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Hart, Derrick N. "Finite Field Models of Roth's Theorem in One and Two Dimensions." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11516.
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Recent work on many problems in additive combinatorics, such as Roth's Theorem, has shown the usefulness of first studying the problem in a finite field environment. Using the techniques of Bourgain to give a result in other settings such as general abelian groups, the author gives a walk through, including proof, of Roth's theorem in both the one dimensional and two dimensional cases (it would be more accurate to refer to the two dimensional case as Shkredov's Theorem). In the one dimensional case the argument is at its base Meshulam's but the structure will be essentially Green's. Let Ϝⁿ [subscript p], p ≠ 2 be the finite field of cardinality N = pⁿ. For large N, any subset A ⊂ Ϝⁿ [subscript p] of cardinality ∣A ∣≳ N ∕ log N must contain a triple of the form {x, x + d, x + 2d} for x, d ∈ Ϝⁿ [subscript p], d ≠ 0. In the two dimensional case the argument is Lacey and McClain who made considerable refinements to this argument of Green who was bringing the argument to the finite field case from a paper of Shkredov. Let Ϝ ⁿ ₂ be the finite field of cardinality N = 2ⁿ. For all large N, any subset A⊂ Ϝⁿ ₂ × Ϝⁿ ₂ of cardinality ∣A ∣≳ N ² (log n) − [superscript epsilon], ε <, 1, must contain a corner {(x, y), (x + d, y), (x, y + d)} for x, y, d ∈ Ϝⁿ₂ and d ≠ 0.
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Henriot, Kevin. "Structures linéaires dans les ensembles à faible densité." Thèse, Paris 7, 2014. http://hdl.handle.net/1866/11116.
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Réalisé en cotutelle avec l'Université Paris-Diderot.Nous présentons trois résultats en combinatoire additive, un domaine récent à la croisée de la combinatoire, l'analyse harmonique et la théorie analytique des nombres. Le thème unificateur de notre thèse est la détection de structures additives dans les ensembles arithmétiques à faible densité, avec un intérêt particulier pour les aspects quantitatifs. Notre première contribution est une estimation de densité améliorée pour le problème, initié entre autres par Bourgain, de trouver une longue progression arithmétique dans un ensemble somme triple. Notre deuxième résultat consiste en une généralisation des bornes de Sanders pour le théorème de Roth, du cas d'un ensemble dense dans les entiers à celui d'un ensemble à faible croissance additive dans un groupe abélien arbitraire. Finalement, nous étendons les meilleures bornes quantitatives connues pour le théorème de Roth dans les premiers, à tous les systèmes d'équations linéaires invariants par translation et de complexité un.
We present three results in additive combinatorics, a recent field at the interface of combinatorics, harmonic analysis and analytic number theory. The unifying theme in our thesis is the detection of additive structure in arithmetic sets of low density, with an emphasis on quantitative aspects. Our first contribution is an improved density estimate for the problem, initiated by Bourgain and others, of finding a long arithmetic progression in a triple sumset. Our second result is a generalization of Sanders' bounds for Roth's theorem from the dense setting, to the setting of small doubling in an arbitrary abelian group. Finally, we extend the best known quantitative results for Roth's theorem in the primes, to all translation-invariant systems of equations of complexity one.
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Dasht, Johan. "Some developments of homogenization theory and Rothe's method /." Luleå : Dept. of Mathematics, Univ, 2005. http://epubl.luth.se/1402-1757/2005/05/LTU-LIC-0505-SE.pdf.
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Ishak, Daniel. "The Thue–Siegel–Roth Theorem." Thesis, Uppsala University, Department of Mathematics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-120222.
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He, Chengjian. "Development and application of a generalized dynamic wake theory for lifting rotors." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/12389.
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Dyer, Jennifer H. "Theory and painting, the work of Mark Rothko." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0009/MQ28562.pdf.
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Carnovale, Marc. "Arithmetic Structures in Small Subsets of Euclidean Space." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555657038785892.
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Tatossian, Charles A. "Aerodynamic shape optimization via control theory of helicopter rotor blades using a non-linear frequency domain approach." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112586.
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This study presents a discrete adjoint-based aerodynamic optimization algorithm for helicopter rotor blades in hover and forward flight using a Non-Linear Frequency Domain approach. The goal is to introduce a Mach number variation into the Non-Linear Frequency Domain (NLFD) method and implement a novel approach to present a time-varying cost function through a multi-objective adjoint boundary condition. The research presents the complete formulation of the time dependent optimal design problem. The approach is firstly demonstrated for the redesign of a NACA 0007 and a NACA 23012 helicopter rotor blade section in forward flight. A three-dimensional inviscid Aerodynamic Shape Optimization (ASO) algorithm is then employed to validate and redesign the Caradonna and Tung experimental blade. The results in determining the optimum aerodynamic configurations require an objective function which minimizes the inviscid torque coefficient and maintains the desired thrust level at transonic conditions.
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O'Leary, Beth Andrews. "Analysis of high-speed rotating systems using Timoshenko beam theory in conjunction with the transfer matrix method /." Online version of thesis, 1989. http://hdl.handle.net/1850/10608.
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Schiff, Sarah Eden. "Family systems theory as literary analysis the case of Philip Roth /." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004875.
