Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 11Citation - Scopus: 13Wind Speed Time Series Chacacterization Hy Hilbert Transform(John Wiley and Sons Inc., 2006) Alpay, Selda; Bilir, Levent; Özdemir, Serhan; Özerdem, BarışPredictions of wind energy potential in a given region are based on on-location observations. The time series of these observations would later be analysed and modelled either by a probability density function (pdf) such as a Weibull curve to represent the data or recently by soft computing techniques, such as neural networks (NNs). In this paper, discrete Hilbert transform has been applied to characterize the wind sample data measured on Izmir Institute of Technology campus area which is located in Urla, Izmir, Turkey, in March 2001 and 2002. By applying discrete Hilbert transform filter, the instantaneous amplitude, phase and frequency are found, and characterization of wind speed is acomplished. Authors have also tried to estimate the hourly wind data using daily sequence by Hilbert transform technique. Results are varying.Other Citation - WoS: 1Citation - Scopus: 1Erratum To "total Solidification Time of a Liquid Phase Change Material Enclosed in Cylindrical/Spherical Containers" [applied Thermal Engineering 25 (10) (2005) 1488-1502] (doi:10.1016/J.applthermaleng.2004.10.005)(Elsevier Ltd., 2007) Bilir, Levent; İlken, ZaferRefers To Levent Bilir, Zafer İlken Total solidification time of a liquid phase change material enclosed in cylindrical/spherical containers Applied Thermal Engineering, Volume 25, Issue 10, July 2005, Pages 1488-1502Article Citation - WoS: 84Citation - Scopus: 96Total Solidification Time of a Liquid Phase Change Material Enclosed in Cylindrical/Spherical Containers(Elsevier Ltd., 2005) Bilir, Levent; İlken, ZaferThis study investigates the inward solidification problem of a phase change material (PCM) encapsulated in a cylindrical/spherical container with a third kind of boundary condition. The governing dimensionless equations of the problem and boundary conditions are formulated and solved numerically by using enthalpy method with control volume approach. The problem is solved many times for different values of the affecting parameters and data sets are obtained for dimensionless total solidification time of the PCM. These data sets are then used to derive correlations which express the dimensionless total solidification time of the PCM in terms of Stefan Number, Biot Number and Superheat Parameter.Article Citation - WoS: 101Citation - Scopus: 132Effect of Geometrical Parameters on Heat Transfer and Pressure Drop Characteristics of Plate Fin and Tube Heat Exchangers(Elsevier Ltd., 2005) Erek, Aytunç; Özerdem, Barış; Bilir, Levent; İlken, ZaferIn this study, the influences of the changes in fin geometry on heat transfer and pressure drop of a plate fin and tube heat exchanger are investigated, numerically. A computational fluid dynamics (CFD) program called Fluent is used in the analysis. The segment of one tenth of fin is used in the modeling, due to symmetrical condition. The results of heat transfer, static, and total pressure drop values of ten different fins are tabulated and the normalized values of them are, also, given for the comparison of the models. The distance between fins is found to have a considerable effect on pressure drop. It is observed that placing the fin tube at downstream region affects heat transfer positively. Another important result of the study is that increasing ellipticity of the fin tube increases the heat transfer while it, also, results in an important reduction in pressure drop.