Dissertations / Theses: 'Projection de graphe'

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Taki, Sara. "Anonymisation de données liées en utilisant la confidentialité différentielle." Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2023. http://www.theses.fr/2023ISAB0009.

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Cette thèse étudie le problème de la protection de la vie privée dans le LinkedOpen Data (ou « LOD », en français « web des données ouvertes » ou encore « donnéesliées ouvertes »). Ce travail se situe à l’intersection d’une longue série de travaux sur laconfidentialité des données et le LOD. Notre objectif est d’étudier l’impact des aspectssémantiques sur la publication des données et sur les fuites éventuelles d’information.Nous considérons RDF comme le format de représentation du LOD et la confidentialitédifférentielle (DP) comme le principal critère de protection de la vie privée. La DP a étéinitialement conçue pour définir la confidentialité dans le domaine des bases de donnéesrelationnelle. Elle est basée sur une quantification de la difficulté pour un attaquantd’identifier, en observant le résultat d’un algorithme, quelle base de données parmis unvoisinage a été utilisée pour le produire.Les objectifs de cette thèse sont au nombre de quatre: O1) améliorer la protectiondes données LOD. En particulier, proposer une approache permettant de construire desméchanismes DP utilisables sur RDF ; O2) étudier comment les définitions des voisinagessur les bases de données relationnelles en présence de contraintes de clés étrangères (FK) peuvent être traduites en RDF : O3) proposer de nouvelles définitions de voisinages sur des bases de données relationnelles équivalente à des notions existantes de voisinage sur les graphes (avec une sémantique précise) et O4) proposer un formalisme facilitant laconception et l’implémentation de mécanismes d’anonymisation de données RDF.Concernant O1, nous proposons une nouvelle approche basée sur la projection degraphes pour adapter le concept de DP à RDF. Pour O2, nous déterminons le modèlede protection qui correspond à la traduction de modèles déjà existants pour des basesde données relationnelles sous contraintes FK. Pour O3, nous introduisons le conceptde restrict deletion neighborhood (voisinage d’effacement limité) équivalent envoisinage de type "typed-node" (noeud typé). Nous proposons également une relaxation de la définition permettant de traduite les voisinages "typed-outedge" (arc sortanttypé). Pour O4, nous proposons un langage de transformation de graphes basé sur leconcept de réécriture de graphes, qui sert de fondation pour construire divers mécanismes d’anonymisation sur des graphes attribués.L’ensemble de nos contributions théoriques ont été implémentées par des prototypes"preuve de concept" et ont été évalués sur des jeux de données réels, afin de montrerl’applicabilité de nos travaux à des cas d’usage réels
This thesis studies the problem of privacy in linked open data (LOD). Thiswork is at the intersection of long lines of work on data privacy and linked open data.Our goal is to study how the presence of semantics impacts the publication of data andpossible data leaks. We consider RDF as the format to represent LOD and DifferentialPrivacy (DP) as the main privacy concept. DP was initially conceived to define privacyin the relational database (RDB) domain and is based on a quantification of the difficultyfor an attacker observing an output to identify which database among a neighborhoodis used to produce it.The objective of this thesis is four-fold: O1) to improve the privacy of LOD. Inparticular, to propose an approach to construct usable DP-mechanisms on RDF; O2) tostudy how neighborhood definitions over RDB in the presence of foreign key (FK) constraints translate to RDF; O3) to propose new neighborhood definitions over relationaldatabase translating into existing graph concepts to ease the design of DP mechanisms;and O4) to support the implementation of sanitization mechanisms for RDF graphs witha rigorous formal foundation.For O1, we propose a novel approach based on graph projection to adapt DP toRDF. For O2, we determine the privacy model resulting from the translation of popularprivacy model over RDB with FK constraints to RDF. For O3, we propose the restrictdeletion neighborhood over RDB with FK constraints whose translation to the RDFgraph world is equivalent to typed-node neighborhood. Moreover, we propose a looserdefinition translating to typed-outedge neighborhood. For O4, we propose a graphtransformation language based on graph rewriting to serve as a basis for constructingvarious sanitization mechanisms on attributed graphs.We support all our theoretical contributions with proof-of-concept prototypes thatimplement our proposals and are evaluated on real datasets to show the applicability ofour work

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Hadjar, Ahmed. "Composition de polyèdres associés aux problèmes d'optimisation combinatoire." Phd thesis, Grenoble INPG, 1996. http://tel.archives-ouvertes.fr/tel-00345405.

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Le polyèdre associé à un problème d'optimisation combinatoire est l'enveloppe convexe des (vecteurs d'incidence des) solutions réalisables de ce problème. De nombreux problèmes d'optimisation combinatoire se formulent comme une maximisation de fonctions linéaires sur les polyèdres qui leurs sont associés. La description du polyèdre par un système d'inéquations linéaires est intimement liée à la résolution du problème correspondant, par le biais de la programmation linéaire. Afin de déterminer un tel système, une approche classique consiste à décomposer le problème en sous-problèmes tels que les polyèdres associés soient connus ; une composition ultérieure de ces derniers conduit à une description du polyèdre associé au problème considéré. L'objet principal de cette thèse est l'étude de la composition des polyèdres. Dans un premier temps, une approche de composition, basée sur la programmation dynamique et les méthodes de projection polyédrale, est étudiée et des résultats généraux sont proposés, permettant ainsi d'unifier des recherches existantes dans ce domaine. Cette approche est, ensuite, appliquée à la composition de polyèdres associés au problème du voyageur de commerce. En seconde partie, considérant le problème du stable, des opérations sur les graphes (composition par identification de sous-graphes de deux graphes donnés, adjonction d'une nouvelle arête) sont traitées. Des résultats polyédraux sont donc donnés, et des conséquences concernant la perfection et la h-perfection des graphes sont montrés

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Phan, Minh-Son. "Contribution à l'estimation de la similarité dans un ensemble de projections tomographiques non-orientées." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAD041/document.

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La cryo-microscopie électronique est une technique tomographique permettant de reconstituer la structure 3D d’un objet complexe en biologie à partir d’un jeu d’acquisitions. Ces images de l’objet complexe sont appelées les projections et sont acquises sous orientations inconnues. Un des avantages de la cryo-microscopie électronique est l’obtention d’un modèle 3D de très haute résolution de l’objet dans un état naturel. La procédure de reconstruction comporte plusieurs étapes telles que l’alignement, la classification des projections, l’estimation de leurs orientations et le raffinement des projections. Lors de ces étapes, la distance entre deux projections est fréquemment mesurée. Le travail réalisé au cours de cette thèse s’organise autour de la recherche théorique d’une distance entre des projections non-orientées avec comme objectif l’amélioration de la procédure de reconstruction tomographique en cryo-microscopie électronique. La contribution de ce travail de thèse est une méthode permettant d’estimer la différence angulaire entre deux projections dans les cas 2D et 3D. Notre méthode est basée sur la construction d’un graphe de voisinage dont les sommets sont les projections, dont les arêtes relient des projections voisines et sont pondérées par une approximation locale de la différence angulaire. Le calcul de ces poids repose sur les propriétés des moments de projection. Notre méthode est testée sur des images simulées de différentes résolutions et de différents niveaux du bruit. La comparaison avec des autres méthodes d’estimation de la différence angulaire est aussi réalisée
Cryo-electron microscopy is a tomographic technique allowing to reconstruct a 3D model of complex structure in biology from a set of acquired images. These images are known as the tomographic projections and are taken at unknown directions. The advantage of the cryo-electron microscopy is the 3D reconstruction at very high resolution. The reconstruction procedure consists of many steps such as projection alignment, projection classification, orientation estimation and projection refinement. During these steps, the distance between two projections is frequently measured. The work in this thesis aims at studying the distances mesured between two unknown-direction projections with the objective of improving the reconstruction result in the cryo-electron microscopy. The contribution of this thesis is the developement of a method for estimating the angular difference between two projections in 2D and 3D. Our method is based on the construction of a neighborhood graph whose vertices are the projections, whose edges link the projection neighbors and are weighted by a local approximation of the angular difference. The calculation of the weights relies on the projection moment properties. The proposed method has been tested on simulated images with different resolutions and at different noise levels. The comparison with others estimation methods of angular difference has been realised

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Sun, Qiang. "A contribution to the theory of (signed) graph homomorphism bound and Hamiltonicity." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS109/document.

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Dans cette thèse, nous etudions deux principaux problèmes de la théorie des graphes: problème d’homomorphisme des graphes planaires (signés) et problème de cycle hamiltonien.Comme une extension du théorème des quatre couleurs, il est conjecturé([80], [41]) que chaque graphe signé cohérent planaire de déséquilibré-maille d+1(d>1) admet un homomorphisme à cube projective signé SPC(d) de dimension d. La question suivant étalés naturelle:Est-ce que SPC(d) une borne optimale de déséquilibré-maille d+1 pour tous les graphes signés cohérente planaire de déséquilibré-maille d+1?Au Chapitre 2, nous prouvons que: si (B,Ω) est un graphe signé cohérente dedéséquilibré-maille d qui borne la classe des graphes signés cohérents planaires de déséquilibré-maille d+1, puis |B| ≥2^{d−1}. Notre résultat montre que si la conjecture ci-dessus est vérifiée, alors le SPC(d) est une borne optimale à la fois en terme du nombre des sommets et du nombre de arêtes.Lorsque d=2k, le problème est équivalent aux problème des graphes:est-ce que PC(2k) une borne optimale de impair-maille 2k+1 pour P_{2k+1} (tous les graphes planaires de impair-maille au moins 2k+1)? Notez que les graphes K_4-mineur libres sont les graphes planaires, est PC(2k) aussi une borne optimale de impair-maille 2k+1 pour tous les graphes K_4-mineur libres de impair-maille 2k+1? La réponse est négative, dans[6], est donné une famille de graphes d’ordre O(k^2) que borne les graphes K_4-mineur libres de impair-maille 2k+1. Est-ce que la borne optimale? Au Chapitre 3, nous prouvons que: si B est un graphe de impair-maille 2k+1 qui borne tous les graphes K_4-mineur libres de impair-maille 2k+1, alors |B|≥(k+1)(k+2)/2. La conjonction de nos résultat et le résultat dans [6] montre que l’ordre O(k^2) est optimal. En outre, si PC(2k) borne P_{2k+1}, PC(2k) borne également P_{2r+1}(r>k).Cependant, dans ce cas, nous croyons qu’un sous-graphe propre de P(2k) serait suffisant à borner P_{2r+1}, alors quel est le sous-graphe optimal de PC2k) qui borne P_{2r+1}? Le premier cas non résolu est k=3 et r= 5. Dans ce cas, Naserasr [81] a conjecturé que le graphe Coxeter borne P_{11}. Au Chapitre 4, nous vérifions cette conjecture pour P_{17}.Au Chapitres 5, 6, nous étudions les problèmes du cycle hamiltonien. Dirac amontré en 1952 que chaque graphe d’ordre n est hamiltonien si tout sommet a un degré au moins n/2. Depuis, de nombreux résultats généralisant le théorème de Dirac sur les degré ont été obtenus. Une approche consiste à construire un cycle hamiltonien à partir d'un ensemble de sommets en contrôlant leur position sur le cycle. Dans cette thèse, nous considérons deux conjectures connexes. La première est la conjecture d'Enomoto: si G est un graphe d’ordre n≥3 et δ(G)≥n/2+1, pour toute paire de sommets x,y dans G, il y a un cycle hamiltonien C de G tel que dist_C(x,y)=n/2.Notez que l’ ́etat de degre de la conjecture de Enomoto est forte. Motivé par cette conjecture, il a prouvé, dans [32], qu’une paire de sommets peut être posé des distances pas plus de n/6 sur un cycle hamiltonien. Dans [33], les cas δ(G)≥(n+k)/2 sont considérés, il a prouvé qu’une paire de sommets à une distance entre 2 à k peut être posé sur un cycle hamiltonien. En outre, Faudree et Li ont proposé une conjecture plus générale: si G est un graphe d’ordre n≥3 et δ(G)≥n/2+1, pour toute paire de sommets x,y dans G et tout entier 2≤k≤n/2, il existe un cycle hamiltonien C de G tel que dist_C(x,y)=k. Utilisant de Regularity Lemma et Blow-up Lemma, au chapitre 5, nous donnons une preuve de la conjeture d'Enomoto conjecture pour les graphes suffisamment grand, et dans le chapitre 6, nous donnons une preuve de la conjecture de Faudree et Li pour les graphe suffisamment grand
In this thesis, we study two main problems in graph theory: homomorphism problem of planar (signed) graphs and Hamiltonian cycle problem.As an extension of the Four-Color Theorem, it is conjectured ([80],[41]) that every planar consistent signed graph of unbalanced-girth d+1(d>1) admits a homomorphism to signed projective cube SPC(d) of dimension d. It is naturally asked that:Is SPC(d) an optimal bound of unbalanced-girth d+1 for all planar consistent signed graphs of unbalanced-girth d+1?In Chapter 2, we prove that: if (B,Ω) is a consistent signed graph of unbalanced-girth d which bounds the class of consistent signed planar graphs of unbalanced-girth d, then |B|≥2^{d-1}. Furthermore,if no subgraph of (B,Ω) bounds the same class, δ(B)≥d, and therefore,|E(B)|≥d·2^{d-2}.Our result shows that if the conjecture above holds, then the SPC(d) is an optimal bound both in terms of number of vertices and number of edges.When d=2k, the problem is equivalent to the homomorphisms of graphs: isPC(2k) an optimal bound of odd-girth 2k+1 for P_{2k+1}(the class of all planar graphs of odd-girth at least 2k+1)? Note that K_4-minor free graphs are planar graphs, is PC(2k) also an optimal bound of odd-girth 2k+1 for all K_4-minor free graphs of odd-girth 2k+1 ? The answer is negative, in [6], a family of graphs of order O(k^2) bounding the K_4-minor free graphs of odd-girth 2k+1 were given. Is this an optimal bound? In Chapter 3, we prove that: if B is a graph of odd-girth 2k+1 which bounds all the K_4-minor free graphs of odd-girth 2k+1,then |B|≥(k+1)(k+2)/2. Our result together with the result in [6] shows that order O(k^2) is optimal.Furthermore, if PC(2k) bounds P_{2k+1},then PC(2k) also bounds P_{2r+1}(r>k). However, in this case we believe that a proper subgraph of PC(2k) would suffice to bound P_{2r+1}, then what’s the optimal subgraph of PC(2k) that bounds P_{2r+1}? The first case of this problem which is not studied is k=3 and r=5. For this case, Naserasr [81] conjectured that the Coxeter graph bounds P_{11} . Supporting this conjecture, in Chapter 4, we prove that the Coxeter graph bounds P_{17}.In Chapter 5,6, we study the Hamiltonian cycle problems. Dirac showed in 1952that every graph of order n is Hamiltonian if any vertex is of degree at least n/2. This result started a new approach to develop sufficient conditions on degrees for a graph to be Hamiltonian. Many results have been obtained in generalization of Dirac’s theorem. In the results to strengthen Dirac’s theorem, there is an interesting research area: to control the placement of a set of vertices on a Hamiltonian cycle such that thesevertices have some certain distances among them on the Hamiltonian cycle.In this thesis, we consider two related conjectures, one is given by Enomoto: if G is a graph of order n≥3, and δ(G)≥n/2+1, then for any pair of vertices x, y in G, there is a Hamiltonian cycle C of G such that dist_C(x, y)=n/2. Motivated by this conjecture, it is proved,in [32],that a pair of vertices are located at distances no more than n/6 on a Hamiltonian cycle. In [33], the cases δ(G) ≥(n+k)/2 are considered, it is proved that a pair of vertices can be located at any given distance from 2 to k on a Hamiltonian cycle. Moreover, Faudree and Li proposed a more general conjecture: if G is a graph of order n≥3, and δ(G)≥n/2+1, then for any pair of vertices x, y in G andany integer 2≤k≤n/2, there is a Hamiltonian cycle C of G such that dist_C(x, y) = k. Using Regularity Lemma and Blow-up Lemma, in Chapter 5, we give a proof ofEnomoto’s conjecture for graphs of sufficiently large order, and in Chapter 6, we give a proof of Faudree and Li’s conjecture for graphs of sufficiently large order

