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Spectroscopic and technological studies of carbon-nanotube-based structures for photonics applications / Etudes spectroscopiques et technologiques de structures à base de nanotube de carbone pour les applications de la photoniqueGu, Qingyuan 08 April 2015 (has links)
Cette thèse est consacrée à l’étude du dépôt uniforme et de l’alignement à haute densité en nanotubes de carbone monoparois (NTCMP) sur différents substrats, à l’analyse qualitative des propriétés optiques excitoniques et aux modes de vibration des échantillons à NTCMP, et à la fabrication de guides d’onde optiques à base de NTCMP, en vue de composants photoniques pour les télécoms, autour de 1550 nm. Deux types de NTCMP ont été étudiés durant cette thèse : des NTCMP « HiPCO » (« high pressure carbon monoxide ») issus de la décomposition du monoxyde de carbone à haute pression, et des NTCMP « LV » (« laser vaporization ») provenant de l’ablation laser d’une cible en graphite. Plusieurs méthodes de dépôt de ces NTCMP ont été développées, telles que la méthode de dépôt assistée-par-tube, la méthode de dépôt en sillon, la méthode par pulvérisation, la méthode par centrifugation à grande vitesse, la méthode optimisée par centrifugation à vitesse réduite (MOCVR) et la méthode à jet d’encre. La qualité, l’épaisseur et l’uniformité des films de NTCMP sont caractérisées par observations au microscope électronique à balayage (MEB). Il est montré ici que l’uniformité des films à base de NTCMP HiPCO dépend fortement de la concentration en surfactants de la dispersion à base de NTCMP déposée. Des films uniformes de NTCMP LV ont été obtenus par la MOCVR et leur épaisseur couvre une gamme de 600nm à 900nm (avec une erreur <10%), qui dépend de la nature du substrat. L’alignement par diélectrophorèse (DEP) de NTCMP HiPCO et LV a été développé et optimisé. Ainsi, une nouvelle méthode (DEP « assistée-parchauffage ») est proposée afin d’obtenir un alignement à très haute densité en NTCMP. Cette méthode d’alignement par DEP assistée-par-chauffage a fait l’objet de travaux de simulation pour comprendre l’effet de la température. Les propriétés optiques excitoniques et les modes de vibration des NTCMP en solution et en film sur substrat ont été caractérisés par spectroscopies d’absorption, de photoluminescence (PL), d’excitation de la PL et Raman. Les niveaux de défauts et d’isolement des NTCMP HiPCO, les distributions en diamètre et en chiralité, les cartographies de l’uniformité et de l’épaisseur des films à base de NTCMP, et l’effet du laser à forte puissance, ont été qualitativement étudiés par spectroscopie Raman. Le rendement quantique interne en PL de NTCMP HiPCO en film est estimée à une valeur de 5%. Le transfert d’exciton entre NTCMP HiPCO individualisés, le rôle du polymère environnant sur les propriétés excitoniques des NTCMP LV, et les excitons sombres sont discutés dans cette thèse. Le design et la fabrication de guides optiques hybrides à une dimension, contenant une ou trois couches de NTCMP HiPCO, et de guides optiques à deux dimensions à base de NTCMP LV ont été menés. Les étapes de fabrication des guides optiques sont ici examinées en détails. La propagation à 1550nm de ces guides d’onde à base de NTCMP est observée. La propagation de la lumière dans les guides d’onde à base de NTCMP LV est une caractéristique préliminaire pour toute cavité optique et confère un fort potentiel aux NTCMP LV pour les composants photoniques de la future génération. / This thesis concentrates on the uniform deposition and highdensity alignment of single-walled carbon nanotubes (SWCNTs) on various substrates, the qualitative analysis of optical and excitonic properties, as well as vibrational modes of SWCNTbased samples by absorption, photoluminescence (PL) and Raman spectroscopies, and the fabrication of SWCNT-based optical waveguides towards photonics devices in the 1.55μm telecom window. Two types of SWCNT were studied during this thesis: “HiPCO” SWCNT from high pressure carbon monoxide conversion process (HiPCO) and “LV” SWCNT from catalytic growth of SWCNT assisted by laser vaporization (LV) of graphite. Several methods for the deposition of these SWCNTs were investigated and performed, including tube-assisted deposition method, groove deposition method, spraying method, high-speed spin coating method, improved low-speed spin coating method (ILSSCM) and inkjet printing method. The quality, thickness and uniformity of SWCNT films are characterized by scanning electron microscopy (SEM). The uniformity of HiPCO SWCNT-based film is shown to depend strongly on the surfactants concentration in deposited SWCNTbased dispersion. Uniform LV SWCNTbased films using ILSSCM were obtained with thicknesses ranging from 600nm to 900nm (with thickness error <10%), depending on substrates nature. Alignment of HiPCO and LV- SWCNTs using a dielectrophoresis method, combining microtechnological processes and SEM observations, is