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T-splines as a design-through-analysis technologyScott, Michael Andrew 12 October 2011 (has links)
To simulate increasingly complex physical phenomena and systems, tightly integrated design-through-analysis (DTA) tools are essential. In this dissertation, the complementary strengths of isogeometric analysis and T-splines are coupled and enhanced to create a seamless DTA framework. In all cases, the technology de- veloped meets the demands of both design and analysis. In isogeometric analysis, the smooth geometric basis is used as the basis for analysis. It has been demonstrated that smoothness offers important computational advantages over standard finite elements. T-splines are a superior alternative to NURBS, the current geometry standard in computer-aided design systems. T-splines can be locally refined and can represent complicated designs as a single watertight geometry. These properties make T-splines an ideal discretization technology for isogeometric analysis and, on a higher level, a foundation upon which unified DTA technologies can be built.
We characterize analysis-suitable T-splines and develop corresponding finite element technology, including the appropriate treatment of extraordinary points (i.e., unstructured meshing). Analysis-suitable T-splines form a practically useful subset of T-splines. They maintain the design flexibility of T-splines, including an efficient and highly localized refinement capability, while preserving the important analysis-suitable mathematical properties of the NURBS basis.
We identify Bézier extraction as a unifying paradigm underlying all isogeometric element technology. Bézier extraction provides a finite element representation of NURBS or T-splines, and facilitates the incorporation of T-splines into existing finite element programs. Only the shape function subroutine needs to be modified. Additionally, Bézier extraction is automatic and can be applied to any T-spline regardless of topological complexity or polynomial degree. In particular, it represents an elegant treatment of T-junctions, referred to as "hanging nodes" in finite element analysis
We then detail a highly localized analysis-suitable h-refinement algorithm. This algorithm introduces a minimal number of superfluous control points and preserves the properties of an analysis-suitable space. Importantly, our local refinement algorithm does not introduce a complex hierarchy of meshes. In other words, all local refinement is done on one control mesh on a single hierarchical “level” and all control points have similar influence on the shape of the surface. This feature is critical for its adoption and usefulness as a design tool.
Finally, we explore the behavior of T-splines in finite element analysis. It is demonstrated that T-splines possess similar convergence properties to NURBS with far fewer degrees of freedom. We develop an adaptive isogeometric analysis framework which couples analysis-suitable T-splines, local refinement, and Bézier extraction and apply it to the modeling of damage and fracture processes. These examples demonstrate the feasibility of applying T-spline element technology to very large problems in two and three dimensions and parallel implementations. / text
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Clovis and Folsom Functionality ComparisonRichard, Andrew Justin January 2015 (has links)
This thesis uses experimental archaeology as a method to discover the functional differences between Clovis and Folsom projectile points filtered through a behavioral ecology paradigm. Porcelain is used as a substitute for tool stone for its consistency and control value. The experiment was devised to find out which technology, Clovis or Folsom, was more functional, had a higher curation rate and contributed to increased group subsistence. Paleoindian tool technology transitions can be seen as indicators for adaptation triggered by environmental conditions and changes in subsistence. Folsom technology, when compared to Clovis technology, was functionally superior in performance, refurbishment and curation. Technological design choices made by Folsom people were engineered toward producing a more functional tool system as a sustainable form of risk management. The Clovis Folsom Breakage Experiment indicates that Folsom tool technology was specifically adapted to bison subsistence based on increased functionality and curation.