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Douar, Brahim. "Fouille de sous-graphes fréquents à base d'arc consistance." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20108/document.

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Avec la croissance importante du besoin d'analyser une grande masse de données structurées tels que les composés chimiques, les structures de protéines ou même les réseaux sociaux, la fouille de sous-graphes fréquents est devenue un défi réel en matière de fouille de données. Ceci est étroitement lié à leur nombre exponentiel ainsi qu'à la NP-complétude du problème d'isomorphisme d'un sous-graphe général. Face à cette complexité, et pour gérer cette taille importante de l'espace de recherche, les méthodes classiques de fouille de graphes ont exploré des heuristiques de recherche basées sur le support, le langage de description des exemples (limitation aux chemins, aux arbres, etc.) ou des hypothèses (recherche de sous-arborescence communes, de chemins communs, etc.). Dans le cadre de cette thèse, nous nous basons sur une méthode d'appariement de graphes issue du domaine de la programmation par contraintes, nommée AC-projection, qui a le mérite d'avoir une complexité polynomiale. Nous introduisons des approches de fouille de graphes permettant d'améliorer les approches existantes pour ce problème. En particulier, nous proposons deux algorithmes, FGMAC et AC-miner, permettant de rechercher les sous-graphes fréquents à partir d'une base de graphes. Ces deux algorithmes profitent, différemment, des propriétés fortes intéressantes de l'AC-projection. En effet, l'algorithme FGMAC adopte un parcours en largeur de l'espace de recherche et exploite l'approche par niveau introduite dans Apriori, tandis que l'algorithme AC-miner parcourt l'espace en profondeur par augmentation de motifs, assurant ainsi une meilleure mise à l'échelle pour les grands graphes. Ces deux approches permettent l'extraction d'un type particulier de graphes, il s'agit de celui des sous-graphes AC-réduits fréquents. Dans un premier temps, nous prouvons, théoriquement, que l'espace de recherche de ces sous-graphes est moins important que celui des sous-graphes fréquents à un isomorphisme près. Ensuite, nous menons une série d'expérimentations permettant de prouver que les algorithmes FGMAC et AC-miner sont plus efficients que ceux de l'état de l'art. Au même temps, nous prouvons que les sous-graphes AC-réduits fréquents, en dépit de leur nombre sensiblement réduit, ont le même pouvoir discriminant que les sous-graphes fréquents à un isomorphisme près. Cette étude est menée en se basant sur une évaluation expérimentale de la qualité des sous-graphes AC-réduits fréquents dans un processus de classification supervisée de graphes
With the important growth of requirements to analyze large amount of structured data such as chemical compounds, proteins structures, social networks, to cite but a few, graph mining has become an attractive track and a real challenge in the data mining field. Because of the NP-Completeness of subgraph isomorphism test as well as the huge search space, frequent subgraph miners are exponential in runtime and/or memory use. In order to alleviate the complexity issue, existing subgraph miners have explored techniques based on the minimal support threshold, the description language of the examples (only supporting paths, trees, etc.) or hypothesis (search for shared trees or common paths, etc.). In this thesis, we are using a new projection operator, named AC-projection, which exhibits nice complexity properties as opposed to the graph isomorphism operator. This operator comes from the constraints programming field and has the advantage of a polynomial complexity. We propose two frequent subgraph mining algorithms based on the latter operator. The first one, named FGMAC, follows a breadth-first order to find frequent subgraphs and takes advantage of the well-known Apriori levelwise strategy. The second is a pattern-growth approach that follows a depth-first search space exploration strategy and uses powerful pruning techniques in order to considerably reduce this search space. These two approaches extract a set of particular subgraphs named AC-reduced frequent subgraphs. As a first step, we have studied the search space for discovering such frequent subgraphs and proved that this one is smaller than the search space of frequent isomorphic subgraphs. Then, we carried out experiments in order to prove that FGMAC and AC-miner are more efficient than the state-of-the-art algorithms. In the same time, we have studied the relevance of frequent AC-reduced subgraphs, which are much fewer than isomorphic ones, on classification and we conclude that we can achieve an important performance gain without or with non-significant loss of discovered pattern's quality

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Matignon, Daniel. "Plans projectifs créés par obturation de Dehn : application à l'impossibilité d'obtenir l'espace projectif réel de dimension trois." Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11024.

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Les principaux resultats de ce travail concernent la possibilite d'obtenir l'espace projectif reel de dimension trois, note p#3, par chirurgie de dehn sur un nud non-trivial de s#3. Nous ramenons le probleme chirurgical a un probleme purement combinatoire. Il s'agit d'etudier les proprietes d'un couple de graphes d'intersection (g, h) provenant respectivement d'un plan projectif minimal (dans p#3) et d'une 2-sphere de niveau prise dans une presentation mince du nud (dans s#3). C. Mca. Gordon et j. Luecke ont utilise une demarche similaire dans la solution au probleme du complement (s#3 jouant le role de p#3). L'existence d'une arete projective nous permet d'utiliser la regle de parite, indispensable dans ce type d'argumentation combinatoire. Nous montrons d'une part que les graphes g et h ne representent pas tous les types, et d'autre part qu'ils ne contiennent pas de grand-cycle. Pour cela, nous utilisons les contraintes topologiques de s#3 et de p#3. Grace a cette etude, nous prouvons le resultat suivant: p#3 n'est pas obtenu par chirurgie de dehn sur un nud s'il a moins de quatre ponts. Nous nous placons ensuite, dans le contexte plus general de la creation d'un plan projectif reel par obturation de dehn. L'espace du nud est substitue par une 3-variete compacte connexe irreductible, avec un bord torique. Nous montrons que si le bord torique contient deux pentes distinctes qui produisent un plan projectif par obturation de dehn, alors elles se coupent essentiellement en un seul point ; par suite il y en a au plus trois en general, et au plus une si la variete est l'espace d'un nud de s#3

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Delhommé, Christian. "Propriétés de projection." Lyon 1, 1995. http://www.theses.fr/1995LYO10159.

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La propriete de projection a ete introduite par ernest corominas pour les ensembles ordonnes : un ensemble ordonne est 2-projectif si les projections sont ses seules operations binaires, croissantes et identiques sur la diagonale. L'objet de cette these est l'etude d'extensions de cette notion, a des operations d'arite superieure (projectivite de hamming finie et projectivite cartesienne infinie) et a des structures plus generales. Notre etude des proprietes de projection de hamming (relatives a des operations regulieres par rapport a chaque argument) est fondee sur des idees de topologie algebrique de base. Nous introduisons divers complexes de chaines, dont les proprietes nous fournissent des criteres de projectivite. Ainsi, nous etablissons par exemple, qu'un graphe fini, connexe, sans sommet pendant, est hamming 2-projectif des qu'il n'a ni triangle ni carre, et plus generalement pour n>2, qu'il est hamming n-projectif, quand il n'a pas cycle de longueur inferieure ou egale a n + 1 et qu'il n'est pas lui-meme un cycle. En particulier, cela fournit les premiers exemples de graphes verifiant la propriete de 3-projection de hamming. Notre point de vue va egalement nous permettre d'introduire les proprietes de n-projection simple et double. Notre approche des proprietes de projection infinies (relatives a des operations infinitaires) est de nature plus ensembliste. Nous montrons en particulier, qu'un graphe projectif de diametre fini est denombrablement projectif, des qu'il n'est pas compact pour les systemes atomiques a un nombre fini d'inconnues. Cette these est partagee en sept chapitres regroupes en trois parties. La premiere est consacree a l'expose de generalites. Nous y etablissons egalement la projectivite de certaines structures homogenes, qui nous permettront d'illustrer la suite de notre propos. Dans une seconde partie, nous mettons en place un cadre algebrique pour l'etude des proprietes de projection de hamming. Dans la troisieme, nous etudions des proprietes de projection infinie, que nous illustrons notamment par les exemples des shift-graphs et des structures homogenes.

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Hansen, Bret. "Graphic Design as Projection." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2117.

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I imagined a world where designing is projecting and where the entire design field is called projection. My research into what it means to be a projector culminates in a participatory creative project that embodies concepts of projection taken from a range of disparate subjects.

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Tsukamoto, Tatsuya. "Knot-inevitable projections of planar graphs /." Electronic version of summary, 1999. http://www.wul.waseda.ac.jp/gakui/gaiyo/2870.pdf.

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Luqman, Muhammad Muzzamil. "Fuzzy multilevel graph embedding for recognition, indexing and retrieval of graphic document images." Thesis, Tours, 2012. http://www.theses.fr/2012TOUR4005/document.

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Cette thèse aborde le problème du manque de performance des outils exploitant des représentationsà base de graphes en reconnaissance des formes. Nous proposons de contribuer aux nouvellesméthodes proposant de tirer partie, à la fois, de la richesse des méthodes structurelles et de la rapidité des méthodes de reconnaissance de formes statistiques. Deux principales contributions sontprésentées dans ce manuscrit. La première correspond à la proposition d'une nouvelle méthode deprojection explicite de graphes procédant par analyse multi-facettes des graphes. Cette méthodeeffectue une caractérisation des graphes suivant différents niveaux qui correspondent, selon nous,aux point-clés des représentations à base de graphes. Il s'agit de capturer l'information portéepar un graphe au niveau global, au niveau structure et au niveau local ou élémentaire. Ces informationscapturées sont encapsulés dans un vecteur de caractéristiques numériques employantdes histogrammes flous. La méthode proposée utilise, de plus, un mécanisme d'apprentissage nonsupervisée pour adapter automatiquement ses paramètres en fonction de la base de graphes àtraiter sans nécessité de phase d'apprentissage préalable. La deuxième contribution correspondà la mise en place d'une architecture pour l'indexation de masses de graphes afin de permettre,par la suite, la recherche de sous-graphes présents dans cette base. Cette architecture utilise laméthode précédente de projection explicite de graphes appliquée sur toutes les cliques d'ordre 2pouvant être extraites des graphes présents dans la base à indexer afin de pouvoir les classifier.Cette classification permet de constituer l'index qui sert de base à la description des graphes etdonc à leur indexation en ne nécessitant aucune base d'apprentissage pré-étiquetées. La méthodeproposée est applicable à de nombreux domaines, apportant la souplesse d'un système de requêtepar l'exemple et la granularité des techniques d'extraction ciblée (focused retrieval)
This thesis addresses the problem of lack of efficient computational tools for graph based structural pattern recognition approaches and proposes to exploit computational strength of statistical pattern recognition. It has two fold contributions. The first contribution is a new method of explicit graph embedding. The proposed graph embedding method exploits multilevel analysis of graph for extracting graph level information, structural level information and elementary level information from graphs. It embeds this information into a numeric feature vector. The method employs fuzzy overlapping trapezoidal intervals for addressing the noise sensitivity of graph representations and for minimizing the information loss while mapping from continuous graph space to discrete vector space. The method has unsupervised learning abilities and is capable of automatically adapting its parameters to underlying graph dataset. The second contribution is a framework for automatic indexing of graph repositories for graph retrieval and subgraph spotting. This framework exploits explicit graph embedding for representing the cliques of order 2 by numeric feature vectors, together with classification and clustering tools for automatically indexing a graph repository. It does not require a labeled learning set and can be easily deployed to a range of application domains, offering ease of query by example (QBE) and granularity of focused retrieval

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Wu, Yingxin. "Hybrid multivariate network visualization combining dimensional projection and graph drawing." Thesis, The University of Sydney, 2008. https://hdl.handle.net/2123/28136.

