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2008

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Articles 391 - 420 of 585

Full-Text Articles in Mathematics

Collection Of Nitrate In A Denuder, Hannah Feig Jan 2008

Collection Of Nitrate In A Denuder, Hannah Feig

Undergraduate Journal of Mathematical Modeling: One + Two

Data are given for aerosol nitrate (NO3-) size distributions in the atmosphere as recorded by a cascade impactor and by an annular denuder. Using this data, our goal is to find the percent of nitrate in the atmosphere that the denuder is able to detect. This requires that we find the size distribution of nitrate that enters the denuder. From these data and calculations, we find that 32.8% of nitrate in the atmosphere can be detected by the denuder. Nitrate was measured to study its affects on seagrass in the Tampa Bay and to compare nitrate levels with …

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Critical Axial Load, Walt Wells Jan 2008

Critical Axial Load, Walt Wells

Undergraduate Journal of Mathematical Modeling: One + Two

Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment …

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Criteria Pollutant Concentration, Victor Neese Jan 2008

Criteria Pollutant Concentration, Victor Neese

Undergraduate Journal of Mathematical Modeling: One + Two

With the assistance of Assistant Professor Jeff Cunningham (Civil & Environmental Engineering Department, USF) a study was carried out pertaining to the amount of CO and NOx pollutants emitted from a highway having two lanes in each direction. The receptor of the pollutants is a hypothetical housing development located near the highway. The concentrations were found by utilizing information regarding meteorological conditions, estimated emissions rates, and distances from the highway less than or equaling 2 km.

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Algae Bloom In A Lake, David Sanabria Jan 2008

Algae Bloom In A Lake, David Sanabria

Undergraduate Journal of Mathematical Modeling: One + Two

The objective of this paper is to determine the likelihood of an algae bloom in a particular lake located in upstate New York. The growth of algae in this lake is caused by a high concentration of phosphorous that diffuses to the surface of the lake. Our calculations, based on Fick's Law, are used to create a mathematical model of the driving force of diffusion for phosphorous. Empirical observations are also used to predict whether the concentration of phosphorous will diffuse to the surface of this lake within a specified time and under specified conditions.

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A Comparison Of Different Methods For Predicting Cancer Mortality Counts At The State Level, Corinne Wilson Jan 2008

A Comparison Of Different Methods For Predicting Cancer Mortality Counts At The State Level, Corinne Wilson

Virginia Journal of Science

Cancer is a major health issue in the United States. Reliable estimates of yearly cancer mortality counts are essential for resourcing and planning. The American Cancer Society has used several methods of forecasting to estimate the future cancer burden and researchers are continually working to develop new methods with improved performance. There have been studies comparing different models for predicting the US cancer mortality counts. This study explores and compares several different models for cancer mortality count predictions at the state level, principally for the state of Virginia. Results of the comparisons appear to show the final improved model to …

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Formulas For The Fourier Series Of Orthogonal Polynomials In Terms Of Special Functions, Nataniel Greene Jan 2008

Formulas For The Fourier Series Of Orthogonal Polynomials In Terms Of Special Functions, Nataniel Greene

Publications and Research

An explicit formula for the Fourier coefficient of the Legendre polynomials can be found in the Bateman Manuscript Project. However, formulas for more general classes of orthogonal polynomials do not appear to have been worked out. Here we derive explicit formulas for the Fourier series of Gegenbauer, Jacobi, Laguerre and Hermite polynomials. The methods described here apply in principle to a class of polynomials, including non-orthogonal polynomials.