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Schleißinger, Sebastian [Verfasser], Oliver [Gutachter] Roth, and Filippo [Gutachter] Bracci. "Embedding Problems in Loewner Theory / Sebastian Schleißinger. Gutachter: Oliver Roth ; Filippo Bracci." Würzburg : Universität Würzburg, 2013. http://d-nb.info/1102824917/34.
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Ragognette, Luis Fernando. "Uma demonstração do teorema de Thue-Siegel-Dyson-Roth." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/45/45131/tde-24072012-234734/.
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Neste trabalho estudamos o célebre Teorema de Klaus F. Roth para aproximações diofantinas, também conhecido como Teorema de Thue-Siegel-Roth. Nossos objetivos consistem em fazer um estudo abrangente da evolução do problema, que se iniciou com um resultado de Liouville em 1844, e chegar à completa compreensão das ideias e das técnicas utilizadas na demonstração do Teorema de Roth.In this work we study the celebrated Klaus F. Roth\'s Theorem in Diophantine approximations, also known as the Thue-Siegel-Roth Theorem. Our goals are to make a comprehensive study of the evolution of the problem that started with a result of Liouville in 1844 and achieve full understanding of ideas and techniques used in the proof of the Roth\'s Theorem.
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Binder, Sven Verfasser], Robert [Akademischer Betreuer] Roth, and Jochen [Akademischer Betreuer] [Wambach. "Coupled-Cluster Theory for Nuclear Structure / Sven Binder. Betreuer: Robert Roth ; Jochen Wambach." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2014. http://d-nb.info/1110792263/34.
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Binder, Sven [Verfasser], Robert Akademischer Betreuer] Roth, and Jochen [Akademischer Betreuer] [Wambach. "Coupled-Cluster Theory for Nuclear Structure / Sven Binder. Betreuer: Robert Roth ; Jochen Wambach." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2014. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-39462.
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Abras, Jennifer N. "Enhancement of aeroelastic rotor airload prediction methods." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28182.
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Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Chair: Smith, Marilyn; Committee Member: Bauchau, Olivier; Committee Member: Costello, Mark; Committee Member: Moulton, Marvin; Committee Member: Ruffin, Stephen.
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Edholm, Roger. "The written and the unwritten world of Philip Roth : fiction, nonfiction, and borderline aesthetics in the Roth books." Doctoral thesis, Örebro universitet, Institutionen för humaniora, utbildnings- och samhällsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-25014.
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This thesis examines five books by the American author Philip Roth commonly referred to as the “Roth Books,” which are The Facts: A Novelist’s Autobiography(1988), Deception (1990), Patrimony: A True Story (1991), Operation Shylock: A Confession (1993), and The Plot Against America (2004). These books, held together by the author’s proper name, are often viewed as texts that conflate fiction and nonfiction or demonstrate the “fictionality” of all factual narrative accounts in compliance with well-known postmodernist and poststructuralist theories. Contrary to this view, I argue that a valid understanding of the Roth Books demands that we acknowledge that these works represent a series of quite different ways for the author to transform his own life into written form, a creative act which is manifested in both fictional and nonfictional writing. In the attempt to argue this view, I turn to a field of study where the question about criteria for distinguishing fictional from nonfictional narrative literature has occupied a prominent place: narrative theory. However, my theoretical and methodological point of departure does not align itself with the “standard” paradigm in narrative theory with its origin in classical, structuralist narratology. Rather, the thesis promotes a pragmatic and rhetorical perspective which is argued to better account for how we read and make sense of different narrative texts. In opposition to standard narrative theory, where all narratives are considered to adhere to the same model of communication, I argue in favour of a view where narrative fiction and narrative nonfiction are conceived as distinct communicative practices. I open the thesis by showing that Roth’s books contribute to the discussion on how to distinguish fictional from nonfictional narrative texts (Chapter 1). I then continue by approaching the distinction between fiction and nonfiction in general theoretical terms (Chapter 2). And in what follows (Chapters 3-5), I present a reading where the Roth Books are juxtaposed against each other. This reading demonstrates how these texts, although in some sense related, because of their divergent qualities and differing intentions still communicate differently with their readers, inviting a readerly attention that is dissimilar from one work to the other.
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Braun, Jonas [Verfasser], Hans-Werner [Akademischer Betreuer] Hammer, and Robert [Akademischer Betreuer] Roth. "Effective Field Theories and Electromagnetic Properties of Light Nuclei / Jonas Braun ; Hans-Werner Hammer, Robert Roth." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1185639632/34.
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Tichai, Alexander [Verfasser], Robert [Akademischer Betreuer] Roth, and Jens [Akademischer Betreuer] Braun. "Many-Body Perturbation Theory for Ab Initio Nuclear Structure / Alexander Tichai ; Robert Roth, Jens Braun." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1143827481/34.
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Wittmann, Rene [Verfasser], Klaus [Akademischer Betreuer] Mecke, and Roland [Akademischer Betreuer] Roth. "Density Functional Theory for Liquid Crystals : Refining Fundamental Measure Theory for anisotropic bodies [[Elektronische Ressource]] / René Wittmann. Gutachter: Klaus Mecke ; Roland Roth." Erlangen : FAU University Press, 2015. http://d-nb.info/1079385371/34.
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Huo, Chao. "Analyse numérique et expérimentale d’un doublet de rotors contrarotatifs caréné au point fixe." Thesis, Toulouse, ISAE, 2012. http://www.theses.fr/2012ESAE0010/document.
