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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.
21

Comparaison de la production de trois technologies différentes de panneaux solaires en fonctionnement réel avec suivi du soleil et intégration de batteries lithium innovantes adaptées au stockage des énergies intermittentes / Comparison of the production of three technologies different from solar panels in real functioning with follow-up of the sun and the integration of battery lithium innovative adapted to the storage of the intermittent energies

Goemaere, Loïc 16 December 2011 (has links)
Dans une vision de développement durable et d'indépendance énergétique visant l'intégration massive des énergies renouvelables à moyen terme dans le mix énergétique, les travaux menés au cours de cette thèse se sont axés sur deux thématiques :- d'une part, la comparaison de la production de trois technologies différentes de panneaux solaires (silicium, silicium avec concentration, CdTe) en fonctionnement réel dans une centrale photovoltaïque au sol dotée du suivi deux axes de la course du soleil ;- d'autre part et étant donné la nature intermittente de l'énergie photovoltaïque et son non-synchronisme avec la consommation, le développement et l'intégration de batteries à base de lithium comme moyen de stockage électrochimique de l'énergie photovoltaïque. L'approche est novatrice et a permis l'étude de nouveaux composés d'électrodes étudiés sous contraintes photovoltaïques réelles et utilisant différentes stratégies de restitution de l'énergie en vue du déploiement prochain des réseaux intelligents. Les simulations portent sur des accumulateurs de petites tailles classiquement utilisés dans les laboratoires de recherche mais préfigurant ce qui pourra être construit à plus grande taille. / In a vision of sustainable development and energy independence aiming at the massive integration of the medium-term renewable energies in the energy mix, the research works are centered on two themes:- On one hand, the comparison of the production of three technologies different from solar panels (silicon, silicon with concentration, CdTe) installed into a photovoltaic power plant with 2-axes sun tracking;- On the other hand and given the intermittent nature of the photovoltaic energy and its non-simultaneity with the consumption, the development and the integration of batteries with lithium as means of electrochemical storage of the photovoltaic energy. The approach is innovative and allowed the study of new compounds of electrodes studied under real photovoltaic constraints and using various strategies of return of the energy with the aim of the next deployment of the intelligent networks. The simulations concern batteries of small sizes classically used in research laboratories but prefiguring what can be built in bigger size.
22

Execution adaptative de trajectoire 5 axes sur structures poly-articulées / Adaptative execution of 5 axis tool path on polyarticulated structure

Grandguillaume, Laureen 07 December 2017 (has links)
L’usinage 5 axes à grande vitesse est de plus en plus utilisé dans l’industrie pour réaliser des pièces de géométrie complexe à forte valeur ajoutée avec pour contrainte de respecter la qualité géométrique tout en maximisant la productivité. Dans ce contexte, la FAO et plus particulièrement la génération des trajectoires d’usinage jouent un rôle prépondérant. Ces travaux proposent de définir des trajectoires en fonction de la pièce à réaliser mais aussi de la structure poly articulée et de ses performances cinématiques. La grande diversité des structures en termes d’architecture et de cinématique impose une méthode de calcul générique facilitant la définition de trajectoires adaptées pour leur suivi. L’état de l’art des travaux réalisé dans les domaines de l’usinage et de la robotique pour répondre à cette problématique conduit à utiliser des polytopes de manipulabilité cinématique pour modéliser les contraintes cinématiques. L’analyse de ces polytopes et de la géométrie de la pièce à usiner permet de générer des trajectoires avec une vitesse outil/pièce maîtrisée et un temps de parcours réduit dans le cas de l’usinage 5 axes positionné et de l’usinage 5 axes continu. Ce formalisme met en avant les fortes dépendances entre les différents paramètres de la stratégie d’usinage (positionnement de la pièce, direction d’avance et orientation de l’outil) et permet de privilégier certaines combinaisons de ces paramètres pour maîtriser la vitesse d’exécution de la trajectoire. / 5 axes high speed milling is increasingly used for manufacturing high addedvalue parts with complex forms in order to respect surface quality while maximizing productivity. In this context, CAM and more specifically toolpath computations play a major part. This work proposes to define toolpath depending on the workpiece but also onkinematical capacities of the polyarticulated structure.The large variety of structure in terms of architecture and kinematic enforce a generic calculation method to simplify adaptative toolpath generation. A state of the art realized in machining and robotics proposes to investigate the use of kinematical manipulability polytopes to represent kinematical capacities. An analysis of the polytopes and of the workpiece allows to generate toolpaths with a controlled feedrate and a decreasing time in 5 axes positionned milling and in 5 axes continous milling. This formalism highlights strong interactions between milling strategy parameters (workpiece setup, feed direction, tool orientation) and allows to prioritize specific parameters mix to have a controlled execution feedrate.
23

