• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 532
  • 430
  • 255
  • 60
  • 54
  • 41
  • 35
  • 14
  • 6
  • 6
  • 6
  • 6
  • 4
  • 4
  • 3
  • Tagged with
  • 1600
  • 197
  • 196
  • 184
  • 171
  • 132
  • 117
  • 89
  • 74
  • 68
  • 66
  • 66
  • 59
  • 58
  • 57
  • 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.
321

Čínský trh - možnosti a rizika vstupu zahraničních subjektů / The Chinese market - possibilities and risks of the engagement of foreign entities

Dressler, Daniel January 2012 (has links)
The thesis provides an analysis of the possibilities for a foreign enterprise to enter the Chinese market. After the introduction of the Chinese economy and its basic characteristics, the thesis focuses on the analysis of different market entry forms. They are divided into export operations, contractual forms of entry in the form of licensing or franchising, and into the capital entry strategy. For each of these forms the legal regulation is discussed along with the useful tips for businesses. The advantages and potential risks are also highlighted. The final chapter of the thesis focuses on the intellectual property protection in China and its regulation. It affects all businesses, regardless the form they choose. The work is based on the current version of Chinese laws and on the latest commentaries on these regulations. It should serve to all foreign entrepreneurs who decide to start business activities in China and take advantage of the countless opportunities that this country has to offer.
322

Initial studies of structure coupling effects for a trolley/RRDF interface

Teh, Chong-Ann 03 1900 (has links)
Approved for public release; distribution is unlimited / The purpose of this thesis is to lay the foundation for analyzing structural coupling effects for a proposed trolley interface between a ship and a roll-on roll-off discharge facility (RRDF). Such a facility could allow heavy cargo transfer at higher sea states. Previous studies have analyzed motions assuming that there is no structural coupling between the trolley and the RRDF. A mathematical model that incorporates structural coupling is developed using the principle of virtual work. In order to assess the degree of necessity for the proposed model we conduct a systematic series of numerical experiments. In these calculations we model the trolley through a generalized stiffness coefficient and assess its influence on RRDF motions. It is shown that modeling of structural coupling may be necessary depending on the relative order of magnitude of trolley structural rigidity and trolley placement. / Major, Republic of Singapore Navy
323

Optical near-field characterization of Slow-Bloch Mode based photonic crystal devices / Nanopointes actives pour la nano-photonique

