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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.
11

Simulations couplées fluide-structure et étude expérimentale d’un hydrofoil composite sous écoulement hydrodynamique / Coupled Fluid-Structure Simulations and Experimental Study of a Composite Hydrofoil Under Hydrodynamic Flow

Pernod, Laëtitia 05 March 2019 (has links)
Les travaux de cette thèse s’inscrivent dans le cadre d’une collaboration CIFRE entre Naval Group, le Laboratoire d’Hydrodynamique, d’Energétique et d’Environnement Atmosphérique (LHEEA) de l’Ecole Centrale de Nantes et de l’Institut de Génie des Matériaux (GeM) de l’ICAM de Nantes, sur la problématique de développement d’hélices marines plus efficaces, plus discrètes, et plus respectueuses de l’environnement. Une des solutions passe par le développement de structures composites plus légères et plus flexibles, capables de se déformer passivement pour s’auto-adapter à l’écoulement incident grâce à leurs propriétés spécifiques de couplage flexion-torsion. En lien direct avec cette problématique, nous avons réalisé les travaux de thèse en deux temps. Nous avons dans un premier temps mis en place, montré la faisabilité et validé une méthode de couplage numérique fluidestructure implicite fort entre les codes commerciaux de CFD Starccm+ et de CSD Abaqus pour un cas d'application issu de résultats expérimentaux disponibles dans la littérature sur deux hydrofoils flexibles déformables. Puis dans un second temps nous avons développé, réalisé et testé, dans le tunnel hydrodynamique de l’Ecole Navale, un profil portant composite spécifiquement conçu pour s’approcher du comportement d’une hélice. L’étude expérimentale et numérique de cette configuration nous a permis i) d’éprouver l'utilisation en milieu académique et industriel de nouvelles méthodes expérimentales d'instrumentation d'une pièce composite par insertion directe de fibres optiques dans les plis de composite, et d'une méthode mixte numérique - expérimentale de calibration fine d'un modèle numérique structure ; ii) d’apporter un éclairage sur la physique de l'interaction fluidestructure se produisant sur une surface portante composite ; et iii) de préciser les limitations actuelles concernant la diffusion en milieu industriel de cette méthode de couplage numérique fluide-structure. / This Ph.D is sponsored by the French company Naval Group in collaboration with LHEEA Laboratory from Ecole Centrale de Nantes and GeM Institute from ICAM de Nantes, and deals with the development of new composite marine propellers with improved efficiency, improved acoustic discretion and more environment-friendly. One of the key solutions lies in the application of composite materials to marine structures, in order to benefit from their reduced weight, increased flexibility and bend-twist coupling capacity. Indeed, the latter enables the shape-adaptability of the structure to passively adapt to the incoming flow. To meet this challenge, we first set-up a tightly coupled numerical fluid-structure method using two commercial CFD (Starccm+) and CSD (Abaqus) solvers on two flexible hydrofoils and we validated this method against experimental results available in the literature. Second, we specifically developed a composite hydrofoil to behave closely like a marine propeller and tested it in the hydrodynamic tunnel of the Ecole Navale. Thanks to the combined experimental and numerical analysis of this composite hydrofoil we reached the following conclusions: i) we helped demonstrate the industrial application of a state-of-the-art strain measurement technique using optical fibers directly embedded within the composite plies, ii) we provided some insights into the physics of the fluid-structure interaction occurring on composite hydrofoils and iii) we presented the current limitations of this coupled numerical fluid-structure method relatively to its industrial application.
12

Post-trade: An Examination of Blockchain Technology’s Capabilities for Future Development / Post-trade: En undersökning av blockkedjeteknikens förmåga för framtida utveckling