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The goal of information visualization is to transform abstract data into efficient visual format which help humans extract useful information from the data collected. Two distinctive types of data are of particular interest to the information visualization community: one is multidimensional data in which each data point/entity is described by various attributes. The other is relational data which represent the interaction between the entities. These two types of data are common in the real world but difficult for people to understand. Many visualization approaches have been developed to help people gain insight in to such data sets. This thesis focuses on visualizing the multivariate networks which contains the aforementioned two types of data. The word “multivariate" has two meanings: l) The entities have multiple attributes. 2) The same set of entities can have different relationships. Visualizations should help viewers to compare attributes of different entities, recognize entities’ roles in various relationships and detect correlation between attributes and relationships. We present a two-phase approach to visualize the multivariate networks. In the first phase, vertices with similar attribute values and short graph distance are mapped to proximate regions on the representation. In the second phase. the layout generated in the first phase is adjusted to separate overlapping vertices. reduce vertex—edge overlaps and edge crossings. A user study is carried out to evaluate the effectiveness of this hybrid approach. Results are compared against the commonly used glyph-based technique. The user study shows that the hybrid approach helps users to find correlations between the vertices’ attribute and relationship. In addition, the users find the hybrid visualization facilitates comparing different relationships between the same set of entities. Finally, the hybrid approach is applied to visualize four international trading networks.

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Passuello, Alberto. "Semidefinite programming in combinatorial optimization with applications to coding theory and geometry." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00948055.

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We apply the semidefinite programming method to obtain a new upper bound on the cardinality of codes made of subspaces of a linear vector space over a finite field. Such codes are of interest in network coding.Next, with the same method, we prove an upper bound on the cardinality of sets avoiding one distance in the Johnson space, which is essentially Schrijver semidefinite program. This bound is used to improve existing results on the measurable chromatic number of the Euclidean space.We build a new hierarchy of semidefinite programs whose optimal values give upper bounds on the independence number of a graph. This hierarchy is based on matrices arising from simplicial complexes. We show some properties that our hierarchy shares with other classical ones. As an example, we show its application to the problem of determining the independence number of Paley graphs.

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Chu, Lei. "Colouring Cayley Graphs." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/1125.

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We will discuss three ways to bound the chromatic number on a Cayley graph. 1. If the connection set contains information about a smaller graph, then these two graphs are related. Using this information, we will show that Cayley graphs cannot have chromatic number three. 2. We will prove a general statement that all vertex-transitive maximal triangle-free graphs on n vertices with valency greater than n/3 are 3-colourable. Since Cayley graphs are vertex-transitive, the bound of general graphs also applies to Cayley graphs. 3. Since Cayley graphs for abelian groups arise from vector spaces, we can view the connection set as a set of points in a projective geometry. We will give a characterization of all large complete caps, from which we derive that all maximal triangle-free cubelike graphs on 2ⁿ vertices and valency greater than 2ⁿ/4 are either bipartite or 4-colourable.

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Speer, Martin Fuller. "Facades: Projecting Identity." VCU Scholars Compass, 2006. http://scholarscompass.vcu.edu/etd_retro/176.

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A goal of environmental graphic design is to create identities that inform the public of a building's contents and occupants. The designer's use of recognizable exterior marks, symbols and signage dictates how well this information is communicated to prospective clients, visitors or observers. My creative project examines how informational environmental and graphic design can improve awareness and understanding of the mission of a building that was not constructed for its current social services use.

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Motta, Robson Carlos da. "Medidas em grafos para apoiar a avaliação da qualidade de projeções multidimensionais." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-19032015-163258/.

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Projeções Multidimensionais são úteis para gerar visualizações adequadas para apoiar a análise exploratória de uma grande variedade de dados complexos e de alta dimensionalidade. Tarefas de análise visual de dados têm se beneficiado de projeções para explorar dados textuais, de imagens, de sensores, entre outros. Porém, diferentes técnicas de projeção e diferentes parametrizações de uma mesma técnica produzem resultados distintos para um mesmo conjunto de dados, pois as técnicas adotam estratégias distintas para representar os dados originais em um espaço cuja dimensionalidade permite sua visualização. Atualmente, ainda há poucos recursos para avaliar a qualidade dessas projeções e, em geral, as soluções existentes avaliam propriedades específicas, demandando grande esforço do analista para uma avaliação mais abrangente. Neste trabalho, introduzimos um arcabouço para computar medidas de avaliação de projeções com enfoque em análise de vizinhanças e de agrupamentos. Para elaborar este arcabouço, foi realizado um estudo de percepção para entender melhor como os usuários observam as projeções e foi conduzida uma investigação de representações dos dados capazes de favorecer a identificação de vizinhanças e de agrupamentos. Os padrões identificados no estudo de percepção auxiliaram a validar a representação dos dados, em que foi proposto um modelo de grafo, chamado de Extended Minimum Spanning Tree (EMST), capaz de capturar características condizentes com as observações dos participantes no estudo. O grafo EMST também foi validado por meio de dois estudos comparativos de identificação de vizinhanças e de agrupamentos. Com base neste arcabouço foram propostas cinco medidas de qualidade de projeções multidimensionais, duas delas para avaliar características relacionadas à separação visual das classes, e outras três para avaliar a preservação de propriedades do espaço original, especificamente a separação das classes, as vizinhanças e os agrupamentos. As medidas são ilustradas por meio de sua aplicação a conjuntos de dados artificiais, favorecendo a sua interpretação, bem como a conjuntos de dados reais, evidenciando a sua potencial utilidade em cenários reais. Também é apresentada uma comparação das novas medidas de preservação de vizinhanças com medidas similares descritas na literatura, permitindo identificar diferenças e semelhanças entre elas.
Multidimensional projections are valuable tools to generate visualizations that support exploratory analysis of a wide variety of complex high-dimensional data. Many examples are found in the literature of visual data analysis tasks that employ projections to explore, for instance, text, image, network and sensor data. Nonetheless, dierent projection techniques applied to a particular data set, or even alternative parameterizations of a single technique, can produce very distinct outcomes, as techniques adopt different strategies to reduce data dimensionality. Few resources are available to support assessing projection quality and, in general, existing solutions focus on specific properties. Thus, a broader assessment typically requires considerable human effort. In this work we introduce a framework to compute projection evaluation measures that focus on neighborhoods and clusters. To elaborate this framework we conducted (i) an experimental study to better understand how users perceive projections and (ii) an investigation of possible data representations capable of favoring the identification of neighborhoods and clusters. The observations resulting from the experimental study have been considered to propose and validate a novel graph data model, called Extended Minimum Spanning Tree (EMST), which captures data properties shown to be consistent with the observations by the participants in the study. The EMST graph has been validated by means of two comparative studies conducted to identify neighborhoods and clusters in multidimensional data. Under this framework, five novel measures of projection quality are introduced, two of them to assess properties related to the visual separation of classes, and three to assess the preservation of data properties in the original space, in particular the preservation of class separation, the preservation of neighborhoods and the preservation of groups. The quality measures have been applied to projections of synthetic data sets, favoring their understanding and interpretation, and also to projections of real data sets, illustrating their potential applicability in real scenarios. The newly introduced neighborhood preservation measures are also compared with existing methods in order to illustrate their differences and similarities.

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Sidère, Nicolas. "Contribution aux méthodes de reconnaissance structurelle de formes : approche à base de projections de graphes." Thesis, Tours, 2012. http://www.theses.fr/2012TOUR4009/document.

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Les travaux exposés dans cette thèse portent sur une contribution aux techniques de projection de graphes, appliquées à la reconnaissance de formes, visant à tirer parti de la richesse des méthodes structurelles et de l’efficacité des outils statistiques. Nous présentons une nouvelle projection s’inscrivant dans la catégorie des sondages de graphes. La première contribution de cette thèse porte sur l’encapsulation de la topologie du graphe dans une représentation vectorielle, en s’appuyant sur le dénombrement de motifs (sous-graphes) issus d’un lexique généré indépendamment du contexte. Ces motifs permettent de minimiser les pertes de l’information topologique lors de la projection. La deuxième contribution porte sur l’intégration de l’information relative aux étiquettes au sein de notre projection par l’adjonction de leurs dénombrements. Aux problèmes liés à la nature et la variabilité des attributs, nous proposons deux solutions dans le but de constituer des classes d’étiquettes moins nombreuses. La première consiste à discrétiser les attributs numériques puis à les combiner. La deuxième vise à former ces classes par un partitionnement global de l’ensemble des étiquettes. Ces propositions sont ensuite évaluées sur différentes bases de graphes et dans différents contextes
The work exposed in this thesis focuses on a contribution to techniques of graph embedding, applied to pattern recognition, aiming to take advantages of the richness of structural methods and the efficiency of statistical tools. We present a new embedding, joining the category of graph probing. The first contribution of this thesis deals with the embedding of the graph topology in a vectorial representation, based on the counting of patterns (subgraphs) stemming of a lexicon generated independently of the context. These patterns permit the minimization of losses of the topological information during the embedding. The second contribution focuses on the integration of the information related to labels inside our embedding by adding their counting. To deal with problems linked to the nature and the variability of the attributes, we suggest two solutions to reduce the number of label classes. The first one consists of discretizing numeral attributes and combining them The second one aims to build these classes by a global clustering on the set of labels. Then, these proposals are evaluated on different datasets of graphs and in different contexts

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Rodriguez, Saul, Sami Viziri, Mikael Östling, Ana Rusu, Eduard Alarcon, and Max Lemme. "RF Performance Projections of Graphene FETs vs. Silicon MOSFETs." KTH, Integrerade komponenter och kretsar, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109266.

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A graphene field-effect-transistor (GFET) model calibrated with extracted device parameters and a commercial 65 nm silicon MOSFET model are compared with respect to their radio frequency behavior. GFETs slightly lag behind CMOS in terms of speed despite their higher mobility. This is counterintuitive, but can be explained by the effect of a strongly nonlinear voltage-dependent gate capacitance. GFETs achieve their maximum performance only for narrow ranges of V-DS and I-DS, which must be carefully considered for circuit design. For our parameter set, GFETs require at least mu = 3000 cm(2) V-1 s(-1) to achieve the same performance as 65 nm silicon MOSFETs.

QC 20130115

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Flórez, Rigoberto. "Four studies in geometry of biased graphs." Online access via UMI:, 2005.

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Asadi, Shahmirzadi Arash. "Minor-minimal non-projective planar graphs with an internal 3-separation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45914.

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The property that a graph has an embedding in the projective plane is closed under taking minors. Thus by the well known Graph Minor theorem of Robertson and Seymour, there exists a finite list of minor-minimal graphs, call it L, such that a given graph G is projective planar if and only if G does not contain any graph isomorphic to a member of L as a minor. Glover, Huneke and Wang found 35 graphs in L, and Archdeacon proved that those are all the members of L, but Archdeacon's proof never appeared in any refereed journal. In this thesis we develop a modern approach and technique for finding the list L, independent of previous work. Our approach is based on conditioning on the connectivity of a member of L. Assume G is a member of L. If G is not 3-connected then the structure of G is well understood. In the case that G is 3-connected, the problem breaks down into two main cases, either G has an internal separation of order three or G is internally 4-connected. In this thesis we find the set of all 3-connected minor minimal non-projective planar graphs with an internal 3-separation. For proving our main result, we use a technique which can be considered as a variation and generalization of the method that Robertson, Seymour and Thomas used for non-planar extension of planar graphs. Using this technique, besides our main result, we also classify the set of minor minimal obstructions for a-, ac-, abc-planarity for rooted graphs. (A rooted graph (G,a,b,c) is a-planar if there exists a split of the vertex a to a' and a' in G such that the new graph G' obtained by the split has an embedding in a disk such that the vertices a', b, a', c are on the boundary of the disk in the order listed. We define b- and c-planarity analogously. We say that the rooted graph (G,a,b,c) is ab-planar if it is a-planar or b-planar, and we define abc-planarity analogously.)

