Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651

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Citation - Scopus: 3
The Confined System Approximation for Solving Non-Separable Potentials in Three Dimensions
(1998) Taşeli, H.; Eid, R.
The Hubert space L2(ℝ3), to which the wavefunction of the three-dimensional Schrödinger equation belongs, has been replaced by L2(Ω), where Ω is a bounded region. The energy spectrum of the usual unbounded system is then determined by showing that the Dirichlet and Neumann problems in L2(Ω) generate upper and lower bounds, respectively, to the eigenvalues required. Highly accurate numerical results for the quartic and sextic oscillators are presented for a wide range of the coupling constants.
Citation - Scopus: 5
Structural Forms and Energies of NiN, N=12-14, Clusters
(Assoc Sci Res, 1999) Güvenç, Ziya B.; Güvenç, Dilek; Jellinek, Julius
Equilibrium structural forms of the $Ni_n$, n=12-14, clusters, as defined by an embedded-atom potential, are obtained using molecular dynamics and thermal quenching simulations. The isomers (locally stable geometric forms) are distinguished from those stationary structures that correspond to saddle points of the potential energy surface. Isomer statistics are obtained using a large number of initial quenching configurations generated along high-energy trajectories (the energies are high enough to "melt" the clusters). Probabilities of sampling the basins of attraction of the different isomers are computed and the spectra of their energies are analyzed.
Citation - WoS: 7
Citation - Scopus: 5
Hamilton-Jacobi Quantization of the Finite-Dimensional Systems With Constraints
(Editrice Compositori Bologna, 1999) Baleanu, Dumitru; Baleanu, D; Güler, Y; Güler, Yurdahan; Matematik
The Hamiltonian treatment of constrained systems in Guler's formalism leads us to the total differential equations in many variables. These equations are integrable if the corresponding system of partial differential equations is a Jacobi system. The main aim of this paper is to investigate the quantization of the finite-dimensional systems with constraints using the canonical formalism introduced by Guler. This approach is applied for two systems with constraints and the results are in agreement with those obtained by Dirac's canonical quatization method and path integral quantization method.
Citation - WoS: 3
Citation - Scopus: 4
Higher Order Finite Element Solution of the One-Dimensional Schrodinger Equation
(John Wiley & Sons inc, 1999) Eid, R
The one-dimensional Schrodinger equation has been examined by means of the confined system defined on a finite interval. The eigenvalues of the resulting bounded problem subject to the Dirichlet boundary conditions are calculated accurately to 20 significant figures using higher order shape functions in the usual isoparametric finite element method. Numerical results are given for an arbitrary polynomial potential of degree M. (C) 1999 John Wiley & Sons, Inc.
Citation - WoS: 8
Citation - Scopus: 7
Sputtering Yield and Dynamical Analysis of Ni(100) Surface: a Comparison of Four Different Ar-Surface Interaction Potentials
(Elsevier Science Bv, 2000) Güvenç, ZB; Hundur, Y; Hippler, R
The sputtering process of the Ar + Ni(100) collision system is investigated by means of constant energy molecular dynamics simulations. The Ni(100) is mimicked by an embedded-atom potential, and the interaction between the projectile and the surface is modelled by using four different screened Coulomb type potentials. The Ni atom emission from the lattice is analysed over the range of 10-40 eV collision energy. The maximum penetration depths of Ar, probability distributions of kinetic energy of the reflected Ar, and energy of the Ar and sputtered Ni atoms in the same collision events are evaluated as functions of the impact energy and sputtering time. Further, angular distributions of the scattered Ar are obtained. The calculated sputtering yields are compared with the available theoretical and experimental data. (C) 2000 Elsevier Science B.V. All rights reserved.
Citation - Scopus: 9
Hamilton-Jacobi Treatment of Fields With Constraints
(Editrice Compositori s.r.l., 2000) Baleanu, D.; Baleanu, Dumitru; Güler, Y.; Güler, Yurdahan; Matematik
In this paper Güler's formalism for the systems with finite degrees of freedom is applied to the field theories with constraints. The integrability conditions are investigated and the path integral quantization is performed using the action given by Hamilton-Jacobi formulation. Proca's model is investigated in details.
Lax Tensors and Separable Coordinates in (2+1) Dimensions
(inst Physics Acad Sci Czech Republic, 2000) Baskal, S; Baleanu, D
We study the Lax tensors of the separable coordinates in (2+1) dimensions. The Lax tensors of the dual manifolds are investigated.