A NEW HIGH EFFICIENCY, AGILE BEAM SCANNING, BROADBAND TRACKING ANTENNA FEED

Richard, Gaetan C. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Two different types of tracking feeds are currently used in the majority of telemetry tracking antenna systems when autotrack operation is required. They are of the conical scanner or of the single channel monopulse family and they employ well known technologies. In broadband applications, these feeds all suffer from the same inherent degradation in efficiency caused by their inability to maintain a constant crossover loss value and by their failure to properly illuminate the reflector. In high dynamics situations they can also generate unwanted and sometimes detrimental modulation whenever on-axis tracking is not maintained. In addition, currently available versions of the conical scanner are not capable of high scan rates or of scan rate agility and they are ill-suited for use in tracking systems based on non-orthogonal axes positioners. This paper describes a new high efficiency tracking feed system based on proven conical scanner technology. Its design incorporates features such as variable crossover, steerable beam, high scan rates, scan rate agility as well as stable reference coordinate system. In addition to these features, this new feed is also capable of delivering, in all but one operational category, levels of performance superior to that achievable to date by any other implementation of the conical scanner or of the single channel monopulse technology.
24

Generalisation of Clairaut's theorem to Minkowski spaces

Saad, A. January 2013 (has links)
The geometry of surfaces of rotation in three dimensional Euclidean space has been studied widely. The rotational surfaces in three dimensional Euclidean space are generated by rotating an arbitrary curve about an arbitrary axis. Moreover, the geodesics on surfaces of rotation in three dimension Euclidean space have been considered and discovered. Clairaut's [1713-1765] theorem describes the geodesics on surfaces of rotation and provides a result which is very helpful in understanding all geodesics on these surfaces. On the other hand, the Minkowski spaces have shorter history. In 1908 Minkowski [1864-1909] gave his talk on four dimensional real vector space, with asymmetric form of signature (+,+,+,-). In this space there are different types of vectors/axes (space-like- time-like and null) as well as different types of curves (space-like- time-like and null). This thesis considers the different types of axes of rotations, then creates three different types of surfaces of rotation in three dimensional Minkowski space, and generates Clairaut's theorem to each type of these surfaces, it also explains the analogy between three dimensional Euclidean and Minkowskian spaces. Moreover, this thesis produces different types of surfaces of rotation in four dimensional Minkowski spaces. It also generalises Clairaut's theorem for these surfaces of rotations in four dimensional Minkowski space. Then we see how Clairaut's theorem characterization carries over to three dimensional and four dimensional Minkowski spaces.
25

Copper shaft-hole axes and early metallurgy in south-eastern Europe : an integrated approach

Heeb, Julia Maria January 2011 (has links)
Although the copper axes with central shaft-hole from south-eastern Europe have a long history of research, they have not been studied on a transnational basis since the 1960s. What has also been missing is an integrated or holistic approach, trying to use as many methods as possible and better understand the production, use and context of these enigmatic objects. This present research therefore approaches the axes from different angles. A database was compiled in order to find answers on questions such as the patterns of distribution, context, fragmentation and deformation of axes. For the distribution of axes in general as well as different attributes like fragmentation and typology, the content of the database was imported into GIS software and analysed. Aspects of production were considered through experimental archaeology, metallographic analysis and a re-discovered axe blank with missing shafthole. Especially the missing moulds make it difficult to fully understand the production sequence. The typology was re-evaluated and modified to ensure comparability across modern national boundaries. The context and background was developed through a thorough review of the literature and combined with theoretical considerations. The integration of all these approaches yielded some interesting results. The great variability in shape combined with the results of metallographic analyses clearly shows that a variety of production techniques were used, but it is as yet difficult to relate these to specific geographic areas or even cultural groups. In fact the typology as well as the practice of marking the axes indicate that traditional archaeological ‘cultures’ rarely correspond to the distribution of a type or to the practice of marking the axes. They show instead that there were different spheres of influence, some even more localised and others much larger (like the Carpathian Basin) than specific ceramic traditions. These different levels of belonging, as well as the increasing visibility of the individual in the archaeological record, show that it was a period of complex cultural patterns and interactions. The axes were a part of these networks of the daily life on many different levels from the strict utilitarian to the ritualised placement in burial contexts.
26

