Araştırma Çıktıları | WoS | Scopus | TR-Dizin | PubMed
Permanent URI for this communityhttps://hdl.handle.net/20.500.14719/1741
Browse
22 results
Search Results
Publication Metadata only A note on the well-posedness of the nonlocal boundary value problem for elliptic difference equations(ELSEVIER SCIENCE INC, 2006) Ashyralyev, A.; Altay, N.; Fatih University; Bahcesehir University; International Turkmen-Turkish UniversityThe nonlocal boundary value problem for elliptic difference equations in an arbitrary Banach space is considered. The well-posedness of this problem is investigated. The stability, almost coercive stability and coercive stability estimates for the solutions of difference schemes of the second order of accuracy for the approximate solutions of the nonlocal boundary value problem for elliptic equation are obtained. The theoretical statements for the solution of these difference schemes are supported by the results of numerical experiments. (c) 2005 Elsevier Inc. All rights reserved.Publication Metadata only Merger criterion for two vortices in 3D quasi-geostrophic flow(AMER INST PHYSICS, 2007) Ozugurlu, E.; Reinaud, J. N.; Dritschel, D. G.; Simos, TE; Bahcesehir University; University of St AndrewsIn this study we examine the interaction between two like-signed quasi-geostrophic vortices containing different uniform potential vorticity. The interaction depends on 6 parameters: the potential vorticity ratio between the two vortices, their volume ratio, their individual height-to-width aspect ratio, their vertical offset and their horizontal separation distance. We first calculate equilibrium states using an asymptotic approach which models the vortices as ellipsoids and then determine their linear stability. It is found that two vortices can merge at farther distances when one has stronger potential vorticity than the other. This tells us that interaction between vortices having significantly different potential vorticity may be more destructive, for a given separation distance. Most of the vortex interactions for the considered parameter space are in the partial-merger regime (where the largest vortex grows in volume) and this happens between vortices of similar po! tential vorticity.Publication Metadata only A note on solitary waves with variable surface tension in water of infinite depth(AUSTRALIAN MATHEMATICS PUBL ASSOC INC, 2006) Ozugurlu, E.; Vanden-Broeck, J. -M.; Bahcesehir University; University of East AngliaTwo-dimensional gravity-capillary solitary waves propagating at the surface of a fluid of infinite depth are considered. The effects of gravity and of variable surface tension are included in the free-surface boundary condition. The numerical results extend the constant surface tension results of Vanden-Broeck and Dias to situations where the surface tension varies along the free surface.Publication Metadata only Nonlocal boundary value problems for the Schrodinger equation(PERGAMON-ELSEVIER SCIENCE LTD, 2008) Ashyralyev, Allaberen; Sirma, Ali; Fatih University; Gebze Technical University; Bahcesehir UniversityIn the present paper, the nonlocal boundary value problem idu/dt + Au = f (t), 0 < t < T, u(0) = Sigma(p)(m=1)alpha(m)u(lambda(m)) + phi, 0 < lambda(1) < lambda(2) < ... lambda(p) <= T for the Schrodinger equation in a Hilbert space H with the self-adjoint operator A is considered. Stability estimates for the solution of this problem are established. Two nonlocal boundary value problems are investigated. The first and second order of accuracy difference schemes for the approximate solutions of this nonlocal boundary value problem are presented. The stability of these difference schemes is established. In practice, stability inequalities for the solutions of difference schemes for the Schr6dinger equation are obtained. A numerical method is proposed for solving a one-dimensional Schrodinger equation with nonlocal boundary condition. A procedure involving the modified Gauss elimination method is used for solving these difference schemes. The method is illustrated by giving numerical examples. (c) 2007 Elsevier Ltd. All rights reserved.Publication Metadata only Deductibles in health insurance(ELSEVIER SCIENCE BV, 2009) Dimitriyadis, I.; Oney, U. N.; Bahcesehir UniversityThis study is an extension to a simulation study that has been developed to determine ruin probabilities in health insurance. The study concentrates on inpatient and outpatient benefits for customers of varying age bands. Loss distributions are modelled through the Allianz tool pack for different classes of insureds. Premiums at different levels of deductibles are derived in the simulation and ruin probabilities are computed assuming a linear loading on the premium. The increase in the probability of ruin at high levels of the deductible clearly shows the insufficiency of proportional loading in deductible premiums. The