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Cette étude se propose d’analyser le comportement du double rotor contra-rotatif caréné dans lecadre des échelles réduites des microdrones, pour exploiter le potentiel d’amélioration desperformances stationnaires des rotors libres. La demande d’une performance propulsive de hautniveau, alors que les échelles sont très réduites constitue un véritable défi scientifique. De façongénérale, par rapport au rotor libre, l’ajout de la carène permet de piloter la contraction del’écoulement et offre un potentiel de poussée de carène. La tuyère par sa condition d’adaptationpilote le débit entrant à puissance donnée. L’augmentation du débit massique, par comparaison ausystème de rotor libre, amplifie la poussée à travers la dépression distribuée sur toute la surface decaptation. Pour comprendre les lois de fonctionnement d’un système propulsif caréné, il a d’abord été proposé un modèle théorique simplifié basé sur une extension de la théorie de Froude pour les rotors libres: le système rotor est assimilé à un disque actuateur, générateur de débit dans une conduite à section variable. Une simulation Navier Stokes 2D axisymétrique a permis d’optimiser les paramètres de forme du carénage. Les simulations ont confirmé l’influence déterminante des sections d’entrée et de sortie, et relativisé l’impact des formes possibles, pourvu que les variations de sections limitent le décollement de la couche limite. Après conception d’un banc d’essai utilisant un doublet de rotor coaxial placé dans cette carène optimisée, l’étude expérimentale complète et confirme les performances globales du système et qualifie l’écoulement méridien. Enfin, une simulation 3D instationnaire a été entreprise pour compléter l’analyse de l’écoulement autour des rotorsThis study aims to analyze the behavior of shrouded, contrarotating coaxial rotor in the reducedMAVs’ scale in order to exploit its potential to improve the free rotor steady performance. The highhover ability under low operational Reynolds number is therefore, a scientific challenge. Generally,comparing with free rotor, the addition of the shroud decreases the flow contraction and gives thepotential to generate an extra thrust. A suitable nozzle can control the mass flow for a given power.The increased mass flow, comparing with free rotor, amplifies the thrust offered by the lowpressure formed at the air entrance. To understand the principals of shrouded propulsion system, a simplified theory model was first proposed through the extension of Froude theory for free rotors: the double rotor is initially treated as an actuator disk, generating the flow at varied sections through the shroud passage. A 2D simulation which accounts for an axial flow of viscous effects within the actual shroud profile, confirmed effects of all defined geometrical parameters. It further demonstrated that within the non-stalling region of the different crosssections, shroud shape and inlet shape do not have asignificant impact on performance. The experimental study, carried out with coaxial rotor, contributed to the confirmation of the overall performance and the approximation of the flow field through the shroud. Meanwhile, the 3D simulation, developed to better model the actual coaxial rotor in counter rotation, was validated to well solve the steady performance. It was applied to complement the analysis of the flow around the coaxial rotor
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Jaouani, Nassim. "Modelling of installation effects on the tonal noise radiated by counter-rotating open rotors." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC002.
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The Counter-Rotating Open Rotors (CROR) are identified as a possible alternative to turbofan engines for middle-range aircrafts. Providing significant fuel savings and reducing the green-house gas emissions, they may lead however to an increased noise radiation due to the absence of nacelle shielding. To properly predict the acoustic radiation of such systems is then mandatory both to reduce the source mechanisms of the isolated engine and to offer an optimal noise installation solution. Such an objective is tackled in the present thesis in two steps. In a first part, the research aims at predicting the tonal noise radiated from the first propeller of CROR mounted on the rear fuselage by means of a pylon (pusher configuration), considering both the pylon-wake and the uniform ow effects. From the Ffowcs Williams & Hawkings' formalism, three noise sources are identified. First the unsteady loading is computed using a similar procedure to the one used for the rotor-rotor wake interaction noise prediction. The velocity deficit in the pylon wake is locally expanded in two-dimensional Fourier gusts in a reference frame attached to the front rotor. The unsteady lift induced by each gust on a blade segment is calculated using a linearized analytical response function that accounts for a realistic geometry. The steady loading is the second source contribution and is evaluated using both a software based on the lifting-line theory and some numerical simulations for different reference source surfaces. Finally the thickness noise due to the blade volume displacement is included in the analysis using Isom's formulation. From the linear acoustic assumptions, all these sources modelled as equivalent acoustic dipoles rotating in a uniformly moving atmosphere are then summed to calculate the far-field noise. The whole methodology is assessed against wind-tunnel test data and reference software predictions. A parametric study considering several pylon positionings and pylon-wake configurations with blowing is performed in order to emphasize the relative contribution of the three noise sources. Secondly, the rotor- rotor wake interaction noise being recognized as the most significant contribution in isolated configuration, its modelling is completed by introducing the dynamics of the vortex occurring near the rear-rotor leading edge. A semi-analytical methodology is developed to determine a vortex attached over a at plate embedded in a uniform ow with incidence. Applied to the case of a rear blade going through a front-rotor wake, it provides a first estimate of the noise contribution of the vortexLes hélices contrarotatives constituent une alternative