Browsing by Author "Yiğit, A."

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Decolorization of Methylene Blue by Silver/Reduced Graphene Oxide-Ethylene Diamine Nanomaterial: Synthesis, Characterization, and Optimization
(Springer, 2024) Ecer, Ü.; Yiğit, A.; Menges, N.; Şahan, T.
In this study, ethylene diamine-coated reduced graphene oxide-supported silver composite (Ag/rGO-ED) was synthesized and used as an efficient catalyst for the decolorization of methylene blue (MB) in the presence of NaBH4. The morphology of the obtained material was elucidated using field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The influences of four parameters (MB concentration (mg/L), NaBH4 amount (mM), catalyst amount (g/L), and contact time (s)) on the decolorization process were appraised and optimized via response surface methodology (RSM). For the decolorization of MB, the optimum solutions were obtained as Co of 32.49 mg/L, NaBH4 amount of 152.89 mM, catalyst amount of 0.83 g/L, and 101.39 s contact time with MB decolorization efficiency of 97.73%. MB, a pollutant in wastewater, was decolorized rapidly by Ag/rGO-ED with an efficiency of approximately 97%. The exploration of kinetics and thermodynamics was another major emphasis of the work. The activation energy (Ea) and rate constant (k) for the decolorization of MB were obtained as 37.9 kJ/mol and 0.0135 s−1, respectively. The obtained results show that the catalyst, a new composite material in the literature, is promising for decolorization of wastewater. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
On the Asymptotic Stability of Solutions of Nonlinear Delay Differential Equations
(Springer, 2022) Tunç, C.; Yiğit, A.
A nonlinear system of delay differential equations (DDEs) is considered. We obtain some new results on the asymptotic stability of a zero solution of the considered system by using well-known inequalities and the Lyapunov–Krasovskii functionals. Two numerical examples illustrate applications of the obtained results. The presented results make contributions to the qualitative theory of DDEs and improve some results known from the modern literature. © 2022, Springer Science+Business Media, LLC, part of Springer Nature.
On the Exponential Admissibility of Singular Systems With Multiply Variable Delays
(Palestine Polytechnic University, 2023) Yiğit, A.; Tunç, C.
We investigate exponential admissibility of singular systems with multiply variable delays. We give new criteria such that the systems are regular, impulse-free (IF) and exponentially stable (ES). The techniques of the proofs are based on the Lyapunov-Krasovskiĭ functional (LKF), convex polyhedron methods and linear matrix inequalities (LMIs). Two numerical examples are given to illustrate the obtained results. Using MATLAB-Simulink software, the trajectories of the solutions are provided. This study generalizes and improves certain results in the present literature. © Palestine Polytechnic University-PPU 2023.
Stability for Fractional Order Delay Singular Systems
(Cambridge Scientific Publishers, 2022) Yiğit, A.; Sivasundaram, S.; Tunç, C.
In this paper, a non-linear fractional order integro-singular system (FrOISS) is considered. Explicit criteria for asymptotic stability of that FrOISS are given via two new theorems. The studies of the paper are based on applications of two Lyapunov-Krasovskiǐ functionals (LKFs). In particular case, two examples and their simulations are included as applications of the results. By this work, some existing results are improved and generalized © CSP - Cambridge, UK; I&S - Florida, USA, 2022