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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.

Riemannian Manifold Trust-Region Methods with Applications to Eigenproblems

Unknown Date (has links)
This thesis presents and evaluates a generic algorithm for incrementally computing the dominant singular subspaces of a matrix. The relationship between the generality of the results and the necessary computation is explored, and it is shown that more efficient computation can be obtained by relaxing the algebraic constraints on the factoriation. The performance of this method, both numerical and computational, is discussed in terms of the algorithmic parameters, such as block size and acceptance threshhold. Bounds on the error are presented along with a posteriori approximations of these bounds. Finally, a group of methods are proposed which iteratively improve the accuracy of computed results and the quality of the bounds. / A Dissertation submitted to the School of Computational Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Degree Awarded: Summer Semester, 2008. / Date of Defense: May 22, 2008. / Riemannian Manifolds, Iterative Methods, Convergence Theory, Numerical Optimization, Eigenvalue Problems, Trust-Region Methods, Riemannian Optimization, Optimization on Manifolds / Includes bibliographical references. / Kyle Gallivan, Professor Co-Directing Dissertation; Pierre-Antoine Absil, Professor Co-Directing Dissertation; Anjaneyulu Krothapalli, Outside Committee Member; Gordon Erlebacher, Committee Member; Anuj Srivastava, Committee Member; Yousuff Hussaini, Committee Member.

Spherical Centroidal Voronoi Tessellations: Point Generation and Density Functions via Images

Unknown Date (has links)
This thesis presents and investigates ideas for improvement of the creation of quality centroidal voronoi tessellations on the sphere (SCVT). First, we discuss the theory of CVTs in general, and specifically on the sphere. Subsequently we consider the iterative processes, such as Lloyd's algorithm, which are used to construct them. Following this, we examine and introduce different schemes for creating their input values, known as generators, and compare the effects of these different initial points with respect to their ability to converge and the amount of work required to meet a given tolerance goal. In addition, we describe a method for density functions via images so that we can shape generator density in an intuitive manner and then implement this method with examples to demonstrate it's efficacy. / A Thesis submitted to the School of Computational Science in partial fulfillment of the requirements for the degree of Master of Science. / Degree Awarded: Summer Semester, 2008. / Date of Defense: June 18, 2008. / Cvt Scvt Centroidal Voronoi Tessellations Sphere D / Includes bibliographical references. / Max Gunzburger, Professor Co-Directing Thesis; Janet Peterson, Professor Co-Directing Thesis; Gordon Erlebacher, Committee Member.

Quasirandom Optimization

Unknown Date (has links)
In this work we apply quasirandom sequences to develop a derivative-free algorithm for approximating the global maximum of a given function. This work is based on previous results which used a single type of quasirandom sequence in a Brute Force approach and in an approach called Localization of Search. In this work we present several methods for computing quasirandom sequences as well as measures for determining their properties. We discuss the shortcomings of the Brute Force and Localization of Search methods and then present modifications which address these issues which culminate in a new algorithm which we call Modified Localization of Search. Our algorithm is applied to a test suite of problems and the results are discussed. Finally we present some comments on code development for our algorithm. / A Thesis submitted to the Department of Scientific Computing in partial fulfillment of the requirements for the degree of Master of Science. / Degree Awarded: Summer Semester, 2011. / Date of Defense: April 25, 2011. / Search, Sequences, Numerical, Quasirandom, Optimization / Includes bibliographical references. / Janet Peterson, Professor Directing Thesis; Max Gunzburger, Committee Member; Gordon Erlebacher, Committee Member; John Burkardt, Committee Member.

An algorithm for the numerical calculation of the degree of a mapping /

Stynes, Martin J. January 1977 (has links)
Thesis (Ph. D.)--Oregon State University, 1977. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Parallel, navier-stokes computation of the flowfield of a hovering helicopter rotor

Geçgel, Murat. January 2003 (has links) (PDF)
Thesis (M.S.)--Middle East Technical University, 2003. / Keywords: Rotary wing, thin₆layer Navier₆Stokes equations, finite volume method, structured grid, parallel processing, MPI, blade₆vortex interactions, flat plate.

Isogeometric analysis and numerical modeling of the fine scales within the variational multiscale method

Cottrell, John Austin, 1980- 28 August 2008 (has links)
This work discusses isogeometric analysis as a promising alternative to standard finite element analysis. Isogeometric analysis has emerged from the idea that the act of modeling a geometry exactly at the coarsest levels of discretization greatly simplifies the refinement process by obviating the need for a link to an external representation of that geometry. The NURBS based implementation of the method is described in detail with particular emphasis given to the numerous refinement possibilities, including the use of functions of higher-continuity and a new technique for local refinement. Examples are shown that highlight each of the major features of the technology: geometric flexibility, functions of high continuity, and local refinement. New numerical approaches are introduced for modeling the fine scales within the variational multiscale method. First, a general framework is presented for seeking solutions to differential equations in a way that approximates optimality in certain norms. More importantly, it makes possible for the first time the approximation of the fine-scale Green's functions arising in the formulation, leading to a better understanding of machinery of the variational multiscale method and opening new avenues for research in the field. Second, a simplified version of the approach, dubbed the "parameter-free variational multiscale method," is proposed that constitutes an efficient stabilized method, grounded in the variational multiscale framework, that is free of the ad hoc stabilization parameter selection that has plagued classical stabilized methods. Examples demonstrate the efficacy of the method for both linear and nonlinear equations. / text

Variations on Newton's method in finite dimensional spaces

Horton, Robert Lind 12 1900 (has links)
No description available.

Two dimensional finite volume weighted essentially non-oscillatory euler schemes with uniform and non-uniform grid coefficients

Elfarra, Monier Ali. Supervisor : Akmandor, İ. Sinan. January 2005 (has links) (PDF)
Thesis (M.S.) -- Middle East Technical University, 2005. / Keywords: weighted essentially non-oscillatory, uniform and non-uniform grid coefficients, Gaussian quadrature

Ueber Tchebychefsche Annaherungsmethoden

Kirchberger, Paul, Chebyshev, P. L. (Pafnutiǐ Lv́ovich), January 1902 (has links)
Thesis (Ph. D.)--Georg-Augustus-Universitat, 1902.

Analysis and implementation of a positivity preserving numerical method for an HIV model/

Wyngaardt, Jo-Anne. Unknown Date (has links) (PDF)
Thesis (M. Sc.) -- University of the Western Cape. / Includes bibliographic references (leaves 80-89).

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