possible aux turboréacteurs pour les avions moyens- courriers. Réduisant significativement la consommation de carburant et les émissions de gaz à effet de serre, ils peuvent néanmoins conduire à un rayonnement sonore accru de par l'absence de carénage. Prédire correctement le rayonnement sonore de telles motorisations est donc indispensable pour réduire les mécanismes sources propres au moteur isolé ou assurer une solution d'installation acoustique optimale. Un tel objectif est abordé dans cette thèse en deux temps. Dans un premier temps, l’étude vise à prédire le bruit tonal rayonné par la première hélice d'un moteur monté à l'arrière du fuselage (configuration dite en pousseur), en considérant les effets du sillage du pylône supportant le moteur et de l'écoulement moyen. Partant du formalisme de Ffowcs Williams & Hawkings, trois sources sonores sont identifiées à cet effet. La charge instationnaire, tout d'abord, est calculée en s'appuyant sur une méthodologie similaire à celle utilisée pour la prédiction du bruit d'interaction de sillages entre les deux rotors. Le déficit de vitesse dans le sillage du mât est décomposé localement en rafales bidimensionnelles dans un repère attaché au rotor amont. La portance instationnaire induite par chaque rafale sur un segment de pale est calculée en utilisant une fonction de réponse analytique linéarisée considérant une géométrie réaliste. Deuxième contribution, la charge stationnaire est évaluée au moyen d'un logiciel s'appuyant sur la théorie de la ligne portante mais également via des simulations numériques pour différentes surfaces sources de référence. Enfin, le bruit d'épaisseur associé au déplacement du volume de la pale est inclus dans l'analyse à partir de la formulation d'Isom. D'après les hypothèses de l'acoustique linéaire, toutes ces sources modélisées comme des dipôles acoustiques tournant dans une atmosphère uniforme en mouvement sont ensuite sommées pour calculer le bruit en champ lointain. L'ensemble de la méthodologie est comparé à des données d'essai et des prédictions d'un logiciel de référence. Une étude paramétrique considérant plusieurs positionnements du pylône et des configurations avec soufflage est effectuée afin de bien mettre en évidence les contributions relatives des trois sources sonores. Dans un deuxième temps, le bruit d'interaction de sillages étant reconnu comme la contribution majoritaire en configuration isolée, sa modélisation est complétée en introduisant la dynamique du tourbillon se développant au voisinage du bord d'attaque du rotor aval. Une méthodologie semi-analytique est développée pour déterminer un tourbillon attaché au-dessus d'une plaque plane plongée dans un écoulement uniforme avec incidence. Appliquée au cas d'une pale aval traversant le sillage du rotor amont, elle fournit une première estimation de la contribution sonore du tourbillon
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Korden, Stephan Verfasser], Kai [Akademischer Betreuer] [Leonhard, and Roland [Akademischer Betreuer] Roth. "Molecular density functional theory based on a hard particle reference potential / Stephan Korden ; Kai Leonhard, Roland Roth." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1127337076/34.
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Korden, Stephan [Verfasser], Kai [Akademischer Betreuer] Leonhard, and Roland [Akademischer Betreuer] Roth. "Molecular density functional theory based on a hard particle reference potential / Stephan Korden ; Kai Leonhard, Roland Roth." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1127337076/34.
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af, Malmborg Solith. "Research: ROTHKO : - ett arbete om att lära känna sig själv genom någon annan." Thesis, Linköpings universitet, Malmstens Linköpings universitet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-146095.
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This thesis project examines both inner and outer circumstances of knowledge in an attempt to emphasize the importance of personal reflection. I search for answers on how to communicate feelings through colour and form by studying Mark Rothko and the abstract expressionism. A personal reflection is made parallelly to expand my own understanding of the subject and my own role in relation to it. I also explore painting as amethod of deepening my understanding of Rothko. Mark Rothko is both subject of study and tutor as I give myself the task of translating his art into my own design. The result offers thoughts and ideas on the significance of the work of hand, the use of colour and the meaning of intention, which I claim are important aspects when aiming for emotional results. However I also reflect upon the fact that the communication remains individual and that it is therefore problematic to confirm success in this matter.Detta är ett undersökande arbete som vänder sig både inåt och utåt. Det är en djupdykning i Mark Rothkos konstnärskap som sker parallellt med en personlig reflektion. Inledningsvis handlar det om att arbeta i gränslandet mellan konst och design och hurdet kan se ut. I förlängningen handlar det om hur den konstnärliga historien kan fungera som inspiratör och vägledare för innebörd och uttryck i formgivningen. Genom att studera den abstrakta expressionismen och Mark Rothko söker jag svar på hur känslomässig kommunikation kan ske genom färg och form. Förutom litterär research utför jag också en praktiskt undersökning där jag använder måleriet som en metod för att förstå mitt studieobjekt; Mark Rothko. Målet är att översätta Mark Rothkos konst till min design. Det handlar om att studera, internalisera och applicera. Resultatet bjuder in till en diskussion om handlagets, färgens och intentionens betydelse för formgivningen, där jag hävdar att dessa aspekter är viktiga för ett emotionellt berörande resultat, men att kommunikationen förblir individuell.
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Baker, Andrew Paul. "The role of mission requirements, vehicle attributes, technologies and uncertainty in rotorcraft system design." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12476.
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Dean, Andrew. "Foes, ghosts, and faces in the water : self-reflexivity in postwar fiction." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:4c2e3b07-2454-457a-bf9f-a3f0734c89ba.
