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Article Citation - WoS: 5Citation - Scopus: 5Electrochemical Polymerization of Para-Substituted Haloanilines(Taylor & Francis inc, 2006) Cihaner, A; Önal, AMPolyhaloanilines: poly(4-fluoroaniline) (P4FAN), poly(4-chloroaniline) (P4CAN), and poly(4-bromoaniline) (P4BAN), are synthesized from para-substituted haloaniline monomers; 4-fluoroaniline (4FAN), 4-chloroaniline (4CAN), and 4-bromoaniline (4BAN), respectively, via constant potential electrolysis (CPE) in acetonitrile-water mixture (1:1 v/v) with NaClO4 as supporting electrolyte. Prior to CPE, electrochemical behavior of the monomers were investigated in organic medium utilizing cyclic voltammetry (CV). The course of CPE was monitored using in-situ UV-VIS spectroscopic technique. Characterization of polymer products have been carried out using FT-IR and NMR spectroscopic techniques and thermal behaviors were studied using differential scanning calorimeter (DSC). Polyhaloanilines synthesized by electrochemical oxidation were doped using iodine and the change in the paramagnetic behavior was monitored by ESR, UV-VIS, and FT-IR.Article 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: 49Citation - Scopus: 54Elimination of Overflow Oscillations in Digital Filters Employing Saturation Arithmetic(Academic Press inc Elsevier Science, 2005) Kar, H; Singh, VA criterion for the nonexistence of overflow oscillations in a class of digital filters employing saturation arithmetic is presented. The criterion is based on a novel characterization of the saturation nonlinearity (namely, the 'reduced sector' characterization) and, hence, is quite distinct from previously reported criteria. (c) 2005 Elsevier Inc. All rights reserved.Article Citation - WoS: 28Citation - Scopus: 30A Piezoelectric Micromotor With a Stator of φ=1.6 Mm and l=4 Mm Using Bulk Pzt(inst Pure Applied Physics, 2004) Cagatay, S; Koc, B; Moses, P; Uchino, KThe smallest discrete piezoelectric ultrasonic motor using bulk ceramics was developed. We are proposing basically a two-part motor: stator and rotor. The stator of the present motor consists of a hollow metal brass tube with outer diameter of 1.6 mm, inner diameter of 0.8 mm and length of only 4 mm with 2 PZT plates bonded onto it. Owing to the asymmetrical stator surface, two degenerated orthogonal bending modes were slightly split, resulting in a wobbling motion. Thus, the motor can be driven by a single driving source. The rotor is a spring, which is basically different from previous designs, pressed at both ends to the stator by a pair of ferrules. Consequently, the length of the whole motor assembly was reduced significantly; a final motor length cf only 5 mm was obtained. The working frequency under zero load was approximately 227-233 kHz. Although the size is small, relatively high power was obtained under an optimized load condition: torque of 0.06mNm, maximum power of 3.2 mW with a speed of 118 rad/s, and maximum efficiency of 11% under 48 Vrms at 221 kHz.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: 1Citation - Scopus: 3Multivariable Nonlinear Model Reference Control of Cement Mills(Arnold, Hodder Headline Plc, 2003) Efe, MÖ; Department of Electrical & Electronics EngineeringThis paper presents a method for model reference control of a cement milling circuit that has previously been studied several times. The approach presented is based on an experimentally justified model of a cement milling circuit. We derive the form of the control vector with the goal of driving the response of the system to that of a desired model in a noisy operating environment. The paper demonstrates the selection of the reference dynamics and the derivation of the control laws. The approach is based on the Lyapunov theory, and the results observed justify the tracking and stability claims of the paper.Letter Citation - WoS: 22Citation - Scopus: 24A Note on Determination of Oscillation Startup Condition(Springer, 2006) Singh, VimalThere prevails a widespread notion that, given a closed-loop system, oscillation will commence and build up therein if the magnitude of loop gain is greater than unity at the frequency at which the angle of loop gain is zero degree. Three novel examples in which this notion fails are presented.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: 4Citation - Scopus: 5Roof Shape Modelling for Multiple Diffraction Loss in Cellular Mobile Communication Systems(Taylor & Francis Ltd, 2002) Kara, A; Yazgan, EThe effects of roof shapes on multiple diffraction loss in cellular mobile communication systems are investigated. Building roofs are modelled as finitely conducting wedges with different, included angles (peaked roofs). Multiple diffraction loss, a measure of diffraction loss due to multiple building geometry, is computed by using the method of UTD (uniform theory of diffraction) for 90degrees and 120degrees wedges over the communication paths oblique to building blocks. The results, compared with the absorbing edge model, 0degrees wedge, show that multiple diffraction loss decreases with increasing wedge angle.Article A boundary value problem for second-order nonlinear difference equations on the integers(Cambridge Univ Press, 2005) Dal, F; Guseinov, GSIn this study, we are concerned with a boundary value problem (BVP) for nonlinear difference equations on the set of all integers Z, under the assumption that the left-hand side is a second-order linear difference expression which belongs to the so-called Weyl-Hamburger limit-circle case. The BVP is considered in the Hilbert space l(2) and includes boundary conditions at infinity. Existence and uniqueness results for solution of the considered BVP are established.