Vo, Thanh Phong 06 September 2011 (has links)
Les structures à cristaux photoniques bidimentionnels ont permis la fabrication d'une large variété de composants nanophotoniques. En particulier, dans les PC parfaits, la densité locale d'états optiques se trouve exacerbée au niveau des points de symétrie du diagramme de bande. Près de ces points, où la vitesse de groupe tend vers zéro, la faible courbure de bande courbure de bande donne lieu à des modes stationnaires, dits de lumière "lente" (ou modes de Bloch lents). Les propriétés de la lumière lente en font de bons candidats pour améliorer l'effet Purcell, pour produire des effets non-linéaires ou pour concevoir des lasers à faible seuil. Parmi ces modes, les modes de Bloch lent émettant dans la direction verticale, c'est à dire situé au niveau du point Γ de la zone de Brillouin, sont particulièrement intéressants pour intégrer des architectures 2D avec de l'optique en espace libre. En particulier, certains de ces modes ont permis la réalisation d'émission laser dans la 3e direction avec des propriétés de polarisation particulières. D'autres applications prometteuses concernent le désordre : en introduisant un désordre aléatoire mais contrôlé dans la structure photonique, il est possible d'induire une transition entre le mode de Bloch lent de la structure ordonnée vers un mode localisé par le désordre, de type localisation d'Anderson dans une structure faiblement désordonnée.Dans cette thèse, les modes de Bloch lents ont été étudiés et caractérisés en Microscopie optique en champ proche. Nous nous sommes concentrés sur les modes en Gamma de la structure graphite. Le SNOM a permis de visualiser la composante évanescente du mode avec une résolution spatiale inférieure à la limite de diffraction. Dans ce travail, nous avons montré que le champ lointain et de l'image en champ proche du mode à la surface du cristal photonique sont différentes et que seules les mesures en champ proche permettent de rendre compte du mode réel à l'intérieur de la membrane de cristal photonique, en accord avec prédiction théorique. L'importance du choix de la sonde (silice, pointe métallisée, Nano-antenne) pour l'étude des structures à cristaux photoniques a également été démontrée. Outre la mesure d'intensité du champ électromagnétique, la polarisation du champ électrique a été mesurée à l'échelle nanométrique pour la première fois par l'aide d'une antenne à ouverture papillon. Ces résultats permettent d'identifier sans équivoque des modes avec les simulations 3D-FDTD.Dans ce travail est également rapporté la première observation de la localisation de la lumière dans deux types de lasers aléatoires à base de cristaux photoniques bidimensionnels. Le caractère aléatoire est introduit soit en déplaçant les positions des motifs du cristal (trous d'air), soit en faisant varier de façon aléatoire le diamètre des trous. Pour la première fois nous avons observé directement par SNOM la localisation de la lumière dans le cristal désordonné. Cela nous a permis d'observer la transition de morphologie du mode de Bloch lent entre le cristal ordonné et le cristal désordonné. / 2D-Photonic crystal (PC) structures have enabled the fabrication of a wide variety of nanophotonic components. In perfect PCs, the exploitation of the enhanced local density of states at critical points of the band diagram has attracted considerable attention. Near these points, where the group velocity vanished, low curvature flat bands give rise to delocalized and stationary optical slow Bloch modes (or slow light modes). Properties of slow light make them good candidates to enhance Purcell or various non-linear effects or to design low-threshold lasers. Among these modes, slow Bloch modes (SBMs) emitting in the vertical direction, i.e. located at the Γ- point of the Brillouin zone are particularly interesting for integrating 2D PC architectures with free space optics. In particular, some SBMs proved to be suitable for achieving strong vertical emission with peculiar polarization properties. Other promising applications concern disorder: by introducing a controlled randomness into the PC structure, it is possible to induce a transition from slow Bloch mode (in ordered PC) to Anderson’s localization (in disordered PC) as a function of disorder degree. In this PhD dissertation, Slow Bloch modes have been studied and characterized by the means of Near-field Scanning Optical microscopy (NSOM). We particularly focused on Slow Bloch laser mode at Γ- point of a honeycomb 2DPC. This NSOM technique enables to visualize the evanescent component of the mode with a spatial resolution below the diffraction limit. In this work, we showed that the far-field and the near-field image of the mode at the 2D-PC surface are different and that near-field results yield a better insight in the real mode structure inside the PC slab in agreement with theoretical prediction. The importance of the probe selection (bare silica, metallized tip and bow-tie aperture nanoantenna) for studying III-V photonic crystal structures was also demonstrated. Besides intensity measurement of the electromagnetic field, the polarization of the electric field has been measured at the nanoscale for the first time by using a bow-tie nano-antenna probe. These results enable the unambiguous identification of the modes with the 3D-FDTD simulations.In this work is also reported the first observation of two-dimensional localization of light in two types of 2D random photonic crystal lasers, where Slow Bloch Mode (SBM) is scattered by artificial structural randomness in triangular PCs. The structural randomness is introduced whether by nanometer displacements in the positions of lattice elements (air holes), whether by variation of the hole diameters. The direct near-field imaging of the lasing mode by use of NSOM for the first time, allowed us to observe the transition of the extended planar SBM to be Anderson localized.
324

Artefakter, modes och semiotiska resurser vid introduktion av matematiklektioner i årskurs 1-3