Parvaneh, Pouria, Strand, Ludvig January 2023 (has links)
Financial markets have a major role in economic development. An area of the financial industry is securities trading consisting of several stages such as pre-trade, trade execution and post-trade processing. This study has focused on the post-trade stage of securities trading with a particular focus on central securities depositories (CSD). Blockchain technology has been a hot topic amongst experts of the financial industry with discussions on a potential to disrupt parts of the industry. The purpose of this study was to investigate if blockchain technology is a relevant choice of technology, to cope with problems in the post-trade industry that need to be addressed. The study has investigated whether challenges in the post-trade can be addressed with the help of blockchain technology by identifying the existing challenges, the capabilities and drawbacks of blockchain technology and finally detecting any obstacles for the potential development of this technology in the post-trade industry. The conducted research was performed through a qualitative research study, a literature review and data collection through primary and secondary sources using an inductive and abductive combination of approaches. The main findings in this report suggest that blockchain can potentially be applied in many different areas of the post-trade industry but is particularly suited to some areas in CSDs and potentially provides new opportunities such as better technology to cope with reconciliation challenges and provide an alternative to archive data, increasing audit possibilities and transparency. Nevertheless, the report also suggests that those problems could be solved with other technologies as well. Blockchain technology also has the potential of removing some intermediaries in the post-trade industry like clearing houses, however several barriers to such a development have been identified related to legal and political aspects. The study identified that blockchain technology in its basic form is not a relevant technology to use in stock exchanges due to its inability to meet the specific requirements of an exchange. The application of smart contracts in blockchain technology opens up possibilities to handle the problem of human errors and presents a solution automating certain financial processes. The theoretical contributions of the study are suggestions on improvements to frameworks used in the report. / Finansiella marknader spelar en betydande roll i ekonomisk utveckling. En del av finansbranschen är värdepappershandel, som består av flera faser såsom pre-trade, trade execution och post-trade-processer. Denna studie har fokuserat på post-tradesteget inom värdepappershandel med särskilt fokus på centrala värdepappersdepåer (CSD). Blockchain-teknologi har varit ett hett ämne bland experter inom finansbranschen med diskussioner om dess potential att vara disruptiv för delar av branschen. Syftet med denna studie var att undersöka om blockchain-teknologi är ett relevant val för att hantera problem inom post-trade-industrin. Studien har undersökt om utmaningarna inom post-trade kan hanteras med hjälp av blockchain-teknologi genom att identifiera befintliga utmaningar, förmågorna och begränsningarna hos blockchain-teknologi samt slutligen upptäcka eventuella hinder för den potentiella utvecklingen av denna teknologi inom post-trade industrin. Den genomförda forskningen utfördes genom en kvalitativ forskningsstudie, en litteraturstudie och datainsamling genom primära och sekundära källor med genom en kombination av induktivt och abduktivt tillvägagångssätt. De främsta resultaten i denna rapport antyder att blockchain potentiellt kan tillämpas inom många olika områden inom post-trade-industrin, men är särskilt lämpad för vissa områden inom CSD och kan möjligtvis erbjuda nya möjligheter såsom en teknologi för att hantera utmaningar med reconciliation och erbjuda ett alternativ för arkivering av data, vilket ökar granskningmöjligheter och transparens. Rapporten antyder dock även att dessa problem också kan lösas med andra teknologier. Blockchain-teknologi har även potential att ta bort vissa mellanhänder inom post-trade, såsom clearinghus, men flera hinder för en sådan utveckling har identifierats i relation till legala och politiska aspekter. Studien identifierade att blockchain-teknologi i sin grundläggande form inte är en relevant teknologi att använda på börsen på grund av dess oförmåga att uppfylla de specifika kraven för en börs. Användningen av smarta kontrakt inom blockchain-teknologi öppnar upp möjligheter att hantera problemet med mänskliga fel och presenterar en lösning genom att automatisera vissa finansiella processer. De teoretiska bidragen från studien är förslag på förbättringar av de ramverk som används i rapporten.
13

Enhancing PhD Preparation through Shared Ideas across CSD Program

Crais, Elizabeth, Bentler, Ruth, Hewitt, Lynne, Lister, Jennifer, Simpson, Jennifer, Gillam, Ronald, Cone, Barbara, Williams, A. Lynn, Tellis, Glen 18 November 2016 (has links)
Shortages of PhD graduates to fill CSD faculty positions have been a concern for over 15 years. The ASHA AAB (collaborating with CAPCSD) completed interviews of Coordinators of almost all 76 CSD PhD Programs. Results and successful aspects of the programs will be highlighted to stimulate discussion among participants.
14