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Vitray, Richard Pierson. "Representativity and flexibility of drawings of graphs on the projective plane /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487325740721098.

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Allali, Oussama. "Structure et dynamique des graphes de terrain bipartis : liens internes et prédiction de liens." Paris 6, 2011. http://www.theses.fr/2011PA066201.

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Beaucoup de graphes de terrain comme les relations acteur-film ou fichier-fournisseur sont modélisables par des graphes bipartis, dont les noeuds sont divisés en deux ensembles avec des liens entre les noeuds de différents ensembles seulement. Cependant, des méthodes manquent actuellement pour analyser correctement ces graphes, la plupart des méthodes existantes étant conçues pour des graphes classiques. Une approche courante, mais limitée, consiste à transformer les graphes bipartis en graphes classiques, par un procédé appelé projection. Cependant ceci entraîne une perte importante d'informations. Nous introduisons dans cette thèse les liens internes, et les proposons comme une nouvelle notion importante pour analyser les graphes de terrain bipartis : elle permet de mesurer la redondance dans ces graphes, et de mesurer la perte d'information entre un graphe biparti et ses projections. Nous montrons en étudiant différents jeux de données que les liens internes sont très fréquents, et que les statistiques associées permettent de souligner leurs ressemblances et leurs différences avec les graphes bipartis aléatoires. Ensuite, nous montrons que nous pouvons tirer profit de cette notion pour modéliser les graphes de terrain bipartis et les stocker dans un format compact. La plupart des graphes de terrain sont de plus dynamiques, c'est-à-dire que leur structure évolue au fil du temps par l'ajout et/ou le retrait de noeuds et/ou de liens. L'étude de la dynamique des graphes de terrain peut s'aborder par le problème de la prédiction de nouveaux liens dans ces graphes. Plusieurs travaux ont étudié le problème de la prédiction de liens dans les graphes classique (non-bipartis). Toutefois, leurs méthodes ne sont pas directement applicables aux graphes bipartis ou sont inappropriées. Nous proposons une approche basée sur les liens internes pour la prédiction dans les graphes bipartis. Nous montrons que notre méthode fonctionne très bien, beaucoup mieux que l'approche de recommandation classique.

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Sivaraman, Vaidyanathan. "Some Topics concerning Graphs, Signed Graphs and Matroids." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354645035.

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Leclerc, Marc-Antoine. "Homogeneous Projective Varieties of Rank 2 Groups." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23558.

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Root systems are a fundamental concept in the theory of Lie algebra. In this thesis, we will use two different kind of graphs to represent the group generated by reflections acting on the elements of the root system. The root systems we are interested in are those of type A2, B2 and G2. After drawing the graphs, we will study the algebraic groups corresponding to those root systems. We will use three different techniques to give a geometric description of the homogeneous spaces G/P where G is the algebraic group corresponding to the root system and P is one of its parabolic subgroup. Finally, we will make a link between the graphs and the multiplication of basis elements in the Chow group CH(G/P).

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Baboin, Anne-Céline. "Calcul quantique : algèbre et géométrie projective." Phd thesis, Université de Franche-Comté, 2011. http://tel.archives-ouvertes.fr/tel-00600387.

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Cette thèse a pour première vocation d'être un état de l'art sur le calcul quantique, sinon exhaustif, simple d'accès (chapitres 1, 2 et 3). La partie originale de cet essai consiste en deux approches mathématiques du calcul quantique concernant quelques systèmes quantiques : la première est de nature algébrique et fait intervenir des structures particulières : les corps et les anneaux de Galois (chapitre 4), la deuxième fait appel à la géométrie dite projective (chapitre 5). Cette étude a été motivée par le théorème de Kochen et Specker et par les travaux de Peres et Mermin qui en ont découlé

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Chowdhury, Ameerah. "Colouring Subspaces." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/1026.

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This thesis was originally motivated by considering vector space analogues of problems in extremal set theory, but our main results concern colouring a graph that is intimately related to these vector space analogues. The vertices of the q-Kneser graph are the k-dimensional subspaces of a vector space of dimension v over F_q, and two k-subspaces are adjacent if they have trivial intersection. The new results in this thesis involve colouring the q-Kneser graph when k=2. There are two cases. When k=2 and v=4, the chromatic number is q²+q. If k=2 and v>4, the chromatic number is (q^(v-1)-1)/(q-1). In both cases, we characterise the minimal colourings. We develop some theory for colouring the q-Kneser graph in general.

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Bréhat, Cécile. "Construction du maternel dans les situations de grande prématurité." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAG058/document.

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Devenue une question de santé publique, la grande prématurité pose des questions éthiques, médicales et psychologiques. Considérée comme un facteur de risque de maltraitance et de troubles du spectre autistique, la littérature scientifique met en avant les effets du traumatisme pour expliquer la difficulté de nouage des liens précoces entre la mère et son enfant. A partir de l’analyse discursive et thématique de 34 entretiens de recherches menés avec 15 femmes primipares dans le cadre d’une recherche longitudinale et comparative, la construction du maternel et le rapport subjectif à la médicalisation et au discours des professionnels de soin rencontrés ont été explorés. Les résultats mettent en lumière l’effet loupe que permet les naissances très prématurées sur la construction du processus de maternalité en dévoilant, à travers le décalage entre la naissance physique et psychique, l’importance de la libidinisation ou de la phallicisation du bébé prématuré dans la création du lien. Ils éclairent également la spécificité de ce contexte de naissance à travers la place que prend cet « autre » qu’est la médecine dans ces naissances dont la survie de l’enfant dépend de sa technique
As a public health issue, extreme premature birth raises ethical, medical and psychological issues. Considered as a risk factor for child maltreatment and autism spectrum disorders, scientific literature puts forward the effects of trauma to explain the difficulty of forming early ties between the mother and her child. From the discursive and thematic analysis of 34 research interviews conducted with 15 primiparous women in the framework of a longitudinal and comparative research, the construction of the maternal and the subjective relationship to medicalization and the rhetoric of healthcare professionals met were explored. The results highlight the magnifying effect that very premature births can have on the construction of the maternal process by revealing, via the gap between physical and psychic birth, the importance of the libidinisation or phallicisation of the premature baby in the establishment of the relationship. They also shed light on this unique birth context by revealing the place that the “other” represented by medicine holds in such births for which the survival of the child depends on its skills

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Baroin, Gilles. "Applications de la théorie des graphes à des objets musicaux : modélisations, visualisations en hyperespace." Phd thesis, Université Toulouse le Mirail - Toulouse II, 2011. http://tel.archives-ouvertes.fr/tel-00943407.

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A la frontière entre musique et mathématiques, cette étude présente un espace musical géométrique original utilisé pour l'analyse et la pédagogie.En utilisant différentes méthodes, les mathématiciens et théoriciens de la musique ont démontré que notre espace des hauteurs tempéré à douze notes peut être considéré comme une combinaison de tierces mineurs et majeures. Nous utilisons le produit cartésien de deux graphes circulaires C3□C4 pour construire le graphe Planet qui répond à ce concept. Comme la décomposition implique deux ensembles et que chaque classe de hauteur est la combinaison unique de ces deux sous-groupes, nous utilisons une coloration en termes de graphes par des nombres complexes et introduisons le concept d'idéogrammes à deux dimensions. Nous effectuons une analyse spectrale du graphe Planet pour déterminer ses espaces propres et obtenir des coordonnées géométriques. Le modèle qui en résulte est appelé Planet-4D, il offre à chaque symbole une position physiquement équivalente. Il comporte plus de symétries que tout modèle discret 3D. A partir de ce modèle, nous construisons une représentation en quatre dimensions où les accords parfaits se trouvent en surface d'une hypersphère. Nous étendons enfin le concept principal pour afficher n'importe quel agrégat de notes sur l'hypersphère dans un cadre atonal. Dans une seconde partie, nous modélisons sous forme de graphes des objets musicaux existants : claviers, réseaux de notes (Tonnetze) ou d'accords ainsi que des schémas de modulation. Nous appliquons des projections spectrales afin de visualiser les symétries inhérentes à ces objets et terminons par des études d'œuvres tonales et atonales, effectuées avec le système de visualisation inventé.

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Elhadji, Ille Gado Nassara. "Méthodes aléatoires pour l’apprentissage de données en grande dimension : application à l'apprentissage partagé." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0032.

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Cette thèse porte sur l’étude de méthodes aléatoires pour l’apprentissage de données en grande dimension. Nous proposons d'abord une approche non supervisée consistant en l'estimation des composantes principales, lorsque la taille de l'échantillon et la dimension de l'observation tendent vers l'infini. Cette approche est basée sur les matrices aléatoires et utilise des estimateurs consistants de valeurs propres et vecteurs propres de la matrice de covariance. Ensuite, dans le cadre de l’apprentissage supervisé, nous proposons une approche qui consiste à, d'abord réduire la dimension grâce à une approximation de la matrice de données originale, et ensuite réaliser une LDA dans l’espace réduit. La réduction de dimension est basée sur l’approximation de matrices de rang faible par l’utilisation de matrices aléatoires. Un algorithme d'approximation rapide de la SVD, puis une version modifiée permettant l’approximation rapide par saut spectral sont développés. Les approches sont appliquées à des données réelles images et textes. Elles permettent, par rapport à d’autres méthodes, d’obtenir un taux d’erreur assez souvent optimal, avec un temps de calcul réduit. Enfin, dans le cadre de l’apprentissage par transfert, notre contribution consiste en l’utilisation de l'alignement des sous-espaces caractéristiques et l’approximation de matrices de rang faible par projections aléatoires. La méthode proposée est appliquée à des données de référence ; elle présente l’avantage d’être performante et adaptée à des données de grande dimension
This thesis deals with the study of random methods for learning large-scale data. Firstly, we propose an unsupervised approach consisting in the estimation of the principal components, when the sample size and the observation dimension tend towards infinity. This approach is based on random matrices and uses consistent estimators of eigenvalues and eigenvectors of the covariance matrix. Then, in the case of supervised learning, we propose an approach which consists in reducing the dimension by an approximation of the original data matrix and then realizing LDA in the reduced space. Dimension reduction is based on low–rank approximation matrices by the use of random matrices. A fast approximation algorithm of the SVD and a modified version as fast approximation by spectral gap are developed. Experiments are done with real images and text data. Compared to other methods, the proposed approaches provide an error rate that is often optimal, with a small computation time. Finally, our contribution in transfer learning consists in the use of the subspace alignment and the low-rank approximation of matrices by random projections. The proposed method is applied to data derived from benchmark database; it has the advantage of being efficient and adapted to large-scale data

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Candel, Gaëlle. "Connecting graphs to machine learning." Electronic Thesis or Diss., Université Paris sciences et lettres, 2022. http://www.theses.fr/2022UPSLE018.

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L’objet de cette thèse est de proposer des approches nouvelles permettant l’utilisation d’algorithmes d’apprentissage automatique travaillant usuellement des données tabulaires aux graphes. Un graphe est une structure de donnée composée de nœuds reliés entre eux par des liens. Cette structure peut être représentée sous la forme d’une matrice, où chaque connexion entre de nœuds est représentée par une valeur non nulle, permettant une manipulation des données plus facile. Néanmoins, par leurs différences structurelles, la transposition d’un algorithme exploitant des données tabulaires aux graphes ne donne pas les résultats escomptés. Deux caractéristiques rendent cette adaptation difficile : la faible connectivité des nœuds ainsi que la distribution en loi de puissance du degré des nœuds. Ces caractéristiques conduisent toutes les deux à des matrices creuses pauvres en information tout en nécessitant beaucoup de mémoire de stockage. Dans ces travaux, nous proposons plusieurs manières de prendre en compte ces différences pour deux types de graphes particuliers. Dans la première partie, nous nous intéressons aux graphes de citations et à leur représentation dans l’optique de la veille technologique, tandis que la seconde partie s’adresse aux graphes bipartites utilisés principalement par les systèmes de recommandation. Ces adaptations permettent la réalisation de taches usuelles en apprentissage automatique, telle que le partitionnement et la visualisation des données. Pour le cas des graphes bipartites, des algorithmes spécifiques de co-partitionnement sont proposés pour la segmentation conjointe des deux parties. La troisième partie prend un revers différent. La méthode développée exploite le graphe des k plus proches voisins construit à partir des données tabulaires afin de corriger des erreurs de classifications. Les différentes méthodes développées utilisent diverses approches pour emmagasiner plus d’information dans un vecteur par rapport à l’encodage binaire habituel, permettant de travailler les graphes avec des algorithmes usuel d’apprentissage automatique
This thesis proposes new approaches to process graph using machine learning algorithms designed for tabular data. A graph is a data structure made of nodes linked to each others by edges. This structure can be represented under a matrix form where the connection between two nodes is represented by a non-zero value, simplifying the manipulation of the data. Nonetheless, the transposition of an algorithm adapted to tabular data to graphs would not give the expected results because of the structural differences. Two characteristics make the transposition difficult: the low nodes’ connectivity and the power-law distribution of nodes’ degree. These two characteristics both lead to sparse matrices with low information content while requiring a large memory. In this work, we propose several methods that consider these two graph’s specificities. In the first part, we focus on citation graphs which belong to the directed acyclic graph category and can be exploited for technical watch, while the second part is dedicated to bipartite graphs mainly use by recommender systems. These adaptations permit the achievement of usual machine learning tasks, such as clustering and data visualization. Specific co-clustering algorithms were designed to segment jointly each side of a bipartite graph and identify groups of similar nodes. The third part approaches graphs from a different perspective. The developed approach exploits the k nearest neighbours graph built from the tabular data to help correcting classification errors. These different methods use diverse methods to embed more information in a vector compared to the usual binary encoding, allowing to process graphs with usual machine learning algorithm

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Tagorti, Manel. "Sur les abstractions et les projections des processus décisionnels de Markov de grande taille." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0005/document.