Asad Kandastar, Ahdia, Stenius Johnson, Peggy January 2017 (has links)
Läroplanen för grundskolan betonar att skolan ska främja elevers utvecklinggenom att använda varierade arbetsformer samt ett varierat innehåll. Skolverkets forskningsrapport; Lusten att lära – med fokus på matematik (2001–2002) skriver att en varierad undervisning är viktig i matematik. Syftet med denna studie är att undersöka hur lärare i årskurs 1–3 använder sig av olika artefakter, modes och semiotiska resurser, och till vilken grad, vid introduktionen av matematiklektioner. Vi använde oss av strukturerade observationer med kompletterande intervjuer och bearbetade det insamlade materialet med kodning och kategorisering. Resultatet visar att vilka modes, semiotiska resurser och artefakter, samt hur de används varierar. Slutsatserna av studien är att det är viktigt att lärare är medvetna om vilka resurser de har tillhands och hur de ska använda sig av dem samt att medvetet välja resurser som tar hänsyn till det multimodala perspektivet.
325

Dual-wavelength fiber laser above 2 mu m based on cascaded single mode-multimode-single mode structures

Fu, Shijie, Shi, Guannan, Sheng, Quan, Shi, Wei, Yao, Jianquan, Zhu, Xiushan, Peyghambarian, N. 06 1900 (has links)
A stable dual-wavelength Tm:Ho co-doped fiber laser operating above 2 mu m based on cascaded single mode-multimode-single mode (SMS) all-fiber structures has been proposed and experimentally demonstrated for the first time.
326

Quantum Shot Noise in Graphene / Bruit de grenaille quantique dans le graphène

Mostovov, Andrey 23 April 2014 (has links)
Nous avons mené une étude expérimentale du bruit de grenaille quantique dans une mono-couche de graphène. La conductance et l'effet Hall quantique ont été également examinés. Le modèle théorique, décrivant la conductance et le bruit quantique dans du graphène idéal (balistique) a été proposé par Tworzydlo et al., 2006. Dans du graphène diffusif, plus facilement réalisable expérimentalement, le bruit de grenaille a été étudié numériquement par plusieurs auteurs (San-Jose et al., 2007, Lewenkopf et al., 2008, Logoteta et al., 2013). Les conclusions des premiers travaux expérimentaux (DiCarlo et al., 2008 and Danneau et al., 2008) sur ce sujet n'en ont pas permis une compréhension suffisamment approfondi et des études complémentaires sont nécessaires. Dans notre expérience nous avons tenté de réduire au maximum les contributions du système de mesure sur le signal détecté en effectuant une mesure du bruit en tension quatre points et en utilisant la détection en cross-corrélation. En plus, notre système de mesure inclut des amplificateurs bas bruit cryogéniques faits maison combinés avec des filtres passe-bande alors que notre couche de graphène contient une constriction au centre. n utilisant les résultats des mesures de la conductance et de l'effet Hall quantique nous avons déterminé le libre parcours moyen dans notre échantillon et conclu qu'il est dans le régime diffusif. Les valeurs du facteur de Fano que nous avons extraites sont en bon accord avec les simulations pour ce régime, un pic au point de Dirac prévu par Lewenkopf et al. a été observé. D'autre part, nos résultats sont compatibles avec ceux de Danneau et al. and DiCarlo et al. / We have conducted an experimental study of the quantum shot noise in a mono-layer graphene device. Conductance of the device and the quantum Hall effect were also investigated. A theoretical model, describing conductance and quantum shot noise in ideal (ballistic) graphene was proposed by Tworzydlo et al., 2006. In diffusive graphene, that is much easier achievable experimentally, shot noise was investigated numerically by several authors (San-Jose et al., 2007, Lewenkopf et al., 2008, Logoteta et al., 2013). Conclusions of the first experimental works (DiCarlo et al., 2008 and Danneau et al., 2008), addressing this problem, didn’t lead to an enough broad understanding of it and a further investigation was required. In our experiment we intended to maximally reduce the contributions of the measurement system to the detected signal by performing four-point voltage noise measurement as well as by using cross-correlation detection. In addition to that, our measurement system include home-made cryogenic low-noise amplifiers combined with band-pass filters, while our experimental device carries a constriction in the center of graphene layer and side-gates are used instead of back-gate. First, using the results of the conductance and of the quantum Hall effect measurements we determined the mean free path in our sample and concluded that it was in diffusive regime. The extracted values of the Fano factor show a good agreement with the above-mentioned simulations for this regime, in particular, the peak at Dirac point, predicted by Lewenkopf et al., was observed. Moreover our results are consistent with those of Danneau et al. and DiCarlo et al.
327

