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Defterli, Özlem

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Profile URL
https://hdl.handle.net/20.500.12416/8908
Name Variants
Defterli, Ö.
Defterli, Ozlem
Özlem, Defterli
Defterli, Ö
Defterli, O.
Defterli, Z
Defterli, O
Job Title
Doç. Dr.
Email Address
defterli@cankaya.edu.tr
Main Affiliation
02.02. Matematik
Matematik
02. Fen-Edebiyat Fakültesi
01. Çankaya Üniversitesi
Status
Current Staff
Website
ORCID ID
0000-0003-0918-9834
Scopus Author ID
8546136600
Turkish CoHE Profile ID
31401
Google Scholar ID
NXCoGeEAAAAJ
WoS Researcher ID
AAH-2521-2020,CLS-5109-2022,JGO-4476-2023,
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00479.jpg (53.86 KB)

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Documents

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Scholarly Output

38

Articles

21

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WoS Citation Count

985

Scopus Citation Count

1019

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JournalCount
Journal of Low Frequency Noise, Vibration and Active Control2
Journal of Vibration and Control2
Computers & Mathematics with Applications2
International Journal of Modeling, Simulation, and Scientific Computing2
1st International Conference on Algorithms for Computational Biology (AlCoB) -- JUL 01-03, 2014 -- Tarragona, SPAIN1
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Now showing 1 - 10 of 38
  • Thumbnail Image
    Master Thesis
    Mathematical aspects of superintgrable systems
    (2004) Defterli, Özlem
    Superintegrallenebilir Sistemler
  • Thumbnail Image
    Book Part
    Hidden symmetries of two dimensional superintegrable systems
    (2007) Defterli, Özlem; Baleanu, Dumitru
    Classification of the invariants of two - dimensional superintegrable systems is presented. The hidden symmetries associated to the existence of Killing - Yano tensors are investigated.
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    Conference Object
    Infectious Disease Dynamics within Advanced Fractional Operators
    (2019) Defterli, Özlem; Arshad, Sadia; Jajarmi, Amin
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    Article
    Citation - WoS: 14
    Citation - Scopus: 14
    Comparative Analysis of Fractional Order Dengue Model With Temperature Effect Via Singular and Non-Singular Operators
    (Pergamon-elsevier Science Ltd, 2021) Defterli, Ozlem
    In this work, we generalize a (deterministic) mathematical model that anticipates the influence of temperature on dengue transmission incorporating temperature-dependent model parameters. The motivation comes by the epidemiological evidence and several recent studies clearly states fluctuations in temperature, rainfall, and global climate indexes are determinant on the transmission dynamic and epidemic behavior of dengue virus that causes deadly diseases with incidence rates significantly risen worldwide in the past decade. Taking into account the importance of the subject in nowadays and the diversity of fractional calculus operators in mathematical modeling of complex real-world systems, in this paper we investigated the importance of the new model based on Mittag-Leffler kernel as being non-singular kernel. The sensitivity analysis of the generalized model is newly investigated. Numerical simulations are carried out in a comparative sense within the temperature fluctuations for both singular and non-singular fractional operators of different orders. (c) 2021 Elsevier Ltd. All rights reserved.
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    Article
    Citation - WoS: 111
    Citation - Scopus: 138
    Fractional Optimal Control Problems With Several State and Control Variables
    (Sage Publications Ltd, 2010) Baleanu, Dumitru; Agrawal, Om P.; Defterli, Ozlem
    In many applications, fractional derivatives provide better descriptions of the behavior of dynamic systems than other techniques. For this reason, fractional calculus has been used to analyze systems having noninteger order dynamics and to solve fractional optimal control problems. In this study, we describe a formulation for fractional optimal control problems defined in multi-dimensions. We consider the case where the dimensions of the state and control variables are different from each other. Riemann-Liouville fractional derivatives are used to formulate the problem. The fractional differential equations involving the state and control variables are solved using Grunwald-Letnikov approximation. The performance of the formulation is shown using an example.
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    Article
    Citation - WoS: 101
    Citation - Scopus: 115
    On a Nonlinear Dynamical System With Both Chaotic and Nonchaotic Behaviors: a New Fractional Analysis and Control
    (Springer, 2021) Jajarmi, Amin; Defterli, Ozlem; Baleanu, Dumitru; Sajjadi, Samaneh Sadat
