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Articles 6421 - 6450 of 7997

Full-Text Articles in Physical Sciences and Mathematics

Surrogate Strategies For Computationally Expensive Optimization Problems With Cpu-Time Correlated Functions, Raymond Magallanez Jr. Mar 2007

Surrogate Strategies For Computationally Expensive Optimization Problems With Cpu-Time Correlated Functions, Raymond Magallanez Jr.

Theses and Dissertations

This research focuses on numerically solving a class of computationally expensive optimization problems that possesses a unique characteristic: as the optimal solution is approached, the computational time required to compute an objective function value decreases. This is motivated by an application in which each objective function evaluation requires both a numerical fluid dynamics simulation and an image registration and comparison process. The goal is to find the parameters of a predetermined image by comparing the flow dynamics from the numerical simulation and the predetermined image through the image comparison process. The generalized pattern search and mesh adaptive direct search methods …

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Bifurcations Of Plane Wave (Cw) Solutions In The Complex Cubic-Quintic Ginzburg-Landau Equation, S.C. Mancas, S. Roy Choudhury Mar 2007

Bifurcations Of Plane Wave (Cw) Solutions In The Complex Cubic-Quintic Ginzburg-Landau Equation, S.C. Mancas, S. Roy Choudhury

Publications

Singularity Theory is used to comprehensively investigate the bifurcations of the steady-states of the traveling wave ODEs of the cubic-quintic Ginzburg-Landau equa- tion (CGLE). These correspond to plane waves of the PDE. In addition to the most general situation, we also derive the degeneracy conditions on the eight coefficients of the CGLE under which the equation for the steady states assumes each of the possible quartic (the quartic fold and an unnamed form), cubic (the pitchfork and the winged cusp), and quadratic (four possible cases) normal forms for singularities of codimension up to three. Since the actual governing equations are …

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The Complex Cubi-Quintic Ginzburg-Landau Equation: Hopf Bifurcations Yielding Traveling Waves, S.C. Mnacas, S. Roy Choudhury Mar 2007

The Complex Cubi-Quintic Ginzburg-Landau Equation: Hopf Bifurcations Yielding Traveling Waves, S.C. Mnacas, S. Roy Choudhury

Publications

In this paper we use a traveling wave reduction or a so{called spatial approxima- tion to comprehensively investigate the periodic solutions of the complex cubic{quintic Ginzburg{Landau equation. The primary tools used here are Hopf bifurcation theory and perturbation theory. Explicit results are obtained for the post{bifurcation periodic orbits and their stability. Generalized and degenerate Hopf bifurcations are also brie y considered to track the emergence of global structure such as homoclinic orbits.

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Classifying Failing States, Nathan E. Nysether Mar 2007

Classifying Failing States, Nathan E. Nysether

Theses and Dissertations

The US is heavily involved in the first major war of the 21st Century -- The Global War on Terror (GWOT). As with any militant group, the foundation of the enemy's force is their people. There are two primary strategies for defeating the terrorists and achieving victory in the GWOT. First, we must root out terrorists where they live, train, plan, and recruit and attack them militarily. Second, we must suffocate them by cutting off the supply of new soldiers willing to choose aggression or even death over their current life. This thesis helps to achieve these objectives by applying …

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Variational Principles For Set-Valued Mappings With Applications To Multiobjective Optimization, Truong Q. Bao, Boris S. Mordukhovich Feb 2007

Variational Principles For Set-Valued Mappings With Applications To Multiobjective Optimization, Truong Q. Bao, Boris S. Mordukhovich

Mathematics Research Reports

This paper primarily concerns the study of general classes of constrained multiobjective optimization problems (including those described via set-valued and vector-valued cost mappings) from the viewpoint of modern variational analysis and generalized differentiation. To proceed, we first establish two variational principles for set-valued mappings, which~being certainly of independent interest are mainly motivated by applications to multiobjective optimization problems considered in this paper. The first variational principle is a set-valued counterpart of the seminal derivative-free Ekeland variational principle, while the second one is a set-valued extension of the subdifferential principle by Mordukhovich and Wang formulated via an appropriate subdifferential notion for …

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Step-Up Simultaneous Tests For Identifying Active Effects In Orthogonal Saturated Designs, Samuel S. Wu, Weizhen Wang Feb 2007

Step-Up Simultaneous Tests For Identifying Active Effects In Orthogonal Saturated Designs, Samuel S. Wu, Weizhen Wang

Mathematics and Statistics Faculty Publications

A sequence of null hypotheses regarding the number of negligible effects (zero effects) in orthogonal saturated designs is formulated. Two step-up simultaneous testing procedures are proposed to identify active effects (nonzero effects) under the commonly used assumption of effect sparsity. It is shown that each procedure controls the experimentwise error rate at a given alpha level in the strong sense.

