Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651
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Article Effects of the Random Walk and the Maturation Period in a Diffusive Predator-Prey System With Two Discrete Delays(Pergamon-elsevier Science Ltd, 2023) Goktepe, S.; Merdan, H.; Bilazeroglu, S.This study aims to present a complete Hopf bifurcation analysis of a model describing the relationship between prey and predator. A ratio-dependent reaction-diffusion system with two discrete time delays operating under Neumann boundary conditions governs the model that represents this competition. The bifurcation parameter for the analysis is a delay parameter that reflects the amount of time needed for the predator to be able to hunt. Bilazeroglu and Merdan's algorithm (Bilazeroglu et al., 2021), which is developed by using the center manifold theorem and normal form theory, is used to establish the existence of Hopf bifurcations and also the stability of the bifurcating periodic solutions. The same procedure is used to illustrate some specific bifurcation properties, such as direction, stability, and period. Furthermore, by examining a model with constant coefficients, we also analyze how diffusion and the amount of time needed for prey to mature impact the model's dynamics. To support the obtained analytical results, we also run some numerical simulations. The results indicate that the dynamic of the mathematical model is significantly influenced by diffusion, the amount of time needed for the predator to gain the capacity to hunt, and the amount of time required for prey to reach maturity that the predator can hunt.Article Citation - WoS: 103Citation - Scopus: 107Some Novel Mathematical Analysis on the Fractal-Fractional Model of the Ah1n1/09 Virus and Its Generalized Caputo-Type Version(Pergamon-elsevier Science Ltd, 2022) Avci, Ibrahim; Kumar, Pushpendra; Baleanu, Dumitru; Rezapour, Shahram; Etemad, SinaIn this paper, we formulate a new model of a particular type of influenza virus called AH1N1/09 in the framework of the four classes consisting of susceptible, exposed, infectious and recovered people. For the first time, we here investigate this model with the help of the advanced operators entitled the fractal-fractional operators with two fractal and fractional orders via the power law type kernels. The existence of solution for the mentioned fractal-fractional model of AH1N1/09 is studied by some special mappings such as ?-psi-contractions and ?-admissibles. The Leray-Schauder theorem is also applied for this aim. After investigating the stability criteria in four versions, to approximate the desired numerical solutions, we implement Adams-Bashforth (AB) scheme and simulate the graphs for different data on the fractal and fractional orders. Lastly, we convert our fractal-fractional AH1N1/09 model into a fractional model via the generalized Liouville-Caputo-type (GLC-type) operators and then, we simulate new graphs caused by the new numerical scheme called Kumar-Erturk method.Article Citation - WoS: 107Citation - Scopus: 107Dynamics Exploration for a Fractional-Order Delayed Zooplankton-Phytoplankton System(Pergamon-elsevier Science Ltd, 2023) Gao, Rong; Xu, Changjin; Li, Ying; Akgul, Ali; Baleanu, Dumitru; Li, PeiluanIn this study, we are concerned with the dynamics of a new established fractional-order delayed zooplankton- phytoplankton system. The existence and uniqueness of the solution are proved via Banach fixed point theorem. Non-negativeness of the solution is studied by mathematical inequality technique. The boundedness of the solution is analyzed by virtue of constructing an appropriate function. A novel delay-independent sufficient condition ensuring the stability and the onset of Hopf bifurcation for the established fractional -order delayed zooplankton-phytoplankton system is derived by means of Laplace transform, stability criterion and bifurcation knowledge of fractional-order differential equation. The global stability condition for the involved fractional-order delayed zooplankton-phytoplankton system is built by using a suitable positive definite function. Taking advantage of hybrid control tactics, we effectively control the time of occurrence of Hopf bifurcation for the established fractional-order delayed zooplankton-phytoplankton system. The study manifests that delay plays a vital role in controlling the stability and the time of occurrence of Hopf bifurcation for the involved fractional-order delayed zooplankton-phytoplankton system and the fractional -order controlled zooplankton-phytoplankton system involving delays. To verify the correctness of established chief results, computer simulation figures are distinctly displayed. The derived conclusions of this research are entirely new and possess potential theoretical value in preserving the balance of biological population. Up to now, there are few publications on detailed and comprehensive dynamic analysis on fractional-order delayed zooplankton-phytoplankton system via various exploration ways.Article Citation - WoS: 16Citation - Scopus: 19A Mathematical Model With Piecewise Constant Arguments of Colorectal Cancer With Chemo-Immunotherapy(Pergamon-elsevier Science Ltd, 2023) Yousef, Ali; Bilgil, Halis; Baleanu, Dumitru; Bozkurt, FatmaWe propose a new mathematical model with piecewise constant arguments of a system of ODEs to investigate the growth of colorectal cancer and its response to chemo-immunotherapy. Our main target in this paper is to analyze and represent the I.S.'s (immune system) efficiency during the chemotherapeutic process. Therefore, we proved and illustrated the necessity of IL-2 that supports the immune system, especially in early-detected cases of tumor density. Thus, the constructed model has been divided into sub-systems: the cell populations, the effects of the medications doxorubicin, and IL-2 concentration.Firstly, we analyze the stability of the equilibrium points (disease-free and co-existing) using the RouthHurwitz criteria. In addition, our study has shown that the system undergoes period-doubling, stationary and Neimark-Sacker bifurcations