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Integrability Of A Singularly Perturbed Model Describing Gravity Water Waves On A Surface Of Finite Depth, Steven Little Jan 2008

Integrability Of A Singularly Perturbed Model Describing Gravity Water Waves On A Surface Of Finite Depth, Steven Little

Electronic Theses and Dissertations

Our work is closely connected with the problem of splitting of separatrices (breaking of homoclinic orbits) in a singularly perturbed model describing gravity water waves on a surface of finite depth. The singularly perturbed model is a family of singularly perturbed fourth-order nonlinear ordinary differential equations, parametrized by an external parameter (in addition to the small parameter of the perturbations). It is known that in general separatrices will not survive a singular perturbation. However, it was proven by Tovbis and Pelinovsky that there is a discrete set of exceptional values of the external parameter for which separatrices do survive the …

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An Existence Principle For Nonlocal Difference Boundary Value Problems With Φ-Laplacian And Its Application To Singular Problems, Ravi P. Agarwal, Donal O'Regan, Svatoslav Staněk Jan 2008

An Existence Principle For Nonlocal Difference Boundary Value Problems With Φ-Laplacian And Its Application To Singular Problems, Ravi P. Agarwal, Donal O'Regan, Svatoslav Staněk

Mathematics and System Engineering Faculty Publications

The paper presents an existence principle for solving a large class of nonlocal regular discrete boundary value problems with the ψ-Laplacian. Applications of the existence principle to singular discrete problems are given.

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Positive Solutions For Singular Three-Point Boundary-Value Problems, Ravi P. Agarwal, Donal O'Regan, Baoqiang Yan Jan 2008

Positive Solutions For Singular Three-Point Boundary-Value Problems, Ravi P. Agarwal, Donal O'Regan, Baoqiang Yan

Mathematics and System Engineering Faculty Publications

Using the theory of fixed point index, this paper discusses the existence of at least one positive solution and the existence of multiple positive solutions for the singular three-point boundary value problem: y″(t) + a(t)f(t, y(t), y′(t)) = 0, 0 < t < 1, y′(0) = 0, y(1) = αy(η), where 0 < α < 1, 0 < η < 1, and f may be singular at y = 0 and y′ = 0. .

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Set-Theoretic Inequalities In Stochastic Noncooperative Games With Coalition, Jewgeni H. Dshalalow, Ailada Treerattrakoon Jan 2008

Set-Theoretic Inequalities In Stochastic Noncooperative Games With Coalition, Jewgeni H. Dshalalow, Ailada Treerattrakoon

Mathematics and System Engineering Faculty Publications

We model and analyze antagonistic stochastic games of three players, two of whom form a coalition against the third one. The actions of the players are modeled by random walk processes recording the cumulative damages to each player at any moment of time. The game continues until the single player or the coalition is defeated. The defeat of any particular player takes place when the associated process (representing the collateral damage) crosses a fixed threshold. Once the threshold is exceeded at some time, the associated player exits the game. All involved processes are being "observed by a third party process" …

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Functorial Coalgebraic Logic: The Case Of Many-Sorted Varieties, Alexander Kurz, Daniela Petrişan Jan 2008

Functorial Coalgebraic Logic: The Case Of Many-Sorted Varieties, Alexander Kurz, Daniela Petrişan

Engineering Faculty Articles and Research

Following earlier work, a modal logic for T-coalgebras is a functor L on a suitable variety. Syntax and proof system of the logic are given by presentations of the functor. This paper makes two contributions. First, a previous result characterizing those functors that have presentations is generalized from endofunctors on one-sorted varieties to functors between many-sorted varieties. This yields an equational logic for the presheaf semantics of higher-order abstract syntax. As another application, we show how the move to functors between many-sorted varieties allows to modularly combine syntax and proof systems of different logics. Second, we show how to associate …

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Fixed-Effect Estimation Of Highly-Mobile Production Technologies, William Clinton Horrace, Kurt E. Schnier Jan 2008

Fixed-Effect Estimation Of Highly-Mobile Production Technologies, William Clinton Horrace, Kurt E. Schnier

Center for Policy Research

Revised from November 2006 and July 2007. We consider fixed-effect estimation of a production function where inputs and outputs vary over time, space, and cross-sectional unit. Variability in the spatial dimension allows for time-varying individual effects, without parametric assumptions on the effects. Asymptotics along the spatial dimension provide consistency and normality of the marginal products. A finite-sample example is provided: a production function for bottom-trawler fishing vessels in the flatfish fisheries of the Bering Sea. We find significant spatial variability of output (catch) which we exploit in estimation of a harvesting function.

