İnşaat Mühendisliği Bölümü Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/395

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Citation Count: Dinçkal, Ç. (2011). "Adaptation of generalized Hill inequalities to anisotropic elastic symmetries", International Journal of Engineering, Science and Technology, Vol.3, No.4.
Adaptation of generalized Hill inequalities to anisotropic elastic symmetries
(2011) Dinçkal, Çiğdem; 26773
Mechanical and elastic behaviors of anisotropic materials are investigated in an innovative way. This is based on generalized Hill inequalities. From different type of anisotropic elastic symmetries, numerical examples are given. Constructing bounds on effective eigenvalues provides a deeper understanding about mechanical behavior of anisotropic materials. Generalized Hill inequalities are adapted to all anisotropic elastic symmetries. The materials selected from the same symmetry type which have larger interval between the bounds, are more anisotropic whereas smaller interval between the bounds, are closer to isotropy. Besides it is proved that there are relations between bulk and shear modulus and eigenvalues of cubic and isotropic symmetry and by these relations, two linear invariants are found out.
Citation Count: Dinckal, Cigdem; Toreyin, Bechet Ugur; Kucukali, Serhat (2017). Adaptive decision fusion based framework for short-term wind speed and turbulence intensity forecasting: case study for North West of Turkey, Turkish Journal Of Electrical Engineering And Computer Sciences, 25(4), 2770-2783.
Adaptive decision fusion based framework for short-term wind speed and turbulence intensity forecasting: case study for North West of Turkey
(Tubitak Scientific & Technical Research Council Turkey, 2017) Dinçkal, Çiğdem; Töreyin, Behçet Uğur; Küçükali, Serhat; 20413; 26773
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 Count: Dinçkal, Ç. (2011). "Analysis of Elastic Anisotropy of Wood Material for Engineering Applications", Journal of Innovative Research in Engineering and Science, Vol.2, No.2.
Analysis of Elastic Anisotropy of Wood Material for Engineering Applications
(2011) Dinçkal, Çiğdem; 26773
This paper presents a convenient method to describe the degree of the elastic anisotropy in a given type of wood and then discusses its practical values. Besides mechanical and elastic behaviour of wood are investigated in order to understand the optimum mechanical behaviour of it in selected directions. Bounds on the wood elastic constants have been constructed in terms of elasticity and compliance tensors for any type of woods by developing Hill (1952) approach. So for any type of wood with known elastic constants, it is possible to choose the best set of elastic constants (effective elastic constants) which determine the optimum mechanical and elastic properties of it. Bounds on the wood elastic constants as well as the degree of elastic anisotropy are significant and critical cases in design of any engineering and structural materials made up of wood.
Citation Count: Dinçkal, Çiğdem (2020). "Design of a Versatile and Rapid Calculator for Oncological Computations", Human-Computer Interaction, USA: Nova Science Publisher, pp. 63-82, 2020.
Design of a Versatile and Rapid Calculator for Oncological Computations
(Nova Science Publisher, 2020) Dinçkal, Çiğdem; 26773
Citation Count: Dinckal, Cigdem, "Design of integral spreadsheet calculator for engineering applications", Computer Applications In Engineering Education, Vol. 26, No. 5, pp. 1159-1172, (2018)
Design of Integral Spreadsheet Calculator for Engineering Applications
(Wiley, 2018) Dinçkal, Çiğdem; 26773
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 Count: Alemdar, B.N.; Dinçkal, Çiğdem (2016). "Dynamic stability of planar frames supported by elastic foundation", Structural Stability Research Council Annual Stability Conference 2016, SSRC 2016, Structural Stability Research Council Annual Stability Conference 2016, SSRC 2016Orlando12 April 2016 through 15 April 2016, pp. 422-441.
Dynamic stability of planar frames supported by elastic foundation
(2016) Alemdar, B.N.; Dinçkal, Çiğdem; 26773
An exact analytical solution for a vibrating beam-column element on an elastic Winkler foundation is derived. The solution covers all cases comprised of constant compressive and tensile axial force with restrictions of ks -mω1 > 0 and ks -ma>2 < 0. Closed form solutions of dynamic shape functions are explicitly derived for each case and they are used to obtain frequency-dependent dynamic stiffness terms. Governing dynamic equilibrium equations are not only enforced at element ends, but also at any point along the element. To this end, derived stiffness terms are exact and they include distributed mass effects and geometric nonlinear effects such as axial-bending coupling. For this reason, the proposed solution eliminates the need of further element discretization to obtain more accurate results. In absence of elastic foundation (i.e., ks → 0), exact dynamic stiffness terms for beam-columns are also derived and presented in this study. Derived stiffness terms are implemented in a software program and several examples are provided to demonstrate the potential of the present study.
