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2013

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Articles 931 - 960 of 1053

Full-Text Articles in Mathematics

Optimization Problem In Single Period Markets, Tian Jiang Jan 2013

Optimization Problem In Single Period Markets, Tian Jiang

Electronic Theses and Dissertations

There had been a number of researches that investigated on the security market without transaction costs. The focus of this research is in the area that when the security market with transaction costs is fair and in such fair market how one chooses a suitable portfolio to optimize the financial goal. The research approach adopted in this thesis includes linear algebra and elementary probability. The thesis provides evidence that we can maximize expected utility function to achieve our goal (maximize expected return under certain risk tolerance). The main conclusions drawn from this study are under certain conditions the security market …

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Nonparametric And Empirical Bayes Estimation Methods, Rida Benhaddou Jan 2013

Nonparametric And Empirical Bayes Estimation Methods, Rida Benhaddou

Electronic Theses and Dissertations

In the present dissertation, we investigate two different nonparametric models; empirical Bayes model and functional deconvolution model. In the case of the nonparametric empirical Bayes estimation, we carried out a complete minimax study. In particular, we derive minimax lower bounds for the risk of the nonparametric empirical Bayes estimator for a general conditional distribution. This result has never been obtained previously. In order to attain optimal convergence rates, we use a wavelet series based empirical Bayes estimator constructed in Pensky and Alotaibi (2005). We propose an adaptive version of this estimator using Lepski’s method and show that the estimator attains …

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Extensions Of S-Spaces, Bernd Losert Jan 2013

Extensions Of S-Spaces, Bernd Losert

Electronic Theses and Dissertations

Given a convergence space X, a continuous action of a convergence semigroup S on X and a compactification Y of X, under what conditions on X and the action on X is it possible to extend the action to a continuous action on Y . Similarly, given a Cauchy space X, a Cauchy continuous action of a Cauchy semigroup S on X and a completion Y of X, under what conditions on X and the action on X is it possible to extend the action to a Cauchy continuous action on Y . We answer the first question for some …

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Accelerated Life Model With Various Types Of Censored Data, Kathryn Pridemore Jan 2013

Accelerated Life Model With Various Types Of Censored Data, Kathryn Pridemore

Electronic Theses and Dissertations

The Accelerated Life Model is one of the most commonly used tools in the analysis of survival data which are frequently encountered in medical research and reliability studies. In these types of studies we often deal with complicated data sets for which we cannot observe the complete data set in practical situations due to censoring. Such difficulties are particularly apparent by the fact that there is little work in statistical literature on the Accelerated Life Model for complicated types of censored data sets, such as doubly censored data, interval censored data, and partly interval censored data. In this work, we …

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Spectrally Uniform Frames And Spectrally Optimal Dual Frames, Saliha Pehlivan Jan 2013

Spectrally Uniform Frames And Spectrally Optimal Dual Frames, Saliha Pehlivan

Electronic Theses and Dissertations

Frames have been useful in signal transmission due to the built in redundancy. In recent years, the erasure problem in data transmission has been the focus of considerable research in the case the error estimate is measured by operator (or matrix) norm. Sample results include the characterization of one-erasure optimal Parseval frames, the connection between two-erasure optimal Parseval frames and equiangular frames, and some characterization of optimal dual frames. If iterations are allowed in the reconstruction process of the signal vector, then spectral radius measurement for the error operators is more appropriate then the operator norm measurement. We obtain a …

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Numerical Simulations For The Flow Of Rocket Exhaust Through A Granular Medium, Kristina Kraakmo Jan 2013

Numerical Simulations For The Flow Of Rocket Exhaust Through A Granular Medium, Kristina Kraakmo

Electronic Theses and Dissertations

Physical lab experiments have shown that the pressure caused by an impinging jet on a granular bed has the potential to form craters. This poses a danger to landing success and nearby spacecraft for future rocket missions. Current numerical simulations for this process do not accurately reproduce experimental results. Our goal is to produce improved simulations to more accurately and effi- ciently model the changes in pressure as gas flows through a porous medium. A two-dimensional model in space known as the nonlinear Porous Medium Equation as it is derived from Darcy’s law is used. An Alternating-Direction Implicit (ADI) temporal …