    In this paper, we aim to analyze the complicated dynamical motion of a quarter-car suspension system with a sinusoidal road excitation force. First, we consider a new mathematical model in the form of fractional-order differential equations. In the proposed model, we apply the Caputo-Fabrizio fractional operator with exponential kernel. Then to solve the related equations, we suggest a quadratic numerical method and prove its stability and convergence. A deep investigation in the framework of time-domain response and phase-portrait shows that both the chaotic and nonchaotic behaviors of the considered system can be identified by the fractional-order mathematical model. Finally, we present a state-feedback controller and a chaos optimal control to overcome the system chaotic oscillations. Simulation results demonstrate the effectiveness of the proposed modeling and control strategies.
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    Article
    Citation - WoS: 104
    Citation - Scopus: 119
    Fractional Treatment: an Accelerated Mass-Spring System
    (Editura Acad Romane, 2022) Defterli, Ozlem; Baleanu, Dumitru; Baleanu, Dumitru; Defterli, Özlem; Jajarmi, Amin; Sajjadi, Samaneh Sadat; Alshaikh, Noorhan; Asad, Jihad H.; Matematik
    The aim of this manuscript is to study the dynamics of the motion of an accelerated mass-spring system within fractional calculus. To investigate the described system, firstly, we construct the corresponding Lagrangian and derive the classical equations of motion using the Euler-Lagrange equations of integer-order. Furthermore, the generalized Lagrangian is introduced by using non-integer, so-called fractional, derivative operators; then the resulting fractional Euler-Lagrange equations are generated and solved numerically. The obtained results are presented illustratively by using numerical simulations.
  • Thumbnail Image
    Conference Object
    Citation - Scopus: 1
    A Fractional Lagrangian Approach for Two Masses With Linear and Cubic Nonlinear Stiffness
    (Institute of Electrical and Electronics Engineers Inc., 2023) Baleanu, D.; Jajarmi, A.; Wannan, R.; Asad, J.; Defterli, O.
    In this manuscript, the fractional dynamics of the two-mass spring system with two kinds of stiffness, namely linear and strongly nonlinear, are investigated. The corresponding fractional Euler-Lagrange equations of the system are derived being a system of two-coupled fractional differential equations with strong cubic nonlinear term. The numerical results of the system are obtained using Euler's approximation method and simulated with respect to the different values of the model parameters as mass, stiffness and order of the fractional derivative in use. The interpretation of the approximate results of the so-called generalized two-mass spring system is discussed via the fractional order. © 2023 IEEE.
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    Book Part
    Application of Various Modelling Techniques Into Consumer Confidence Index
    (CRC Press, 2025) Kalayci, B.; Purutçuoğlu, V.; Weber, G.W.; Uğur, Ö.; Defterli, Ö.
    The principles of sentiment are presented by economic conditions such that most of the variance in consumer sentiment is caused by economic situations, either directly or indirectly. There are political and economic repercussions to investors’ economic optimism or pessimism. Customer expenditures and hence, the direction of the economy’s future are predicted by the degree of consumer confidence. Investors, who are in a similar way, are positioned economically, but, have different biased thoughts bringing forward quite different sentiments about the future of economics. © 2025 CRC Press.
  • Thumbnail Image
    Article
    Citation - WoS: 167
    A Central Difference Numerical Scheme for Fractional Optimal Control Problems
    (Sage Publications Ltd, 2009) Agrawal, Om P.; Baleanu, Dumitru; Defterli, Ozlem
    This paper presents a modified numerical scheme for a class of fractional optimal control problems where a fractional derivative (FD) is defined in the Riemann-Liouville sense. In this scheme, the entire time domain is divided into several sub-domains, and a FD at a time node point is approximated using a modified Grunwald-Letnikov approach. For the first-order derivative, the proposed modified Grunwald-Letnikov definition leads to a central difference scheme. When the approximations are substituted into the fractional optimal control equations, it leads to a set of algebraic equations which are solved using a direct numerical technique. Two examples, one time-invariant and the other time-variant, are considered to study the performance of the numerical scheme. Results show that 1) as the order of the derivative approaches an integer value, these formulations lead to solutions for the integer-order system, and 2) as the sizes of the sub-domains are reduced, the solutions converge. It is hoped that the present scheme would lead to stable numerical methods for fractional differential equations and optimal control problems.