Citation Count: Dinckal, Cigdem; Alemdar, Bulent N.; Gulkan, Polat H., "Dynamics of a beam-column element on an elastic foundation", Canadian Journal of Civil Engineering, Vol. 43, No. 8, pp. 685-701, (2016).
Dynamics of a beam-column element on an elastic foundation
(Canadian Science Publishing, 2016) Dinçkal, Çiğdem; Alemdar, Bülent N.; Gülkan, Polat H.; 26773; 5743
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.
Citation Count: Dinçkal, Ç. (2021). "Exact Forecasting for COVID-19 Data: Case Study for Turkey", Advances in Data Science and Adaptive Analysis, Vol.13, No.2.
Exact Forecasting for COVID-19 Data: Case Study for Turkey
(2021) Dinçkal, Çiğdem; 26773
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.
Citation Count: Dinçkal, Ç. (2016). "Finite Element Modeling for Vibration of Initially Stressed Non- local Euler-Bernoulli Beams", Celal Bayar Üniversitesi Fen Bilimleri Dergisi, Vol.12, No.3, pp.399-412.
Finite Element Modeling for Vibration of Initially Stressed Non- local Euler-Bernoulli Beams
(2016) Dinçkal, Çiğdem; 26773
This paper is concerned with a precise finite element model for vibration analysis of initially stressed micro/nano beams based on nonlocal Euler-Bernoulli and Eringen's nonlocal elasticity theory. For this purpose analytical solutions for the exact dynamic shape functions has been derived by also use of Hamiltonian's principle for the governing equations. The solution is applicable to various initial stresses such as tensile and compressive and scaling effect. The exact dynamic shape functions have been constructed to obtain analytic expressions for the exact dynamic element stiffness matrix components. Numerical results are displayed to indicate the effects of initial stresses and scaling effect parameters on the vibration characteristics of initially stressed clamped nonlocal Euler-Bernoulli beams. For the first time in literature, this study presents such an element formulation that it provides adequate and accurate representation of the vibration behavior of initially stressed micro/nano beams based on nonlocal Euler-Bernoulli beam theory.
Citation Count: Dinckal, C., "Free Vibration Analysis of Carbon Nanotubes by Using Finite Element Method", Iranian Journal of Science and Technology-Transactions of Mechanical Engineering, Vol. 40, No. 1, pp. 43-55, (2016).
Free Vibration Analysis of Carbon Nanotubes by Using Finite Element Method
(Springer, 2016) Dinçkal, Çiğdem; 26773
In the present study, an efficient and accurate finite element model for vibration analysis of carbon nanotubes (CNTs) with both Euler-Bernoulli and Timoshenko beam theory has been presented. For this purpose, an analytical solution for the exact dynamic shape functions of CNTs based on both Euler-Bernoulli and Timoshenko beam theories has been derived. The solution is general and is not restricted to a particular range of magnitudes of the nonlocal parameters. The exact dynamic shape functions have been utilized to derive analytic expressions for the coefficients of the exact dynamic (frequency-dependent) element stiffness matrix. Numerical results are presented to figure out the effects of nonlocal parameter, mode number and slenderness ratio on the vibration characteristics of CNTs. It is shown that these results are in good agreement with those reported in the literature. Present element formulation will be useful for structural analyses of nanostructures with complex geometries, loadings, material properties and boundary conditions.
Citation Count: Dinçkal, Çiğdem. "Harmonic Decomposition of Elastic Constant Tensor and Crystal Symmetry", in Transactions on Engineering Technologies, Springer, pp. 177- 194, 2014.
