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Yayın Design of optimum nyquist signals based on generalized sampling theory for data communications(IEEE, Piscataway, NJ, United States, 1999-06) Panayırcı, Erdal; Özuğur, Timuçin; Çağlar, HakanA new method is given for the optimal design of bandlimited Nyquist-type signal shapes for data communications, which maximizes its energy in a given time interval. The method is based on the periodically nonuniform sampling (PNS) theory making use of the linear splines. The computation is straightforward, and the constraint for intersymbol interferrence is shown to be easy to include in the problem. A numerical example is given, and performance of the optimal signal shapes is compared with that resulting from the use of previously obtained signal shapes in the literature. It is also concluded that the optimal signal shapes thus obtained are almost immune to small offsets at the sampling instants.Yayın Comments on "upper cutoff frequency of the bound wave and new leaky wave on the slotline"(IEEE-INST Electrical Electronics Engineers Inc, 1999-05) İdemen, Mehmet Mithat; Büyükaksoy, İbrahim Alinur[No abstract available]Yayın Adaptive identification and equalization of magnetic recording channels(Wiley-Blackwell, 1998-03) Özden, Mehmet Tahir; Kayran, Ahmet Hamdi; Panayırcı, ErdalA new RLS adaptive Volterra filter is presented. The nonlinear filtering problem is transformed into an equivalent multichannel, but linear, filtering problem. The multichannel input signal is completely orthogonalized using sequential processing multichannel lattice stages. Thus, a fast convergent, highly modular and, simple filter with good numerical properties is designed. In the identification of magnetic recording channels, the filter identifies the channels directly and parameters for the channel nonlinearity are quantified simultaneously. In the equalization of magnetic channels, the most effective equalizer length can be assigned dynamically.Yayın Sürdürülebilir turizm ve Türkiye(Detay Yayıncılık, 1999-06-01) Akış, SevginÖnemli bir döviz kaynağı ve istihdam alanı olan turizm, pek çok ülkenin kalkınmasına katkıda bulunmaktadır. Uluslararası turizmin giderek yaygınlaşması, doğal ve fiziksel çevre ile sosyal ve kültürel yaşamda önemli değişmelere yol açmaktadır. Oysa turizmin dengeli bir şekilde gelişebilmesi için, turizmin dayandığı çevresel kaynakların, yani doğal ve insan yapısı kaynaklar ile sosyal dokununın korunması gerekmektedir. Sürdürülebilir turizm ile hedeflenen, turistik bölgelerin yerel özelliklerini koruyarak, turizmin devamlılığını sağlamaktır. Özellikle 1980'li yıllarda artan "yeşil" harekete paralel olarak, sürdürülebilir turizm tartışmaları da hızlanmıştır. Bu çalışmada önce sürdürülebilir turizm kavramı irdelenmiş, daha sonra turizmin Türkiye ekonomisindeki yeri sürdürülebilirlik çerçevesinde ele alınarak değerlendirilmiştir. Görünen odur ki, Türkiye 'de turizm politikaları belirlenirken turist sayısını ve yatak kapasitesini artırmak temel hedef olmuş, çevre korumacılığına dikkat edilmemiştir. Son yıllarda turizmin çeşitlendirilmesi ve alt yapının iyileştirilmesi yolunda alınan kararlar hem yetersizdir, hem de tam olarak uygulanamamaktadır.Yayın Modulation of nonlinear waves in a thin elastic tube filled with a viscous fluid(Pergamon-Elsevier Science Ltd, 1999-11) Demiray, HilmiIn the present work, utilizing the nonlinear equations of a prestressed thin elastic tube filled with an incompressible viscous fluid the propagation of weakly nonlinear waves in such a medium is studied. Considering that the arteries are initially subjected to a large static transmural pressure P-0 and an axial stretch lambda(z) and, in the course of blood flow, a finite time dependent displacement is added to this initial field, the nonlinear equations governing the motion of the tube in the radial direction is obtained. Utilizing the reductive perturbation technique the amplitude modulation of weakly nonlinear and dissipative but strongly dispersive waves is examined. The localized travelling wave solution to the evolution equation is given and the stability condition is discussed.Yayın A numerical real frequency broadband matching technique based on parametric representation of scattering parameters(IEEE, 1998-11-24) Aksen, Ahmet; Çimen, Ebru