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Les processus décisionnels de Markov (MDP) sont un formalisme mathématique des domaines de l'intelligence artificielle telle que la planification, l'apprentissage automatique, l'apprentissage par renforcement... Résoudre un MDP permet d'identifier la stratégie (politique) optimale d'un agent en interaction avec un environnement stochastique. Lorsque la taille de ce système est très grande il devient difficile de résoudre ces processus par les moyens classiques. Cette thèse porte sur la résolution des MDP de grande taille. Elle étudie certaines méthodes de résolutions: comme les abstractions et les méthodes dites de projection. Elle montre les limites de certaines abstractions et identifie certaines structures "les bisimulations" qui peuvent s'avérer intéressantes pour une résolution approchée du problème. Cette thèse s'est également intéressée à une méthode de projection l'algorithme Least square temporal difference LSTD(λ). Une estimation de la borne sur la vitesse de convergence de cet algorithme a été établie avec une mise en valeur du rôle joué par le paramètre [lambda]. Cette analyse a été étendue pour déduire une borne de performance pour l'algorithme Least square non stationary policy iteration LS(λ)NSPI en estimant la borne d'erreur entre la valeur calculée à une itération fixée et la valeur sous la politique optimale qu'on cherche à identifier
Markov Decision Processes (MDP) are a mathematical formalism of many domains of artifical intelligence such as planning, machine learning, reinforcement learning... Solving an MDP means finding the optimal strategy or policy of an agent interacting in a stochastic environment. When the size of this system becomes very large it becomes hard to solve this problem with classical methods. This thesis deals with the resolution of MDPs with large state space. It studies some resolution methods such as: abstractions and the projection methods. It shows the limits of some approachs and identifies some structures that may be interesting for the MDP resolution. This thesis focuses also on projection methods, the Least square temporal difference algorithm LSTD(λ). An estimate of the rate of the convergence of this algorithm has been derived with an emphasis on the role played by the parameter [lambda]. This analysis has then been generalized to the case of Least square non stationary policy iteration LS(λ)NSPI . We compute a performance bound for LS([lambda])NSPI by bounding the error between the value computed given a fixed iteration and the value computed under the optimal policy, that we aim to determine

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Baboin, Anne-Céline. "Calcul quantique : algèbre et géométrie projective." Electronic Thesis or Diss., Besançon, 2011. http://www.theses.fr/2011BESA2028.

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Cette thèse a pour première vocation d’être un état de l’art sur le calcul quantique, sinon exhaustif, simple d’accès (chapitres 1, 2 et 3). La partie originale de cet essai consiste en deux approches mathématiques du calcul quantique concernant quelques systèmes quantiques : la première est de nature algébrique et fait intervenir des structures particulières : les corps et les anneaux de Galois (chapitre 4), la deuxième fait appel à la géométrie dite projective (chapitre 5). Cette étude a été motivée par le théorème de Kochen et Specker et par les travaux de Peres et Mermin qui en ont découlé
The first vocation of this thesis would be a state of the art on the field of quantum computation, if not exhaustive, simple access (chapters 1, 2 and 3). The original (interesting) part of this treatise consists of two mathematical approaches of quantum computation concerning some quantum systems : the first one is an algebraic nature and utilizes some particular structures : Galois fields and rings (chapter 4), the second one calls to a peculiar geometry, known as projective one (chapter 5). These two approaches were motivated by the theorem of Kochen and Specker and by work of Peres and Mermin which rose from it

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Pibernat, Jérôme. "Conception d'une électronique de traitement de signaux de forte dynamique issus d'une chambre à projection temporelle." Bordeaux 1, 2007. http://www.theses.fr/2007BOR13600.

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La mise en évidence de décroissances radioactives à plusieurs particules nécessite un détecteur multi-trace tel qu'une chambre à projection temporelle (TPC) dont le point de fonctionnement peut-être réglé selon la nature des éléments étudiés. La modélisation électrique d'un détecteur de ce type révèle qu'en fonction des conditions d'utilisation et de la nature des éléments étudiés, la dynamique des signaux générés peut s'élever au-delà de cinq ordres de grandeur. Un système de traitement spécifiquement dédié à cette application doit donc être étudié. Pour satisfaire aux contraintes du matériel expériemental, ce système doit être intégré et son architecture fonctionnelle doit être semblable à celle du prototype présenté. La topologie de l'étage d'entrée du prototype restreint la dynamique de traitement. La solution étudiée pour résoudre ce problème consite à substituer cet étage par un circuit convoyeur de courant de deuxième génération (CCII) à sorties multiples. L'étude de sa linéarité conduit à envisager l'amplitude maximale des signaux qu'il est apte à traiter. Une dynamique supérieure à 1. 10(exposant 5) est atteinte en simulation, en réalisant des circuits de filtrage adapté. L'optimisation de ce convoyeur et des filtres permettrait d'augmenter encore cette dynamique
The emphasis on many-particles radioactive decays requires a tracking detector like a Time Projection Chamber (TPC), which operating point can be set in accordance with the nucleides analyzed. The electrical model of such a detector reveals that, depending on its operating conditions and the nature of elements under study, the signals dynamic range can be up to more than five orders of magnitude. Consequently, an application specific processing system has to be designed. To meet the requirements of the experimental equipment, this system muste be integrated and its functional architecture muste be similar to the one of the prototype presented. The topology of the input stage of the protoype narrows the dynamics of the processing. The solution suffested to solve this problem consists in substituting this stage by a second generation current conveyor (CCII) with multiple outputs. The study of its linearity leads to predict the highest signal amplitude that it's able to process. A dynamic range greater than 1. 10(5) obtained in simulation with adapted filters. Optimization of this conveyor and filters coukd lead to extend even more this dynamic range

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Heulot, Nicolas. "Etude des projections de données comme support interactif de l’analyse visuelle de la structure de données de grande dimension." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112127.

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Acquérir et traiter des données est de moins en moins coûteux, à la fois en matériel et en temps, mais encore faut-il pouvoir les analyser et les interpréter malgré leur complexité. La dimensionnalité est un des aspects de cette complexité intrinsèque. Pour aider à interpréter et à appréhender ces données le recours à la visualisation est indispensable au cours du processus d’analyse. La projection représente les données sous forme d’un nuage de points 2D, indépendamment du nombre de dimensions. Cependant cette technique de visualisation souffre de distorsions dues à la réduction de dimension, ce qui pose des problèmes d’interprétation et de confiance. Peu d’études ont été consacrées à la considération de l’impact de ces artefacts, ainsi qu’à la façon dont des utilisateurs non-familiers de ces techniques peuvent analyser visuellement une projection. L’approche soutenue dans cette thèse repose sur la prise en compte interactive des artefacts, afin de permettre à des analystes de données ou des non-experts de réaliser de manière fiable les tâches d’analyse visuelle des projections. La visualisation interactive des proximités colore la projection en fonction des proximités d’origine par rapport à une donnée de référence dans l’espace des données. Cette technique permet interactivement de révéler les artefacts de projection pour aider à appréhender les détails de la structure sous-jacente aux données. Dans cette thèse, nous revisitons la conception de cette technique et présentons ses apports au travers de deux expérimentations contrôlées qui étudient l’impact des artefacts sur l’analyse visuelle des projections. Nous présentons également une étude de l’espace de conception d’une technique basée sur la métaphore de lentille et visant à s’affranchir localement des problématiques d’artefacts de projection
The cost of data acquisition and processing has radically decreased in both material and time. But we also need to analyze and interpret the large amounts of complex data that are stored. Dimensionality is one aspect of their intrinsic complexity. Visualization is essential during the analysis process to help interpreting and understanding these data. Projection represents data as a 2D scatterplot, regardless the amount of dimensions. However, this visualization technique suffers from artifacts due to the dimensionality reduction. Its lack of reliability implies issues of interpretation and trust. Few studies have been devoted to the consideration of the impact of these artifacts, and especially to give feedbacks on how non-expert users can visually analyze projections. The main approach of this thesis relies on an taking these artifacts into account using interactive techniques, in order to allow data scientists or non-expert users to perform a trustworthy visual analysis of projections. The interactive visualization of the proximities applies a coloring of the original proximities relatives to a reference in the data-space. This interactive technique allows revealing projection artifacts in order to help grasping details of the underlying data-structure. In this thesis, we redesign this technique and we demonstrate its potential by presenting two controlled experiments studying the impact of artifacts on the visual analysis of projections. We also present a design-space based on the lens metaphor, in order to improve this technique and to locally visualize a projection free of artifacts issues

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Luong, Quang-Tuan. "Matrice fondamentale et calibration visuelle sur l'environnement. Vers une plus grande autonomie des système robotiques." Phd thesis, Université Paris Sud - Paris XI, 1992. http://tel.archives-ouvertes.fr/tel-00549134.

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Cette thèse s'attaque au problème général de la calibration d'une caméra mobile en utilisant uniquement des vues quelconques de l'environnement, donc sans utiliser de mire, ni de connaissance a priori sur le mouvement de la caméra. La méthode, appelée autocalibration, est fondée sur des propriétés algébriques de géométrie projective. Elle implique dans un premier temps le calcul de la transformation épipolaire grâce à la matrice fondamentale, notion que nous avons définie, qui est d'une importance primordiale pour tous les problèmes de vision où nous ne disposons pas déjà d'une calibration métrique complète. La détermination sans ambiguïté de cette matrice nécessite un minimum de huit correspondances de points. Les premières techniques que nous avons étudiées sont fondées sur la conservation du birapport et une méthode due à Sturm. Elles visent à calculer les épipoles. Nous avons ensuite introduit de multiples critères et paramétrages permettant l'estimation robuste de la matrice fondamentale par des techniques dérivées de l'algorithme de Longuet-Higgins, que nous avons comparées. Nous mettons en évidence le fait qu'une configuration de points particulière, les ensembles de plans, se prête à d'autres méthodes de calcul qui leur sont propres, mais rend de toutes manières l'estimation moins précise. L'influence du choix des mouvements eux-mêmes sur la stabilité du calcul est importante, nous le caractérisons par des calculs de covariance, et expliquons certaines situations grâce à la surface critique dont nous proposons une étude opérationnelle. Dans un second temps, lorsqu'un minimum de trois mouvements a été effectué, nous pouvons obtenir les paramètres intrinsèques de la caméra au moyen d'un système d'équations polynomiales dites de Kruppa, dont nous avons établi quelques importantes propriétés. Nous proposons d'abord une méthode semi-analytique de résolution, puis une approche itérative performante qui nous permet de prendre en compte des longues séquences d'images, ainsi que l'incertitude. Le calcul des paramètres extrinsèques, et une extension de la méthode à la calibration d'un système stéréo par une nouvelle méthode complètent ce travail, dont la partie expérimentale comporte de très nombreuses simulations, ainsi que des exemples réels.

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Farkas, Ábel. "Dimension and measure theory of self-similar structures with no separation condition." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7854.

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We introduce methods to cope with self-similar sets when we do not assume any separation condition. For a self-similar set K ⊆ ℝᵈ we establish a similarity dimension-like formula for Hausdorff dimension regardless of any separation condition. By the application of this result we deduce that the Hausdorff measure and Hausdorff content of K are equal, which implies that K is Ahlfors regular if and only if Hᵗ (K) > 0 where t = dim[sub]H K. We further show that if t = dim[sub]H K < 1 then Hᵗ (K) > 0 is also equivalent to the weak separation property. Regarding Hausdorff dimension, we give a dimension approximation method that provides a tool to generalise results on non-overlapping self-similar sets to overlapping self-similar sets. We investigate how the Hausdorff dimension and measure of a self-similar set K ⊆ ℝᵈ behave under linear mappings. This depends on the nature of the group T generated by the orthogonal parts of the defining maps of K. We show that if T is finite then every linear image of K is a graph directed attractor and there exists at least one projection of K such that the dimension drops under projection. In general, with no restrictions on T we establish that Hᵗ (L ∘ O(K)) = Hᵗ (L(K)) for every element O of the closure of T , where L is a linear map and t = dim[sub]H K. We also prove that for disjoint subsets A and B of K we have that Hᵗ (L(A) ∩ L(B)) = 0. Hochman and Shmerkin showed that if T is dense in SO(d; ℝ) and the strong separation condition is satisfied then dim[sub]H (g(K)) = min {dim[sub]H K; l} for every continuously differentiable map g of rank l. We deduce the same result without any separation condition and we generalize a result of Eroğlu by obtaining that Hᵗ (g(K)) = 0. We show that for the attractor (K1, … ,Kq) of a graph directed iterated function system, for each 1 ≤ j ≤ q and ε > 0 there exists a self-similar set K ⊆ Kj that satisfies the strong separation condition and dim[sub]H Kj - ε < dim[sub]H K. We show that we can further assume convenient conditions on the orthogonal parts and similarity ratios of the defining similarities of K. Using this property we obtain results on a range of topics including on dimensions of projections, intersections, distance sets and sums and products of sets. We study the situations where the Hausdorff measure and Hausdorff content of a set are equal in the critical dimension. Our main result here shows that this equality holds for any subset of a set corresponding to a nontrivial cylinder of an irreducible subshift of finite type, and thus also for any self-similar or graph directed self-similar set, regardless of separation conditions. The main tool in the proof is an exhaustion lemma for Hausdorff measure based on the Vitali's Covering Theorem. We also give several examples showing that one cannot hope for the equality to hold in general if one moves in a number of the natural directions away from `self-similar'. Finally we consider an analogous version of the problem for packing measure. In this case we need the strong separation condition and can only prove that the packing measure and δ-approximate packing pre-measure coincide for sufficiently small δ > 0.

