Browsing by Author "Dinckal, Cigdem"

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Adaptive Decision Fusion Based Framework for Short-Term Wind Speed and Turbulence Intensity Forecasting: Case Study for North West of Turkey
(Tubitak Scientific & Technological Research Council Turkey, 2017) Dinckal, Cigdem; Toreyin, Bechet Ugur; Kucukali, Serhat; Din Çkal, Çigdem
In this paper, an online learning framework called adaptive decision fusion (ADF) is employed for short-term wind speed and turbulence intensity forecasting by use of wind speed data for each season for the city of Izmit, located in the northwest of Turkey. Fixed-weight (FW) linear combination is derived and used for comparison with ADF. Wind speeds and turbulence intensities are predicted from the existing wind speed data and computed turbulence intensities, respectively, using the ADF and FW methods. Simulations are carried out for each season and the results are tested on mean absolute percentage error criterion. It is shown that the proposed model captured the system dynamic behavior and made accurate predictions based on the seasonal wind speed characteristics of the site. The procedure described here can be used to estimate the local velocity and turbulence intensity in a wind power plant during a storm.
Citation - WoS: 4
Citation - Scopus: 4
Design of Integral Spreadsheet Calculator for Engineering Applications
(Wiley, 2018) Dinckal, Cigdem
Although Newton-Cotes integration formulas in engineering have been the subject of the study for a long time, the improvement in formulations is still object of interest. In this sense, design of calculators based on these formulations becomes significant. The purpose of this paper is to design an integral calculator for any engineering problems. Since the integral calculator, easy-to-understand and use, is aimed to be employed by any kind of users. Visual Basic for Applications (VBA) is the programming language of Excel. Excel spreadsheet with VBA is preferred for this purpose. In this study, a user interface input form is introduced. This form is composed of the embedded algorithm. This algorithm includes not only rules and formulations of each Newton-Cotes such as Composite Trapezoidal rule, Simpson's rules, Boole's rules, and Gauss Legendre formulations with 2, 6, 10, 16, and 24 points and exact result of any integral (if it exists) with computed true percent relative error for comparison purposes. This calculator is tested for civil, mechanical, and chemical engineering applications. The results and screenshots for each application obtained from calculator are presented. The present study allows design of an integral spreadsheet calculator for any integral given. If exact result of the integral cannot be obtainable, the calculator can perform only integral calculations numerically without exact solution and computed true percent relative error. Otherwise, user can solve the integrals completely with this tool easily and accurately again but this time by both numerically and analytically with true percent relative error calculations.
Citation - WoS: 1
Citation - Scopus: 1
Dynamics of a Beam-Column Element on an Elastic Foundation
(Canadian Science Publishing, Nrc Research Press, 2016) Alemdar, Bulent N.; Gulkan, Polat H.; Dinckal, Cigdem
An exact analytical solution of a harmonically vibrating beam-column element resting on an elastic Winkler foundation is derived. The solution covers four cases comprised of constant compressive or tensile axial force with the restrictions k(s) - m omega(2) < 0 and k(s) - m omega(2) > 0. The proposed solution is not restricted to a particular range of magnitudes of the foundation parameter. Closed form solutions of dynamic shape functions are explicitly derived for each sub-case to obtain frequency-dependent dynamic stiffness terms that constitute the exact dynamic stiffness matrices. Four numerical examples are provided to demonstrate the merits of the present study.
Exact Forecasting for Covid-19 Data: Case Study for Turkey
(World Scientific Publ Co Pte Ltd, 2021) Dinckal, Cigdem
The novel coronavirus COVID-19 (SARS-CoV-2) with the first clinical case emerged in the city of Wuhan in China in December 2019. Then it has spread to the entire world in very short time and turned into a global problem, namely, it has rapidly become a pandemic. Within this context, many studies have attempted to predict the consequences of the pandemic in certain countries. Nevertheless, these studies have focused on some parameters such as reproductive number, recovery rate and mortality rate when performing forecasting. This study aims to forecast COVID-19 data in Turkey with use of a new technique which is a combination of classical exponential smoothing and moving average. There is no need for reproductive number, recovery rate and mortality rate computation in this proposed technique. Simulations are carried out for the number of daily cases, active cases (those are cases with no symptoms), daily tests, recovering patients, patients in the intensive care unit, daily intubated patients, and deaths forecasting and results are tested on Mean Absolute Percentage Error (MAPE) criterion. It is shown that this technique captured the system dynamic behavior in Turkey and made exact predictions with the use of real time dataset.
On the Mechanical and Elastic Properties of Anisotropic Engineering Materials Based Upon Harmonic Representations
(int Assoc Engineers-iaeng, 2013) Dinçkal, Çiğdem; Dinckal, Cigdem; İnşaat Mühendisliği
This paper presents a new aspect of harmonic decomposition method for elastic constant tensor of various anisotropic materials. Some misprints found in literature are corrected. This procedure derived here, is applied to anisotropic engineering materials possessing different elastic symmetries. In order to gain insight about these applications, numerical illustrations are presented for anisotropic engineering materials. A new description of norm in terms of harmonic tensors is introduced instead of well-known form of norm. This case is a significant innovation for specifying the anisotropy degree of any engineering materials to have opinion about the mechanical and elastic properties of these materials.
Citation - WoS: 1
Citation - Scopus: 4
Orthonormal Decomposition of Third Rank Tensors and Applications
(int Assoc Engineers-iaeng, 2013) Dinckal, Cigdem; Dinçkal, Çiğdem; İnşaat Mühendisliği
A new procedure for representation of third rank tensors in terms of its orthonormal irreducible decomposed parts, namely as irreducible decomposition is presented. Orthonormal tensor basis method is developed by using the results of existing theory in the literature. As an example to third rank tensors, piezoelectricity tensor is decomposed by each method and results of this decomposition methods are compared for this tensor in hexagonal symmetry. As a result of comparison process, it is stated that the results for new method and other one are consistent and each decomposed parts have physical meaning. Moreover, the norm concept of piezoelectricity tensor is used to study the piezoelectric effect of some materials. It is also shown that one can determine in which material the piezoelectric effect is stronger by using the norm for different materials with the same symmetries.
Citation - WoS: 32
Citation - Scopus: 31
Wind Energy Resource Assessment of Izmit in the West Black Sea Coastal Region of Turkey
(Pergamon-elsevier Science Ltd, 2014) Kucukali, Serhat; Dinckal, Cigdem
The wind energy potential of Izmit (41.19 N, 30.30 E), which is located in the West Black Sea Coastal Region of Turkey, is assessed with the statistical analysis of the gathered wind data at the 50-m height measurement mast covering the period of 06/2008-06/2009. The annual average wind speed is calculated as 6 m/s and the prevailing wind direction is ENE (60 degrees). The Weibull distribution parameters of shape and scale factor are found as 2.03 and 6.73 m/s, respectively. The measured wind speed data are compared with the data of nearby meteorological stations and the results show that there is a considerable difference between the onsite measurements and the measurements of the meteorological stations. Moreover, a turbulence analysis is carried out and the turbulence intensity is negatively correlated with the normalized height from ground level with canopy height. The energy generation performances of three different wind turbines are evaluated by using the onsite wind speed measurements and the assessment shows that the capacity factor increase by a factor of two from 17% to 34% depending on the type of the turbine. Furthermore, an economic analysis is carried out for a 50 MW wind energy project for the potential site and the proposed project benefit/cost ratio is calculated as 8. (C) 2013 Elsevier Ltd. All rights reserved.