Global ETD Search

1	Development of a general three-dimensional model for on-line control of modern rolling processes Stubbs, Richard Edward January 1996 (has links) No description available. 670
2	On Visualizing Branched Surface: an Angle/Area Preserving Approach Zhu, Lei 12 September 2004 (has links) The techniques of surface deformation and mapping are useful tools for the visualization of medical surfaces, especially for highly undulated or branched surfaces. In this thesis, two algorithms are presented for flattened visualizations of multi-branched medical surfaces, such as vessels. The first algorithm is an angle preserving approach, which is based on conformal analysis. The mapping function is obtained by minimizing two Dirichlet functionals. On a triangulated representation of vessel surfaces, this algorithm can be implemented efficiently using a finite element method. The second algorithm adjusts the result from conformal mapping to produce a flattened representation of the original surface while preserving areas. It employs the theory of optimal mass transport via a gradient descent approach. A new class of image morphing algorithms is also considered based on the theory of optimal mass transport. The mass moving energy functional is revised by adding an intensity penalizing term, in order to reduce the undesired "fading" effects. It is a parameter free approach. This technique has been applied on several natural and medical images to generate in-between image sequences. Algorithms Area-preserving flattening Conformal mapping Image interpolation Interpolation Monge-Kantorovich problem Surface flattening Surfaces (Technology) Analysis Surfaces (Technology) Analysis Free radicals (Chemistry) Organosulfur compounds Oxidation Algorithms Conformal mapping Interpolation Chemical kinetics Dimethyl sulfide Oxidation
3	A variational approach for viewpoint-based visibility maximization Rocha, Kelvin Raymond 19 May 2008 (has links) We present a variational method for unfolding of the cortex based on a user-chosen point of view as an alternative to more traditional global flattening methods, which incur more distortion around the region of interest. Our approach involves three novel contributions. The first is an energy function and its corresponding gradient flow to measure the average visibility of a region of interest of a surface from a given viewpoint. The second is an additional energy function and flow designed to preserve the 3D topology of the evolving surface. This latter contribution receives significant focus in this thesis as it is crucial to obtain the desired unfolding effect derived from the first energy functional and flow. Without it, the resulting topology changes render the unconstrained evolution uninteresting for the purpose of cortical visualization, exploration, and inspection. The third is a method that dramatically improves the computational speed of the 3D topology-preservation approach by creating a tree structure of the triangulated surface and using a recursion technique. Cortex Partial differential equations Annulal tissues Visibility Visibility maximization Topology preservation Area preservation Length preservation Calculus of variation Partial differential equations Gridding Harmonic function Harmonic embedding Correspondence trajectories Thickness Surface unfolding Surface flattening Eulerian Lagrangian Three-dimensional imaging Algorithms Three-dimensional imaging in medicine

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