境界層の超音速パネルフラッタへの影響

橋本, 敦, HASHIMOTO, Atsushi, 八木, 直人, YAGI, Naoto, 中村, 佳朗, NAKAMURA, Yoshiaki 05 April 2007 (has links)
No description available.
15

Using tightly-coupled CFD/CSD simulation for rotorcraft stability analysis

Zaki, Afifa Adel 17 January 2012 (has links)
Dynamic stall deeply affects the response of helicopter rotor blades, making its modeling accuracy very important. Two commonly used dynamic stall models were implemented in a comprehensive code, validated, and contrasted to provide improved analysis accuracy and versatility. Next, computational fluid dynamics and computational structural dynamics loose coupling methodologies are reviewed, and a general tight coupling approach was implemented and tested. The tightly coupled computational fluid dynamics and computational structural dynamics methodology is then used to assess the stability characteristics of complex rotorcraft problems. An aeroelastic analysis of rotors must include an assessment of potential instabilities and the determination of damping ratios for all modes of interest. If the governing equations of motion of a system can be formulated as linear, ordinary differential equations with constant coefficients, classical stability evaluation methodologies based on the characteristic exponents of the system can rapidly and accurately provide the system's stability characteristics. For systems described by linear, ordinary differential equations with periodic coefficients, Floquet's theory is the preferred approach. While these methods provide excellent results for simplified linear models with a moderate number of degrees of freedom, they become quickly unwieldy as the number of degrees of freedom increases. Therefore, to accurately analyze rotorcraft aeroelastic periodic systems, a fully nonlinear, coupled simulation tool is used to determine the response of the system to perturbations about an equilibrium configuration and determine the presence of instabilities and damping ratios. The stability analysis is undertaken using an algorithm based on a Partial Floquet approach that has been successfully applied with computational structural dynamics tools on rotors and wind turbines. The stability analysis approach is computationally inexpensive and consists of post processing aeroelastic data, which can be used with any aeroelastic rotorcraft code or with experimental data.
16

Evaluation de l'impact d'un centre de stockage de déchets sur la qualité de l'air : approche par méthodes statistiques et modélisation déterministe

Riesenmey, Caroline 28 March 2008 (has links) (PDF)
Les Centres de Stockage de Déchets (CSD) ménagers et assimilés peuvent avoir des impacts importants sur la qualité de l'air à proximité. Cependant, ces impacts restent difficiles à évaluer avec les outils classiquement utilisés en pollution de l'air. Ceci est dû à différentes particularités propres aux CSD : la source d'émission (surfacique, passive, située parfois dans une zone en relief, ...), le type de pollution (olfactive) et l'échelle spatio-temporelle du phénomène (pics de pollution relativement courts et ne touchant qu'une zone restreinte autour du site). Après une mise en évidence des liens entre les conditions météorologiques et la qualité de l'air, trois types d'outils ont été élaborés et testés successivement afin d'évaluer cette pollution : * Un tunnel de vent pour quantifier les émissions : le principal inconvénient de cet outil couramment utilisé est la forte dépendance des résultats aux conditions de mesure et au type de tunnel utilisé. Une modélisation, avec le logiciel Fluent, des échanges sol / air et des écoulements dans différents types de tunnel permet d'évaluer l'incertitude de la mesure liée à l'utilisation du tunnel. * Un modèle de dispersion : le modèle météorologique à très fine échelle ARPS (Advanced Regional Prediction System) a été couplé à un modèle de dispersion eulérien afin de représenter la météorologie locale sur le site et la dispersion des polluants avec une résolution fine (100 m). Le modèle a été testé et validé sur un CSD situé dans une zone présentant un relief important pour des conditions météorologiques particulièrement favorables aux épisodes de pollution. * Un outil de quantification de l'exposition des populations : Il s'agit d'un outil SIG (Systèmes d'Information Géographique) permettant d'évaluer l'exposition par superposition des cartes de panache (obtenues dans la deuxième étape) avec des cartes de densité de population afin d'obtenir des cartes d'exposition. L'ensemble de la chaîne présentée ci-dessus permet d'évaluer avec précision l'exposition d'une population aux émissions d'un CSD en tenant compte des conditions météorologiques et des modifications du relief à long terme liées au stockage des déchets.
17