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Approximations Of Continuous Newton's Method: An Extension Of Cayley's Problem, Jon T. Jacobsen, Owen Lewis '05, Bradley Tennis '06 Feb 2007

Approximations Of Continuous Newton's Method: An Extension Of Cayley's Problem, Jon T. Jacobsen, Owen Lewis '05, Bradley Tennis '06

All HMC Faculty Publications and Research

Continuous Newton's Method refers to a certain dynamical system whose associated flow generically tends to the roots of a given polynomial. An Euler approximation of this system, with step size h=1, yields the discrete Newton's method algorithm for finding roots. In this note we contrast Euler approximations with several different approximations of the continuous ODE system and, using computer experiments, consider their impact on the associated fractal basin boundaries of the roots

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Hartman-Grobman Theorems Along Hyperbolic Stationary Trajectories, Edson A. Coayla-Teran, Salah-Eldin A. Mohammed, Paulo Régis C. Ruffino Feb 2007

Hartman-Grobman Theorems Along Hyperbolic Stationary Trajectories, Edson A. Coayla-Teran, Salah-Eldin A. Mohammed, Paulo Régis C. Ruffino

Articles and Preprints

We extend the Hartman-Grobman theorems on discrete random dynamical systems (RDS), proved in [7], in two directions: For continuous RDS and for hyperbolic stationary trajectories. In this last case there exists a conjugacy between traveling neighbourhoods of trajectories and neighbourhoods of the origin in the corresponding tangent bundle. We present applications to deterministic dynamical systems.

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Modular Exponentiation Via The Explicit Chinese Remainder Theorem, Daniel J. Bernstein, Jonathan P. Sorenson Jan 2007

Modular Exponentiation Via The Explicit Chinese Remainder Theorem, Daniel J. Bernstein, Jonathan P. Sorenson

Scholarship and Professional Work - LAS

In this paper we consider the problem of computing xe mod m for large integers x, e, and m. This is the bottleneck in Rabin’s algorithm for testing primality, the Diffie-Hellman algorithm for exchanging cryptographic keys, and many other common algorithms.

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Codes Generated By Matrix Expansions, Chris Meyer Jan 2007

Codes Generated By Matrix Expansions, Chris Meyer

Morehead Electronic Journal of Applicable Mathematics Archives

No abstract provided.

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On A Spatial Rock-Paper-Scissors Game, Robert D. Macmartin, Jan Rychtar Jan 2007

On A Spatial Rock-Paper-Scissors Game, Robert D. Macmartin, Jan Rychtar

Morehead Electronic Journal of Applicable Mathematics Archives

No abstract provided.

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Analysis Of A Modified Feedback Control Technique For Suppressing Electrical Alternans In Cardiac Tissue, Srinivasan V. Narayanan, John W. Cain Jan 2007

Analysis Of A Modified Feedback Control Technique For Suppressing Electrical Alternans In Cardiac Tissue, Srinivasan V. Narayanan, John W. Cain

Morehead Electronic Journal of Applicable Mathematics Archives

No abstract provided.

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The Origin Of 2 Sexes Through Optimization Of Recombination Entropy Against Time And Energy, Bo Deng Jan 2007

The Origin Of 2 Sexes Through Optimization Of Recombination Entropy Against Time And Energy, Bo Deng

Department of Mathematics: Faculty Publications

Sexual reproduction in nature requires two sexes, which raises the question why the reproductive scheme did not evolve to have three or more sexes. Here we construct a constrained optimization model based on the communication theory to analyze trade-offs among reproductive schemes with arbitrary number of sexes. More sexes on one hand lead to higher reproductive diversity, but on the other hand incur greater cost in time and energy for reproductive success. Our model shows that the two-sexes reproduction scheme maximizes the recombination entropy-to-cost ratio, and hence is the optimal solution to the problem.