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Three Hundred Years Of The St. Petersburg Paradox, Keguo Huang Jan 2013

Three Hundred Years Of The St. Petersburg Paradox, Keguo Huang

Dissertations, Master's Theses and Master's Reports - Open

The St. Petersburg Paradox was first presented by Nicholas Bernoulli in 1713. It is related to a gambling game whose mathematical expected payoff is infinite, but no reasonable person would pay more than $25 to play it. In the history, a number of ideas in different areas have been developed to solve this paradox, and this report will mainly focus on mathematical perspective of this paradox. Different ideas and papers will be reviewed, including both classical ones of 18th and 19th century and some latest developments. Each model will be evaluated by simulation using Mathematica.

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On Quasiconformal Harmonic Mappings Lifting To Minimal Surfaces, Hakan Mete Taştan, Yaşar Polatoğlu Jan 2013

On Quasiconformal Harmonic Mappings Lifting To Minimal Surfaces, Hakan Mete Taştan, Yaşar Polatoğlu

Turkish Journal of Mathematics

We prove a growth theorem for a function to belong to the class \sum(\mu;a) and generalize a Weierstrass-Enneper representation type theorem for the minimal surfaces given in [5] to spacelike minimal surfaces which lie in 3-dimensional Lorentz-Minkowski space L^3. We also obtain some estimates of the Gaussian curvature of the minimal surfaces in 3-dimensional Euclidean space R^3 and of the spacelike minimal surfaces in L^3.

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A Note On Unmixed Ideals Of Veronese Bi-Type, Monica La Barbiera Jan 2013

A Note On Unmixed Ideals Of Veronese Bi-Type, Monica La Barbiera

Turkish Journal of Mathematics

We classify the unmixed ideals of Veronese bi-type and in some cases we give a description of their associated prime ideals.

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G-Frames As Special Frames, Abas Askarizadeh, Mohammad Ali Dehghan Jan 2013

G-Frames As Special Frames, Abas Askarizadeh, Mohammad Ali Dehghan

Turkish Journal of Mathematics

G-frames are generalizations of ordinary frames for Hilbert spaces. In the present paper we study frames, and operators on a special separable Hilbert C^*-module, B(H,K), where H and K are Hilbert spaces, and we prove that every g-frame for H is a frame for B(H,K) and vice versa. Also, we derive some relationships between g-Riesz bases for H and Riesz bases in B(H,K). Similar results for orthogonal bases will be discussed.

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On Pseudo Semi-Projective Modules, Truong Cong Quynh Jan 2013

On Pseudo Semi-Projective Modules, Truong Cong Quynh

Turkish Journal of Mathematics

A right R-module M is called semi-projective if, for any submodule N of M, every epimorphism \pi: M \rightarrow N and every homomorphism \alpha: M \rightarrow N, there exists a homomorphism \beta: M \rightarrow M such that \pi \beta = \alpha (see [11]). In this paper, we consider some generalizations of semi-projective module, that is quasi pseudo principally projective module. Some properties of this class of module are studied.

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Generating Systems Of Differential Invariants And The Theorem On Existence For Curves In The Pseudo-Euclidean Geometry}, Djavvat Khadjiev, İdri̇s Ören, Ömer Pekşen Jan 2013

Generating Systems Of Differential Invariants And The Theorem On Existence For Curves In The Pseudo-Euclidean Geometry}, Djavvat Khadjiev, İdri̇s Ören, Ömer Pekşen

Turkish Journal of Mathematics

Let M(n, p) be the group of all motions of an n-dimensional pseudo-Euclidean space of index p. It is proved that the complete system of M(n,p)-invariant differential rational functions of a path (curve) is a generating system of the differential field of all M(n,p)-invariant differential rational functions of a path (curve), respectively. A fundamental system of relations between elements of the complete system of M(n,p)-invariant differential rational functions of a path (curve) is described.

