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Article Citation - WoS: 12Citation - Scopus: 17Limit and Application Range of the Slope-Diffraction Method for Wireless Communications(Ieee-inst Electrical Electronics Engineers inc, 2003) Kara, A; Bertoni, HL; Yazgan, E; Bertoni, L.Limitations on the use of the uniform theory of diffraction (UTD) slope-diffraction. method for propagation past knife edges are investigated. The settled field that is diffracted past rows of buildings, as computed by numerical integration, has the characteristics of amplitude and phase variation with a scale length that is large compared to wavelength and,has small amplitude near the edges. Using this field, it is shown that the error in the UTD slope-diffraction method for diffraction past a final screen is connected with the Fresnel width, as compared to the scale length of the settledArticle Citation - WoS: 7Citation - Scopus: 9Electrochemical Copolymerization of 2-Substituted Thiophene Derivative Linked by Polyether Bridge With Thiophene(Elsevier Science Sa, 2005) Cihaner, A; Önal, AMNew conducting copolymers have been synthesized via electrochemical oxidation of thiophene (Th) in the presence of monomer bis(2-thienyl)ethyl (1). Cyclic voltammetry (CV) studies showed that the presence of monomer I in the electrolytic solution greatly changes the CV behaviour of the formation of the polythiophene films. It is found that the increasing ratio of I was found to decrease electroactivity of copoly(I-Th). Electrochemical synthesis of copolymer films was achieved via constant potential electrolysis (CPE) in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF(6)) dissolved in CH3CN. Spectroelectrochemical (SPEL) properties of the films were investigated using UV-vis spectroscopic technique. (C) 2005 Elsevier B.V. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Spectroelectrochemical Investigation of the Anodic Oxidation of Dibenzo-18(Elsevier Science Sa, 2004) Cihaner, A; Önal, AMPoly(dibenzo-18-crown-6) (poly-DB18C6) was synthesized by electrochemical oxidation of dibenzo-18-crown-6 (DB18C6) using a mixture of acetonitrile and dichloromethane as the solvent and tetrabutylammonium tetrafluoroborate (TBABF(4)) or tetrabutylammonium hexafluorophosphate (TBAPF(6)) as supporting electrolyte. The anodic polymerization of DB18C6 was investigated using in situ ESR and in situ UV-Vis spectroscopic techniques. Spectroelectrochemical (SPEL), properties and thermal analysis of the resulting polymers have been investigated using UV-Vis spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). (C) 2004 Elsevier B.V. All rights reserved.Article Citation - WoS: 47Citation - Scopus: 68On the Positive Solutions of the System of Rational Difference Equations(Academic Press inc Elsevier Science, 2006) Ozban, Ahmet YasarOur aim in this paper is to investigate the periodic nature of solutions of the system of rational difference equations x(n+1) = 1/y(n-k), y(n+1) = yn/x(n-mYn-m-k), n = 0, 1,..., where k is a nonnegative integer, m is a positive integer and the initial values x(-m), x(-m+1),..., x(0), y(-m-k), y(-m-k+1),..., y(0) are positive real numbers. (c) 2005 Elsevier Inc. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 6Synthesis and Polymerization of 2-And 3-Substituted Thiophene Derivatives Linked by Polyether Bridges(Elsevier Science Sa, 2004) Tirkes, S; Cihaner, A; Önal, AMNew compounds consisting of 2- and 3-thienyl units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis (CPE) in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF(6)) dissolved in CH3CN. 2-Thienyl monomers (I and II), but not 3-thienyl monomers (III and IV), were also polymerized via chemical oxidation, which yielded broken pi-conjugated polymer products. The polymers were characterized using H-1 NMR and FT-IR spectroscopic techniques. It was found that both chemical and electrochemical oxidation of 2-thienyl monomers gave mainly poly(2,2'-bithiophenemethylene) due to elimination of polyether chains during the polymerization reaction. On the other hand, electrochemical oxidation of 3-thienyl monomers resulted in corresponding polymers without any