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The role of emotional intelligence in enhancing intercultural sensitivitySaberi, Maria Akbar January 2012 (has links)
Emotions have been noted for their crucial role in survival behaviour relating to resistance to cross-cultural ambiguity. Today's globalised multinational corporations (MNCs) have recognised the importance of developing their diverse workforces' intercultural sensitivity (ICS) – a worldview towards cultural difference – as a means of reducing resistance to cross-cultural ambiguity hence maintaining a professional multicultural work environment. However, no studies have yet been made investigating the role of emotional intelligence (EI) in enhancing intercultural sensitivity and simultaneously regulating emotions produced from resistance to cultural difference. Therefore, this study has explored the role of EI in enhancing ICS aiming at increasing the effectiveness of intercultural training within the context of multinational organisations. A theoretical framework was constructed presenting the idea of EI entry-points into intercultural sensitivity and resistance to difference. Through an inductive research approach, a chosen multinational airline company's flight attendants were targeted with in-depth semi-structured interviews. Grounded theory analysis was applied. The analysis resulted in the development of a grounded emotional-cognitive intercultural adaptation process together with three adaptive cognitive states. These were named: Learn, Understand, and Know. Each cognitive state was noted to be associated with a particular emotional state that causes the interacting individual to shift into the relevant cognitive state. The emotions surprise and curiosity were found to be associated with Learn while empathy was found to be associated with Understand, and finally acceptance was found to be associated with Know. The research results strongly support the proposed EI entry-points within the grounded emotional-cognitive content of the produced intercultural adaptation process. The results address the research aim regarding the role of EI in enhancing ICS. Through the EI entry-points, ICS is indirectly enhanced through the development of intercultural performance as EI mental abilities are proposed which would regulate one's behaviour towards the three grounded emotional-cognitive intercultural adaptation states. The developed model is suggested to contribute to enhancing the effectiveness of intercultural training. The trainee's intercultural performance could be enhanced through directing the emotional-cognitive dynamics, during intercultural interaction, towards the empirically grounded set of emotional-cognitive states. As linking EI and ICS remains an important and under-explored topic, it is hoped that the findings of this study will present a better understanding of the dynamics of emotions within the context of multinational organisations, as well as the role of EI in enhancing ICS, subsequently leading to further research.
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Do Changing Reference Levels affect the Long-Term Effectiveness of Incentive Contracts?Kersting, Lee Michael 11 February 2013 (has links)
This study examines whether reference levels change over time and the impact on individuals' risk-taking behavior. I apply expectations-based reference-dependent preferences theory to analyze whether individuals' reference levels change over time in an economic setting. The theory suggests that individuals develop reference levels based on expectations of future outcomes (Koszegi and Rabin 2006). Therefore, this study examines whether individuals' expectations affect the setting of their reference level and how possible changes in reference levels affect subsequent risk-taking behavior. This study also provides evidence on how budget-based contracts impact individual risk taking behavior in a single period setting. Prior research has used multiple theories in an attempt to explain contradictory results relating to budget target difficulty and risk-taking behaviors. This study provides more evidence to the literature by further examining the impact of budget-based contracts on individuals' risk-taking behavior. A 1 x 2 between subjects experiment was conducted over five periods. Budget target was the manipulated factor at two levels: easy and moderate. Results suggest that individuals under easy budget targets make riskier decisions. Additionally, individuals' reference levels change over time and the change in reference level is greater for those individuals who continually attain their budget target, suggesting that expectations do increase the reference level. Lastly, in the current study, changes in reference level do not have a significant impact on risky decision making.
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Μελέτη οικογενειών περιοδικών λύσεων γύρω από τα τριγωνικά σημεία ισορροπίας στο φωτοβαρυτικό πρόβλημα των τριών σωμάτωνΚόλλιας, Νικόλαος 12 November 2008 (has links)
Αντικείμενο της παρούσης διπλωματικής εργασίας αποτελεί το Φωτοβαρυτικό Πρόβλημα των Τριών Σωμάτων, ένα άλυτο πρόβλημα που απασχόλησε και εξακολουθεί να απασχολεί τον τομέα των Εφαρμοσμένων Μαθηματικών και της Κλασικής Αστροφυσικής τουλάχιστον τους τελευταίους δύο αιώνες. Διεξάγεται μελέτη των σημείων ισορροπίας του συστήματος και προσδιορίζονται οικογένειες περιοδικών λύσεων, οι οποίες στην περίπτωσή μας διακρίνονται σε δύο κατηγορίες που χαρακτηρίζονται από το μέγεθος της περιόδου τους. / The topic of this thesis deals with the Restricted Photogravitational Three Body Problem, which is an unsolved problem in Astrophysics and Celestial Mechanics. Research is carried out concerning the equilibrium points, around which families of periodic solutions can be identified.