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This thesis examines the nature and value of metafictional practices in the careers of postwar novelists. Discussions of metafiction have been central to accounts of postwar literature. Where debates in the 1980s and 1990s about metafiction tended to make claims about its distinctive political and theoretical power, recent work in the study of institutions has folded metafiction into the routine operation of the literary field, and attacked previous claims to distinctive value. In this thesis I both historicize self-reflexive literary practices in the literary field, an element largely absent from the earlier scholarship, and present historically determinate claims about the value of these practices, an element I suggest is missing from the more recent work. To do so, I turn to the study of autobiography, specifically Philippe Lejeune's concept of 'autobiographical space.' In the first chapter, I explore how J. M. Coetzee develops academic literary criticism in his fiction. In the second chapter, I examine how Janet Frame responds to both the demands of a national literature and biographical inquiry into her life. In the third chapter, I address how Philip Roth handles the relationship between the politics of identity and the postwar novel. Self-reflexive practices, I show throughout, are ways of writing that were encouraged by particular formations in the literary field and were handled by writers through more or less explicit treatments of autobiographical space. I argue, though, that while these practices can be remarkably inventive, they carry no guarantees for political, theoretical, or aesthetic value.
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Nijaki, Nadine. "Public Service Motivation im Nonprofit-Bereich : eine Fallstudie am Beispiel des Deutschen Roten Kreuzes." Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5448/.
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Public Service Motivation (PSM), als ein Konzept des öffentlichen Sektors, beruht auf der Annahme bestimmter Motive, die charakteristisch für öffentlich Bedienstete sind. Mit dem Versuch dieses Konstrukt auf den Nonprofit-Sektor zu übertragen, wird das Ziel verfolgt ein tieferes Verständnis für die Motivation der Beschäftigten zu erlangen und die dazu existierenden, eher geringen Befunde der PSM-Forschung um ein qualitatives Vorgehen zu erweitern. Die vorliegende Arbeit bereitet hierfür zunächst den theoretischen Hintergrund der PSM auf und nimmt Bezug zu der von Perry (1996) weiterentwickelten Theorie der PSM. Im anschließenden empirischen Teil werden in einer Fallstudie verschiedene Anstellungsformen sowie Tätigkeitsbereiche der Nonprofit-Organisation „Deutsches Rotes Kreuz“ untersucht. Anhand der ermittelten Ergebnisse kann dabei die Existenz der PSM nachgewiesen werden. Nicht zuletzt werden durch die Wahl eines qualitativen Forschungsdesigns aufschlussreiche Erkenntnisse bezüglich der untersuchten Einflussfaktoren gewonnen. Es kann festgehalten werden, dass sich Haupt- und Ehrenamtliche in Ihrer PSM nicht gravierend unterscheiden. Hingegen die PSM zwischen Arbeitern der Verwaltungs- und Arbeitern der Street-Level-Ebene hinsichtlich ihrer Ausprägung von einander abweicht. Darüber hinaus liefert die Arbeit erste Erklärungsversuche und geht dabei unter anderem auf die Theorie der extrinsischen und intrinsischen Motivation, sowie auf die Selbstbestimmungstheorie ein.Public Service Motivation (PSM) as a concept for the public sector is based on certain motives which are typical for public employees. The goal in attempting to transfer this construct to the nonprofit sector is to get a better understanding of motivation of employees and to extend the existing, somewhat scant findings in PSM research using a qualitative approach. This paper begins by presenting the theoretical background of PSM and refers to the developed theory of PSM by Perry (1996). The subsequent empirical section presents a case study which examines different types of appointments as well as areas of operation within the “German Red Cross”, a nonprofit organization. The results indicated here demonstrate the existence of PSM. Lastly, useful insights are delivered in terms of the influencing factors, this due in no small part to the choice of a qualitative study design. It may be noted that no significant difference in PSM is found between full-time employees and volunteer workers. By contrast, the way PSM is expressed by street-level workers differs widely from that of those working at an administrative level. In addition, the paper provides first attempts at an explanation and refers to the theory of the extrinsic and intrinsic motivation, as well as to self-determination theory.
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Potkalitsky, Nicolas J. "Refracted Realism and the Ethical Dominant in Contemporary American Fiction." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563283222402333.
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Timmermans, Benoît. "Les origines romantiques de la pensée abstraite: histoire et enjeux de l'algèbre moderne." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210698.
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Bonneau, Virginie. "Prévision du bruit d'interaction tonal et à large bande d'une soufflante de nouvelle génération en régime subsonique." Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2272.
