Applied Mathematics Commons^™

Multiple Solutions For A Dirichlet Problem With Jumping Nonlinearities Ii, Alfonso Castro, Ratnasingham Shivaji

All HMC Faculty Publications and Research

No abstract provided for this article.

Remarks On A Semilinear Elliptic Equation On Rn, Yi Li

Mathematics and Statistics Faculty Publications

No abstract provided.

Spectral Measures, Orthogonal Polynomials, And Absolute Continuity, Joanne Dombrowski

Mathematics and Statistics Faculty Publications

This paper studies the spectral measure of an unbounded tridiagonal matrix operator for which the matrix entries satisfy a certain growth condition, and presents a sufficient condition for the existence of an absolutely continuous part. The results are related to a class of orthogonal polynomials with exponential weights.

Stability Of Steady Cross-Waves: Theory And Experiment, Seth Lichter, Andrew J. Bernoff

All HMC Faculty Publications and Research

A bifurcation analysis is performed in the neighborhood of neutral stability for cross waves as a function of forcing, detuning, and viscous damping. A transition is seen from a subcritical to a supercritical bifurcation at a critical value of the detuning. The predicted hysteretic behavior is observed experimentally. A similarity scaling in the inviscid limit is also predicted. The experimentally observed bifurcation curves agree with this scaling.

Nonnegative Solutions For A Class Of Nonpositone Problems, Alfonso Castro, Ratnasingham Shivaji

All HMC Faculty Publications and Research

In the recent past many results have been established on non-negative solutions to boundary value problems of the form

-u''(x) = λf(u(x)); 0 < x < 1,

u(0) = 0 = u(1)

where λ>0, f(0)>0 (positone problems). In this paper we consider the impact on the non-negative solutions when f(0)<0. We find that we need f(u) to be convex to guarantee uniqueness of positive solutions, and f(u) to be appropriately concave for multiple positive solutions. This is in contrast to the case of positone problems, where the roles of convexity and concavity were interchanged to obtain similar results. We further establish the existence of non-negative solutions with interior zeros, which did not exist in positone problems.

Reliable Computation By Formulas In The Presence Of Noise, Nicholas Pippenger

All HMC Faculty Publications and Research

It is shown that if formulas are used to compute Boolean functions in the presence of randomly occurring failures then: (1) there is a limit strictly less than 1/2 to the failure probability per gate that can be tolerated, and (2) formulas that tolerate failures must be deeper (and, therefore, compute more slowly) than those that do not. The heart of the proof is an information-theoretic argument that deals with computation and errors in very general terms. The strength of this argument is that it applies with equal ease no matter what types of gate are available. Its weaknesses is …

On Conformal Scalar Curvature Equations In Rn, Yi Li, Wei-Ming Ni

Mathematics and Statistics Faculty Publications

No abstract provided.

Uniform L1 Behavior In Classes Of Integrodifferential Equations With Convex Kernels, Richard Noren

Mathematics & Statistics Faculty Publications

No abstract provided.

Periodic Solutions Of Volterra Integral Equations, Muhammad Islam

Mathematics Faculty Publications

Consider the system of equations

x(t)=f(t)+∫−∞tk(t,s)x(s)ds,           (1)

and

x(t)=f(t)+∫−∞tk(t,s)g(s,x(s))ds.        (2)

Existence of continuous periodic solutions of (1) is shown using the resolvent function of the kernel k. Some important properties of the resolvent function including its uniqueness are obtained in the process. In obtaining periodic solutions of (1) it is necessary that the resolvent of k is integrable in some sense. For a scalar convolution kernel k some explicit conditions are derived to determine whether or not the resolvent of k is integrable. Finally, the existence and uniqueness of continuous periodic solutions of (1) and (2) are obtained using the …

A Mathematical Model Of The Dynamics Of An Optically Pumped Four-Level Solid State Laser System, Lila Freeman Roberts

Mathematics & Statistics Theses & Dissertations

This is a study of a mathematical model of the dynamics of an optically pumped four-level solid state laser system. A general mathematical model that describes the spatial and temporal evolution of the electron populations in the laser rod as well as the development of the left and right traveling photon fluxes in the cavity is developed. The model consists of a coupled set of first order semilinear partial differential equations. While the model was developed for Titanium-doped sapphire lasers, it is applicable to three and four level lasers in general.