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Spatial Ecology Of The Coachwhip, Masticophis Flagellum (Squamata: Colubridae), In Eastern Texas, Richard W. Johnson, Robert R. Fleet, Michael B. Keck, D. Craig Rudolph Jan 2007

Spatial Ecology Of The Coachwhip, Masticophis Flagellum (Squamata: Colubridae), In Eastern Texas, Richard W. Johnson, Robert R. Fleet, Michael B. Keck, D. Craig Rudolph

Faculty Publications

We radio-tracked nine Masticophis flagellum (Coachwhips) to determine home range, habitat use, and movements in eastern Texas from April to October 2000. Home ranges of Coachwhips contained more oak savanna macrohabitat than early-successional pine plantation or forested seep, based on the availability of these three macrohabitats in the study area. Likewise, within their individual home ranges, Coachwhips used oak savanna more than the other two macrohabitats, based on availability. An analysis of microhabitat use revealed that, relative to random sites within their home range, Coachwhips were found at sites with fewer pine trees and more herbaceous vegetation taller than 30 …

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Covering Properties And Cohen Forcing, Akira Iwasa Jan 2007

Covering Properties And Cohen Forcing, Akira Iwasa

Faculty Publications

We will show that adding Cohen reals preserves the covering property that every open cover has a σ-P Q refinement and deduce that adding Cohen reals preserves covering properties such as paracompactness, subparacompactness and screenability.

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A Distributed Parabolic Control With Mixed Boundary Conditions, Jose-Luis Menaldi, Domingo Alberto Tarzia Jan 2007

A Distributed Parabolic Control With Mixed Boundary Conditions, Jose-Luis Menaldi, Domingo Alberto Tarzia

Mathematics Faculty Research Publications

We study the asymptotic behavior of an optimal distributed control problem where the state is given by the heat equation with mixed boundary conditions. The parameter α intervenes in the Robin boundary condition and it represents the heat transfer coefficient on a portion Γ1 of the boundary of a given regular n-dimensional domain. For each α, the distributed parabolic control problem optimizes the internal energy g. It is proven that the optimal control ĝα with optimal state uĝαα and optimal adjoint state pĝαα are convergent as α → 1 …

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Discrete Approximations, Relaxation, And Optimization Of One-Sided Lipschitzian Differential Inclusions In Hilbert Spaces, Tzanko Donchev, Elza Farkhi, Boris S. Mordukhovich Jan 2007

Discrete Approximations, Relaxation, And Optimization Of One-Sided Lipschitzian Differential Inclusions In Hilbert Spaces, Tzanko Donchev, Elza Farkhi, Boris S. Mordukhovich

Mathematics Research Reports

We study discrete approximations of nonconvex differential inclusions in Hilbert spaces and dynamic optimization/optimal control problems involving such differential inclusions and their discrete approximations. The underlying feature of the problems under consideration is a modi- fied one-sided Lipschitz condition imposed on the right-hand side (i.e., on the velocity sets) of the differential inclusion, which is a significant improvement of the conventional Lipschitz continuity. Our main attention is paid to establishing efficient conditions that ensure the strong approximation (in the W^1,p-norm as p greater than or equal to 1) of feasible trajectories for the one-sided Lipschitzian differential inclusions under. consideration by …

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Newton's Method For Solving A System Of Dual Fuzzy Nonlinear Equations, Saeid Abbasbandy Jan 2007

Newton's Method For Solving A System Of Dual Fuzzy Nonlinear Equations, Saeid Abbasbandy

Saeid Abbasbandy

In this paper, we propose a numerical solution for a system of dual fuzzy nonlinear equations by Newton’s method. The fuzzy quantities are presented in parametric form. Some numerical illustrations are given to show the efficiency of algorithm.

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Variational Iteration Method - Some Recent Results And New Interpretations, Ji-Huan He Jan 2007

Variational Iteration Method - Some Recent Results And New Interpretations, Ji-Huan He

Ji-Huan He

This paper is an elementary introduction to the concepts of variational iteration method. First, the main concepts in variational iteration method, such as general Lagrange multiplier, restricted variation, correction functional, are explained heuristically. Subsequently, the solution procedure is systematically addressed, in particular, for nonlinear oscillators. Particular attention is paid throughout the paper to give an intuitive grasp for the method. The main motivation is to put things together in a convenient form for later reference and systematic use. (C) 2006 Elsevier B.V. All rights reserved.