Gürsu; Yarman, Bekir Sıddık BinboğaIn this study, a computer, aided broadband matching technique based on the parametric representation of scattering parameters is proposed. The new technique combines the advantageous of the so called parametric approach utilizing the impedance formalizm and the real frequency scattering technique. With the reformulation of these real frequency techniques, some laborous numerical computational steps are omitted. The descriptive network functions are obtained in an explicit form without any need to the polynomial factorizations and the solution of equation sets. The application of the technique and the comparision of the results with those of the other real frequency approaches is discussed on examples.Yayın Analysis of self noise in a clock recovery systems with a high-order nonlinearity(IEEE, 1998) Panayırcı, ErdalThis paper presents a new technique to compute efficiently the I and Q spectra, and the I - Q cross-spectrum of the self noise appearing at the output of the zero-memory, high order nonlinear device employed in a clock recovery system. It is known that these spectra play an important role in the phase jitter performance of the clock regenerator. The results are very general and applicable to many cases of practical interest. A numerical example provided at the end of the paper shows that the new approach yields very accurate results and is much faster that the usual computer simulation method.Yayın Analysis of self noise in a clock recovery systems with a high-order nonlinearity(Bogazici University Bebek, 1999) Panayırcı, ErdalThis paper presents a new technique to compute efficiently the I and Q spectra, and the I - Q cross-spectrum of the self noise appearing at the output of the zero-memory, high order nonlinear device employed in a clock recovery system. It is known that these spectra play an important role in the phase jitter performance of the clock regenerator. The results are very general and applicable to many cases of practical interest. A numerical example provided at the end of the paper shows that the new approach yields very accurate results and is much faster that the usual computer simulation method.Yayın A modified reductive perturbation method as applied to nonlinear ion-acoustic waves(Physical Society Japan, 1999-06) Demiray, HilmiThe basic equations describing the nonlinear ion-acoustic waves in a cold collisionless plasma, in the longwave limit, is re-examined through the use of a modified reductive perturbation method. Introducing the concept of a scale parameter and expanding the variables and the scale parameter into a power series of the smallness parameter epsilon, a set of evolution equations is obtained for various order terms in the perturbation expansion. To illustrate the present derivation, a localized travelling wave solution is studied for the derived field equations and the result is compared with those of obtained by Sugimoto and Kakutani(3)) who introduced some slow scales, Kodama and Taniuti(4)) who employed the renormalization method and Malfliet and Wieers,(6)) who employed the dressed solitary wave approach from the outset of their study.Yayın Weakly nonlinear waves in a prestressed thin elastic tube containing a viscous fluid(Pergamon-Elsevier Science Ltd, 1999-11) Antar, Nalan; Demiray, HilmiIn this work, we studied the propagation of weakly nonlinear waves in a prestressed thin elastic tube filled with an incompressible viscous fluid. In order to include the geometrical and structural dispersion into analysis, the wall's inertial and sheer deformation are taken into account in determining the inner pressure-inner cross sectional area relation. Using the reductive perturbation technique, the propagation of weakly nonlinear waves, in the long-wave approximation, is shown to be governed by the Korteweg-de Vries-Burgers (KdVB) equation. Due to dependence of coefficients of the governing equation on the initial deformation, the material and viscosity parameters, the profile of the travelling wave solution to the KdVB equation changes with these parameters. These variations are calculated numerically for some elastic materials and the effects of initial deformation and the viscosity parameter on the propagation characteristics are discussed.