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Semiparametric Deconvolution With Unknown Error Variance, William C. Horrace, Christopher F. Parmeter Jan 2008

Semiparametric Deconvolution With Unknown Error Variance, William C. Horrace, Christopher F. Parmeter

Center for Policy Research

Deconvolution is a useful statistical technique for recovering an unknown density in the presence of measurement error. Typically, the method hinges on stringent assumptions about the nature of the measurement error, more specifically, that the distribution is *entirely* known. We relax this assumption in the context of a regression error component model and develop an estimator for the unknown density. We show semi-uniform consistency of the estimator and provide Monte Carlo evidence that demonstrates the merits of the method.

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A Manifold Structure For The Group Of Orbifold Diffeomorphisms Of A Smooth Orbifold, Joseph E. Borzellino, Victor Brunsden Jan 2008

A Manifold Structure For The Group Of Orbifold Diffeomorphisms Of A Smooth Orbifold, Joseph E. Borzellino, Victor Brunsden

Mathematics

For a compact, smooth Cr orbifold (without boundary), we show that the topological structure of the orbifold diffeomorphism group is a Banach manifold for 1 ≤ r < ∞ and a Fréchet manifold if r = ∞. In each case, the local model is the separable Banach (Fréchet) space of Cr (C ∞, resp.) orbisections of the tangent orbibundle.

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Nearly-Hamiltonian Structure For Water Waves With Constant Vorticity, Adrian Constantin, Rossen Ivanov, Emil Prodanov Jan 2008

Nearly-Hamiltonian Structure For Water Waves With Constant Vorticity, Adrian Constantin, Rossen Ivanov, Emil Prodanov

Articles

We show that the governing equations for two-dimensional gravity water waves with constant non-zero vorticity have a nearly-Hamiltonian structure, which becomes Hamiltonian for steady waves.

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Bipartite Toughness And The K-Factors In Bipartite Graphs, Guizhen Liu, Jianbo Quan, Jonathan Z. Sun, Rui Xu Jan 2008

Bipartite Toughness And The K-Factors In Bipartite Graphs, Guizhen Liu, Jianbo Quan, Jonathan Z. Sun, Rui Xu

Faculty Publications

We define a new invariant tB(G) in bipartite graphs that is analogous to the toughness t(G) and we give sufficient conditions in term of tB(G) for the existence of k-factors in bipartite graphs. We also show that these results are sharp.

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Legendrian Torus Links, Jennifer Dalton Jan 2008

Legendrian Torus Links, Jennifer Dalton

Bryn Mawr College Dissertations and Theses

A basic problem in contact topology is to determine whether two Legendrian knots or links are equivalent. In this dissertation, we will study the equivalence and non-equivalence of Legendrian links that are topologically torus links.

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Multiplicative Properties Of Integral Binary Quadratic Forms, A. G. Earnest, Robert W. Fitzgerald Jan 2008

Multiplicative Properties Of Integral Binary Quadratic Forms, A. G. Earnest, Robert W. Fitzgerald

Articles and Preprints

In this paper, the integral binary quadratic forms for which the set of represented values is closed under k-fold products, for even positive integers k, will be characterized. This property will be seen to distinguish the elements of odd order in the form class group of a fixed discriminant. Further, it will be shown that this closure under k-fold products can always be expressed by a k-linear mapping from (Z2)k to Z2. In the case k = 2, this resolves a conjecture of Aicardi and Timorin.