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Application Of Ansys In Seismic Response Analysis Of Constructing Of High Buildings, Yang Xiaojun Jan 2007

Application Of Ansys In Seismic Response Analysis Of Constructing Of High Buildings, Yang Xiaojun

Xiao-Jun Yang

The dynamic feature of high buildings is discussed in the present study with the application of ANSYS，the large finite element analysis software，aimed at the analysis of dynamic response of high buildings．Based on the case of a 15一story-building，a model of beam and shell 3-D finite element structure is built and the frequency of structure and the mode of vibration are computed in the study；furthermore，the structural dynamic response is discussed under different seismic waves with the use of the history analysis method．The results show that the more intense the seismic wave is，the bigger is the dynamic response of the buildings．The information can …

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Laser Capture Sampling And Analytical Issues In Proteomics, Howard Gutstein, Jeffrey S. Morris Jan 2007

Laser Capture Sampling And Analytical Issues In Proteomics, Howard Gutstein, Jeffrey S. Morris

Jeffrey S. Morris

Proteomics holds the promise of evaluating global changes in protein expression and post-translational modificaiton in response to environmental stimuli. However, difficulties in achieving cellular anatomic resolution and extracting specific types of proteins from cells have limited the efficacy of these techniques. Laser capture microdissection has provided a solution to the problem of anatomical resolution in tissues. New extraction methodologies have expanded the range of proteins identified in subsequent analyses. This review will examine the application of laser capture microdissection to proteomic tissue sampling, and subsequent extraction of these samples for differential expression analysis. Statistical and other quantitative issues important for …

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Variational Iteration Method: New Development And Applications, Ji-Huan He, Xu-Hong Wu Jan 2007

Variational Iteration Method: New Development And Applications, Ji-Huan He, Xu-Hong Wu

Ji-Huan He

Variational iteration method has been favourably applied to various kinds of nonlinear problems. The main property of the method is in its flexibility and ability to solve nonlinear equations accurately and conveniently. In this paper recent trends and developments in the use of the method are reviewed. Major applications to nonlinear wave equation, nonlinear fractional differential equations, nonlinear oscillations and nonlinear problems arising in various engineering applications are surveyed. The confluence of modem mathematics and symbol computation has posed a challenge to developing technologies capable of handling strongly nonlinear equations which cannot be successfully dealt with by classical methods. Variational …

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Application Of Parameter-Expanding Method To Strongly Nonlinear Oscillators, Ji-Huan He, Da-Hua Shou Jan 2007

Application Of Parameter-Expanding Method To Strongly Nonlinear Oscillators, Ji-Huan He, Da-Hua Shou

Ji-Huan He

The parameter-expanding method is applied to a strongly nonlinear oscillator. The obtained frequency is of high accuracy which is valid for the whole solution domain. Comparison of the obtained solution with exact solution is also given.

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A Fully Lagrangian Numerical Method For Calculating The Dynamics Of Oscillating Micro And Nanoscale Objects Immersed In Fluid, Nicole N. Hashemi, Mark Paul, Javier Alcazar, Raul Radovitzky Jan 2007

A Fully Lagrangian Numerical Method For Calculating The Dynamics Of Oscillating Micro And Nanoscale Objects Immersed In Fluid, Nicole N. Hashemi, Mark Paul, Javier Alcazar, Raul Radovitzky

Nastaran Hashemi

Many micro and nano-technologies rely upon the complicated motion of objects immersed in a viscous fluid. It is often the case that for such problems analytical theory is not available to quantitatively describe and predict the device dynamics. In addition, the numerical simulation of such devices involves moving boundaries and use of the standard Eulerian computational approaches are often difficult to implement. In order to address this problem we use and validate a fully Lagrangian finite element approach that treats the moving boundaries in a natural manner. We validate the method for use in calculating the dynamics of oscillating objects …

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Thermal Effects On Mechanical Grinding-Induced Surface Texture In Tetragonal Piezoelectrics, Wonyoung Chang, Alexander H. King, Keith J. Bowman Jan 2007

Thermal Effects On Mechanical Grinding-Induced Surface Texture In Tetragonal Piezoelectrics, Wonyoung Chang, Alexander H. King, Keith J. Bowman

Alexander H. King

The effect of temperature on grinding-induced texture in tetragonal lead zirconate titanate (PZT) and lead titanate (PT) has been investigated using in situ x-ray diffraction (XRD) with an area detector. In contrast with previous results on electrical poling, mechanically-ground PT and soft PZT materials retain strong ferroelastic textures during thermal cycling, even after excursions to temperatures slightly above the Curie temperature. The relationship between the residual stresses in the surface region, caused by grinding, and those resulting from domain wall motion is elucidated by in situ texture measurements obtained during thermal cycling.