Citation - WoS: 12
Citation - Scopus: 14
Reactions of Small Ni Clusters With a Diatomic Molecule: Md Simulation of D2+nin (n=7-10) Systems
(Elsevier Science Bv, 2000) Durmus, P; Böyükata, M; Özçelik, S; Güvenç, ZB; Jellinek, J
The kinetics of the reactions of nickel clusters with a deuterium molecule are studied, Dissociative chemisorption probabilities of the D(2) molecule on the small Ni(n) (n=7-10) clusters are computed by a quasi-classical molecular dynamics computer simulation technique. Structures of the clusters are obtained by an embedded-atom potential, and the interaction between the D(2) and Ni(n) is modelled by an LEPS (London-Eyring-Polanyi-Sato) function (energy surface). This analysis includes the chemisorption probabilities as functions of the impact parameter and of the relative translational energy of the D(2). The corresponding reactive cross-sections for the ground state of the molecule are calculated as functions of the collision energy and the size of the cluster. The role of the size of the clusters is examined. An indirect mechanism to the reaction, which involves formation of molecular adsorption as precursors to dissociative adsorption in the low collision energy region (less than 0.1eV), is observed. Results are discussed by comparing with the other similar theoretical and experimental studies. (C) 2000 Elsevier Science B.V. All rights reserved.
Citation - WoS: 10
Citation - Scopus: 6
Geometrization of the Lax Pair Tensors
(World Scientific Publ Co Pte Ltd, 2000) Baskal, S; Baleanu, D
The tensorial form of the Lax pair equations are given in a compact and geometrically transparent form in the presence of Cartan's torsion tensor. Three-dimensional space-times admitting Lax tensors are analyzed in detail. Solutions to Lax tensor equations include interesting examples as separable coordinates and the Toda lattice.
Citation - Scopus: 1
Efficiency Evaluation of the Averaging Noise Reduction System
(Ieee, 2001) Kondakci, S
This paper presents the development of a method for estimation of denoising performance performed by an averaging algorithm presented in an earlier work Ill. The method was designed to evaluate statistical results when the noise reduction algorithm was applied to Gaussian-distributed noisy responses from a measurement system. Iterative noise reconstruction algorithm is efficient when number of iterations is kept at a higher level. However, the reduction in noise tends to converge slowly after a certain number of recursions were achieved[l]. Determination of the slow convergence point is important in order to find an optimum system configuration. Otherwise, improper usage will cause reduced system bandwidth, thus making the system useless for real-time measurements.
Citation - WoS: 8
Citation - Scopus: 8
Dynamics of the D2+ni(100) Collision System: Analysis of the Reactive and Inelastic Channels
(Wiley-blackwell, 2001) Böyükata, M; Güvenç, ZB; Jackson, B; Jellinek, J
The reactive and scattering channels of the D(2)(v, j) + Ni(100) collision system are studied using quasiclassical molecular dynamics simulations. The interaction between the D(2) and the atoms of the surface is modeled by a LEPS (London-Eyring-Polani-Sato) potential energy function. The molecule is aimed at three different impact sites (atop, bridge, and center) of a rigid Ni(100) surface along the normal direction with various collision energies less than or equal to1.0 eV. Dissociative chemisorption probabilities are computed for different rotational states of the molecule. Probability distributions of the final rovibrational states of the ground-state Dp molecule scattered from those impact sites are also computed as a function of the collision energy. Higher collision energy results in excitation of higher rotational and/or vibrational states of the scattered molecule. At collision energies below 0.1 eV an indirect dissociation mechanism (through molecular adsorption) dominates the reaction. (C) 2001 John Wiley & Sons, Inc.
Citation - WoS: 27
Citation - Scopus: 29
Nonnormal Regression. I. Skew Distributions
(Taylor & Francis inc, 2001) Islam, MQ; Tiku, ML; Yildirim, F
In a linear regression model of the type y = thetaX + e, it is often assumed that the random error e is normally distributed. In numerous situations, e.g., when y measures life times or reaction times, e typically has a skew distribution. We consider two important families of skew distributions, (a) Weibull with support IR: (0, infinity) on the real line, and (b) generalised logistic with support IR: (-infinity, infinity). Since the maximum likelihood estimators are intractable in these situations, we derive modified likelihood estimators which have explicit algebraic forms and are, therefore, easy to compute. We show that these estimators are remarkably efficient, and robust. We develop hypothesis testing procedures and give a real life example.
Citation - WoS: 14
Citation - Scopus: 14
The Hamilton-Jacobi Treatment of Supersymmetric Quantum Mechanics
(World Scientific Publ Co Pte Ltd, 2001) Baleanu, D; Güler, Y
We study the Hamilton-Jacobi quantization of supersymmetric quantum mechanics. The equations of motion of the Grassmann variables are obtained from the integrability conditions. The results are in agreement with those obtained by Dirac's procedure.