An empirical inquiry of strategic corporate sustainable development orientation - taxonomy, and interrelationships with antecedents, consequences, contingencies and pathways

Xu, Ying , Marketing, Australian School of Business, UNSW January 2009 (has links)
This thesis addresses two research objectives: i).empirically develop a taxonomy based on firms strategic Corporate Sustainable Development (CSD) orientation to better understand and describe their characteristics and business differentials; and ii).develop and empirically test an integrated framework of antecedents and consequences of the strategic CSD, including pathways and contingencies. The full study involves two consecutive steps: a qualitative study using in-depth interviews with senior marketing executives/experts from eight selected organisations; and a quantitative inquiry using an online survey, with a final sample of 183 medium to large Australian companies across manufacturing, mining and utilities/energy industries. Collectively, this two-stage study yields interesting research findings that are of substantial academic and managerial value as follows: The taxonomy analysis identifies three distinct groups: Strategic Achievers, Risk Avoiders and Suspicious Observers, that represent the three levels/stages of CSD adoption from high to low. These three clusters are described by what they do, why they do it, the major barriers and performance differentials. These findings contribute to the classification scheme and may assist managers to determine current levels of CSD, identify possible business opportunities and/or decide on the strategies of CSD adoption. Through developing CSD measures and testing the relationships within the proposed framework, Innovation Capability (IC) is found to be a pathway (mediator) for firms to gain competitive advantage from Corporate Sustainable Development, whereas CSD does not impact on Business Performance directly when IC is absent. This inconsistent mediating effect of IC provides interesting new insight. In addition, CSD exhibits a positive impact on firms Member Organisation Identification, a surrogate measure of corporate reputation from the perspective of employees. As part of the second research objective, this study also conducts the first empirical testing of the Menon and Menon (1997) model, and found that Industry Reputation moderated the Enviropreneurial Marketing and Business Performance relationship. These findings provide new knowledge concerning strategic Corporate Sustainable Development (CSD) orientation as well as the underlying mechanisms, which may inform managers with viable directions for integrating corporate economic benefits with social and environmental considerations.
18

Role of ASF1 in histone deposition during replication / Rôle de la chaperonne d'histone ASF1 dans la déposition des histones au cours de la réplication

Tripathi, Vivek 07 November 2012 (has links)
Cette thèse traite du rôle de la chaperonne d'histone ASF1 dans la déposition des histones au cours de la réplication. / That thesis is about the role of ASF1 in histone deposition during replication.
19

Multicultural/Multilingual Issues in CSD Research Methods Coursework: A Neglected Topic?

Davis, Emmy, Gonzalez, Alexis, Wolske, Kyle, Louw, Brenda 01 January 2020 (has links)
Insufficient research training contributes to the current shortage of researchers in the field of speech-language pathology, but also to the dearth of multicultural and multilingual (MCML) research. There is limited information regarding how MCML issues are addressed in Research Methods courses in Communication Sciences and Disorders (CSD). One of the ways in which this problem can be addressed is to include MCML issues into CSD research methods courses. A survey, “Integration of MCML Issues in Research Coursework” was developed based on an in-depth literature review. The aim of the survey was to gain information from instructors by examining the extent to which MCML issues are included in their CSD research methods courses. A total of 56 instructors responded to the survey. In the survey, 41.03% respondents indicated that it was very important to include MCML issues but only 28.21% included this topic in their course objectives. Time constraints, curricula overload, and specific courses on MCML were most cited as reasons for not including MCML. 44.44% used Research Ethics and 27.78% used EBP as strategies to infuse MCML into courses. 61.11% had further interest in the topic. By addressing MCML issues and culturally responsive research in CSD research methods classes, it is hypothesized that future speech-language pathologists will be better equipped not only to provide evidence-based services to the diverse populations they serve, but also be better prepared to conduct research on these diverse populations.
20

Fast X-ray diffraction crystal size distribution analysis

Neher, Sigmund Heinrich 03 July 2018 (has links)
No description available.

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