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Rings Over Which Every Module Has A Flat \\Delta-Cover, Pinar Aydoğdu Jan 2013

Rings Over Which Every Module Has A Flat \\Delta-Cover, Pinar Aydoğdu

Turkish Journal of Mathematics

Let M be a module. A \delta-cover of M is an epimorphism from a module F onto M with a \delta-small kernel. A \delta-cover is said to be a flat \delta-cover in case F is a flat module. In the present paper, we investigate some properties of (flat) \delta-covers and flat modules having a projective \delta-cover. Moreover, we study rings over which every module has a flat \delta-cover and call them right generalized \delta-perfect rings. We also give some characterizations of \delta-semiperfect and \delta-perfect rings in terms of locally (finitely, quasi-, direct-) projective \delta-covers and flat \delta-covers.

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Formulas For The Fourier Coefficients Of Cusp Form For Some Quadratic Forms (Correction To A Paper By Ahmet Tekcan With The Same Title), Bariş Kendi̇rli̇ Jan 2013

Formulas For The Fourier Coefficients Of Cusp Form For Some Quadratic Forms (Correction To A Paper By Ahmet Tekcan With The Same Title), Bariş Kendi̇rli̇

Turkish Journal of Mathematics

In this study M_1(\Gamma _0(3) ,\chi _{-3}) , M_2(\Gamma_0(5), \chi _5) and M_3(\Gamma _0(7),\chi _{-7}) have been examined and the formulas for the Fourier Coefficients of theta series and the representation number of positive integers by some quadratic forms 3x_1^2+3x_1x_2+x_2^2, 5(x_1^2+x_1x_2+x_1x_3+x_1x_4+x_2^2+x_2x_3+ x_2x_4+x_3^2+x_3x_4)+2x_4^2, and 7(x_1^2+x_1x_2+x_1x_3+x_1x_4+x_1x_5+x_2^2+x_2x_3+x_2x_4+x_2x_5+ x_3^2+x_3x_4+x_3x_5+x_4^2+x_4x_5+x_5^2+7(x_1x_6+x_2x_6+x_3x_6+ x_4x_6+x_5x_6)+3x_6^2, are determined. This work is a correction to a paper of the same title by Ahmet Tekcan [5].

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On The Existence Of (400, 57, 8) Non-Abelian Difference Sets, Adegoke Solomon Osifodunrin Jan 2013

On The Existence Of (400, 57, 8) Non-Abelian Difference Sets, Adegoke Solomon Osifodunrin

Turkish Journal of Mathematics

Difference sets with parameters (\frac{q^{d + 1} - 1}{q - 1}, \frac{q^d - 1}{q - 1}, \frac{q^{d - 1} - 1}{q - 1}), where q is a prime power and d \geq 1, are known to exist in cyclic groups and are called classical Singer difference sets. We study a special case of this family with q = 7 and d = 3 in search of more difference sets. According to GAP, there are 220 groups of order 400 out of which 10 are abelian. E. Kopilovich and other authors showed that the remaining nine abelian groups of order 400 …

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Gorenstein Transpose With Respect To A Semidualizing Bimodule, Zengfeng Liu, Xiaoguang Yan Jan 2013

Gorenstein Transpose With Respect To A Semidualizing Bimodule, Zengfeng Liu, Xiaoguang Yan

Turkish Journal of Mathematics

Let S and R be rings and _SC_R be a semidualizing bimodule. We first give the definitions of C-transpose and n-C-torsionfree and give a criterion for a module A to be G_C-projective by some property of the C-transpose of A. Then we introduce the notion of C-Gorenstein transpose of a module over two-sided Noetherian rings. We prove that a module M in \mod R^{op} is a C-Gorenstein transpose of a module A \in \mod S if and only if M can be embedded into a C-transpose of A with the cokernel G_C-projective. Finally we investigate some homological properties of the …

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Algorithm To Solve Certain Ternary Quartic Diophantine Equations, Laszlo Szalay Jan 2013

Algorithm To Solve Certain Ternary Quartic Diophantine Equations, Laszlo Szalay

Turkish Journal of Mathematics

In this paper, we develop an algorithm to solve completely the Diophantine equation F(x,y)=z^2, where the quartic inhomogeneous polynomial F(x,y) with integer coefficients satisfies certain technical conditions. The procedure is an extension of the version of Runge's method given by Poulakis.