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Lima, Joaquim Moreira. "Coordenação da actividade de fiscalização do grande projecto de aumento da capacidade de produção térmica da cidade de Luanda." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6216.

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Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores
Este relatório de actividade descreve de um modo geral toda actividade realizada durante o exercício da profissão como Engenheiro ao longo de 29 anos nas diversas áreas da Engenharia Electrotécnica no domínio da energia electrica com ênfase na PRODUCAO, TRANSPORTE, DISTRIBUICÃO e COMERCIALIZACÃO conjugada com alguma actividade de docência na Universidade Agostinho Neto em Luanda Republica de Angola. Não querendo apenas fazer-se simples descrições, propõe-se em destaque como caso mais relevante a coordenação da actividade fiscalizadora de um grande projecto designado por “ PROJECTO DE AUMENTO DA CAPACIDADE TÉRMICA DA CIDADE DE LUANDA” , que consistiu em instalar quatro Centrais Térmicas sendo duas de Terra e duas marítimas sobre Barcaça , caracterizadas por grupos Turbinas a Gás [ GTG], de marcas GE e SIEMENS e todas equipadas com geradores da marca BRUSH refrigerados a ar e, designadas por Central Térmica de Viana com 1x25 MW , Central Térmica do Cazenga com 2x25MW , Central Boavista I versão marítima com 2x46 MW e Central Boavista II com 1x42,1 MW. Estas quatro centrais duas das quais equipadas com turbinas aero-derivativas queimando como combustível JET-B, acabam por apresentar custos de produção elevados devidos ao preço do combustível comparadas com as restantes da versão marítima mas do tipo Heavy duty que queimam gasóleo por sinal muito mais barato que o Jet-B. A exploração preconizada foi em ilha adequando os reguladores a esta situação operando no modo ISÓCRONO e deste modo não contribuindo para a força sincronizante do sistema, mas sim como substituição das fontes principais, aliviando deste modo as Linhas de distribuição e algumas Subestações que operavam no seu limite de capacidade. Desta forma pretende-se considerar esta parte deste relatório como um caso de estudo uma vez que permitiu no desenrolar desta actividade Fiscalizadora reanalisar a Lei Nacional nº 40/05 que regula as Empreitadas e o seu difícil entendimento ao aplicar-se a empreendimentos do género, podendo provocar e daí resultar modelo de contratações que podem não ser a que melhor defenda os interesses do dono da obra .

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Liennard, Mathilda. "Dynamique des tubes parcourus à grande vitesse : influence de la géométrie des tubes et leur environnement sur la justesse et la dispersion." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2033.

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La précision de tir d’une arme dépend de nombreux facteurs intervenant aux différentes étapes du parcours de la munition (balistique intérieure, intermédiaire et extérieure). Certains travaux ont démontré l’importance de l’influence de la phase de balistique intérieure, pendant laquelle la munition traverse le tube, sur les résultats à la cible. En effet, c’est cette phase qui détermine les conditions de sortie du tube de la munition et par conséquent son comportement au cours du vol. Les conditions d’entrée du projectile, la géométrie du tube et de l’arme, et les mouvements de ces derniers au cours du tir, sont autant de paramètres pouvant modifier l’interaction tube/projectile et ainsi entraîner un changement des vitesses angulaires et de translation de la munition au moment du largage. Cette étude a donc pour but de mettre en exergue les paramètres géométriques de l’arme et du tube qui influencent la justesse et la dispersion. Une analyse statistique a été réalisée à partir de la base de données des résultats de tir du 25 mm. Elle a permis de mettre en évidence l’influence de plusieurs paramètres dont la rectitude du tube. Par la suite, des essais ont été conduits en appareil de tir dans le but d’isoler la part de la géométrie du tube sur les écarts à la cible et ainsi de confirmer la contribution de la rectitude. Un modèle numérique tridimensionnel a été développé afin de faire varier ce paramètre et d’étudier son influence sur le comportement de la munition en phase de balistique intérieure. La représentativité du modèle a été vérifiée à l’aide d’accéléromètres embarqués dans la munition. Ces tirs ont nécessité le développement d’une solution innovante optoélectronique afin de transmettre les accélérations en temps réel. Les résultats expérimentaux obtenus ont permis de constater que les accélérations de la munition modélisée étaient représentatives. Le modèle permet maintenant de réaliser des études paramétriques et de déterminer les profils de tube les plus pénalisants pour la précision de tir
Gun accuracy is influenced by several factors during the stages of the ammunition course (internal, intermediate and external ballistics). According to previous studies, internal ballistics are the major contributor to deviations from target. Indeed, this phase determines projectile exit conditions and, consequently, his behavior during the flight. The projectile entry conditions, the weapon and barrel geometry and their movements during firing, can modify the interaction tube / projectile and change ammunition angular rates and its transversal velocities. The purpose of this thesis is to determine the parameters related to barrel and gun geometry, which influence the bias and the dispersion. A statistical analysis was led thanks to the data base of the 25 mm firing results. It was found that some parameters, including barrel straightness, affect accuracy. Subsequently, tests were conducted with a firing appliance in order to isolate the barrel geometry influence on the deviations from the target and to confirm the straightness impact. A tridimensional numerical model was created in order to vary this parameter and to study its influence on the ammunition behavior during internal ballistics. The representativeness of the model was validated using accelerometers embedded in the ammunitions. The firing of these ammunitions has required the development of an optoelectronic system to transmit accelerations in real time. The comparison between experimental and numerical results has shown close amplitudes and similar shapes curves that proves the representativeness of the model. The model can be used now to lead parametric analysis and to determine the straightness shapes the most penalizing for gun accuracy

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Pires, Tiago Alexandre Taniças. "O compromisso organizacional como o grande desafio da gestão estratégica de recursos humanos : O caso dos projectos de outsourcing da IBM Portugal." Master's thesis, Universidade de Évora, 2010. http://hdl.handle.net/10174/19233.

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Num contexto empresarial globalizado, a gestão de recursos humanos assume importância crescente. A valorização do capital humano e a preocupação com o compromisso e produtividade das pessoas revelam-se imperativos para a gestão de recursos humanos na contemporaneidade. As políticas e práticas de recursos humanos revelam-se a forma mais eficaz de comprometer as pessoas e, consequentemente, melhorar a performance organizacional. Este trabalho final de mestrado resultou de um estágio realizado num agrupamento complementar de empresa da IBM. Além das actividades desenvolvidas em contexto organizacional, efectuou-se urna descrição de todo o processo de gestão de recursos humanos e analisou-se a relação entre as políticas e práticas de recursos humanos e o compromisso organizacional, nas suas diferentes dimensões. Os resultados deste diagnóstico revelam que os colaboradores apresentam índices elevados de compromisso organizacional para com o ACE. Este compromisso materializa-se no alinhamento dos objectivos de negócio com os objectivos dos colaboradores. A principal causa destes índices elevados de compromisso são as políticas e práticas de recursos humanos. ABSTRACT: ln a globalized business environment, HRM assumes increasing importance. The human capital and concern for the commitment and productivity of people tum out to be imperative for the contemporary human resource management. Policies and practices of human resources prove to be the most effective way to engage people and thus improve organizational performance. This scientific work resulted from one stage held in a complementary group of the IBM Company. Besides the activities in organizations, took place a description of the whole process of resource management and examined the relationship of policies and practices in human resources with organizational commitment, in its various levels. The results of this diagnosis show that employees have high levels of organizational commitment towards the ACE. This commitment is materialized in the alignment of business goals with employee objectives. The main cause of these high levels of commitment are the policies and practices of human resources.

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Assunção, Cátia Cristina Pinto. "Sines. Interpretação das relações urbanas entre cidade, porto e paisagem. Paisagens metropolitanas. Morfogénese e projecto de grande escala na cidade europeia actual." Master's thesis, Faculdade de Arquitectura de Arquitectura, 2010. http://hdl.handle.net/10400.5/2888.

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Tese de Mestrado em Arquitectura com a especialização em Planeamento Urbano e Territorial
A interpretação de um território do ponto de vista da sua formação urbana, exige o conhecimento das diversas lógicas que lhe estão subjacentes, e implica a identificação dos elementos determinantes que justificam a sua evolução e fundamentam os seus vários estádios de formação. É neste sentido que surge a vontade de reflexão sobre a formação urbana da área de Sines, bem como a sua interpretação e leitura compreensiva, elaboradas a partir de três elementos-chave – cidade, porto e paisagem -, que constituem efectivamente as grandes determinantes da formação urbana deste território e determinam a sua matriz de leitura a qual resulta do entendimento da importância que o oceano, o desenvolvimento urbano e a paisagem florestal, detêm na formação urbana deste território e da interpretação das relações que estes estabelecem entre si, mais ou menos próximas, e que justificam e caracterizam a sua expressão temporal conceptualizada em vários estádios da sua formação – 1940, 1970, 1980, 1990, 2000. A metodologia adoptada, permitiu definir um critério de análise rigoroso, coerente, harmonioso e transversal aos vários períodos identificados e às leituras teóricas e cartográficas apresentadas. Esta investigação tem particular interesse pela inovação do processo de interpretação e caracterização de Sines, um território em crescente transformação.
The interpretation of the territory from the point of view of urban formation, requires knowledge of the various logics that underlie it, and involves identifying of the critical factors that justify their evolution and their underlying various stages of development. In this way arises the desire to reflect about the urban formation of the area of Sines, as well as is interpretation and comprehension reading, prepared from three key elements - city, harbor and landscape -, that are indeed the major determinants of the urban formation of this area and determine their reading frame which results from the understanding of the importance of the ocean, the urban development and the forest landscape, it holds in the urban structure of this territory and its interpretation of the relationships that they establish between themselves, more or less close, and that justify and characterize its temporal expression, conceptualized in various stages of its formation - 1940, 1970, 1980, 1990, 2000. The methodology adopted, allowed to defining a criterion for rigorous analysis, coherent, harmonious and transverse across the various periods identified and to theoretical interpretations and cartographic presented. This research has particular interest in the innovation process of interpretation and characterization of Sines, a growing area in transformation.

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Alexandre, João da Conceição Mendes. "Princípios de Gestão de Benefícios em Projectos de SI/TI adoptados nas organizações de média e grande dimensão em Portugal - Um estudo exploratório." Master's thesis, Instituto Superior de Economia e Gestão, 2011. http://hdl.handle.net/10400.5/4542.

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Mestrado em Gestão de Sistemas de Informação
A gestão e realização dos benefícios obtidos pelos investimentos em Sistemas e Tecnologias de Informação (SI/TI) tem-se revelado uma tarefa de elevada complexidade para as organizações, apesar do crescente enfoque dado ao tema nos últimos anos. A aprovação de investimentos em SI/TI gera discussões pelos consideráveis valores envolvidos, mas nem sempre é dada a devida importância ao modo de obtenção dos benefícios esperados. Como indicador deste fenómeno, verifica-se que grande parte dos projectos de SI/TI não atingem os seus objectivos. Os Investimentos em SI/TI são frequentemente considerados projectos de pura tecnologia, quando o seu impacto se repercute nas organizações, ao nível financeiro, estratégico, táctico e operacional. As causas do sucesso ou insucesso dos projectos parecem residir mais do lado da gestão e não tanto da tecnologia. A Gestão de Benefícios deve ser considerada uma prioridade em qualquer projecto, porque incide na concretização dos benefícios, ao invés de efectuar boas previsões. O presente trabalho visa proporcionar o conhecimento dos princípios da Gestão de Benefícios em investimentos de SI/TI, recomendados pela literatura, adoptados nas organizações de média e grande dimensão em Portugal. Os resultados permitem concluir que a generalidade das organizações não adopta um processo de gestão de benefícios que garanta uma correcta tomada de decisão, maximização dos benefícios e uma monitorização e acompanhamento dos investimentos.
The management and realization of benefits obtained by the investments in systems and information technology (IS/IT) has proved a highly complex task for organizations, despite the growing focus given to the subject in recent years. The approval of investments in IS/IT generates substantial amounts of discussion, but not always is paid attention to the way the expected benefits are obtained. As an indicator of this phenomenon, many IT projects fail to achieve their objectives. Investments in IS/IT projects are often seen as pure technology projects and the fact is that its impact in organizations is made at various levels, such as financial, strategic, tactical and operational levels. The causes of success or failure of projects appear to be rather on the side of management rather than on the technology itself. The Management of Benefits should be considered a priority in any project because it focuses on achieving the benefits, rather than in making good forecasts. This work aims to provide knowledge about the principles of IS/IT benefits investment management, recommended by the literature, and adopted in medium and large organizations in Portugal. The results conclude that most organizations do not adopt a benefits management process that ensures correct decision-making, maximizing benefits and monitoring of investments.