based on specific conditions. In the end, we illustrate some simulations to assist the theory of the manuscript.Article Citation - WoS: 7Citation - Scopus: 9Hopf Bifurcations in a Class of Reaction-Diffusion Equations Including Two Discrete Time Delays: an Algorithm for Determining Hopf Bifurcation, and Its Applications(Pergamon-elsevier Science Ltd, 2021) Merdan, H.; Bilazeroglu, S.We analyze Hopf bifurcation and its properties of a class of system of reaction-diffusion equations involving two discrete time delays. First, we discuss the existence of periodic solutions of this class under Neumann boundary conditions, and determine the required conditions on parameters of the system at which Hopf bifurcation arises near equilibrium point. Bifurcation analysis is carried out by choosing one of the delay parameter as a bifurcation parameter and fixing the other in its stability interval. Second, some properties of periodic solutions such as direction of Hopf bifurcation and stability of bifurcating periodic solution are studied through the normal form theory and the center manifold reduction for functional partial differential equations. Moreover, an algorithm is developed in order to determine the existence of Hopf bifurcation (and its properties) of variety of system of reaction-diffusion equations that lie in the same class. The benefit of this algorithm is that it puts a very complex and long computations of existence of Hopf bifurcation for each equation in that class into a systematic schema. In other words, this algorithm consists of the conditions and formulae that are useful for completing the existence analysis of Hopf bifurcation by only using coefficients in the characteristic equation of the linearized system. Similarly, it is also useful for determining the direction analysis of the Hopf bifurcation merely by using the coefficients of the second degree Taylor polynomials of functions in the right hand side of the system. Finally, the existence of Hopf bifurcation for three different problems whose governing equations stay in that class is given by utilizing the algorithm derived, and thus the feasibility of the algorithm is presented. (C) 2020 Elsevier Ltd. All rights reserved.Article Citation - WoS: 21Citation - Scopus: 22Dynamics and Numerical Investigations of a Fractional-Order Model of Toxoplasmosis in the Population of Human and Cats(Pergamon-elsevier Science Ltd, 2021) Ali, Nigar; Baleanu, Dumitru; Zafar, Zain Ul AbadinIn this paper an arbitrary order model for Toxoplasmosis ailment in the humanoid and feline is verbalized and explored. The dynamics of this ailment is discovered using an epidemiology type paradigm. We have proposed the fractional order multistage differential transform method for the Toxoplasmosis model. It is employed to analyze and find the elucidation for the model, and the numerical simulations have been conducted in order to study the effectiveness of the technique. The suggested algorithm can be considered as a fractional extension of the well know method known as Multistage Differential Transform Method. The sensitivity analysis of the strictures of the specimen is discussed. The numeric imitations of the projected non-integer specimens are conceded out to illustrate different dynamics of the model, which depend on R-0. (C) 2021 Elsevier Ltd. All rights reserved.Article Citation - WoS: 27Citation - Scopus: 28New Observations on Optimal Cancer Treatments for a Fractional Tumor Growth Model With and Without Singular Kernel(Pergamon-elsevier Science Ltd, 2018) Arshad, Sadia; Baleanu, Dumitru; Akman Yildiz, TugbaThe aim of this study is to examine a fractional optimal control problem (FOCP) governed by a cancer-obesity model with and without singular kernel, separately. We propose a new model including the population of immune cells, tumor cells, normal cells, fat cells, chemotherapeutic and immunotherapeutic drug concentrations. Existence and stability of the tumor free equilibrium point and coexisting equilibrium point are investigated analytically. We obtain the numerical solution of the fractional cancer-obesity model using L1 formula. The aim behind the FOCP is to find the optimal doses of chemotherapeutic and immunotherapeutic drugs which minimize the difference between the number of tumor cells and normal cells. To do so, we insert some weight constants as the coefficients of tumor and normal cells in the cost functional so that normal cell population is larger compared to tumor burden. On the other hand, we investigate the effect of obesity to the choice and schedules of treatment strategies in case of low and high caloric diets. Moreover, we discuss the choice of the differentiation operator, namely operators with and without singular kernel. Lastly, some illustrative examples are shown to examine the impact of the fractional derivatives of different orders on cancer-obesity model and we observe the contribution of the cost functional to eradicate tumor burden and regenerate normal cell population. Our model predicts the negative effect of obesity on the health of patient and we show that the most efficient treatment choice to eradicate the tumor is to apply combined therapy together with low caloric diet. (C) 2018 Elsevier Ltd. All rights reserved.Article Citation - WoS: 90Citation - Scopus: 94Stability of Q-Fractional Non-Autonomous Systems(Pergamon-elsevier Science Ltd, 2013) Jarad, Fahd; Abdeljawad, Thabet; Baleanu, DumitruIn this manuscript, using Lyapunov's direct method, the stability of non-autonomous systems within the frame of the q-Caputo fractional derivative is studied. The conditions for stability, uniform stability and asymptotic stability are discussed. (C) 2012 Elsevier Ltd. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5On Disconjugacy and Stability Criteria for Discrete Hamiltonian Systems(Pergamon-elsevier Science Ltd, 2011) Zafer, A.; Mert, R.By making use of new Lyapunov type inequalities, we establish disconjugacy and stability criteria for discrete Hamiltonian systems. The stability criteria are given when the system is periodic. (C) 2011 Elsevier Ltd. All rights reserved.