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La soufflante de la nouvelle génération de moteurs Snecma est caractérisée par des pales de rotor aux bords de fuite épais, ainsi que par un OGV hétérogène intégrant les bras supports.L’objectif de cette thèse est de caractériser l’influence de ces innovations technologiques sur la génération des sources et le rayonnement sonore dans la manche secondaire liés à l’interaction du sillage du rotor avec l’OGV. Ce mécanisme est principalement responsable des émissions tonales et à large bande qui sont traitées indépendamment. D’une part, une simulation URANS de l’étage rotor-stator fournit les sources déterministes sur le stator hétérogène ainsi que le champ sonore dans la manche traversée par les bras supports. L’extension de modèles acoustiques permet d’accéder au spectre de raies obtenu soit en propageant les sources par un modèle fondé sur le principe de l’analogie acoustique, soit directement à partir du champ sonore issu de la CFD. Il est alors montré que l’hétérogénéité du stator induit l’émergence de la raie du fondamental, et que les bras supports engendrent une onde stationnaire dans la manche secondaire.D’autre part, la simulation d’un canal complet du rotor avec une approche ZDES permet d’accéder aux perturbations turbulentes du sillage. Ces dernières alimentent un code acoustique fondé sur la théorie d’Amiet permettant de prévoir le bruit à large bande rayonné en conduit. Bien que plus coûteuse, la ZDES permet de s’affranchir des hypothèses restrictives et du calibrage délicat des modèles de turbulence homogène isotrope en fournissant des données directement exploitables, conduisant ainsi à des estimations plus précises.L’ensemble des simulations numériques et des prévisions acoustiques est validé grâce aux mesures issues d’une campagne d’essais au banc RACEModern turbofans are characterized by rotor blades with large chords, as well as heterogeneous OGV with mechanical struts integrated.The aim of this thesis is to characterize the impact of these technological innovations on sources generation and sound radiation in the bypass duct due to the interaction of the rotor wakes with the OGV. This mechanism is mainly responsible in tonal and broadband noise emissions which are dealt separately.On one hand, a URANS computation of the rotor-stator row provides the periodic sources on the heterogeneous stator as well as the sound field in the bypass duct crossed by the struts. The expansion of sound models allows to access to the tonal spectra obtained either by propagating sources thanks to a model based on the acoustic analogy principle, or by the sound field directly issued from the CFD. Then, it is shown that the stator heterogeneity induces the appearance of the fundamental tone, and that the struts lead to standing waves in the bypass duct.On the other hand, the simulation of a complete rotor channel with a ZDES approach provides the turbulent wakes. These erturbations feed an acoustic code based on the Amiet theory to predict the broadband noise radiated in the bypass duct. Despite the cost, ZDES stays clear of restrictive assumptions and sensitive calibration of isotropic homogeneous turbulence models by providing data directly workable, leading to more accurate predictions. Each of numerical simulations and acoustic predictions is validated thanks to the measurements performed in the RACE test rig
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Mercado-Ravell, Diego Alberto. "Autonomous navigation and teleoperation of unmanned aerial vehicles using monocular vision." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2239/document.
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Ce travail porte, de façon théorétique et pratique, sur les sujets plus pertinents autour des drones en navigation autonome et semi-autonome. Conformément à la nature multidisciplinaire des problèmes étudies, une grande diversité des techniques et théories ont été couverts dans les domaines de la robotique, l’automatique, l’informatique, la vision par ordinateur et les systèmes embarques, parmi outres.Dans le cadre de cette thèse, deux plates-formes expérimentales ont été développées afin de valider la théorie proposée pour la navigation autonome d’un drone. Le premier prototype, développé au laboratoire, est un quadrirotor spécialement conçu pour les applications extérieures. La deuxième plate-forme est composée d’un quadrirotor à bas coût du type AR.Drone fabrique par Parrot. Le véhicule est connecté sans fil à une station au sol équipé d’un système d’exploitation pour robots (ROS) et dédié à tester, d’une façon facile, rapide et sécurisé, les algorithmes de vision et les stratégies de commande proposés. Les premiers travaux développés ont été basés sur la fusion de donnés pour estimer la position du drone en utilisant des capteurs inertiels et le GPS. Deux stratégies ont été étudiées et appliquées, le Filtre de Kalman Etendu (EKF) et le filtre à Particules (PF). Les deux approches prennent en compte les mesures bruitées de la position de l’UAV, de sa vitesse et de son orientation. On a réalisé une validation numérique pour tester la performance des algorithmes. Une tâche dans le cahier de cette thèse a été de concevoir d’algorithmes de commande pour le suivi de trajectoires ou bien pour la télé-opération. Pour ce faire, on a proposé une loi de commande basée sur l’approche de Mode Glissants à deuxième ordre. Cette technique de commande permet de suivre au quadrirotor de trajectoires désirées et de réaliser l’évitement des collisions frontales si nécessaire. Etant donné que la plate-forme A.R.Drone est équipée d’un auto-pilote d’attitude, nous avons utilisé les angles désirés de roulis et de tangage comme entrées de commande. L’algorithme de commande proposé donne de la robustesse au système en boucle fermée. De plus, une nouvelle technique de vision monoculaire par ordinateur a été utilisée pour la localisation d’un drone. Les informations visuelles sont fusionnées avec les mesures inertielles du drone pour avoir une bonne estimation de sa position. Cette technique utilise l’algorithme PTAM (localisation parallèle et mapping), qui s’agit d’obtenir un nuage de points caractéristiques dans l’image par rapport à une scène qui servira comme repère. Cet algorithme n’utilise pas de cibles, de marqueurs ou de scènes bien définies. La contribution dans cette méthodologie a été de pouvoir utiliser le nuage de points disperse pour détecter possibles obstacles en face du véhicule. Avec cette information nous avons proposé un algorithme de commande pour réaliser l’évitement d’obstacles. Cette loi de commande utilise les champs de potentiel pour calculer une force de répulsion qui sera appliquée au drone. Des expériences en temps réel ont montré la bonne performance du système proposé. Les résultats antérieurs