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Nzi Rings, Long Wang, Junchao Wei, Libin Li Jan 2013

Nzi Rings, Long Wang, Junchao Wei, Libin Li

Turkish Journal of Mathematics

A ring R is called NZI if for any a \in R, l(a) is an N-ideal of R. In this paper, we first study some basic properties and basic extensions of NZI rings. Next, we study the strong regularity of NZI rings and obtain the following results: (1) Let R be a left SF-ring. Then R is a strongly regular ring if and only if R is an NZI ring; (2) If R is an NZI left MC2 ring and every simple singular left R-module is nil-injective, then R is reduced; (3) Let R be an NZI ring. Then R …

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Continuous Invariant Averagings, Djavvat Khadjiev, Abdullah Çavuş Jan 2013

Continuous Invariant Averagings, Djavvat Khadjiev, Abdullah Çavuş

Turkish Journal of Mathematics

Main results: For every equicontinuous almost periodic linear representation of a group in a complete locally convex space L with the countability property, there exists the unique invariant averaging; it is continuous and is expressed by using the L-valued invariant mean of Bochner and von-Neumann. An analog of Wiener's approximation theorem for an equicontinuous almost periodic linear representation in a locally convex space with the countability property is proved.

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A Class Of 3-Dimensional Almost Cosymplectic Manifolds, İrem Küpeli̇ Erken, Cengi̇zhan Murathan Jan 2013

A Class Of 3-Dimensional Almost Cosymplectic Manifolds, İrem Küpeli̇ Erken, Cengi̇zhan Murathan

Turkish Journal of Mathematics

The main interest of the present paper is to classify the almost cosymplectic 3-manifolds that satisfy \Vert grad\lambda \Vert = const.(\neq 0) and \bigtriangledown_{\xi} h=2ah\phi.

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Cartan Equivalence Problem For Third-Order Differential Operators, Mehdi Nadjafikhah, Rohollah Bakhshandeh Chamazkoti Jan 2013

Cartan Equivalence Problem For Third-Order Differential Operators, Mehdi Nadjafikhah, Rohollah Bakhshandeh Chamazkoti

Turkish Journal of Mathematics

This article is dedicated to solving the equivalence problem for a pair of third-order differential operators on the line under general fiber-preserving transformation using the Cartan method of equivalence. We will treat 2 versions of equivalence problems: first, the direct equivalence problem, and second, an equivalence problem to determine conditions on 2 differential operators such that there exists a fiber-preserving transformation mapping one to the other according to gauge equivalence.

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Orthogonal Systems In L^2 Spaces Of A Vector Measure, Eduardo Jiménez Fernández Jan 2013

Orthogonal Systems In L^2 Spaces Of A Vector Measure, Eduardo Jiménez Fernández

Turkish Journal of Mathematics

Let m:\Sigma \to X be a Banach space valued countably additive vector measure. In this paper we present a procedure to construct an m-orthogonal system in the space L^2(m) of square integrable functions with respect to m. If the vector measure is constructed from a family of indeterminate scalar measures, it is possible to obtain a family of polynomials that is orthogonal with respect to this vector measure. On the other hand, if the vector measure is fixed, then we can obtain sequences of orthogonal functions using the Kadec-Pelczynski disjointification method.

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On Quotients Of Ith Affine Surface Areas, Chang-Jian Zhao Jan 2013

On Quotients Of Ith Affine Surface Areas, Chang-Jian Zhao

Turkish Journal of Mathematics

Following the volume difference function, we first introduce the notion of the affine surface area quotient function. We establish Brunn--Minkowski type inequalities for the affine surface area quotient function, which in special cases yield some well-known results.

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Attractors For Parabolic Problems In Weighted Spaces, Xiaojun Li, Ying Tang Jan 2013

Attractors For Parabolic Problems In Weighted Spaces, Xiaojun Li, Ying Tang

Turkish Journal of Mathematics

The purpose of this paper is to investigate the asymptotic behavior of the solutions of parabolic equations with singular initial data in weighted spaces L^r_{\delta(x)}(\Omega) where \delta(x) is the distance to the boundary. We first establish the existence of the attractor for that equation in L^r_{\delta(x)}(\Omega) and then show the existence of the exponential attractor in L^2_{\delta(x)}(\Omega). In contrast to our previous results, we get the existence of attractors in weak topology spaces.