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Melo, Tirzah Moreira de. "Simulação estocástica dos impactos das mudanças climáticas sobre as demandas de água para irrigação na região noroeste do Rio Grande do Sul." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/129854.

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Esta tese foi desenvolvida para avaliar os impactos das mudanças climáticas ao longo deste século sobre as demandas futuras de água para irrigação da soja na região Noroeste do Estado do Rio Grande do Sul sob uma abordagem estocástica e considerando diferentes projeções de modelos climáticos para o período de 2011-2100, comparando com o passado (1961-1990). As demandas de água para irrigação da soja (IWR) foram obtidas por simulação com o modelo SWAP. O aspecto estocástico desta avaliação foi conduzido pela incorporação da variabilidade espacial da condutividade hidráulica do solo (Ksat) e dos parâmetros da curva de retenção de água no solo (CR). Inicialmente, foi realizada uma análise estocástica destes atributos físico-hidráulicos na bacia do Arroio Donato (1,1 Km2), a qual serviu de área representativa dos solos e do uso do solo da região Noroeste. Foi empregada a técnica de simulação sequencial Gaussiana (SSG) para geração de 100 campos aleatórios de cada variável. Os resultados revelaram maiores incertezas para Ksat e o parâmetro α da CR e permitiu identificar que a grande heterogeneidade espacial e temporal das variáveis analisadas pode estar associada a fatores tais como clima, manejo e cobertura do solo, erros de amostragem, adensamento da malha amostral e também ao grau de compactação do solo. Em seguida foi feita uma investigação para detectar mudanças nos padrões de temperatura (T) e precipitação (P) na região Noroeste do RS (~65.000 Km2) pelo uso de diferentes modelos climáticos de circulação geral e regional (MCGs e MCRs, respectivamente). Sete distintas localizações na região foram consideradas, para as quais há dez diferentes projeções climáticas destes modelos. Adicionalmente, também foram investigadas a frequência e a intensidade de eventos de precipitação extrema utilizando-se de índices de eventos extremos. As projeções indicam um aumento na média anual de temperatura de quase 3ºC até o final do século, bem como um aumento na precipitação anual. Também foi realizada uma análise sazonal de T e P, a qual demonstrou que os maiores aumentos de temperatura são projetados para o inverno e início da primavera e, portanto, não coincidem com os meses de verão da principal cultura da região (soja). De posse das informações anteriores, o modelo SWAP foi utilizado para estimar as demandas de água para irrigação da soja (IWR), sem considerar perdas devido à eficiência de qualquer método de irrigação. Foram feitos também testes de hipóteses sobre as séries de IWR simuladas e os resultados suportam a premissa de que IWR a curto prazo (2025s) não será estatisticamente diferente do período base (1961-1990). Por outro lado, as IWR em 2055s e 2085s rejeitam esta hipótese. Por fim, avaliou-se a influência da distribuição espacial da condutividade hidráulica saturada (Ksat) e dos parâmetros do modelo da curva de retenção de água no solo (α, n e sat) sobre as demandas futuras de água para a irrigação da soja (IWR), segundo uma abordagem estocástica. Os valores simulados pelo método geoestatístico de simulação sequencial Gaussiana foram utilizados como dados de entrada no modelo SWAP. Como dados meteorológicos foram consideradas apenas as projeções do modelo climático regional ETA 20 e ETA 40 CTRL, bem como as projeções dadas pelo modelo climático global HADCM3 nas sete localizações na região. As estimativas obtidas pelo método estocástico foram então comparadas com as estimativas de IWR obtidas sem considerar a variabilidade espacial dos atributos físico-hidráulicos do solo. Os resultados indicaram grande variabilidade espacial dos valores de IWR. Além disso, observou-se que as menores incertezas de IWR foram obtidas a partir das projeções do modelo de melhor resolução espacial, o ETA 20, enquanto o modelo HADCM3 revelou as maiores diferenças entre os períodos futuros e o período atual (base). Os resultados também demonstraram que a maior incerteza é devido aos modelos climáticos, pois a abordagem estocástica praticamente não agregou incerteza aos valores de IWR simulados anteriormente. Por fim, as séries de IWR obtidas pela abordagem determinística e estocástica foram comparadas pelo teste de hipóteses de Kolmogorov-Smirnov, o qual comprovou que as séries só não diferem a curto prazo (2025s) e que, portanto, a variabilidade espacial do solo não pode ser negligenciada nas estimativas desta variável.
This Thesis has been developed to assess the impacts of climate change throughout this century on future water demands for soybean irrigation in the Northwest region of Rio Grande do Sul under a stochastic approach and considering different projections of climate models for the period 2011-2100, compared to the past (1961-1990). The water demands for irrigation (IWR) were obtained by simulation with the SWAP model. The stochastic aspect of this evaluation was conducted by incorporating the spatial variability of the saturated hydraulic conductivity (Ksat) and the parameters of the soil water retention curve (CR). Initially, a stochastic analysis of soil physical-hydraulic attributes (Ksat and CR parameters) in the Donato basin (1,1 Km2) was carried out. This basin served as a representative area of soils and land uses of the Northwest region. The Sequential Gaussian Simulation (SSG) technique was used to generate 100 random fields of each variable. The results revealed greater uncertainty for Ksat and for α parameter of the CR and identified that the large spatial and temporal heterogeneity of the variables may be associated with factors such as climate, management and land cover, sampling error, spatial density of the sampling grid and also the degree of soil compaction. After, an investigation was made to detect changes in temperature (T) and precipitation (P) patterns in the Northwest region of RS (~65.000 Km2) by using different global and regional circulation models (GCM and RCM, respectively). Seven distinct locations in the region were considered, for which there are ten different climate projections of these models. Additionally, it was also investigated the frequency and intensity of extreme rainfall events using extreme event indices. Projections indicate an increase in average annual temperature of almost 3 °C by the end of this century, as well as an increase in annual precipitation. It was also performed a seasonal analysis of T and P, which showed that the largest temperature increases are projected for the winter and early spring and, therefore, do not coincide with the summer months the main crop in the region (soy). Making use of the above information, the SWAP model was applied to estimate the water demand for soybean irrigation (IWR), excluding losses due to the efficiency of any method of irrigation. A hypothesis test for the simulated IWR series and the results supports the premise that in short-term IWR (2025s) is not statistically different from base period (1961-1990). On the other hand, IWR in 2055s and 2085s reject this hypothesis. Finally, the influence of the spatial distribution of the saturated hydraulic conductivity (Ksat) and the parameters of the soil water retention curve (α, sat and n) on IWR was evaluated, according to a stochastic approach. The simulated values form the geostatistical method of Sequential Gaussian Simulation (SGS) were used as input data in the SWAP model. Input data of meteorological information were provided by the projections of regional climate model ETA 20 and ETA 40 CTRL, as well as the projections given by global climate model HADCM3 for the seven locations in the region. Estimates obtained by the stochastic method were then compared with the IWR estimates obtained without considering the spatial variability of physical and hydraulic soil properties. The results indicated large spatial variability of IWR values. Furthermore, it was observed that the smallest uncertainties of IWR were obtained from the projections with better spatial resolution, the ETA 20 model, while the HADCM3 model revealed the highest differences between future periods and the current period (baseline). The results also showed that the greatest uncertainties are probably due to climate models, since the stochastic approach did not add uncertainties to the IWR values simulated previously. Finally, the series of IWR obtained by stochastic and deterministic approaches were compared by the hypothesis test of Kolmogorov-Smirnov, which proved that only the series in the short term (2025s) differ, and, therefore, the soil spatial variability may not be neglected when estimating this variable.

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Sarin, Anika. "open / close: assimilating immersive spaces in visual communication." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4876.

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I am interested in two spaces obverse to each other: open and closed. An open space develops organically based on how people inhabit it. Interacting with an open space is a dynamic, sporadic, multisensory, immersive, and subjective experience. In such spaces, we are confronted with an alternative aesthetic, one that is in conflict with the seamlessness of a closed space. A closed space is anchored on definite variables like structure, use and boundaries. While interaction between people and space is important, the space is tightly controlled and interaction is designed. Through this thesis project, I present a method that metaphorically transforms the experience of a walk through a closed space into an open-ended and immersive experience. When space develops as a response to our actions, it affords intimacy and a sense of belonging. It facilitates deeper expressiveness through engagement. By applying a method that uses fragmentation, recurrence and motion, I am metaphorically transforming an urban closed space to open. Through this transformation I am creating a fresh person-space dialogue that temporarily destabilizes perception and encourages physical sensation which allows for an intimate experience of the space. An immersive interaction with an open space transgresses the urban sterility of a closed space and is capable of creating a diversity of distinct experiences.

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Silva, Neto Antonio Rodrigues da. "Cenários de abastecimento futuro de Palmas - TO com base na simulação da disponibilidade hídrica do Ribeirão Taquarussu Grande." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/35351.

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A falta de dados hidrológicos é fator limitante da representação mais precisa do comportamento hídrico, comprometendo a gestão de bacias hidrográficas. Quando estas bacias são responsáveis pelo abastecimento publico a situação torna-se crítica. Este trabalho tem como objetivo desenvolver uma metodologia para avaliação da disponibilidade hídrica para o abastecimento, utilizando cenários adaptados ao clima do cerrado, mesmo com carência de dados hidrometeorológicos, sendo aplicada na Sub-bacia do Ribeirão Taquarussu Grande em Palmas-TO. A proposta de metodologia consiste na Estimava da Oferta Hídrica, onde propôs obter os dados de disponibilidade hídrica através dos Métodos de Proporção de Área, de Regressão e do modelo chuva-vazão Win_IPH II, posteriormente adotando a Q90 e a Q7,10 como as vazões de referência; na Estimativa da Demanda e Projeções, que identificou os usos consultivos e a taxa de crescimento da população urbana e rural, da criação animal e os seus respectivos consumos per capita, necessária para a projeção de demanda futura; nos Cenários Propostos, foram aplicadas simulações para atendimento do abastecimento publico no horizonte de 20 anos, considerando a variabilidade climática na região e/ou inserção de novos usuários, no qual a vazão de referência adotada foi cotejada com a curva de demanda, avaliando a disponibilidade hídrica e identificando a variação do máximo déficit. Os resultados obtidos foram que a metodologia proposta se mostrou adequada, como uma ferramenta de analise e tomadas de decisões no gerenciamento integrado dos usos dos recursos hídricos; observou que a Q90 e a Q7,10 anual adotada restringe o uso da água na maior parte do tempo, enquanto a Q90 e a Q7,10 mensal possui uma maior capacidade de disponibilizar água; o maior usuário da Sub-bacia do Ribeirão Taquarussu Grande é a população urbana do município de Palmas, sendo esta responsável por 98,5% do total consumido; nos cenários, o Caso 01 do Cenário 02, demonstrou ser a tendência futura no atendimento da demanda de 66% da população urbana (ETA 006) utilizando a Q90 mensal, tendo o déficit de 47,17% no ano de 2010.
The lack of hydrological data is a limitante factor of the most precise representation of the hydric behaviour, compromising the management of hydrological basins, when these basins are responsible for the publish supply the situation becomes critical.This paper proposes a methodology for assessment of watershed conditions in the supply scenarios adapted to the scarcity of hydrometeorological data, being applied in the sub-basin of the Great Stream Taquarussu Palmas-TO.The proposed methodology is the estimate of Water Supply, which aimed to obtain data on water availability through the methods of Area Ratio, Regression and model rainfall-runoff Win_IPH II, later adopting the Q90 and Q7,10 as the flow of reference; Estimation of the Demand and Projections, which identified the uses advisory and the growth rate of urban and rural population of the animal creation and their respective per capita, which is necessary for the projection of future demand, in the proposed scenario, simulations were applied to attend the public supply in the 20-year horizon, given the climate variability in the region and / or adding new users, in which the reference flow used was checked against the demand curve, assessing water availability and identifying the shift of the maximum deficit and Estimated Cost of Work, which has proposed alternatives to increase water availability by estimating the costs of these works. The results were that the proposed methodology was adequate as a tool for analysis and decision making in integrated management of water resources uses; noted that the Q90 and Q7,10 adopted restricts the annual water use in most of the time , While the Q90 and Q7,10 monthly has a greater capacity to provide water, the biggest user of the Sub-basin Taquarussu Ribeirão Grande is the Palmas city urban population which is responsible for 98.5% of total consumption, in the scenarios, the case 01 of Scenario 02, proved to be the future trend in meeting demand of 66% of urban population (ETA 006) monthly using the Q90, with the deficit of 47.17% in 2010.

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Alarid, Renee Aurelia. "Propolis: Immersive Environment." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/102378.