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États de bord dans les isolants de Chern et les fermions de Majorana dans les supraconducteurs topologiquesSticlet, Doru Cristian 27 November 2012 (has links) (PDF)
Cette thèse poursuit deux directions dans le domaine des isolants et supraconducteurs topologiques.Dans la première partie de la thèse nous étudions des isolants en deux dimensions sur réseau, présentant un effet Hall quantique anormal (c'est-à-dire en l'absence d'un champ magnétique externe), induit par la présence d'un flux magnétique inhomogène dans la maille. Le système possède des phase isolantes caractérisés par un invariant topologique, le nombre de Chern, qui est lié à la conductance portée par le bord états. Nous montrons que les modèles à deux bandes admettent des phase à nombre de Chern arbitraire, ou, de façon équivalente, un nombre arbitraire d'états de bord, quand on augmente la portée des couplages sur réseau. Cette compréhension est rendue possible grâce à la démonstration d'une formule montrant que le nombre de Chern d'une bande dépend de certains propriétés d'un ensemble discret de points dans la zone de Brillouin, les points de Dirac en l'absence du gap. Ces idées sont rendues plus concrètes dans l'étude du modèle de Haldane et dans la création d'un modèle artificiel avec cinq phases de Chern dont les états de bord sont déterminés en détail. La deuxième partie de la thèse porte sur les supraconducteurs topologiques unidimensionnels qui exhibent des états exotiques d'énergie zéro: les états liés de Majorana. Nous étudions ici la présence de fermions de Majorana dans des fils de semiconducteurs à fort couplage spin-orbite sous l'effet de proximité d'un supraconducteur d'onde s. Nous montrons que la polarisation de spin des degrés de liberté électroniques dans la fonction d'onde Majorana dépend du poids relatif du couplage spin-orbite Dresselhaus et Rashba. Nous étudions également les fermions de Majorana dans des jonctions linéaires longues supraconducteur-normal et supraconducteur-normal-supraconducteur (SNS) où ils apparaissent comme des états étendus dans la jonction normale. En outre, la géométrie d'anneaux peut être mise en correspondance avec une jonction SNS, et, sous l'action de gradients dans la phase supraconductrice, des fermions Majorana étendus se forment encore à l'intérieur du fil normal. Enfin, un modèle à deux bandes avec des fermions de Majorana multiples est traité. Nous démontrons que les jonctions Josephson construites à partir de ce modèle maintiennent l'une des signatures remarquables des fermions de Majorana, à savoir la périodicité 4π de l'effet Josephson fractionnaire.
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Merge in Transit, a distribution method in the industrial environmentGattolin, Elena January 2008 (has links)
In a fast moving environment and in a globalized market, companies are searching efficient distribution methods that enable broad product assortment, lower level of inventories, shorter customer order fulfilment, lower transportation costs in order to achieve a more efficient procurement process and a improved customer service. This paper will focus on a new solution in supply chain design to solve these trade-offs between management cost cutting and higher customer level within markets characterized by an increasing globalisation. Merge in transit (MIT) distribution method allows companies to reduce inventory and transportation costs while guaranteeing a high customer perceived service level. It is a new technique in which goods shipped from several supply locations are consolidated into one final customer delivery. The company needs to coordinate shipments so that they arrive simultaneously and goods can be bundled and shipped immediately to the final customer for arrival on due date. Economical benefits and drawbacks will be investigated from a supply chain prospective.