Harmonic Decomposition of Elastic Constant Tensor and Crystal Symmetry
(2014) Dinçkal, Çiğdem; 26773
This paper presents a new outlook on harmonic decomposition method for elastic constant tensor. Harmonic decomposition method is developed in such a way that it is applied to anisotropic engineering materials exhibiting different crystal symmetry. The explicit results for each crystal symmetry types are presented. Numerical examples serve to illustrate and verify the developed method. This new representation of elastic constant tensor is compared with other theories such as orthogonal and non-orthogonal irreducible decompositions in literature. The results demonstrate that there are significant relationships between harmonic, non-orthogonal irreducible and orthogonal irreducible decomposition methods. While in harmonic and non-orthogonal irreducible decomposition methods, decomposition of total scalar part is not orthogonal. It is proposed that it is possible to make these parts orthogonal to each other.
Citation Count: Dinçkal, Çiğdem. (2018). "Initial value problems spreadsheet solver using VBA for engineering education", Fundamental Journal of Mathematics and Applications, Vol.1, No.1, pp.88-101.
Initial value problems spreadsheet solver using VBA for engineering education
(2018) Dinçkal, Çiğdem; 26773
Spreadsheet solver using VBA programming has been designed for solving initial value problems (IVPs), analytically and numerically by all Runge-Kutta (RK) methods including also fifth order with calculation of true percent relative error for corresponding RK method. This solver is user-friendly especially for beginner users of Excel and VBA.
Citation Count: Dinçkal, Çiğdem, "Lecture Notes in Engineering and Computer Science", Lecture Notes in Engineering and Computer Science, Vol. 2197, pp. 187-193 ,(2019).
Lecture Notes in Engineering and Computer Science
(Newswood Limited, 2012) Dinçkal, Çiğdem; 26773
A new procedure for representation of elastic constant tensor in terms of its orthonormal decomposed parts is presented. Form invariants and orthonormalized basis elements are used to generate this decomposition method. Numerical examples from various engineering materials serve to illustrate and verify the decomposition procedure. The norm concept of elastic constant tensor and norm ratios are used to study the anisotropy of these materials. It is shown that this method allows to investigate the elastic and mechanical properties of an anisotropic material possessing any material symmetry and determine anisotropy degree of that material. For a material given from an unknown symmetry, it is possible to determine its material symmetry type by this method.
Citation Count: Dinçkal, Çiğdem. (2017). "New predictor-corrector type iterative methods for solving nonlinear equations", Sakarya University Journal of Science, pp.464-468.
New predictor-corrector type iterative methods for solving nonlinear equations
(2017) Dinçkal, Çiiğdem; 26773
This paper proposes two new predictor-corrector type iterative methods for finding roots of nonlinear equations. These methods are generated by based on the combination of the two well known Bisection method and Newton-Raphson method. Various numerical examples serve to verify the main purpose of these methods and compare the numerical results. Numerical results are also presented to test the convergence rate of these new proposed methods in terms of number of iterations achieved to reach the exact root of any nonlinear equation. These numerical results obtained also indicate that new proposed methods perform better than both well known methods Bisection and Newton-Raphson and also the other methods in literature.
Citation Count: Dinçkal, Çiğdem. (2011). "Norm, norm ratio calculations and anisotropy degree", International Journal of Pure and Applied Mathematics, Vol.69, No.2, pp.125-136.
Norm, norm ratio calculations and anisotropy degree
(2011) Dinçkal, Çiğdem; 26773
In this paper, for elastic constant tensor, the norm concept, norm ratio and anisotropy degree are described. The norm of a tensor is used as a criterion for comparing the overall effect of the properties of anisotropic materials and norm ratios are used as a criterion to represent the anisotropy degree of the properties of these materials. Norm and norm ratios as well as the measure of "nearness" to the nearest isotropic tensor are computed for several examples from various anisotropic materials possessing elastic symmetries such as cubic, transversely isotropic, tetragonal, trigonal and orthorhombic. These computations are used to compare and assess the anisotropy in various anisotropic materials by means of strength or magnitude and also determine the "nearness" of the nearest isotropic tensor for the materials with lower symmetry types.
Citation Count: Dinçkal, Çiğdem (2020). "Novel Alternative Methods to Romberg Integration and Richardson’s Extrapolation with Matlab Package:Integral_Calculator", MathLAB Journal, Vol. 5.