Aquilo pelo que se luta nos discursos sobre TDAH dirigidos a professores e pais / The thing for which and by which there is a struggle in discourse about ADDH addressed to teachers and parents

Galhardo, Nathaly Dironze 28 March 2014 (has links)
Esta pesquisa busca trazer um questionamento sobre a tentativa de diferentes setores da sociedade de tomar para si os cuidados da criança desautorizando as condições do núcleo social inicial, a família, de cuidar dos filhos. Para tanto, a questão de pesquisa que nos dá a direção é: Em que medida textos veiculados pela mídia sobre o TDAH (Transtorno do Déficit de Atenção e Hiperatividade), mais do que descrever um problema de saúde, delineiam produtos, oferecidos ao público apoiados em diferentes eixos argumentativos? Pretendemos tomar os enunciados básicos sobre o transtorno como objeto de estudos e, assim, os argumentos dos posicionamentos como corpus. Como pesquisa inicial, buscamos o que é oferecido como informação relativa ao transtorno nas publicações entre os anos 2000 e 2012 no banco de dados eletrônico da Editora Abril. Dentre as matérias que apareceram, selecionamos 15 para uma análise detalhada. Tais publicações apresentam características discursivas marcadas por elementos que contribuem para configurar posicionamentos em relação ao transtorno: defender a existência da doença, questionar a existência do transtorno como doença, propulsionar os perigos relativos à utilização do medicamento e caracterizar a sociedade atual para delinear uma forma de tratamento do Déficit de atenção. Após a análise pudemos compreender quais são os eixos argumentativos em torno do TDAH e os recursos utilizados pelos posicionamentos para argumentar a favor de seu ponto de vista. / This research seeks to bring a questioning about an attempt of different sectors of the society take to herself the care of the child, disallowing the initial core conditions, the family, of take care of the children. For this, the research question that gives us the direction is: To what extent the texts of the media about ADDH (Attention Deficit Disorder with Hiperactivity), more than describing a health problem, delineate products offered to the public supported by different argumentation axes? We intend to take basic statements about the disorder as an object of study, and thus the arguments of the positionings as corpus. As initial research, we seek what is offered as information about the disorder in publications between 2000 and 2012 in the Editora Abril electronic database. Among the texts that have appeared, we selected 15 for detailed analysis. These publications present discursive features marked by elements that contribute to configure positions in relation to the disorder: the defense of the disease existence, put in question the disorder existence as a disease, the power of the dangers relating to the use of the drug and characterize the current society to devise a way to treatment of attention Deficit. After the analysis we could understand what are the argumentative axes around ADDH and the resources used by each position to argue for their point of view.
27

Prise en compte des contraintes associées au couple MO-CN en génération de trajectoires 5 axes UGV

Lavernhe, Sylvain 30 November 2006 (has links) (PDF)
Les pièces de formes complexes des domaines aéronautique et automobile sont fabriquées par usinage 5 axes UGV pour accroître leur qualité ou la productivité. Cependant, la gestion combinée du multi-axe et des vitesses élevées posent divers problèmes au couple MO-CN lors de l'exécution des trajectoires.<br />Ces travaux portent sur l'optimisation de l'usinage 5 axes UGV au travers de l'étude des trajectoires et de leur suivi. Après avoir analysé le processus de réalisation des trajectoires et identifié les limites associées, un modèle d'évaluation des performances cinématiques lors du suivi est développé ; il permet de détecter les portions critiques des trajets ainsi que les éléments limitants. Une structure d'optimisation, basée sur un modèle de description surfacique des trajets est ensuite présentée. L'optimisation de l'orientation de l'axe de l'outil, tenant compte des contraintes précédentes y est plus spécifiquement étudiée pour évaluer la faisabilité d'une telle démarche.
28