investigated and optimized. Thus, a new method (“heating-enhanced DEP”) for ultra-high alignment density of HiPCO SWCNTs is proposed. The effect of temperature in this heating-enhanced DEP process is further explained by simulation works. Optical and excitonic properties, vibrational modes of SWCNT solutions and films are characterized by absorption, PL and PL excitation, Raman spectroscopies. The defects and the isolation levels of HiPCO SWCNT, the chirality- and diameterdistributions of SWCNT, the uniformity and the thickness mapping of SWCNT-based films, and the effect of high energy laser are qualitatively analyzed by Raman spectra. We estimated the PL quantum efficiency value of HiPCO SWCNT film of around 5%. The exciton energy transfer between individualized HiPCO SWCNTs, the role of polymer environment on excitonic properties of LV SWCNTs, and the dark excitons are discussed in this thesis. One-layer and three-layers of HiPCO SWCNT-based onedimensional slab optical waveguides of hybrid core structures, and LV SWCNT-based twodimensional optical waveguides are designed and fabricated. The fabrication process steps of the optical waveguides are investigated in details. 1.55μm propagation in these SWCNT-based waveguides is highlighted. Single- or multi-mode emissions around 1.5μm and 1.6μm are observed in LV SWCNTbased optical waveguides. The light propagation in the LV SWCNT-based optical waveguide is the preliminary characteristic of an optical cavity, which confers great potential for future generation LV SWCNT-based photonics devices.
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Responsabilidade Social Empresarial Uma nova forma de gest?o O Estudo de Caso de Empresas do Setor Sider?gico. / Social Enterprising Responsibility A new way of management The Case Study of Steel Companies.Morcerf, Sonia de Oliveira 25 July 2007 (has links)
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Previous issue date: 2007-07-25 / The aim of this paper is to study the social enterprising responsibility and more specifically,
the use of that performance guides as a way to evaluate the companies social management.
First, there is the introduction of the matter, running over the problem which needs inspection
and the purposes to be reached. Then, a theoretical basis is showed through the document,
about the evolution of social corporative responsibility and of the Ethos guides of social
responsibility. The empirical research done at Usiminas and Arcelor Companies, two great
representatives of the Brazilian steel segment, tried to identify and describe the social
responsibility guides which were addopted by the companies as to evaluate the benefits and
the results provided by the social management to the organizational performance. The
methodology applied at the work identifies the multicase study and the qualitative approach.
The bibliographical and documental research was used as the source, as well as the check-list,
in order to get information by the companies. The results of the research made possible to
check the group of action, politics and values of the organizations, the benefits got by the
companies and the recognition of the importance in practicing social responsible action to all
the stakeholders, as well as the necessity of putting them about and to keep improving such
action. Finally, there are the conclusions about the work and the advices about future studies
and researches. / Este trabalho tem como tema de estudo a responsabilidade social empresarial, e mais
especificamente, a utiliza??o dos indicadores desta pr?tica, como forma de avaliar a gest?o
social das empresas. Inicialmente, faz-se a introdu??o ao assunto, discorrendo sobre o
problema a ser investigado e os objetivos a serem alcan?ados. E, ao longo do documento
apresenta-se uma base te?rica, sobre a evolu??o da responsabilidade social corporativa e dos
indicadores Ethos de responsabilidade social. A pesquisa emp?rica, realizada junto ?s
empresas Usiminas e Arcelor, duas grandes representantes do setor sider?rgico brasileiro,
objetivou identificar e descrever os indicadores de responsabilidade social adotados pelas
empresas e avaliar os benef?cios e resultados que a gest?o social proporciona ao desempenho
organizacional. A metodologia utilizada identifica o estudo multicaso e a abordagem
qualitativa. Como fonte de coleta de dados fez-se uso de pesquisa documental e bibliogr?fica,
al?m do check-list, para levantamento das informa??es junto ?s empresas. Os resultados da
pesquisa permitiram verificar o conjunto de a??es, pol?ticas e valores das organiza??es, os
benef?cios gerados para as empresas, o reconhecimento da import?ncia de se praticar a??es de
responsabilidade social a todos os seus stakeholders, bem como, a necessidade de torn?-las
p?blicas e de continuar investindo e aprimorando tais a??es. Ao final da disserta??o,
apresenta-se as conclus?es sobre o trabalho realizado e recomenda??es a futuros estudos e
pesquisas.