PH-transform pricing rule developed by Wang is analyzed as an alternative pricing rule. A simple case, where an insured is assumed to be an exponential utility decision maker while the insurer's pricing rule is a PH-transform is also treated. (C) 2008 Elsevier B.V. All rights reserved.Publication Metadata only Computational complexity investigations for high dimensional model representation algorithms used in multivariate interpolation problems(WORLD SCIENTIFIC AND ENGINEERING ACAD AND SOC, 2007) Tunga, M. Alper; Demiralp, Metin; Demiralp, M; Udriste, C; Bognar, G; Soni, R; Nassar, H; Bahcesehir University; Istanbul Technical UniversityIn multivariate interpolation problems, increase in both the number of independent variables of the sought function and the number of nodes appearing in the data set cause computational and mathematical difficulties. It may be a better way to deal with less variate partitioned data sets instead of an N-dimensional data set in a multivariate interpolation problem. New algorithms such as High Dimensional Model Representation (HDMR), Generalized HDMR, Factorized HDMR, Hybrid HDMR are developed or rearranged for these types of problems. Up to now, the efficiency of the methods in mathematical sense were discussed in several papers. In this work, the efficiency of these methods in computational sense will be discussed. This investigation will be done by using several numerical implementations.Publication Metadata only A Reverse Technique for Lumping High Dimensional Model Representation Method(WORLD SCIENTIFIC AND ENGINEERING ACAD AND SOC, 2009) Tunga, M. Alper; Demiralp, Metin; Demiralp, M; Baykara, NA; Mastorakis, NE; Bahcesehir University; Istanbul Technical UniversityAn orthogonal hyperprismatic grid whose all nodes are accompanied by the given function Values Call not be generally constructed due to the random nature of the given function data. This prevents the reduction Of the single multivariate interpolation to More than One univariate or bivariate interpolations even approximately. It is generally quite difficult to determine an analytical structure for the target function in these problems. Lumping HDMR method is an indexing based High Dimensional Model Representation (HDMR) algorithm used to reconstruct these types Of multivariate data by imposing an Indexing scheme to obtain an orthogonal geometry for the given problem. By this way, the training Of the given data call be accomplished. The next problem, is to determine I reverse algorithm for the testing data. This work is about it new algorithm to find the correct coordinate of the given testing data in the orthogonal geometry obtained through Lumping HDMR.Publication Metadata only Holditch Theorem and Steiner Formula for the Planar Hyperbolic Motions(SPRINGER BASEL AG, 2009) Yuce, Salim; Kuruoglu, Nuri; Yildiz Technical University; Bahcesehir UniversityThe Steiner formula and the Holditch Theorem for one-parameter closed planar Euclidean motions [1, 7] were expressed by H.R. Muller [9] under the one-parameter closed planar motions in the complex sense. In this paper, in analogy with complex motions as given by Muller [9], the Steiner formula and the mixture area formula are obtained under one parameter hyperbolic motions. Also Holditch theorems were expressed in the hyperbolic sense.Publication Metadata only Application of Fluctuationlessness Theorem on the Numerical Solution of Higher Order Linear Ordinary Differential Equations(AMER INST PHYSICS, 2008) Altay, Nejla; Demiralp, Metin; Simos, TE; Psihoyios, G; Tsitouras, C; Bahcesehir University; Istanbul Technical UniversityThis work focuses on the numerical solution of ordinary differential equations in the absence of fluctuation. Here only the initial value problems are considered and the solutions are obtained over the unit interval [0, 1]. The main purpose of this work is to obtain a general procedure for the numerical solution of Ordinary Differential Equations. Although there are many methods for these problems, the method that we develop here has some impressive features. Numerical solution approximates to the exact solution rapidly without using too many mesh points.Publication Metadata only Cauchy Formulas for Enveloping Curves in the Lorentzian Plane and Lorentzian Kinematics(BIRKHAUSER VERLAG AG, 2009) Yuce, Salim; Kuruoglu, Nuri; Yildiz Technical University; Bahcesehir UniversityIn the Lorentzian plane, we give Cauchy-length formulas to the envelope of a family of lines. Using these, we prove the length of the enveloping trajectories of non-null lines under the planar Lorentzian motions and give the Holditch-type theorems for the length of the enveloping trajectories. Furthermore, Holditch-type theorem for the orbit areas of three collinear points which is given by Yuce and Kuruoglu [8] is generalized to three non-collinear points.
- «
- 1 (current)
- 2
- 3
- »