Novel Alternative Methods to Romberg Integration and Richardson’s Extrapolation with Matlab Package:Integral_Calculator
(2020) Dinçkal, Çiğdem; 26773
This paper introduces new integration methods for numerical integration problems in science and engineering applications. It is shown that the exact results of these integrals can be obtained by these methods with the use of only 2 segments. So no additional function and integrand evaluations are required for different levels of computation. This situation overcomes the computational inefficiency. A new Matlab Package; Integral_Calculator is presented. Integral_Calculator provides a user-friendly computational platform which requires only 3 data entries from the user and performs the integration and give the results for any functions to be integrated. This package has been tested for each numerical example considered below.
Citation Count: Dinçkal, Çiǧdem (2013). "On the mechanical and elastic properties of anisotropic engineering materials based upon harmonic representations", Lecture Notes in Engineering and Computer Science, Vol. 3, pp. 2177-2183.
On the mechanical and elastic properties of anisotropic engineering materials based upon harmonic representations
(2013) Dinçkal, Çiǧdem; 26773
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 Count: Dinçkal, Çiğdem (2012). "On the properties of anisotropic engineering materials based upon orthonormal representations", IAENG International Journal of Applied Mathematics, Vol. 42, No. 3, pp. 183-192.
On the properties of anisotropic engineering materials based upon orthonormal representations
(2012) Dinçkal, Çiğdem; 26773
A decomposition method[5] based upon orthonormal representations is reviewed and improved toexpress any anisotropic engineering tensor showing the effect of the material properties on the structures. A new decomposed form for the stress tensor (example for symmetric second rank tensor) different from the one available in the literature where the engineering understanding is improved, is presented. Numerical examples from different engineering materials serve to illustrate and verify the decomposition procedure. The norm concept of elastic constant tensor and norm ratios are used to study the anisotropy of these materials. It is shown that this method allows to investigate the elastic and mechanical properties of an anisotropic material possessing any material symmetry and determine anisotropy degree of that material. For a material given from an unknown symmetry, it is possible to determine its material symmetry type by this method.
Citation Count: Dinçkal, Çiğdem, "On the properties of piezoelectric materials based upon orthonormal representations" Iaeng Transactions On Engineering Sciences, pp.61-70, (2013)
On the properties of piezoelectric materials based upon orthonormal representations
(CRC Press-Taylor, 2013) Dinçkal, Çiğdem; 26773
For piezoelectric tensor, the decomposition method based upon irreducible orthogonal representation is overviewed. Besides, orthonormal tensor basis method is improved to express any third rank tensors such as piezoelectric tensor showing the piezoelectric effect of the material properties on the structures. Numerical examples for materials from different crystal symmetry classes serve to illustrate and verify the orthonormal tensor basis method. The differences and similarities are stated by comparing the methods presented in this work and the others in literature. It is also demonstrated that for hexagonal symmetry, each decomposed parts obtained from orthonormal tensor basis method has physical meaning. Furthermore, the norm based upon orthonormal tensor basis representation of piezoelectric tensor is obtained explicitly for each crystal symmetry classes and those results are used to study the piezoelectric effect of different materials. It is also shown that one can determine in which material the piezoelectric effect is stronger by using the norm concept for any material from various crystal symmetry classes.
Citation Count: Dinçkal, Çiğdem. (2010). "Orthonormal decomposition of symmetric second rank tensors", International Journal of Pure and Applied Mathematics, Vol.65, No.2, pp.225-241.
Orthonormal decomposition of symmetric second rank tensors
(2010) Dinçkal, Çiğdem; 26773
In this paper, a new orthonormal decomposition method for symmetric second rank tensors namely as, orthonormal tensor basis is presented. Complex variable representation method is developed by using the existing theories in literature. For comparison purposes, a brief review of the spectral method is given. It is shown that stress tensor, as an example to symmetric second rank tensors, is decomposed into six orthonormal parts by orthonormal tensor basis and complex variable representation methods. The matrix forms of these decomposed parts are given. This is the first time in literature that physical meanings of each six decomposed parts which are obtained from the orthonormal decomposition of stress tensor by orthonormal tensor basis and complex variable representation methods, different from the traditionally form, are emphasized. Illustrative applications on orthonormal tensor basis and complex variable representation decomposition methods are given. Finally, it is proved that the spectral method is a non-linear decomposition method which yields three non-linear orthonormal decomposed parts. This case is a significant innovation in decomposition procedures for symmetric second rank tensors in literature.

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