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Trace Classes And Fixed Points For The Extended Modular Group \Overline{\Gamma}, Özden Koruoğlu, Recep Şahi̇n, Sebahatti̇n İki̇kardeş Jan 2008

Trace Classes And Fixed Points For The Extended Modular Group \Overline{\Gamma}, Özden Koruoğlu, Recep Şahi̇n, Sebahatti̇n İki̇kardeş

Turkish Journal of Mathematics

The extended modular group \overline{\Gamma}=PGL(2,\mathbb{Z}) is the group obtained by adding the reflection R(z)=1/\overline{z} to the generators of the modular group \Gamma =PSL(2, {Z}). In this paper, we find the trace classes of the extended modular group \overline{\Gamma}. Using this, we classify the elements of \overline{\Gamma}.

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On The Regular Elements In Z_N, Osama Alkam, Emad Abu Osba Jan 2008

On The Regular Elements In Z_N, Osama Alkam, Emad Abu Osba

Turkish Journal of Mathematics

All rings are assumed to be finite commutative with identity element. An element a \in R is called a regular element if there exists b \in R such that a=a^2b, the element b is called a von Neumann inverse for a. A characterization is given for regular elements and their inverses in Z_n, the ring of integers modulo n. The arithmetic function V(n), which counts the regular elements in Z_n is studied. The relations between V(n) and Euler's phi-function \varphi (n) are explored.

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Linear Connections On Light-Like Manifolds, Teki̇n Dereli̇, Şahi̇n Koçak, Murat Li̇moncu Jan 2008

Linear Connections On Light-Like Manifolds, Teki̇n Dereli̇, Şahi̇n Koçak, Murat Li̇moncu

Turkish Journal of Mathematics

It is well-known that a torsion-free linear connection on a light-like manifold (M,g) compatible with the degenerate metric g exists if and only if Rad(TM) is a Killing distribution. In case of existence, there is an infinitude of connections with none distinguished. We propose a method to single out connections with the help of a special set of 1-forms by the condition that the 1-forms become parallel with respect to this connection. Such sets of 1-forms could be regarded as an additional structure imposed upon the light-like manifold. We consider also connections with torsion and with non-metricity on light-like manifolds.

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A Decomposition Method For Solving Unsteady Convection-Diffusion Problems, Shaher Momani Jan 2008

A Decomposition Method For Solving Unsteady Convection-Diffusion Problems, Shaher Momani

Turkish Journal of Mathematics

In this study, a decomposition method for approximating the solutions of unsteady convection-diffusion problems is implemented. The approximate solution is calculated in the form of a convergent series with easily computable components. The calculations are accelerated by using the noise terms phenomenon for nonhomogeneous problems. Numerical examples are investigated to illustrate the pertinent features of the proposed algorithm.

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Mirror Principle For Flag Manifolds, Vehbi̇ Emrah Paksoy Jan 2008

Mirror Principle For Flag Manifolds, Vehbi̇ Emrah Paksoy

Turkish Journal of Mathematics

In this paper, using mirror principle developped by Lian, Liu and Yau [8, 9, 10, 11, 12, 13] we obtained the A and B series for the equivariant tangent bundles over homogenous spaces using Chern polynomial. This is necessary to obtain related cohomology valued series for given arbitrary vector bundle and multiplicative characteristic class. Moreover, this can be used as a valuable testing ground for the theories which associates quantum cohomologies and J functions of non-abelian quotient to abelian quotients via quantization.

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Mixed Type Of Integral Equation With Potential Kernel, Mohamed Abdella A. Abdou, Gamal Mohamed Abd Al-Kader Jan 2008

Mixed Type Of Integral Equation With Potential Kernel, Mohamed Abdella A. Abdou, Gamal Mohamed Abd Al-Kader

Turkish Journal of Mathematics

This paper presents the solution of an integral equation of a mixed type in three-dimensions in the space L_2 (\Omega) \times C[0,T], where T < \infty, and \Omega is the domain of integration with respect to position. The kernel of position integral term is considered in the potential function form, while the kernel of time is considered as a continuous kernel. A linear system of Fredholm integral equations of the first and second kinds are obtained and solved. Krein's method is used to solve the Fredholm integral equation of the first kind, while the second kind is solved numerically.

