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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Trilateration adjustment and network design : a critical compendium of methods and techniques proposed for the adjustment and design of trilaterated networks /

Hanigan, Francis Lawrence January 1970 (has links)
No description available.
22

Independent model aerial triangulation refinements and error studies /

Philip, Aldwyn Thomas January 1973 (has links)
No description available.
23

Delaunay-admissiblité en dimensions 2 et 3

Pébay, Philippe 14 June 2000 (has links) (PDF)
La méthode des éléments finis, largement utilisée en analyse numérique, requiert que le domaine considéré soit préalablement maillé, c'est-à-dire partitionné en un ensemble de polytopes généralement, mais pas nécessairement, simpliciaux. Parmi les méthodes permettant la génération de tels maillages, la triangulation de Delaunay présente le double intérêt d'avoir un support théorique fondant la robustesse des algorithmes, ainsi que de produire des éléments de qualité, conditionnant fortement la précision des calculs ultérieurs. Elle présente cependant l'inconvénient de ne pas être à même de prendre en compte des considérations topologiques, lui interdisant de facto d'être utilisée en l'état pour produire des maillages. Un certain nombre de méthodes ont été proposées pour tenter de résoudre ce problème, mais aucune ne constitue une solution générale. Par ailleurs, les maillages qu'elles restituent ne possèdent plus la propriété de Delaunay. Ce travail étudie les conditions dans lesquelles une contrainte, en dimensions 2 et 3, apparaîtra dans toute triangulation de Delaunay du nuage de points auquel elle est associée. En particulier, des théorèmes de Delaunay-admissibilité a priori sont établis. A l'aide de ces résultats, des algorithmes de redéfinition de contraintes sont proposés, de telle sorte que les nouvelles discrétisations, recouvrements des anciennes, soient construites par toute triangulation de Delaunay. Ainsi, les contraintes étant satisfaites automatiquement, aucune opération de forçage a posteriori n'est requise, et les maillages produits sont de Delaunay. En raison du coût prohibitif de la convergence en dimension 3, deux algorithmes efficaces sont proposés, sans qu'aucune conjecture sur leur convergence ne soit formulée. A titre d'application de la méthode en dimension 3, l'interfaçage avec un mailleur de Delaunay contraint existant est étudié. En particulier, la pertinence de la méthode est illustrée grâce au déblocage d'une configuration que ce mailleur ne parvient pas à résoudre. D'autres applications possibles, ainsi que les développements en cours sont également évoqués.
24

Unistructuralité des algèbres amassées de type Ã

Bazier-Matte, Véronique January 2016 (has links)
Assem, Schiffler et Shramchenko ont émis comme conjecture que toute algèbre amassée est unistructurelle, c'est-à-dire que l'ensemble des variables amassées détermine uniquement la structure d'algèbre amassée. En d'autres mots, il existe une unique décomposition de l'ensemble des variables amassées en amas. Cette conjecture est prouvée dans le cas des algèbres amassées de type Dynkin ou de rang 2. Le but de ce mémoire de la prouver également dans le cas des algèbres amassées de type Ã. Nous utilisons les triangulations de couronnes et l'indépendance algébrique des amas pour prouver l'unistructuralité des algèbres provenant de couronnes, donc de type Ã. Nous prouvons également la conjecture des automorphismes pour les algèbres de type à comme conséquence immédiate.
25

CLOSURE AND ADJUSTMENT OF CONTROL SURVEY NETS

Hillman, Harry Fred, 1929-, Hillman, Harry Fred, 1929- January 1976 (has links)
No description available.
26

The application of geomorphological triangular databases in geotechnical engineering /

Brimicombe, A. J. January 1900 (has links)
Thesis--M. Phil., University of Hong Kong, 1986.
27

Protocol design for dynamic Delaunay triangulation

Lee, Dong-young, 1973- 28 September 2012 (has links)
Delaunay triangulation (DT) is a useful geometric structure for net-working applications. We define a distributed DT and present a necessary and sufficient condition for a distributed DT to be correct. This condition is used as a guide for protocol design. We investigate the design of join, leave, failure, and maintenance protocols for a set of nodes in d-dimension (d > 1) to construct and maintain a distributed DT in a dynamic environment. The join, leave, and failure protocols in the suite are proved to be correct for a single join, leave, and failure, respectively. For a system under churn, it is impossible to maintain a correct distributed DT continually. We define an accuracy metric such that accuracy is 100% if and only if the distributed DT is correct. The suite also includes a maintenance protocol designed to recover from incorrect system states and to improve accuracy. In designing the protocols, we make use of two novel observations to substantially improve protocol efficiency. First, in the neighbor discovery process of a node, many replies to the node's queries contain redundant information. Second, the use of a new failure protocol that employs a proactive approach to recovery is better than the reactive approaches used in prior work. Experimental results show that our new suite of protocols maintains high accuracy for systems under churn and each system converges to 100% accuracy after churning stopped. They are much more efficient than protocols in prior work. To illustrate the usefulness of distributed DT for networking applications, we also present several application protocols including greedy routing, finding a closest existing node, clustering, broadcast, and geocast. Bose and Morin proved in 2004 that greedy routing always succeeds to find the destination node on a DT. We prove that greedy routing always finds a closest existing node to a given point, and our broadcast and geocast protocols always deliver a message to every target node. Our broadcast and geocast protocols are also efficient in the sense that very few target nodes receive duplicate messages, and non-target nodes receive no message. Performance characteristics of greedy routing, broadcast, and geocast are investigated using simulation experiments. We also investigate the impact of inaccurate coordinates on the performance of greedy routing, broadcast, and geocast. / text
28

Triangulation of a Hierarchical Hexagon Mesh

Guenette, Matthew 21 January 2009 (has links)
Recently, a multi-resolution, hierarchical version of the hexagon mesh was introduced. In order for computers to display this mesh of hexagons, it must be triangulated. This thesis describes an algorithm to triangulate the multi-resolution, hierarchical hexagon mesh. The triangulation provides good triangle strips, which result in efficient rendering of the hexagon mesh, and well-proportioned triangles, which avoid rendering artifacts. This algorithm was designed for the rendering of hexagon meshes on the globe, though it currently does not support the pentagons of the truncated icosahedron. / Thesis (Master, Computing) -- Queen's University, 2009-01-21 12:11:02.532
29

Adaptive triangulations

Maizlish, Oleksandr 17 April 2014 (has links)
In this dissertation, we consider the problem of piecewise polynomial approximation of functions over sets of triangulations. Recently developed adaptive methods, where the hierarchy of triangulations is not fixed in advance and depends on the local properties of the function, have received considerable attention. The quick development of these adaptive methods has been due to the discovery of the wavelet transform in the 1960's, probably the best tool for image coding. Since the mid 80's, there have been many attempts to design `Second Generation' adaptive techniques that particularly take into account the geometry of edge singularities of an image. But it turned out that almost none of the proposed `Second Generation' approaches are competitive with wavelet coding. Nevertheless, there are instances that show deficiencies in the wavelet algorithms. The method suggested in this dissertation incorporates the geometric properties of convex sets in the construction of adaptive triangulations of an image. The proposed algorithm provides a nearly optimal order of approximation for cartoon images of convex sets, and is based on the idea that the location of the centroid of certain types of domains provides a sufficient amount of information to construct a 'good' approximation of the boundaries of those domains. Along with the theoretical analysis of the algorithm, a Matlab code has been developed and implemented on some simple cartoon images.
30

Examining laser triangulation system performance using a software simulation

Collier, Jeff. January 1998 (has links)
Thesis (M.S.)--Ohio University, June, 1998. / Title from PDF t.p.

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