Contribution à l'amélioration de la qualité des surfaces fabriquées sur centre d'usinage à 5 axes

Tournier, Christophe 01 October 2009 (has links) (PDF)
Le thème abordé est celui de la fabrication de pièces de formes complexes sur centre d'usinage à 5 axes et plus particulièrement le point de vue de la génération de trajectoires et de leurs exécutions sur les machines. Quatre thèmes distincts seront abordés dans les quatre chapitres proposés : la prise en compte des performances cinématiques du couple MO-CN en FAO, la prise en compte du modèle géométrique de la machine en FAO, Les formats d'échange et de description des données dans la chaîne numérique de fabrication et enfin l'industrialisation du polissage automatique sur MOCN 5 axes. Enfin dans la troisième partie sont regroupés les articles publiés dans des revues internationales et qui sont proposés comme documents de références pour les développements de la deuxième partie.
29

A novel SU-8 stamping and electrostatic pulling method for microlens array fabrication

Kuo, Shu-Ming 16 February 2011 (has links)
This research reports a simple and novel method to fabricate microlens arrays by soft stamping the unexposed SU-8 photoresist. A SU-8 based stamp composed of micro-nozzle arrays with a reservoir structure on a glass substrate is first fabricated using a process of dosage control exposure. The unexposed SU-8 is then encapsulated in the cross-linked SU-8 shell and was used as the ¡§ink¡¨ for the stamping process. The proposed SU-8 microlens array is then formed by stamping the formed SU-8 structure on a bare glass substrate at a temperature higher than the glass transition temperature (Tg) of the unexposed SU-8 microlens array. Lenses with various radii of curvature can be formed by controlling the working temperature during the stamping process. In addition, this work also employed a simple electric static pulling scheme to manipulate the fabricated lenses profiles. Aspherical SU-8 microlens arrays with a wide range of tunable focal lengths were fabricated with this approach. Furthermore, we develop an advanced localize E-field control technique to fabricate microlenses with various focus length and microlenses with different tilt angle in a single lens array sheet. A novel grayscale mask fabrication technique is also proposed first. This low cost and rapid method is applied on stepwise and continuous tilt plane fabrication for produces a gradually changed E-field. Hetero axes and focus lengths microlenses are fabricated with this approach. In order to farther understand the real E-field distribution, a novel PCF based E-field sensor fabrication technique is also proposed. This technique also shows the potential on various PCF based devices fabrications.
30

An Architectural Investigation Of Leisure Spaces In The Roman Domestic Context: The Case Of Ephesus

Cinici, Ahmet 01 October 2006 (has links) (PDF)
Leisure is most basically defined as the time free from work. The ancient conception and forms of leisure were quite different from the modern ones, which came into discussion during the industrial era. The Roman society was highly stratified and comprised of diverse social classes for which leisure acquired different forms and meanings. Every stratum of the Roman society enjoyed the possibilities and pleasures of leisure proportional to its hierarchy in the social system, so that leisure can be investigated in both public and private contexts in the Roman world. This study aims to investigate leisure, which was one of the main driving social forces in the Roman society, in spatial terms with reference to Roman domestic architecture. The study focuses on central Italy and particularly on Ephesus, the latter of which is a good example to discuss how the Roman conception of leisure was spatially materialized in a provincial private setting since a group of well studied, documented, and published houses constitute an appropriate comparative sample and context in Ephesus. The spatial organization and characteristics of the spaces housing leisurely activities are discussed on the basis of an axes-scheme that regulated and even dictated the visual and bodily interaction of the participants with certain spaces and elements during leisure activities either in a static state (sitting, reclining), or a kinetic one (walking, perambulating). The visual axes are those perceived in either of these states, along which the eye is directed towards a visual focal point, whereas the dynamic axes are those along which people move during a kinetic leisurely activity. The location, architecture, and use of leisure-oriented spaces in the Roman period houses in Ephesus, such as triclinium, exedra, oecus, museion, and peristyle courtyard are examined with reference to the proposed axes-scheme to present and compare the operation of leisure in the Roman provincial and private setting.

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