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Isoclinic Extensions Of Lie Algebras, Hamid Mohammadzadeh, Ali Reza Salemkar, Zahra Riyahi Jan 2013

Isoclinic Extensions Of Lie Algebras, Hamid Mohammadzadeh, Ali Reza Salemkar, Zahra Riyahi

Turkish Journal of Mathematics

In this article we introduce the notion of the equivalence relation, isoclinism, on the central extensions of Lie algebras, and determine all central extensions occurring in an isoclinism class of a given central extension. We also show that under some conditions, the concepts of isoclinism and isomorphism between the central extensions of finite dimensional Lie algebras are identical. Finally, the connection between isoclinic extensions and the Schur multiplier of Lie algebras are discussed.

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Bbm Equation With Non-Constant Coefficients, Amutha Senthilkumar Jan 2013

Bbm Equation With Non-Constant Coefficients, Amutha Senthilkumar

Turkish Journal of Mathematics

In this article, a model for the propagation of long waves over an uneven bottom is considered. We provide both theoretical and numerical results for this model. We also discuss the changes which occur in a solitary wave solution of the BBM equation as it travels through a channel of decreasing depth.

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Labelings Of Type (1,1,1) For Toroidal Fullerenes, Martin Baca, Muhammad Numan, Ayesha Shabbir Jan 2013

Labelings Of Type (1,1,1) For Toroidal Fullerenes, Martin Baca, Muhammad Numan, Ayesha Shabbir

Turkish Journal of Mathematics

In this paper we deal with the problem of labeling the vertices, edges, and faces of a toroidal fullerene H_m^n with mn hexagons by the consecutive integers from 1 up to V(H_m^n) + E(H_m^n) + F(H_m^n) in such a way that the set of face-weights of 6-sided faces forms an arithmetic progression with common difference d, where by face-weight we mean the sum of the label of that face and the labels of vertices and edges surrounding that face. The paper examines the existence of such labelings for several differences d.

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Bifurcations And Parametric Representations Of Traveling Wave Solutions For The Green--Naghdi Equations, Shengqiang Tang, Libing Zeng, Dahe Feng Jan 2013

Bifurcations And Parametric Representations Of Traveling Wave Solutions For The Green--Naghdi Equations, Shengqiang Tang, Libing Zeng, Dahe Feng

Turkish Journal of Mathematics

By using the bifurcation theory of dynamical systems to study the dynamical behavior of the Green--Naghdi equations, the existence of solitary wave solutions along with smooth periodic traveling wave solutions is obtained. Under different regions of parametric spaces, various sufficient conditions to guarantee the existence of the above solutions are given. Some exact and explicit parametric representations of traveling wave solutions are constructed.

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On Nearly Kenmotsu Manifolds, Behzad Najafi, Niloufar Hosseinpour Kashani Jan 2013

On Nearly Kenmotsu Manifolds, Behzad Najafi, Niloufar Hosseinpour Kashani

Turkish Journal of Mathematics

We prove that on a nearly Kenmotsu manifold a second-order symmetric closed recurrent tensor is a multiple of the associated metric tensor. We then find the necessary condition under which a vector field on a nearly Kenmotsu manifold will be a strict contact or Killing vector field. Finally, we prove that every \phi-recurrent nearly Kenmotsu manifold is an Einstein manifold and every locally \phi-recurrent nearly Kenmotsu manifold is a manifold of constant curvature -1 .

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Can One Hear...? An Exploration Into Inverse Eigenvalue Problems Related To Musical Instruments, Christine Adams Jan 2013

Can One Hear...? An Exploration Into Inverse Eigenvalue Problems Related To Musical Instruments, Christine Adams

Electronic Theses and Dissertations

The central theme of this thesis deals with problems related to the question, “Can one hear the shape of a drum?” first posed formally by Mark Kac in 1966. More precisely, can one determine the shape of a membrane with fixed boundary from the spectrum of the associated differential operator? For this paper, Kac received both the Lester Ford Award and the Chauvant Prize of the Mathematical Association of America. This problem has received a great deal of attention in the past forty years and has led to similar questions in completely different contexts such as “Can one hear the …

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