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Proposta de uma gramática para análise de textos com estrutura OCC-RDD por meio de tradução com semântica de redes de PetriFerrari, Carla Marye Bicas 14 September 2017 (has links)
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Previous issue date: 2017-09-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The aim of this research is to design a grammar that recognizes an educational text written in
the narrative structure OCC-RDD and from its own generated a Petri Net model, in order to be
possible analyzed and interpreted as network property on the educational history. The research will
start with a bibliographic research from which a grammar and other components of this research
are prepared, whose main objective is to advice the teacher on the class preparation which uses
the narrative structure. A text following the narrative model in order to use it on the tool will be
prepared and the same will go through each step of the research, which are: recognition of the fable,
creation of the Petri Net model, network analysis and production of the results of fable’s analysis.
The result of this project is the fable recognition grammar that can be used in a special tool with anexample and the analysis of the properties of this example / O objetivo da pesquisa é projetar uma gramática que reconheça um texto educativo escrito na
estrutura da narrativa OCC-RDD e que a partir dela seja gerada um modelo de Rede de Petri, a
fim de que seja possível analisar e interpretar as propriedades da rede na história educacional. A
pesquisa terá início com um trabalho de consultas bibliográficas a partir do qual será preparada
uma gramática e os outros componentes da pesquisa que possuem como principal objetivo auxiliar
o professor na preparação de uma aula que utilize a estrutura narrativa. Um texto seguindo o modelo
da narrativa com o intuito de utilizá-lo na ferramenta será preparado e o mesmo passará por cada
etapa da pesquisa, que são: reconhecimento da fábula, criação do modelo de rede de Petri, análise
da rede e produção dos resultados de análise da fábula. O resultado do trabalho ´e a gramática de
reconhecimento de fábula que poderá ser utilizada numa ferramenta junto com um exemplo e a
análise das propriedades deste exemplo
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Geometric guides for interactive evolutionary designRetzepi, Theodora January 2018 (has links)
This thesis describes the addition of novel Geometric Guides to a generative Computer-Aided Design (CAD) application that supports early-stage concept generation. The application generates and evolves abstract 3D shapes, used to inspire the form of new product concepts. It was previously a conventional Interactive Evolutionary system where users selected shapes from evolving populations. However, design industry users wanted more control over the shapes, for example by allowing the system to influence the proportions of evolving forms. The solution researched, developed, integrated and tested is a more cooperative human-machine system combining classic user interaction with innovative geometric analysis. In the literature review, different types of Interactive Evolutionary Computation (IEC), Pose Normalisation (PN), Shape Comparison, and Minimum-Volume Bounding Box approaches are compared, with some of these technologies identified as applicable for this research. Using its Application Programming Interface, add-ins for the Siemens NX CAD system have been developed and integrated with an existing Interactive Evolutionary CAD system. These add-ins allow users to create a Geometric Guide (GG) at the start of a shape exploration session. Before evolving shapes can be compared with the GG, they must be aligned and scaled (known as Pose Normalisation in the literature). Computationally-efficient PN has been achieved using geometric functions such as Bounding Box for translation and scaling, and Principle Axes for the orientation. A shape comparison algorithm has been developed that is based on the principle of non-intersecting volumes. This algorithm is also implemented with standard, readily available geometric functions, is conceptually simple, accessible to other researchers and also offers appropriate efficacy. Objective geometric testing showed that the PN and Shape Comparison methods developed are suitable for this guiding application and can be efficiently adapted to enhance an Interactive Evolutionary Design system. System performance with different population sizes was examined to indicate how best to use the new guiding capabilities to assist users in evolutionary shape searching. This was backed up by participant testing research into two user interaction strategies. A Large Background Population (LBP) approach where the GG is used to select a sub-set of shapes to show to the user was shown to be the most effective. The inclusion of Geometric Guides has taken the research from the existing aesthetic focused tool to a system capable of application to a wider range of engineering design problems. This system supports earlier design processes and ideation in conceptual design and allows a designer to experiment with ideas freely to interactively explore populations of evolving solutions. The design approach has been further improved, and expanded beyond the previous quite limited scope of form exploration.
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Electromagnetic Homogenization-simulations of MaterialsTörnqvist, Julia January 2019 (has links)
This thesis aims to determine the distribution of the relative permittivity for random mixtures of material using electromagnetic simulations. The algorithm used in the simulations is the FDTD method which solves Maxwell's equations numerically in the time-domain. The material is modeled as randomly shaped particles with radius 12 ± 10 micrometre in x- and y-direction and radius 3 ± 1 micrometre in zdirection. The scattering parameters from the transmitted and reflected electric field when a plane wave interacts with the material are measured. The relative permittivity is determined from the scattering parameters using the iterative Baker-Jarvis method. The simulations shows that both the distribution and the value of the relative permittivity is low when the particles have non conducting layers to force interruptions to prevent percolation, a conducting path between the particles. The most important result is of the kind where the simulations do not have any boundaries to prevent percolation. These simulations reflects how the relative permittivity distributes in real measurements. It is established that the value of the relative permittivity has a large distribution and also that percolation occurs because of the periodic structures.