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Le théorème de concentration et la formule des points fixes de Lefschetz en géométrie d'ArakelovTang, Shun 18 February 2011 (has links) (PDF)
Dans les années quatre-vingts dix du siècle dernier, R. W. Thomason a démontréun théorème de concentration pour la K-théorie équivariante algébrique sur lesschémas munis d'une action d'un groupe algébrique G diagonalisable. Comme d'habitude,un tel théorème entraîne une formule des points fixes de type Lefschetz qui permetde calculer la caractéristique d'Euler-Poincaré équivariante d'un G-faisceau cohérent surun G-schéma propre en termes d'une caractéristique sur le sous-schéma des points fixes.Le but de cette thèse est de généraliser les résultats de R.W. Thomason dans le contextede la géométrie d'Arakelov. Dans ce travail, nous considérons les schémas arithmétiquesau sens de Gillet-Soulé et nous tout d'abord démontrons un analogue arithmétiquedu théorème de concentration pour les schémas arithmétiques munis d'une action duschéma en groupe diagonalisable associé à Z/nZ. La démonstration résulte du théorèmede concentration algébrique joint à des arguments analytiques. Dans le dernier chapitre,nous formulons et démontrons deux types de formules de Lefschetz arithmétiques. Cesdeux formules donnent une réponse positive à deux conjectures énoncées par K. Köhler,V. Maillot et D. Rössler.
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Iškilojo taškų aibės apvalkalo algoritmų tyrimas / Investigation of the convex hullVyšniauskaitė, Laura 19 June 2006 (has links)
All possible convex hull (i.e. the minimum area convex polygon containing the planar set) algorithms ever published in scientific press have been analysed in this work. Two new convex hull algorithms created by myself have been presented. The running time of analysed algorithms has been surveyed. Three most popular algorithms (Graham Scan, Jarvis March and Quickhull), the oldest algorithm (Brute Force) as well as the both new ones have been implemented. Efficiency experiments have been carried out with them. The algorithms created by me achieved the best results. In order to raise the efficiency of all the algorithms I suggested a priori filtration of points, which decreases the amount of the original points by almost 50% and, consequently, the speed of algorithms is increased. The major part of this master work will be published in the magazine “Technological and economic development of economy”. Besides, the report of this work has been made in the conference of Lithuanian young scientists, called “Operation analysis and application”.
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Reconnaissance d'objets 3D par points d'intérêtShaiek, Ayet 21 March 2013 (has links) (PDF)
Soutenue par les progrès récents et rapides des techniques d'acquisition 3D, la reconnaissance d'objets 3D a suscité de nombreux efforts de recherche durant ces dernières années. Cependant, il reste à résoudre dans ce domaine plusieurs problématiques liées à la grande quantité d'information, à l'invariance à l'échelle et à l'angle de vue, aux occlusions et à la robustesse au bruit.Dans ce contexte, notre objectif est de reconnaitre un objet 3D isolé donné dans une vue requête, à partir d'une base d'apprentissage contenant quelques vues de cet objet. Notre idée est de formuler une méthodologie locale qui combine des aspects d'approches existantes et apporte une amélioration sur la performance de la reconnaissance.Nous avons opté pour une méthode par points d'intérêt (PIs) fondée sur des mesures de la variation locale de la forme. Notre sélection de points saillants est basée sur la combinaison de deux espaces de classification de surfaces : l'espace SC (indice de forme- intensité de courbure), et l'espace HK (courbure moyenne-courbure gaussienne).Dans la phase de description de l'ensemble des points extraits, nous proposons une signature d'histogrammes, qui joint une information sur la relation entre la normale du point référence et les normales des points voisins, avec une information sur les valeurs de l'indice de forme de ce voisinage. Les expérimentations menées ont permis d'évaluer quantitativement la stabilité et la robustesse de ces nouveaux détecteurs et descripteurs.Finalement nous évaluons, sur plusieurs bases publiques d'objets 3D, le taux de reconnaissance atteint par notre méthode, qui montre des performances supérieures aux techniques existantes.
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