Scopus İndeksli Yayınlar Koleksiyonu

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

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Now showing 1 - 20 of 4859

Citation - Scopus: 7
On the solution of a parabolic PDE involving a gas flow through a semi-infinite porous medium
(Amsterdam, 22) Pop, Daniel N.; Vrinceanu, N.; Al-Omari, S.; Ouerfelli, N.; Baleanu, D.; Nisar, K. S.; 56389; Matematik
Taking as start point the parabolic partial differential equation with the respective initial and boundary conditions, the present research focuses onto the flow of a sample of waste-water derived from a standard/conventional dyeing process. In terms of a highly prioritized concern, meaning environment decontamination and protection, in order to remove the dyes from the waste waters, photocatalyses like ZnO or TiO2 nanoparticles were formulated, due to their high surface energy which makes them extremely reactive and attractive. According to the basics of ideal fluid, the key point is the gas flow through an ideal porous pipe consisting of nanoparticles bound one to each other, forming a porous matrix/pipe. The modeling of the gas flow through a porous media is quite valuable because of its importance in investigating the gas-solid processes. The present study is a valid contribution to the existing literature, by developing a nonstandard line method for the partial differential equation, in order to obtain a numerical solution of unsteady flow of gas through nano porous medium. Hence, the physical problem is modeled by a highly nonlinear ordinary differential equation detailed on a semi-finite domain and represents a guidance for several questions originating in the gas flow theory. The findings of this study offered a facile approach to improve an attractive issue related to materials science/chemistry, like synthesis of ZnO or TiO2 nanoparticles forming an ideal nano porous pipe with efficiency in industrial waste waters decontamination.
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The Hubert space L2(ℝ3), to which the wavefunction of the three-dimensional Schrödinger equation belongs, has been replaced by L2(Ω), where Ω is a bounded region.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 - WoS: 2
Citation - Scopus: 3
Higher order finite element solution of the one-dimensional Schrodinger equation
(John Wiley & Sons inc, 1999) Eid, R; 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: 7
Citation - Scopus: 5
Hamilton-Jacobi quantization of the finite-dimensional systems with constraints
(Editrice Compositori Bologna, 1999) Baleanu, D; Güler, Y; 56389; 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: 0
Citation - Scopus: 0
Lax tensors and separable coordinates in (2+1) dimensions
(inst Physics Acad Sci Czech Republic, 2000) Baleanu, D; Baskal, S; 56389; Matematik
We study the Lax tensors of the separable coordinates in (2+1) dimensions. The Lax tensors of the dual manifolds are investigated.
Citation - WoS: 10
Citation - Scopus: 6
Geometrization of the Lax pair tensors
(World Scientific Publ Co Pte Ltd, 2000) Baleanu, D; Baskal, S; 56389; Matematik
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 - WoS: 12
Citation - Scopus: 14
Reactions of small Ni clusters with a diatomic molecule: MD simulation of D(2)+Ni(n) (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: 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.; Güler, Y.; 56389; 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.
Citation - WoS: 3
Citation - Scopus: 2
Symmetries of NUT-Kerr-Newman dual metrics
(Soc Italiana Fisica, 2001) Baleanu, D; 56389; Matematik
The symmetries of NUT-Kerr-Newman (NUT-KN) dual metrics are analysed. The NUT-Kerr-Newman dual spinning space is constructed in the presence of torsion.
Citation - WoS: 0
Citation - Scopus: 0
An approach to noise reduction in human skin admittance measurements
(Ieee, 2001) Kondakci, S; Kondakci, S; 102350; Bilgisayar Mühendisliği
This paper presents the development of a signal averaging algorithm for recovering excitation responses contaminated by overwhelming amount of various types of interference in skin admittance measurements. The algorithm is designed to eliminate Gaussian-distributed noise by use of a recursive approach. The process of recovering low magnitude voltage responses from highly noise-contaminated waveforms is a CPU-intensive task. In real-time measurements, iterative reconstruction algorithm is inefficient and time consuming when slow varying input waveforms are present. To increase the quality of the reconstruction a considerably large number of recursions is required. Increasing the number of recursions is appropriate for batch processing of measurement data. However, the algorithm considers measurements in real-time, whereas required quality of signal reconstruction should be kept independent from the number of recursions.
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: 14
Citation - Scopus: 14
The hamilton-jacobi treatment of supersymmetric quantum mechanics
(World Scientific Publ Co Pte Ltd, 2001) Baleanu, D; Güler, Y; 56389; Matematik
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: 57
Citation - Scopus: 67
Spectrophotometric multicomponent analysis of a mixture of metamizol, acetaminophen and caffeine in pharmaceutical formulations by two chemometric techniques
(Pergamon-elsevier Science Ltd, 2001) Dinç, E; Baleanu, D; Onur, F; 56389; Matematik
Inverse least squares (ILS) and factor-based (principal component analysis (PCA)) techniques were proposed for the spectrophotometric multicomponent analysis of a ternary mixture consisting of metamizol, acetaminophen and caffeine, without prior separation. In these chemometric techniques, the measurements of the absorbance values were realized in the spectral range from 225 to 285 nm in the intervals of Delta lambda = 5 nm at the 13 wavelengths in the zero-order spectra of the different ternary mixtures of these active ingredients in 0.1 M HCl. The prepared calibrations of both techniques using the absorbance data and concentration matrix data sets were used to predict the concentration of the unknown concentrations of metamizol acetaminophen and caffeine in their ternary mixture. The 'MAPLE V' software was used for the numerical calculations, Mean recoveries and relative standard deviations for ILS and PCA techniques were found to be 99.8 and 1.68%, 99.9 and 1,66% for caffeine, 99.8 and 1.84%, 100.4 and 2.85% for metamizol, and 99.7 and 1.04%, 99.6 and 1.34/ for acetaminophen, respectively, for the first and second techniques. The techniques were successfully applied to two pharmaceutical formulations marketed in Turkey and results were compared with a new high-performance liquid chromatography method. (C) 2001 Elsevier Science B.V. All rights reserved.
Citation - WoS: 0
Citation - Scopus: 0
Hamilton-Jacobi quantization of constrained systems
(inst Physics Acad Sci Czech Republic, 2001) Baleanu, D; Güler, Y; 56389; Matematik
The path integral quantization of contrained systems is analysed using Hamilton-Jacobi formalism. The integrability conditions are investigated and the results are in agreement with those obtained by Dirac's method.
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: 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: 0
Citation - Scopus: 1
Efficiency evaluation of the averaging noise reduction system
(Ieee, 2001) Kondakci, S; Kondakci, S; 102350; Bilgisayar Mühendisliği
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: 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) Demirtürk, S; Seferoglu, N; Aydin, M; Gündüç, Y; Matematik
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: 3
Citation - Scopus: 2
Hamilton-Jacobi treatment of chiral schwinger model
(Kluwer Academic/plenum Publ, 2001) Baleanu, D; Güler, Y; 56389; Matematik
We investigate the path integral quantization of the bosonic chiral Schwinger model using multi-Hamilton-Jacobi procedure. The integrability conditions require the extension of the initial phase space. The Wess-Zumino term was recovered calculating the action corresponding to the extended system.

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