The analysis of the model is conducted in two …

Matrix Methods Of Approximating Classical Predator-Prey Problems, E. Y. Rodin, R. Greenberg, B. Nelson

Computer Science: Faculty Publications and Other Works

No abstract provided.

Generalized Linear Inversion Using Tau-P Forward Modeling, Stephen Dade Walker

Graduate Theses

The Generalized Linear Inversion (GLI) method is used in conjunction with a tau-p forward model to successfully perform inversions of test and real-data examples. All data examples used are one-dimensional velocity profiles that represent several different cases. The stability of the technique is demonstrated in all the test-data sets. The use of simple models and wel1-control 1ed test data results in a minimum of iterations of the inversion process. Different levels of perturbation of the model and test-data examples are used to reveal insight into the robust nature of the inversion.

Pontryagin's Maximum Principle, Chirasakdi Varuntanya

Theses

In a detailed presentation of Boltyanskii "elementary" proof of the Pontryagin's Maximum Principle, several gaps have been filled in the original one: The control processes which are considered in this paper are described by a system of ordinary differential equations, hence the uniform approach to O of certain O(ε) is proved. Moreover, a complete proof of a theorem about convex cones in Rn and a theorem from Topology are presented. An example of time optimal control illustrating the principle is also solved.

Infinitely Many Radially Symmetric Solutions To A Superlinear Dirichlet Problem In A Ball, Alfonso Castro, Alexandra Kurepa

All HMC Faculty Publications and Research

In this paper we show that a radially symmetric superlinear Dirichlet problem in a ball has infinitely many solutions. This result is obtained even in cases of rapidly growing nonlinearities, that is, when the growth of the nonlinearity surpasses the critical exponent of the Sobolev embedding theorem. Our methods rely on the energy analysis and the phase-plane angle analysis of the solutions for the associated singular ordinary differential equation.

Cyclic Operators, Commutators, And Absolutely Continuous Measures, Joanne Dombrowski

Mathematics and Statistics Faculty Publications

Commutator equations are used to study the relationship between the tridiagonal matrix structure of an unbounded cyclic selfadjoint operator and its spectrum. Sufficient conditions are given for absolute continuity. Results are related to the study of systems of orthogonal polyomials for which the measure of orthogonality is supported on an unbounded subset of the real line.

Applied Mathematics As Social Contract, Philip J. Davis

Humanistic Mathematics Network Journal

The author takes the position that mathematical education must redefine its goals so as to create a citizenry with sufficient knowledge to provide social backpressure on future mathematizations. This can be accomplished by increasing the part of mathematical education that is devoted to the description and interpretation of the processes of mathematization and by allowing the technicalities of the formal operations within mathematics itself to be deemphasized or automated out by computer.

On Weakly Coupled Hyperbolic And Parabolic Partial Differential Equations Arising In Chemical Engineering Problems, Zhifeng Zhang

Theses

Many of the mathematical models arising in dynamical chemical processes are systems of weakly coupled hyperbolic and parabolic partial differential equations with constant coefficients. It is shown in this paper that this kind of systems of partial differential equations can be treated using generalizations of Green's functions. The Green's function is completely defined, including all boundary conditions, for systems with nonselfadjoint operators as well as those which are selfadjoint. The Green's functions can be expressed in terms of eigenvalues and eigenfunctions of the operator and the adjoint operator when they can be obtained. We develop a method based on higher …

Variational Theory And Applications To Nonlinear Elliptic Equations Involving Critical Sobolev Exponents, Hwei-Ling Wu

Theses

This thesis consists of two parts. In the first part, Chapters I and II, we present some basic critical point theory,for functionals bounded from below on some Banach space and are either weakly lower semicontinuous or satisfy the Palais-Smale compactness condition. Moreover, we also prove some Mountain Pass type theorems of Ambrosetti and Rabinowit for functionals which are neither bounded from below nor above. In the second part, Chapters III - V, we apply these Mountain Pass type results to the problems of the existence of positive solutions for nonlinear elliptic equations of the Δu = u^p + f(x,u) …