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The influence of the transition plan in developing communication programsTanaka, Yuki 01 January 1991 (has links)
The transition of students with moderate to severe handicaps from school to work and adult life has become a principal concern of special education over the last decade. Despite of these attentions, there has been little attention to the need for including plans for the student's communication needs in his or her Transition Plan. Thus, it is important to study the relationship between the inclusion of a student's communication needs in his or her Transition Plan and the effectiveness of communication programs. The purpose of this study is to identify the relationship between the Transition Plan and the effectiveness of communication programs, considering the individual's functioning level, family involvement, and communication mode.
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Can a Three-Day Training Focusing on the Nature of Science and Science Practices as They Relate to Mind in the Making Make a Difference in Preschool Teachers' Self-Efficacy Engaging in Science Education?Meacham, Colleen 20 November 2017 (has links)
As technology and our world understanding develop, we will need citizens who are able to ask and answer questions that have not been thought of yet. Currently, high school and college graduates entering the workforce demonstrate a gap in their ability to develop unique solutions and fill the current technology-driven jobs. To address this gap, science needs to be prioritized early in children's lives. The focus of this research was to analyze a science training program that would help pre-school teachers better understand Mind in the Making life skills, the nature of science, science practices, and improve their self-efficacy integrating science education into their classrooms and curriculum. Seventy-one teachers enrolled in two three-day, professional development trainings that were conducted over three, five-hour sessions approximately one month apart.
During that training the teachers learned hands-on activities for young children that introduced life and physical science content. They were also given the task of developing and implementing a science-based lesson for their students and then analyzing it with other participants.
The information from the lesson plans was collected for analysis. After the last training the teachers were given a pre/post retrospective survey to measure effective outcomes. The results from the lesson plans and surveys indicate that the trainings helped improve the teachers' understanding of Mind in the Making, the nature of science, and science practices. The results also show that the teachers felt more comfortable integrating science education into their classrooms and curriculum.
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An in situ test for stress corrosion damage and tension in boltsBarke, Derek Woolrich, 1975- January 2002 (has links)
Abstract not available
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Analyse Informatique de Guides de Bonnes Pratiques CliniquesGeorg, Gersende 06 September 2006 (has links) (PDF)
Les Guides de Bonnes Pratiques Cliniques sont des documents normalisés destinés à l'amélioration de la qualité des soins. L'informatisation des Guides de Bonnes Pratiques est un enjeu majeur pour leur diffusion mais aussi pour les différentes étapes de leur cycle de vie depuis leur rédaction. De nombreux travaux de recherche ont été consacrés à l'informatisation des Guides de Bonnes Pratiques. Parmi eux, les approches documentaires utilisent les développements récents des langages à base de balises pour la structuration des documents, facilitant le traitement informatisé de ces documents. Nous proposons une extension de l'approche documentaire qui est basée sur une analyse intelligente des marqueurs de structuration des recommandations utilisant un analyseur à états finis. Cette approche a été intégrée à l'environnement informatique G-DEE (Guideline Document Engineering Environment) dédié à l'étude des Guides de Bonnes Pratiques, et peut servir pour une aide à la rédaction, un support au consensus lors de l'écriture, et un support pour la maintenance et l'actualisation des Guides de Bonnes Pratiques.
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Lasers guides d'onde dans le niobate de lithium dopé erbiumGrisard, Arnaud 11 December 1997 (has links) (PDF)
Le niobate de lithium dopé à l'erbium permet de tirer parti des propriétés optiques des ions terre rare et du fort coefficient électro-optique de la matrice. Il constitue ainsi un matériau prometteur pour la réalisation de lasers déclenchés monolithiques émettant vers 1,5 µm. En configuration guidée, l'obtention d'impulsions à forte puissance crête est en particulier envisageable à partir d'un pompage par diode laser du commerce et avec de faibles tensions de commande.<br />Dans cette perspective, un mécanisme prépondérant de réduction du gain aux fortes concentrations de dopant, caractéristique des cristaux dopés dans la masse, a été identifié et une méthode originale développée pour évaluer simplement ses effets de façon quantitative.<br />Ce mémoire souligne l'excellent accord entre les prévisions théoriques du modèle d'amplification optique mis en place puis adapté au cas de guides monomodes et les mesures réalisés sur les composants fabriqués dans le même temps par diffusion de bandes de titane dans des substrats dopés dans la masse et en surface.<br />Ceci a permis d'observer pour la première fois l'effet laser en continu dans des guides d'onde sur niobate de lithium dopé à l'erbium dans la masse et pompés par une diode à 1,48 µm. L'intégration de modulateurs électro-optiques a également conduit à l'observation d'impulsions déclenchées. Pour l'instant limitées par la puissance de pompe disponible, elles devraient pouvoir atteindre plusieurs centaines de watts de puissance crête avec des durées de quelques nanosecondes.
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