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Propolis – Creating and using an immersive 2D honey bee environment to educate children between the ages of 3-10, about the importance of honey bees. This capstone project will showcase this researcher's skills in graphic design, spatial sound, architecture, exhibition design, and character illustration. Within this structure, individuals will be able to observe, determine, and make comparisons between a healthy bee colony and one that is fragile and dying.
Master of Fine Arts
"Honey bees have been on the decline. As of 2016, eight species of bees made it on the United States (U.S.) endangered species list. It reported that the decline of pollinators is due to industrial agriculture, parasites, pathogens, and climate change" (Contributors 2020). The loss of habitat and lack of nectar is due to monocultures and bee-killing pesticides. These are significant threats to honey bees and wild pollinators. There is a need for good, clean food providing for a healthy existence for the honey bee. When bees have proper nutrients, the result is a healthy hive that gives mature bees a better chance to fight off diseases. To showcase the life of a honey bee, this researcher created an immersive environment that simulates a hive structure. The structure, along with the motion graphics and critical takeaway printed pieces, is to help children between the ages of 3-10 understand the importance of honey bees. By comparing healthy and unhealthy bees in their natural habitat in an illustration format, the children could empathize with the honey bees. Hopefully, they will one day change the fate of these amazing creatures. The immersive environment will emulate a spatial audio, 2D character illustration, and animation projected onto a honeycomb structure. Custom seed packets and a brochure will accompany the immersive environment to allow the children to plant a bee-friendly garden and to learn more about the honey bees. This capstone project will showcase the researcher's skills in graphic design, spatial sound, architecture, exhibition design, and character illustration. This structure will allow individuals to observe, determine, and make comparisons between a healthy colony and one that is fragile and dying.

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Kourtellis, Nicolas. "On the Design of Socially-Aware Distributed Systems." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4107.

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Social media services and applications enable billions of users to share an unprecedented amount of social information, which is further augmented by location and collocation information from mobile phones, and can be aggregated to provide an accurate digital representation of the social world. This dissertation argues that extracted social knowledge from this wealth of information can be embedded in the design of novel distributed, socially-aware applications and services, consequently improving system response time, availability and resilience to attacks, and reducing system overhead. To support this thesis, two research avenues are explored. First, this dissertation presents Prometheus, a socially-aware peer-to-peer service that collects social information from multiple sources, maintains it in a decentralized fashion on user-contributed nodes, and exposes it to applications through an interface that implements non-trivial social inferences. The system's socially-aware design leads to multiple system improvements: 1) it increases service availability by allowing users to manage their social information via socially-trusted peers, 2) it improves social inference performance and reduces message overhead by exploiting naturally-formed social groups, and 3) it reduces the opportunity of attackers to influence application requests. These performance improvements are assessed via simulations and a prototype deployment on a local cluster and on a worldwide testbed (PlanetLab) under emulated application workloads. Second, this dissertation defines the projection graph, the result of decentralizing a social graph onto a peer-to-peer system such as Prometheus, and studies the system's network properties and how they can be used to design more efficient socially-aware distributed applications and services. In particular: 1) it analytically formulates the relation between centrality metrics such as degree centrality, node betweenness centrality, and edge betweenness centrality in the social graph and in the emerging projection graph, 2) it experimentally demonstrates on real networks that for small groups of users mapped on peers, there is high association of social and projection graph properties, 3) it shows how these properties of the (dynamic) projection graph can be accurately inferred from the properties of the (slower changing) social graph, and 4) it demonstrates with two search application scenarios the usability of the projection graph in designing social search applications and unstructured P2P overlays. These research results lead to the formulation of lessons applicable to the design of socially-aware applications and distributed systems for improved application performance such as social search, data dissemination, data placement and caching, as well as for reduced system communication overhead and increased system resilience to attacks.

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Kendra, Matej. "Rozhraní pro hry s dataprojektorem a Leap Motion." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2016. http://www.nusl.cz/ntk/nusl-255471.

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This thesis describes various game interfaces for human and gradually there are shown more modern and common available interfaces. Work closely describes how you can play games on a regular projector and sensors for gestures detection - Kinect and Leap Motion. This work focus on evaluation of aspects of table-game design with these components and also on display view calibration between projector and Leap Motion. Part of the project is devoted to describing the board game Catan, of which rules are taken to write down specification and options of player. According to this knowledge is then described the design of the play-set and the design of several interfaces of the game. Implementation is briefly described and final chapters covers forms of the testing methods of interfaces and testing evaluation from user perspective.

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Marquer, Mathieu. "Étude comparative du comportement tribologique de revêtements frottant à grande vitesse sur un alliage de titane : CoCrAlYSiBN, CuNiIn, et MAO." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0402.

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Dans le cadre du développement d'un nouveau type de revêtement anodique pour le Ti6Al4V, l'application au pied d'aube de turboréacteur est étudiée. En cas d'impact d'un corps étranger sur l'aube, du frottement sévère peut avoir lieu entre le pied d'aube et le disque de rotor, tous deux en Ti6Al4V. Ces travaux visent à évaluer, en conditions sévères de glissement, le comportement de revêtements de référence (CoCrAlYSiBN et CuNiIn), déjà employés au niveau de ce contact, ainsi que du nouveau revêtement (MAO). Pour cela, un tribomètre spécifique a été conçu et adapté sur un banc balistique, permettant de mesurer les efforts de frottement pendant l'interaction et en déduire le coefficient de frottement moyen. L'évolution du volume usé et de la microstructure en fonction de la vitesse de glissement et de la pression de contact, a été analysée. Ceci a permis de proposer des scénarios de comportement tribologique pour les revêtements. Il a été possible de conclure de ces résultats que le revêtement MAO étudié n'est pas applicable au contact pied d'aube/disque de rotor en conditions sévères. Un modèle thermique intégrant l'abaissement du coefficient de frottement causé par le troisième corps a été développé mais nécessite encore quelques évolutions avant de pouvoir lier les conditions de glissement aux altérations microstructurales engendrées. La comparaison des propriétés thermiques aux résultats précédents a permis de proposer un mécanisme d'action, en fonction de ses propriétés, du revêtement sur les altérations thermiques et mécaniques de la pièce non-revêtue. Ces travaux de thèse ont étés réalisés dans le cadre du Projet MAO de l'IRT M2P et sont le fruit d'une collaboration entre l'IRT M2P, le LEM3, et Safran Aircraft Engines
As part of the development of a new type of anodic coating for Ti6Al4V, its application to jet engine blades roots is studied. In the event of an impact of a foreign object on the blade, severe friction can occur between the blade root and the rotor disc, both in Ti6Al4V. This work aims to evaluate, under severe sliding conditions, the behaviour of reference coatings (CoCrAlYSiBN and CuNiIn), already applied to this contact, as well as the new coating (MAO). For this purpose, a specific tribometer was designed and adapted on a ballistic test bench, allowing to measure the friction forces during the interaction and to deduce the average friction coefficient. The wear volume and microstructure evolution was sliding speed and contact pressure, was analyzed. This led to propose tribological behaviour scenarios for coatings. From these results, it was possible to conclude that the studied MAO coating is not applicable to the blade foot/rotor disc contact under severe conditions. A thermal model incorporating the reduction of the friction coefficient caused by the third body was developed but still requires some evolutions before the sliding conditions can be linked to the microstructural alterations generated. The comparison of the thermal properties with the previous results has made it possible to propose a mechanism of action, according to its properties, of the coating on the thermal and mechanical alterations of the uncoated part. This thesis work was carried out as part of the MAO Project of IRT M2P and is the result of a collaboration between IRT M2P, LEM3, and Safran Aircraft Engines

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Subrin, Kévin. "Optimisation du comportement de cellules robotiques par gestion des redondances : application à la découpe de viande et à l’Usinage Grande Vitesse." Thesis, Clermont-Ferrand 2, 2013. http://www.theses.fr/2013CLF22417/document.

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Les robots industriels ont évolué fondamentalement ces dernières années pour répondre aux exigences industrielles de machines et mécanismes toujours plus performants. Ceci se traduit aujourd’hui par de nouveaux robots anthropomorphes plus adaptés laissant entrevoir la réalisation de tâches plus complexes comme la découpe d’objets déformables telle que la découpe de viande ou soumis à de fortes sollicitations comme l’usinage. L’étude du comportement des robots anthropomorphes, à structures parallèles ou hybrides montre une anisotropie aussi bien cinématique, que dynamique, impactant la précision attendue. Ces travaux de thèse étudient l’intégration des redondances cinématiques qui permettent de pallier en partie ce problème en positionnant au mieux la tâche à réaliser dans un espace de travail compatible avec les capacités attendues. Ces travaux ont suivi une démarche en trois étapes : la modélisation analytique de cellules robotiques par équivalent sériel basée sur la méthode TCS, la formalisation des contraintes des processus de découpe de viande et d’usinage et une résolution par optimisation multicritère. Une première originalité de ces travaux réside en le développement d’un modèle à 6 degrés de liberté permettant d’analyser les gestes de l’opérateur qui optimise naturellement le comportement de son bras pour garantir la tâche qu’il réalise. La seconde originalité concerne le placement optimisé des redondances structurales (cellules à 9 ddls) où les paramètres de positionnement sont incorporés comme des variables pilotables (cellule à 11 ddls). Ainsi, ces travaux de thèse apportent des contributions à : - la définition de critères adaptés à la réalisation de tâches complexes et sollicitantes pour la gestion des redondances cinématiques ; - l’identification du comportement des structures sous sollicitations par moyen métrologique (Laser tracker) et l’auto-adaptation des trajectoires par l’utilisation d’une commande en effort industrielle ; - l’optimisation du comportement permettant l’amélioration de la qualité de réalisation des différents processus de coupe (découpe de viande et usinage)
Industrial robots have evolved fundamentally in recent years to reach the industrial requirements. We now find more suitable anthropomorphic robots leading to the realization of more complex tasks like deformable objects cutting such as meat cutting or constrained to high stresses as machining. The behavior study of anthropomorphic robots, parallel or hybrid one highlights a kinematic and dynamic anisotropy, which impacts the expected accuracy. This thesis studied the integration of the kinematic redundancy that can partially overcome this problem by well setting the task to achieve it in a space compatible with the expected capacity. This work followed a three-step approach: analytical modeling of robotic cells by serial equivalent based on the TCS method, formalizing the constraints of meat cutting process and machining process and a multicriteria optimization.The first originality of this work focuses on the development of a 6 DoFs model to analyze the operator actions who naturally optimizes his arm behavior to ensure the task it performs. The second originality concerns the optimized placement of structural redundancy (9 DoFs robotic cell) where positioning parameters are incorporated as controllable variables (11 DoFs robotic cell). Thus, the thesis makes contributions to : - the definition of criteria adapted to the realization of complex and under high stress task for the management of the kinematic redundancy; - the structural behavior identification, under stress, by metrology tools (Laser tracker ) and the self- adaptation paths by using an industrial force control; - the behavior optimization to improve the cutting process quality (meat cutting and machining)

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Franke, Ingmar, and Martin Zavesky. "Perspektivkontrast Kp - Zur Relevanz von Proportion und Ausrichtung für computergrafische Visualisierungen." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-237679.

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Ausgehend von einer Analyse computergrafischer Visualisierungen wird in diesem Beitrag eine formale Beschreibung grundlegend gestalterischer Herausforderung bei der wahrnehmungskonformen Darstellung von räumlichen Szenen vorgenommen. Anschließend werden erste algorithmische Umsetzungen zur perspektivischen Optimierung vorgestellt. Anwendungsbezüge werden an Hand von Fallbeispielen verdeutlicht. Ingmar S. Franke und Martin Zavesky, Technische Universität Dresden anlässlich beyond rendering, 8. Tagung der Deutschen Gesellschaft für Geometrie und Grafik, Berlin -16. bis 18. Mai 2012

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Sanejouand, Yves-Henri. "Etude théorique des mouvements internes de grande amplitude de la décaalanine et du fragment C-terminal de la protéine ribosomale L7/L12." Phd thesis, Université Paris Sud - Paris XI, 1990. http://tel.archives-ouvertes.fr/tel-00266537.

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La plasticité des protéines joue un rôle majeur dans l'expression de leur fonction. Or, les déplacements amples de groupes d'atomes à l'intérieur des protéines sont souvent difficiles à étudier expérimentalement. Par exemple, on ne sait dire ce qui distingue entre eux les sous-états conformationels mis en évidence par Frauenfelder. Pour préciser l'interprétation de ce type de donnée expérimentale, les méthodes de dynamique moléculaire seraient idéales si le calcul de trajectoires d'environ 100 nsec était possible. La méthode de dynamique moléculaire confinée que nous avons développée repose sur la description que donne la théorie des modes normaux des mouvements amples et lents d'une protéine. Elle permet de calculer des trajectoires beaucoup plus longues que d'ordinaire. Cependant, un comportement anharmonique méconnu perturbe le déroulement des trajectoires calculées ainsi, et ce même dans le cas d'un polypeptide ne subissant aucun changement de conformation (la décaalanine). Pour préciser les voies de développement ultérieur de notre méthode, la dernière partie de cette thèse est consacrée à l'étude d'un mouvement ample et lent d'une petite protéine, le fragment C-terminal de la protéine ribosomale L7/L12.

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Dissertations / Theses on the topic 'Projection de graphe'

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