong coupling. This result is important in light of the relation between 5D theory and the world-volume theories of M5-branes, playing a significant role in string theory. We have also explored rich phase structure of 5D SU(N) N=1 super Yang-Mills theory coupled to massive matter in different representations of the gauge group. We have shown that in the case of the massive adjoint hypermultiplet theory undergoes infinite chain of the third order phase transitions while interpolating between weak and strong coupling in the decompactification limit. Finally, we obtain several interesting results for 5D Chern-Simons theory, suggesting existence of the holographic duals to this theory. In particular, we derive <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?N%5E%7B5/2%7D" /> behavior of the free energy of this theory, which reproduces the behavior of the free energy for 5D theories with known  holographic duals.
169

Counting And Constructing Boolean Functions With Particular Difference Distribution Vectors

Yildirim, Elif 01 June 2004 (has links) (PDF)
In this thesis we deal with the Boolean functions with particular difference distribution vectors. Besides the main properties, we especially focus on strict avalanche criterion for cryptographic aspects. Not only we deal with known methods we also demonstrate some new methods for counting and constructing such functions. Furthermore, performing some statistical tests, we observed a number of interesting properties.
170

Political Economy Of Labour Law In Turkey: Work Employment And International Division Of Labour

Ozdemir, Ali Murat 01 December 2004 (has links) (PDF)
This thesis aims to evaluate the Turkish Labour Law on the basis of a new approach to legal studies that follow the internal tendency of legal science to resolve its own problem, which is that of convincingly defining the point of contact between norm and fact (form and content), materially connecting the juridical organisation of power with the social structuring of power, while avoiding both formalist and positivist deviations. Against this background, the thesis aims to assess the correlation between the recent changes in the international division of labour and the structural forms, on the axis of which the Turkish legal system functions. This endeavour includes an attempt to view law in its location as a component to a general and persistent process of social regulation that secures general patterns of social domination. This study argues that the role of the collective labour law over the stabilisation of wage relations is increasingly deteriorated by the changing nature of the state and of work, including the new institutionality and the increasing influence of business over labour politics. After the &lsquo / discovery&rsquo / of the importance of the universal principle of the freedom of contract in labour law, the regulatory powers of individual labour law have extended to the realm of capital-labour relations having an impact over the social division of labour and have acquired a relative dominance.

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