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How Surface Stresses Lead To Size-Dependent Mechanics Of Tensile Deformation In Nanowires, M. Ravi Shankar, Alexander H. King Jan 2007

How Surface Stresses Lead To Size-Dependent Mechanics Of Tensile Deformation In Nanowires, M. Ravi Shankar, Alexander H. King

Alexander H. King

It has been proposed that surface and interface stresses can modify the elastic behavior in nanomaterials such as nanowires. The authors show that surface stresses modify the tensile response of nanowires only when nonlinear elastic effects become important leading to cross terms between the applied stress and the surface stress. These effects are only significant when the radius of the nanowire is of the order of a few nanometers. The resulting alteration of tensile stiffness, though effected in part by the nonlinear elastic modulus, is particularly wrought by a modification of the stress state in the deformed nanowire.

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A "Sound" Approach To Fourier Transforms: Using Music To Teach Trigonometry, Bruce Kessler Jan 2007

A "Sound" Approach To Fourier Transforms: Using Music To Teach Trigonometry, Bruce Kessler

Bruce Kessler

If a large number of educated people were asked, ``What was your most exciting class?'', odds are that very few of them would answer ``Trigonometry.'' The subject is generally presented in a less-than-exciting fashion, with the repeated caveat that ``you'll need this when you take calculus,'' or ``this has lots of applications'' without ever really seeing many of them. This manuscript addresses how the author is trying to change this tradition by exposing casual students from kindergarten to college to Joseph Fourier's secret, that nearly any function can be built out of sine and cosine curves. And music serves as …

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Spatial Symmetry Groups As Sensorimotor Guidelines, Gin Mccollum Jan 2007

Spatial Symmetry Groups As Sensorimotor Guidelines, Gin Mccollum

Gin McCollum

While some aspects of neuroanatomical organization are related to packing and access rather than to function, other aspects of anatomical/physiological organization are directly related to function. The mathematics of symmetry groups can be used to determine logical structure in projections and to relate it to function. This paper reviews two studies of the symmetry groups of vestibular projections that are related to the spatial functions of the vestibular complex, including gaze, posture, and movement. These logical structures have been determined by finding symmetry groups of two vestibular projections directly from physiological and anatomical data. Logical structures in vestibular projections are …

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Rectification Of The Bias In The Wavelet Power Spectrum, Yonggang Liu, X. San Liang, Robert H. Weisberg Jan 2007

Rectification Of The Bias In The Wavelet Power Spectrum, Yonggang Liu, X. San Liang, Robert H. Weisberg

Yonggang Liu

This paper addresses a bias problem in the estimate of wavelet power spectra for atmospheric and oceanic datasets. For a time series comprised of sine waves with the same amplitude at different frequencies the conventionally adopted wavelet method does not produce a spectrum with identical peaks, in contrast to a Fourier analysis. The wavelet power spectrum in this definition, that is, the transform coefficient squared (to within a constant factor), is equivalent to the integration of energy (in physical space) over the influence period (time scale) the series spans. Thus, a physically consistent definition of energy for the wavelet power …

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Current Patterns On The West Florida Shelf From Joint Self-Organizing Map Analyses Of Hf Radar And Adcp Data, Yonggang Liu, Robert H. Weisberg, Lynn K. Shay Jan 2007

Current Patterns On The West Florida Shelf From Joint Self-Organizing Map Analyses Of Hf Radar And Adcp Data, Yonggang Liu, Robert H. Weisberg, Lynn K. Shay

Yonggang Liu

To assess the spatial structures and temporal evolutions of distinct physical processes on the West Florida Shelf, patterns of ocean current variability are extracted from a joint HF radar and ADCP dataset acquired from August to September 2003 using Self-Organizing Map (SOM) analyses. Three separate ocean– atmosphere frequency bands are considered: semidiurnal, diurnal, and subtidal. The currents in the semidiurnal band are relatively homogeneous in space, barotropic, clockwise polarized, and have a neap-spring modulation consistent with semidiurnal tides. The currents in the diurnal band are less homogeneous, more baroclinic, and clockwise polarized, consistent with a combination of diurnal tides and …

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