Mathematical Reflections: Standing On The Shoulders Of Giants, Karl J. Smith

ACMS Conference Proceedings 1987

The layperson's response to mathematics is often that of desperation. When we tell people our occupation, do we more often than not hear about their unpleasant experiences with mathematics. They often tell us, "I studied algebra in high school and haven't used it since!" Indeed, that may be true. However, we can reply, "How many times has algebra been used on you?" We are all restricted, and protected, by the formulas of mathematics. In the mysterious metaphors we have agreed to cal mathematics, all creation is involved, from the symbol-happy logician down to the cunning geometers, the bees. When I …

Observations On Mathematics And The Christian Faith, W. David Laverell, Carl J. Sinke

ACMS Conference Proceedings 1987

There is little doubt that mathematicians are becoming more concerned with the foundations on which their discipline rests, the meaning of their work, and the philosophical stance implicit in what they do. This concern is prompted by serious questions which have been raised in recent years, questions dealing with the nature of mathematical truth, the nature of proof, certainty (or lack thereof) in mathematics, and the relationship of mathematics to the physical world. This has been particularly true for those of us involved in teaching since it is apparent that good mathematics education cannot ignore these issures.

Proof And Intution, Michael Detlefsen

ACMS Conference Proceedings 1987

This paper discusses various perspectives on proof and intuition by examing two epistemic systems, Intuition Intensive and Logic Intensive, and Jules Henri Poincaré's objections to the latter.

Logic And Proof For Mathematics: A Twentieth Century Perspective, Calvin Jongsma

ACMS Conference Proceedings 1987

This talk reports on the author's experience in teaching college mathematics students the basics of logic and proof in preparation for their transitioning to upper-level proof-based mathematics courses, following that up with a philosophical and historical analysis of mathematicians' attitudes toward such a project going back to nineteenth- and twentieth-century developments in logic and foundations (De Morgan, Boole, Frege, Russell, and Hilbert). The natural deduction approach to logic and inference developed in the mid-twentieth century by Jaskowski and Fitch is recommended as a much better focused approach for learning how to do proofs in mathematics. This idea is systematically developed …

Riesz Spaces And Their Applications In Economics, Calvin E. Piston

ACMS Conference Proceedings 1987

We will examine an economic model of pure exchange and some results concerning different notions of equilibrium. In particular, we will focus on the role played by the theory of Riesz space.

Variations On A Theme, Robert Creighton Buck

ACMS Conference Proceedings 1987

An autobiographical narration by Robert Creighton Buck, detailing his experiences in the field of mathematics, and the various questions and themes reoccurring in the mathematical sciences.

The Role Of Computer Science In A Liberal Arts College, Russell C. Bjork

ACMS Conference Proceedings 1987

The question the panel has been asked to discuss actually encompasses two related, but distinct, questions - each of which, in turn, has two subquestions.

The first question concerns the place of a computer science as a major program of study among the offerings of a liberal arts college. The two subquestions here are as follows: First, is computer science an appropriate field of study to offer in a liberal arts college? (Is it a liberal art?) Second, is a liberal arts college an appropriate home for a computer science program? (Can a high quality program be offered in such …

Another Look At Pick's Theorem, Dale Varberg

ACMS Conference Proceedings 1987

In this paper, the author discusses his experience building a proof for Pick's Theorem and theorem's history.

Computer Science In Liberal Arts Colleges, James Bradley

ACMS Conference Proceedings 1987

This paper looks at the strengths and weaknesses of computer science curricula and how liberal arts colleges can best teach the concepts of mathematics required in computer science.

An Activist Model Of The Metaphysics Of Mathematics, Christopher Menzel

ACMS Conference Proceedings 1987

No abstract provided.

Conic Sections In Ip, Richard Laatsch

ACMS Conference Proceedings 1987

No abstract provided.

3:16 - An Approach To Bible Study, Donald E. Knuth

ACMS Conference Proceedings 1987

No abstract provided.