The experience of traveling for young people with a hearing impairment– Voices of invisible disabled

Nilsson, Lina January 2020 (has links)
Tourism has become a major part of today's society and has been seen as a human privilege. The expansion of tourism makes travel more accessible to more people. Still, people with a disability can face difficulties when traveling for the purpose of tourism. Information becomes important to accomplish accessible tourism for everyone, but the problem in various tourism disciplines occurs with the lack of knowledge about people with disabilities.  Tourism has different disciplines. Transportation is one of the basics of making tourism accessible around the world. Transportation has a major impact on tourism development but also in tourist experiences. If the transportation mode is not accessible, it can be a negative experience for people with a disability and can affect the entire journey and their willingness to attempt further trips. Disability is a broad definition and it is important to understand that different disabilities require different needs and that everyone is individual. This study analyzes how hearing loss affects travelers and the understanding of; (1) What may be needed to assist people with hearing impairments when traveling; (2) How does traveling affect people with hearing impairment when they do not have accessibility? The method is a qualitative method with in-depth interviews because this study wants to understand and reflect participants’ experiences when traveling with a hearing impairment.
328

Comprendre le processus de prise de décision opérationnelle en agriculture : une approche en rationalité limitée

Dayde, Charlotte 17 January 2017 (has links) (PDF)
Afin d’expliquer la diversité des pratiques des agriculteurs, cette thèse explore le rôle des caractéristiques du processus de décision dans les choix opérationnels réalisés. Sur la base d’une méthode à deux volets (modélisation et enquêtes), nous avons proposé un modèle conceptuel du processus de prise de décision des agriculteurs, caractérisé les différences possibles au sein de ce processus (appelées modes de décisions), mis en évidence le lien entre ces modes et les pratiques, précisé les modalités de simplification du processus de décision et identifié de nouveaux leviers d’action pour l’accompagnement des agriculteurs. De nature générique, les modèles et les méthodes d’enquêtes proposés ont été appliqués à un cas d’étude qui à permis d’expliquer l’hétérogénéité des pratiques antifongiques des agriculteurs sur le blé tendre en MidiPyrénées par leurs caractéristiques personnelles, par les caractéristiques de leurs exploitations et par leurs modes de décision
329

The Swedish path to retail expansion : a multiple case study of swedish retailers

Bernhardsson, Bianca, Klamkin, Max, Lindsjö, Albin January 2019 (has links)
The purpose of this thesis is to study Swedish retailers in order to find out which factors are the most crucial and influencing when it comes to international market selection. We as authors could find studies about international market selection, but not a single one regarding why Swedish MNEs choose to enter certain markets. We as authors therefore see a need for a better understanding of which factors have the greatest influence over market selection. The literature review that has been established in this study includes theories related to behavioristics, economics, risk and entry modes. By using an abductive approach and interviewing both large firms like H&M and IKEA, as well as smaller companies like Clas Ohlson and Happy Socks, our results shows that the important factors differ depending on the company size. The analysis chapter also involves a discussion of the different entry modes of the four firms and how they could come to affect the internationalization process. This qualitative multi case research will serve as a foundation for firms aiming for international expansion and for people who wish to educate themselves further on how Swedish firms internationalize and why. It will also generate new research questions for future researchers to study whilst informing them of why this particular research gap is important to fill.
330

Modos não-lineares de vibração e controle ativo de risers. / Non-linear vibration modes and active control of risers.