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A Note On A Problem Of J. Galambos, Lu-Ming Shen, Yue-Hua Liu, Yu-Yuan Zhou Jan 2008

A Note On A Problem Of J. Galambos, Lu-Ming Shen, Yue-Hua Liu, Yu-Yuan Zhou

Turkish Journal of Mathematics

For any x\in (0,1], letx = \frac{1}{d_1} + \frac{a_1}{b_1} \frac{1}{d_2} + ··· + \frac{a_1a_2 ··· a_n}{b_1b_2 ··· b_n} \frac{1}{d_{n+1}} + ··· be the Oppenheim series expansion of x. In this paper, we investigate the Hausdorff dimension of the set B_m={x:1

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Cover For Modules And Injective Modules, N. Amiri Jan 2008

Cover For Modules And Injective Modules, N. Amiri

Turkish Journal of Mathematics

Let R be a commutative ring with identity and M be an R-module with Spec(M) \neq \phi. A cover of the R-submodule K of M is a subset C of Spec(M) satisfying that for any x \in K, x \neq 0, there is N \in C such that ann(x) \subset (N:M). If we denote by J = \bigcap_{N \in C} (N:M) and assume that M is finitely generated, then JM=M implies that M=0, M is called C-injective provided each R-homomorphism \phi : (N:M) \rightarrow M with N \in C can be lifted to an R-homomorphism \lambda : R \rightarrow M. …

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On Non-Existence Of Lightlike Hypersurfaces Of Indefinite Kenmotsu Space Form, Nesi̇p Aktan Jan 2008

On Non-Existence Of Lightlike Hypersurfaces Of Indefinite Kenmotsu Space Form, Nesi̇p Aktan

Turkish Journal of Mathematics

In this paper, lightlike hypersurfaces of indefinite Kenmotsu space form are studied. Some characterizations of non-existence of lightlike hypersurfaces of indefinite Kenmotsu space form are given.

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Cr-Submanifolds Of An S-Manifold, A. Alghanemi Jan 2008

Cr-Submanifolds Of An S-Manifold, A. Alghanemi

Turkish Journal of Mathematics

The study of CR-submanifolds of a Kaehler manifold was initiated by Bejancu [1]. Since then many papers have appeared on CR-submanifolds. The purpose of this paper is to studied the CR-submanifolds of an S-manifold. In particular, we studied the integrability of the distributions D and D^{\bot} of a CR-submanifold of an S-manifold.

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Real Gromov-Witten Invariants On The Moduli Space Of Genus 0 Stable Maps To A Smooth Rational Projective Space, Seongchun Kwon Jan 2008

Real Gromov-Witten Invariants On The Moduli Space Of Genus 0 Stable Maps To A Smooth Rational Projective Space, Seongchun Kwon

Turkish Journal of Mathematics

We characterize transversality, non-transversality properties on the moduli space of genus 0 stable maps to a rational projective surface. If a target space is equipped with a real structure, i.e, anti-holomorphic involution, then the results have real enumerative applications. Firstly, we can define a real version of Gromov-Witten invariants. Secondly, we can prove the invariance of Welschinger's invariant in algebraic geometric category.

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Proximinality In L^1(I,X), Sharifa Al-Sharif, R. Khalil Jan 2008

Proximinality In L^1(I,X), Sharifa Al-Sharif, R. Khalil

Turkish Journal of Mathematics

Let X be a Banach space and let (I,\Omega ,\mu) be a measure space. For 1 \leq p < \infty, let L^p(I,X) denote the space of Bochner p-integrable functions defined on I with values in X. The object of this paper is to give sufficient conditions for the proximinality of L^1(I,H)+L^1(I,G) in L^1(I,X), where H and G are two proximinal subspaces of X which include as a special case the proximality of L^1(I) \stackrel{\wedge}{\otimes} G + H \stackrel{\wedge}{\otimes} L^1(I) in L^1(I \times I).

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