ont motivé la conception et développement d’un drone capable de réaliser en sécurité l’interaction avec les hommes et les suivre de façon autonome. Un classificateur en cascade du type Haar a été utilisé pour détecter le visage d’une personne. Une fois le visage est détecté, on utilise un filtre de Kalman (KF) pour améliorer la détection et un algorithme pour estimer la position relative du visage. Pour réguler la position du drone et la maintenir à une distance désirée du visage, on a utilisé une loi de commande linéaireThe present document addresses, theoretically and experimentally, the most relevant topics for Unmanned Aerial Vehicles (UAVs) in autonomous and semi-autonomous navigation. According with the multidisciplinary nature of the studied problems, a wide range of techniques and theories are covered in the fields of robotics, automatic control, computer science, computer vision and embedded systems, among others. As part of this thesis, two different experimental platforms were developed in order to explore and evaluate various theories and techniques of interest for autonomous navigation. The first prototype is a quadrotor specially designed for outdoor applications and was fully developed in our lab. The second testbed is composed by a non expensive commercial quadrotor kind AR. Drone, wireless connected to a ground station equipped with the Robot Operating System (ROS), and specially intended to test computer vision algorithms and automatic control strategies in an easy, fast and safe way. In addition, this work provides a study of data fusion techniques looking to enhance the UAVs pose estimation provided by commonly used sensors. Two strategies are evaluated in particular, an Extended Kalman Filter (EKF) and a Particle Filter (PF). Both estimators are adapted for the system under consideration, taking into account noisy measurements of the UAV position, velocity and orientation. Simulations show the performance of the developed algorithms while adding noise from real GPS (Global Positioning System) measurements. Safe and accurate navigation for either autonomous trajectory tracking or haptic teleoperation of quadrotors is presented as well. A second order Sliding Mode (2-SM) control algorithm is used to track trajectories while avoiding frontal collisions in autonomous flight. The time-scale separation of the translational and rotational dynamics allows us to design position controllers by giving desired references in the roll and pitch angles, which is suitable for quadrotors equipped with an internal attitude controller. The 2-SM control allows adding robustness to the closed-loop system. A Lyapunov based analysis probes the system stability. Vision algorithms are employed to estimate the pose of the vehicle using only a monocular SLAM (Simultaneous Localization and Mapping) fused with inertial measurements. Distance to potential obstacles is detected and computed using the sparse depth map from the vision algorithm. For teleoperation tests, a haptic device is employed to feedback information to the pilot about possible collisions, by exerting opposite forces. The proposed strategies are successfully tested in real-time experiments, using a low-cost commercial quadrotor. Also, conception and development of a Micro Aerial Vehicle (MAV) able to safely interact with human users by following them autonomously, is achieved in the present work. Once a face is detected by means of a Haar cascade classifier, it is tracked applying a Kalman Filter (KF), and an estimation of the relative position with respect to the face is obtained at a high rate. A linear Proportional Derivative (PD) controller regulates the UAV’s position in order to keep a constant distance to the face, employing as well the extra available information from the embedded UAV’s sensors. Several experiments were carried out through different conditions, showing good performance even under disadvantageous scenarios like outdoor flight, being robust against illumination changes, wind perturbations, image noise and the presence of several faces on the same image. Finally, this thesis deals with the problem of implementing a safe and fast transportation system using an UAV kind quadrotor with a cable suspended load. The objective consists in transporting the load from one place to another, in a fast way and with minimum swing in the cable
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Griffith, Kent Joseph. "Atomic and electronic structure of complex metal oxides during electrochemical reaction with lithium." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271191.
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Lithium-ion batteries have transformed energy storage and technological applications. They stand poised to convert transportation from combustion to electric engines. The discharge/charge rate is a key parameter that determines battery power output and recharge time; typically, operation is on the timescale of hours but reducing this would improve existing applications and open up new possibilities. Conventionally, the rate at which a battery can operate has been improved by synthetic strategies to decrease the solid-state diffusion length of lithium ions by decreasing particle sizes down to the nanoscale. In this work, a different approach is taken toward next-generation high-power and fast charging lithium-ion battery electrode materials. The phenomenon of high-rate charge storage without nanostructuring is discovered in niobium oxide and the mechanism is explained in the context of the structure–property relationships of Nb2O5. Three polymorphs, T-Nb2O5, B-Nb2O5, and H-Nb2O5, take bronze-like, rutile-like, and crystallographic shear structures, respectively. The bronze and crystallographic shear compounds, with unique electrochemical properties, can be described as ordered, anion-deficient nonstoichiometric defect structures derived from ReO3. The lessons learned in niobia serve as a platform to identify other compounds with related structural motifs that apparently facilitate high-rate lithium insertion and extraction. This leads to the synthesis, characterisation, and electrochemical evaluation of the even more complicated composition–structure–property relationships in ternary TiO2–Nb2O5 and Nb2O5–WO3 phases. Advanced structural characterisation including multinuclear solid-state nuclear magnetic resonance spectroscopy, density functional theory, X-ray absorption spectroscopy, operando high-rate X-ray diffraction, and neutron diffraction is conducted throughout to understand the evolution of local and long-range atomic structure and changes in electronic states.
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Naymie, Cassandra. "Generalisations of Roth's theorem on finite abelian groups." Thesis, 2012. http://hdl.handle.net/10012/7162.