Sanches, César Tarabay 12 March 2009 (has links)
Este trabalho tem por objetivos: o estudo do comportamento dinâmico nãolinear de risers oceânicos, utilizando modos não-lineares de vibração, e o controle ativo das vibrações neles induzidas. Uma formulação não-linear do método dos elementos finitos é utilizada para a modelagem dos sistemas estruturais com vários graus de liberdade. Pela aplicação do método das variedades invariantes ao modelo de elementos finitos, determinam-se os modos normais não-lineares. Para o caso de ressonâncias internas, pode ser necessário determinar multi-modos não-lineares, o que se faz pela aplicação do método das múltiplas escalas. Apreciável esforço científico ainda é necessário para uma compreensão profunda da dinâmica de risers. Muitas das questões em aberto estão relacionadas a aplicações em águas ultraprofundas. Recentemente, novas reservas de óleo e gás foram descobertas no mar brasileiro em águas ultraprofundas, com lâminas dágua superiores a 2500m. Assim, a indústria offshore se depara com um novo conjunto de problemas e desafios relacionados à dinâmica não-linear de risers. Desta forma, a análise modal não-linear pode ter um importante papel na modelagem de Riser- Towers, SCRs (Steel Catenary Riser), entre outros sistemas oceânicos. Um procedimento completo consideraria diversos aspectos como movimentos induzidos por ondas (WIM Wave Induced Motion) e por correntes oceânicas. Nesta última categoria, ressaltam-se as vibrações induzidas por vórtices (VIV Vortex Induced Vibration). A todos esses fenômenos se somam o escoamento interno, deslocamento imposto, contato com o solo marinho, etc. Nota-se que a análise modal não-linear é adequada para representar o comportamento da dinâmica global dos risers por meio de modelos matemáticos com poucos graus de liberdade. Diferenças relevantes entre as abordagens linear e nãolinear são encontradas na forma modal e nos diagramas de fase. Tais diferenças podem ser importantes quando o arrasto e a inércia do fluido forem considerados. Multi-modos são utilizados para abordar ressonâncias internas utilizando análises acopladas que são importantes no caso de excitação multi-modal de modos altos por VIV. De fato, modos não-lineares podem ser úteis na elaboração de modelos matematicamente reduzidos que apresentem uma resposta qualitativa e quantitativamente coerente com a resposta da análise de risers sob carregamentos reais. A análise modal não-linear é uma técnica inovadora que permite um aprofundamento do entendimento do comportamento da dinâmica dos risers e a elaboração de modelos matemáticos com poucos graus de liberdade. Por serem modelos menores, consomem menos tempo de processamento levando a respostas mais rápidas, essenciais para sistemas de controle eficientes. Alguns exemplos de sistemas de controle são estudados neste trabalho. / The present work has the following objectives: deep understanding of the nonlinear structural behaviour of riser dynamics, by using non-linear modal analysis, and the study of these structural systems when an active control system is coupled. The finite element method provides a set of non-linear equations of motion for the structural system considered. These non-linear equations of motion are handled by the so-called invariant manifold approach: non-linear vibration modes are defined as movements whose trajectories in phase space are confined to a two-dimensional invariant manifold. In addition, the method of multiple scales is used to determine the non-linear multi-modes, when internal resonances come into play. Riser dynamics still demands great research efforts, many of the open topics being related to deep and ultra-deep water applications. The offshore industry has already begun to explore in water depths at the limits of the current technology and has plans to access sites over 2500 metre-deep. Therefore, offshore industry will face new challenges concerning the non-linear dynamics of risers. Non-linear modal analysis will play an important role in the project development of hybrid towers, SCRs and so on. A complete design procedure considers several issues associated with the dynamic response to wave-induced motions (WIM) of the Floating Production Unity (FPU) and to ocean currents. In this latter category one may cite vortex-induced motions (VIM) of spar-type FPUs and vortex-induced vibration (VIV). Results point out that non-linear modal analysis is adequate to capture the global dynamic behaviour of risers. Relevant differences with respect to linear analysis might then appear in the modal shape and phase trajectories. Such differences might be important when drag and inertia fluid loads will be further considered. Multi-modes should be considered to approach internal resonance. Coupling analysing may be relevant in the case of multi-modal excitation of higher modes in VIV. Non-linear modes are believed to play an important role in degree-of-freedom model reduction, thus allowing for good qualitative and quantitative response analysis of risers under sea loading. Non-linear modal analysis is an innovative technique that allows for deeper understanding of riser dynamics. In addition, reduced models can be found in order to diminish the processing time. Reducing the calculation time is very important when control systems are considered. This work studies some examples of risers that are controlled by active systems, which are considerably affected by the processing time.

Page generated in 0.0453 seconds