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Applied Mathematics Commons™

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2005

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Articles 121 - 129 of 129

Full-Text Articles in Applied Mathematics

Wavelet Sets With And Without Groups And Multiresolution Analysis, Mihaela Dobrescu Jan 2005

Wavelet Sets With And Without Groups And Multiresolution Analysis, Mihaela Dobrescu

LSU Doctoral Dissertations

In this dissertation we study a special kind of wavelets, the so-called minimally supported frequency wavelets and the associated wavelet sets. Most of the examples of wavelet sets are for dilation sets which are groups. In this work we construct wavelet sets for which the dilation set, D, is of the form D=MN, where the product is direct, and so D is not necessarily group. In the second part of this dissertation we construct multiwavelets associated with MRA's and we generalize the rotations in the dilation sets to Coxeter groups.


Impulsive Systems, Stanislav Zabic Jan 2005

Impulsive Systems, Stanislav Zabic

LSU Doctoral Dissertations

Impulsive systems arise when dynamics produce discontinuous trajectories. Discontinuties occur when movements of states happen over a small interval that resembles a point-mass measure. We adopt the formalism in which the controlled dynamic inclusion is the sum of a slow and a fast time velocities belonging to two distinct vector fields. Fast time velocities are controlled by a vector valued Borel measure. The trajectory of impulsive systems is a function of bounded variation. To give a definition of solutions, a notion of graph completion of the control measure is needed. In the nonimpulsive case, a solution can be defined as …


Zeta Functions Of Finite Graphs, Debra Czarneski Jan 2005

Zeta Functions Of Finite Graphs, Debra Czarneski

LSU Doctoral Dissertations

Ihara introduced the zeta function of a finite graph in 1966 in the context of p-adic matrix groups. The idea was generalized to all finite graphs in 1989 by Hashimoto. We will introduce the zeta function from both perspectives and show the equivalence of both forms. We will discuss several properties of finite graphs that are determined by the zeta function and show by counterexample several properties of finite graphs that are not determined by the zeta function. We will also discuss the relationship between the zeta function of a finite graph and the spectrum of a finite graph.


Laguerre Functions Associated To Euclidean Jordan Algebras, Michael Aristidou Jan 2005

Laguerre Functions Associated To Euclidean Jordan Algebras, Michael Aristidou

LSU Doctoral Dissertations

Certain differential recursion relations for the Laguerre functions, defined on a symmetric cone Ω, can be derived from the representations of a specific Lie algebra on L2(Ω,dμv). This Lie algebra is the corresponding Lie algebra of the Lie group G that acts on the tube domain T(Ω)=Ω+iV, where V is the associated Euclidean Jordan algebra of Ω. The representations involved are the highest weight representations of G on L2(Ω,dμv). To obtain these representations, we start from the highest weight representations of G on Hv(T(Ω)), the Hilbert space of holomorphic functions …


Dissipative Lipschitz Dynamics, Vinicio Rafael Rios Jan 2005

Dissipative Lipschitz Dynamics, Vinicio Rafael Rios

LSU Doctoral Dissertations

In this dissertation we study two related important issues in control theory: invariance of dynamical systems and Hamilton-Jacobi theory associated with optimal control theory. Given a control system modelled as a differential inclusion, we provide necessary and sufficient conditions for the strong invariance property of the system when the dynamic satisfies a dissipative Lipschitz condition. We show that when the dynamic is almost upper semicontinuous and satisfies the dissipative Lipschitz property, these conditions can be expressed in terms of approximate Hamilton-Jacobi inequalities, which subsumes the classic infinitesimal characterization of strongly invariant systems given under the Lipschitz assumtion. In the important …


Dynamical Systems With Time Delay, Norma Ortiz Jan 2005

Dynamical Systems With Time Delay, Norma Ortiz

LSU Doctoral Dissertations

In this dissertation, we study necessary conditions and weak invariance properties of dynamical systems with time delay. A number of results have been obtained recently that refine necessary conditions of optimal solutions for nonsmooth dynamical systems without time delay. In this dissertation, we examine the extension of some of these results to problems with time delay. In particular, we study the generalized problem of Bolza with the addition of delay in the state and velocity variables and refer to this problem as the Neutral Problem of Bolza. We consider the relationship between the generalized problem of Bolza with time delay …


Error Estimates For Stabilized Approximation Methods For Semigroups, Sarah Campbell Mcallister Jan 2005

Error Estimates For Stabilized Approximation Methods For Semigroups, Sarah Campbell Mcallister

LSU Doctoral Dissertations

In this work we analyze error estimates for rational approximation methods, and their stabilizations, for strongly continuous semigroups. Chapter 1 consists of a brief survey of time discretization methods for semigroups. In Chapter 2, we demonstrate a new method for obtaining convergent approximations in the absence of stability for strongly continuous semigroups with arbitrary initial data. In Section 2.2, we state the stabilization result in more general form and show that this method can be used to improve known error estimates by a magnitude of up to one half for smooth initial data. In Section 2.3, we give concrete examples …


Quasicontinuous Derivatives And Viscosity Functions, Rodica Cazacu Jan 2005

Quasicontinuous Derivatives And Viscosity Functions, Rodica Cazacu

LSU Doctoral Dissertations

In this work we demonstrate how the continuous domain theory can be applied to the theory of nonlinear optimization, particularly to the theory of viscosity solutions. We consider finding the viscosity solution for the Hamilton-Jacobi equation H(x, y) = g(x), with continuous hamiltonian, but with possibly discontinuous right-hand side. We begin by finding a new function space Q(X,L), the space of equivalence classes of quasicontinuous functions from a locally compact set X to a bicontinuous lattice L and we will define on Q(X,L) the qo-topology, which is a variant of classical order topology defined on complete lattices. On this …


Multiscale Strain Analysis, Timothy Donald Breitzman Jan 2005

Multiscale Strain Analysis, Timothy Donald Breitzman

LSU Doctoral Dissertations

The mathematical homogenization and corrector theory relevant to prestressed heterogeneous materials in the linear-elastic regime is discussed. A suitable corrector theory is derived to reconstruct the local strain field inside the composite. Based on this theory, we develop an inexpensive numerical method for multi scale strain analysis within a prestressed heterogeneous material. The theory also provides a characterization of the macroscopic strength domain. The strength domain places constraints on the homogenized strain field which guarantee that the actual strain in the heterogeneous material lies inside the strength domain of each material participating in the structure.