Citation - WoS: 22
Citation - Scopus: 21
Structure and Reactivity of Nin (n=7-14, 19) Clusters
(Wiley, 2001) Böyükata, M; Güvenç, ZB; Özçelik, S; Durmus, P; Jellinek, J
Results of a computer simulation study of Ni-n (n = 7-14, 19) clusters, their structures, energetics, and reactivity with a D-2 molecule are presented. The clusters are described by an embedded atom potential, whereas the interaction between the molecule and the clusters is modeled by an LEPS (London-Eyring-Polanyi-Sato) potential energy function. The focus is on structures of the dusters and their reactive channels. The total numbers of stable isomers of the clusters are obtained by sampling their phase space, and the isomers' energy spectra are determined. On the reactive side, dissociative chemisorptions cross sections and decay-rate constants are calculated. (C) 2001 John Wiley & Sons, Inc.
Citation - WoS: 7
Citation - Scopus: 8
Fragmentation of Water Clusters: Molecular-Dynamics Simulation Study
(Springer-verlag, 2001) Erkoç, S; Kökten, H; Güvenç, Z
The fragmentation of water clusters, [(H2O)(n): n = 2-8], have been investigated by using molecular-dynamics simulation method. In the simulations a polarizable-dissociable potential energy function for water has been used. Particular attention has been paid to investigate the effect of structural properties and cluster size of the fragmentation.
Citation - WoS: 3
Citation - Scopus: 3
Finite Size Scaling by Using Scaling Functions in Two-Dimensional Q=2 and 7 State Potts Models
(World Scientific Publ Co Pte Ltd, 2001) Seferoglu, N; Aydin, M; Gündüç, Y; Demirtürk, S
The scaling behaviors of the percolation cumulant and the surface renormalization are studied on q = 2 and 7 state Potts models. The results show that the scaling functions can be safely used to determine infinite lattice transition points and the thermal and magnetic exponents indicating that these functions have very small correction to scaling contributions.
Citation - WoS: 42
Citation - Scopus: 47
Nonnormal Regression.: Ii.: Symmetric Distributions
(Taylor & Francis inc, 2001) Tiku, ML; Islam, MQ; Selçuk, AS
Salient features of a family of short-tailed symmetric distributions, introduced recently by Tiku and Vaughan [1], are enunciated. Assuming the error distribution to be one of this family, the methodology of modified likelihood is used to derive MML estimators of parameters in a linear regression model. The estimators are shown to be efficient, and robust to inliers. This paper is essentially the first to achieve robustness to infers. The methodology is extended to long-tailed symmetric distributions and the resulting estimators are shown to be efficient, and robust to outliers. This paper should be read in conjunction with Islam et al. [2] who develop modified likelihood methodology for skew distributions in the context of linear regression.
Citation - WoS: 10
Citation - Scopus: 9
Dual Metrics for a Class of Radiative Space-Times
(World Scientific Publ Co Pte Ltd, 2001) Baskal, S; Baleanu, D
Second-rank nondegenerate Killing tensors for some subclasses of space-times admitting parallel null one-planes ace investigated. Lichnerowicz radiation conditions are imposed to provide a physical meaning to space-times whose metrics are described through their associated second-rank Killing tensors. Conditions under which the dual space-times retain the same physical properties are presented.
Citation - WoS: 21
Citation - Scopus: 23
Hamilton-Jacobi Treatment of a Non-Relativistic Particle on a Curved Space
(Iop Publishing Ltd, 2001) Baleanu, D; Güler, Y
In this paper a non-relativistic particle moving on a hypersurface in a curved space and the multidimensional rotator are investigated using the Hamilton-Jacobi formalism. The equivalence with the Dirac Hamiltonian formalism is demonstrated in both Cartesian and curvilinear coordinates. The energy spectrum of the multidimensional rotator is equal to that of a pure Laplace-Beltrami operator with no additional constant arising from the curvature of the sphere.
Citation - WoS: 18
Citation - Scopus: 21
Multi-Hamilton Quantization of O(3) Nonlinear Sigma Model
(World Scientific Publ Co Pte Ltd, 2001) Baleanu, D; Güler, W
The O(3) nonlinear sigma model is investigated using multi-Hamilton-Jacobi formalism. The integrability conditions are investigated and the results are in agreement with those obtained by Dirac's method. By choosing an adequate extension of phase space we describe the transformed system by a set of three Hamilton-Jacobi equations and calculate the corresponding action.

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