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Roth's theorem, proved by Roth in 1953, states that when A is a subset of the integers [1,N] with A dense enough, A has a three term arithmetic progression (3-AP). Since then the bound originally given by Roth has been improved upon by number theorists several times. The theorem can also be generalized to finite abelian groups. In 1994 Meshulam worked on finding an upper bound for subsets containing only trivial 3-APs based on the number of components in a finite abelian group. Meshulam’s bound holds for finite abelian groups of odd order. In 2003 Lev generalised Meshulam’s result for almost all finite abelian groups. In 2009 Liu and Spencer generalised the concept of a 3-AP to a linear equation and obtained a similar bound depending on the number of components of the group. In 2011, Liu, Spencer and Zhao generalised the 3-AP to a system of linear equations. This thesis is an overview of these results.
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Nishizawa, Yui. "A survey of Roth's Theorem on progressions of length three." Thesis, 2011. http://hdl.handle.net/10012/6406.
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For any finite set B and a subset A⊆B, we define the density of A in B to be the value α=|A|/|B|. Roth's famous theorem, proven in 1953, states that there is a constant C>0, such that if A⊆{1,...,N} for a positive integer N and A has density α in {1,...,N} with α>C/loglog N, then A contains a non-trivial arithmetic progression of length three (3AP). The proof of this relies on the following dichotomy: either 1) A looks like a random set and the number of 3APs in A is close to the probabilistic expected value, or 2) A is more structured and consequently, there is a progression P of about length α√N on which A∩P has α(1+cα) for some c>0. If 1) occurs, then we are done. If 2) occurs, then we identify P with {1,...,|P|} and repeat the above argument, whereby the density increases at each iteration of the dichotomy. Due to the density increase in case 2), an argument of this type is called a density increment argument. The density increment is obtained by studying the Fourier transforms of the characterstic function of A and extracting a structure out of A. Improving the lower bound for α is still an active area of research and all improvements so far employ a density increment. Two of the most recent results are α>C(loglog N/log N)^{1/2} by Bourgain in 1999 and α>C(loglog N)^5/log N by Sanders in 2010. This thesis is a survey of progresses in Roth's theorem, with a focus on these last two results. Attention was given to unifying the language in which the results are discussed and simplifying the presentation.
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Liao, Chung-Chih, and 廖常至. "Applications of finite Fourier analysis to combinations and Roth theorem." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/36624689294118134126.
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碩士國立中央大學
數學系
103
The celebrated result of Roth asserts that there exists an arithmetic progression of length three in a subset in integers with positive upper density. The result has been reproved and generalized later by many people. In this thesis, we study the approaches of Fourier analysis methods. We will see that the Finite Fourier analysis is powerful enough to prove the Roth theorem.
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Rothe, Jörg [Verfasser]. "On some promise classes in structural complexity theory / von Jörg Rothe." 1995. http://d-nb.info/982713215/34.
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Roth, Fridolin [Verfasser]. "Galois and Hopf-Galois theory for associative S-algebras / von Fridolin Roth." 2009. http://d-nb.info/997066164/34.
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Rothe, Jörg [Verfasser]. "Complexity of certificates, heuristics, and counting types, with applications to cryptography and circuit theory / von Jörg-Matthias Rothe." 1999. http://d-nb.info/982741014/34.
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Roth, Jürgen [Verfasser]. "Methodologie und Ideologie des Konzepts der Sprachgemeinschaft : fachgeschichtliche und systematische Aspekte einer soziologischen Theorie der Sprache bei Leo Weisgerber / vorgelegt von Jürgen Roth." 2004. http://d-nb.info/971961395/34.
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Aquino, Bryce B. "New Generator Control Algorithms for Smart-Bladed Wind Turbines to Improve Power Capture in Below Rated Conditions." 2014. https://scholarworks.umass.edu/masters_theses_2/66.
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With wind turbines growing in size, operation and maintenance has become a more important area of research with the goal of making wind energy more profitable. Wind turbine blades are subjected to intense fluctuating loads that can cause significant damage over time. The need for advanced methods of alleviating blade loads to extend the lifespan of wind turbines has become more important as worldwide initiatives have called for a push in renewable energy. An area of research whose goal is to reduce the fatigue damage is smart rotor control. Smart bladed wind turbines have the ability to sense aerodynamic loads and compute an actuator response to manipulate the aerodynamics of the wind turbine. The wind turbine model for this research is equipped with two different smart rotor devices. Independent pitch actuators for each blade and trailing edge flaps (TEFs) on the outer 70 to 90% of the blade span are used to modify aerodynamic loads. Individual Pitch Control (IPC) and Individual Flap Control (IFC) are designed to control these devices and are implemented on the NREL 5 MW wind turbine.
The consequences of smart rotor control lie in the wind turbine’s power capture in below rated conditions. Manipulating aerodynamic loads on the blades cause the rotor to decelerate, which effectively decreases the rotor speed and power output by 1.5%. Standard Region 2 generator torque control laws do not take into consideration variations in rotor dynamics which occur from the smart rotor controllers. Additionally, this research explores new generator torque control algorithms that optimize power capture in below rated conditions.
FAST, an aeroelastic code for the simulation of wind turbines, is utilized to test the capability and efficacy of the controllers. Simulation results for the smart rotor controllers prove that they are successful in decreasing the standard deviation of blade loads by 26.3% in above rated conditions and 12.1% in below rated conditions. As expected, the average power capture decreases by 1.5%. The advanced generator torque controllers for Region 2 power capture have a maximum average power increase of 1.07% while still maintaining load reduction capabilities when coupled with smart rotor controllers. The results of this research show promise for optimizing wind turbine operation and increasing profitability.