cleavage of polyether bridges. Spectroelectrochemical (SPEL) properties of the products were investigated using UV-Vis spectroscopic techniques. (C) 2004 Elsevier B.V. All rights reserved.Article Citation - WoS: 50Citation - Scopus: 55Plane Strain Analytical Solutions for a Functionally Graded Elastic-Plastic Pressurized Tube(Elsevier Sci Ltd, 2006) Eraslan, Ahmet N.; Akis, TolgaPlane strain analytical solutions to functionally graded elastic and elastic-plastic pressurized tube problems are obtained in the framework of small deformation theory. The modulus of elasticity and the uniaxial yield limit of the tube material are assumed to vary radially according to two parametric parabolic forms. The analytical plastic model is based on Tresca's yield criterion, its associated flow rule and ideally plastic material behaviour. Elastic, partially plastic and fully plastic stress states are investigated. It is shown that the elastoplastic response of the functionally graded pressurized tube is affected significantly by the material nonhomogeneity. Different modes of plasticization may take place unlike the homogeneous case. It is also shown mathematically that the nonhomogeneous elastoplastic solution presented here reduces to that of a homogeneous one by appropriate choice of the material parameters. (c) 2006 Elsevier Ltd. All rights reserved.Editorial Citation - Scopus: 59Elimination of Overflow Oscillations in Fixed-Point State-Space Digital Filters With Saturation Arithmetic: an Lmi Approach(2004) Kar,H.; Singh,V.A novel, linear-matrix inequality (LMI) based, criterion for the nonexistence of overflow oscillations in fixed-point state-space digital filter employing saturation arithmetic is presented. The criterion is based on a unique characterization (as prevailing in the filter under consideration) of the saturation nonlinearities, namely, an “effective” reduction of the sector. © 2004, The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 4Multi Input Dynamical Modeling of Heat Flow With Uncertain Diffusivity Parameter(Taylor & Francis inc, 2003) Efe, MÖ; Özbay, HThis paper focuses on the multi-input dynamical modeling of one-dimensional heat conduction process with uncertainty on thermal diffusivity parameter. Singular value decomposition is used to extract the most significant modes. The results of the spatiotemporal decomposition have been used in cooperation with Galerkin projection to obtain the set of ordinary differential equations, the solution of which synthesizes the temporal variables. The spatial properties have been generalized through a series of test cases and a low order model has been obtained. Since the value of the thermal diffusivity parameter is not known perfectly, the obtained model contains uncertainty. The paper describes how the uncertainty is modeled and how the boundary conditions are separated from the remaining terms of the dynamical equations. The results have been compared with those obtained through analytic solution.Article Citation - WoS: 21Citation - Scopus: 21Special Standard Static Space-Times(Pergamon-elsevier Science Ltd, 2004) Dobarro, F; Ünal, B; Debarro, FernandoEssentially, some conditions for the Riemannian factor and the warping function of a standard static space-time are obtained in order to guarantee that no nontrivial warping function on the Riemannian factor can make the standard static space-time Einstein. (C) 2004 Elsevier Ltd. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 8Hybrid Electrooptic and Piezoelectric Laser Beam Steering in Two Dimensions(Ieee-inst Electrical Electronics Engineers inc, 2005) Scrymgeour, DA; Koc, B; Tian, LL; Gentzel, MW; Uchino, K; Gopalan, VWith modern optical technology, there is a great demand for devices capable of steering a laser beam. at high speed. A hybrid electrooptical scanner and an electromechanical scanner capable of two-dimensional (2-D) laser beam scanning Eire demonstrated. This device can scan a laser beam in 2-D. A V scanning angle in the horizontal axis at 50 Hz using electrooptic scanning and a 5.23 degrees scanning angle in vertical axis at 25.6 kHz using piezoelectric scanning are shown.
