Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
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Article Multiparticle Correlations and Higher Order Harmonics in Ppb Collisions at Root S(nn)=8.16 Tev(Elsevier Ltd., 2019) Karapınar, Güler; CMS CollaborationThe elliptic and higher-order azimuthal anisotropy Fourier harmonics (v(n)) are obtained for pPb collisions at root s(NN) = 8.16 TeV over a wide range of event multiplicities based on multiparticle correlations. The data were collected by the CMS experiment during the 2016 LHC run. A sample of peripheral PbPb collisions at root s(NN) = 5.02 TeV covering a similar range of event multiplicities to the pPb results is also analyzed for comparison. The ratios of different harmonic moments are obtained for both v(2) and v(3) with high precision, which allows a direct comparison to theoretical predictions assuming a hydrodynamic evolution of the created medium with initial-state density fluctuations, particularly probing the non-Gaussian nature of initial-state fluctuations in small collision systems. The presented results provide crucial insights into the origin of collective long-range correlations observed in small collision systems.Article Citation - WoS: 12Citation - Scopus: 12Stability Analysis by a Nonlinear Upper Bound on the Derivative of Lyapunov Function(Elsevier Ltd., 2020) Şahan, GökhanIn this work, we give results for asymptotic stability of nonlinear time varying systems using Lyapunov-like Functions with indefinite derivative. We put a nonlinear upper bound for the derivation of the Lyapunov Function and relate the asymptotic stability conditions with the coefficients of the terms of this bound. We also present a useful expression for a commonly used integral and this connects the stability problem and Lyapunov Method with the convergency of a series generated by coefficients of upper bound. This generalizes many works in the literature. Numerical examples demonstrate the efficiency of the given approach. © 2020 European Control AssociationArticle Citation - WoS: 7Citation - Scopus: 7Complex Ginzburg–landau Equations With Dynamic Boundary Conditions(Elsevier Ltd., 2018) Corrêa, Wellington José; Özsarı, TürkerThe initial-dynamic boundary value problem (idbvp) for the complex Ginzburg–Landau equation (CGLE) on bounded domains of RN is studied by converting the given mathematical model into a Wentzell initial–boundary value problem (ibvp). First, the corresponding linear homogeneous idbvp is considered. Secondly, the forced linear idbvp with both interior and boundary forcings is studied. Then, the nonlinear idbvp with Lipschitz nonlinearity in the interior and monotone nonlinearity on the boundary is analyzed. The local well-posedness of the idbvp for the CGLE with power type nonlinearities is obtained via a contraction mapping argument. Global well-posedness for strong solutions is shown. Global existence and uniqueness of weak solutions are proven. Smoothing effect of the corresponding evolution operator is proved. This helps to get better well-posedness results than the known results on idbvp for nonlinear Schrödinger equations (NLS). An interesting result of this paper is proving that solutions of NLS subject to dynamic boundary conditions can be obtained as inviscid limits of the solutions of the CGLE subject to same type of boundary conditions. Finally, long time behavior of solutions is characterized and exponential decay rates are obtained at the energy level by using control theoretic tools.Article Citation - WoS: 7Citation - Scopus: 7Finite-Parameter Feedback Control for Stabilizing the Complex Ginzburg–landau Equation(Elsevier Ltd., 2017) Kalantarova, Jamila; Özsarı, TürkerIn this paper, we prove the exponential stabilization of solutions for complex Ginzburg–Landau equations using finite-parameter feedback control algorithms, which employ finitely many volume elements, Fourier modes or nodal observables (controllers). We also propose a feedback control for steering solutions of the Ginzburg–Landau equation to a desired solution of the non-controlled system. In this latter problem, the feedback controller also involves the measurement of the solution to the non-controlled system.Article CMS Collaboration(Elsevier Ltd., 2016) CMS Collaboration; Karapınar, GülerArticle Citation - WoS: 3Citation - Scopus: 3The Effect of Coupling Conditions on the Stability of Bimodal Systems in R3(Elsevier Ltd., 2016) Eldem, Vasfi; Şahan, GökhanThis paper investigates the global asymptotic stability of a class of bimodal piecewise linear systems in R3. The approach taken allows the vector field to be discontinuous on the switching plane. In this framework, verifiable necessary and sufficient conditions are proposed for global asymptotic stability of bimodal systems being considered. It is further shown that the way the subsystems are coupled on the switching plane plays a crucial role on global asymptotic stability. Along this line, it is demonstrated that a constant (which is called the coupling constant in the paper) can be changed without changing the eigenvalues of subsystems and this change can make bimodal system stable or unstable.Article Citation - WoS: 6Citation - Scopus: 6Well Posedness Conditions for Bimodal Piecewise Affine Systems(Elsevier Ltd., 2015) Şahan, Gökhan; Eldem, VasfiThis paper considers well-posedness (the existence and uniqueness of the solutions) of Bimodal Piecewise Affine Systems in ℝn. It is assumed that both modes are observable, but only one of the modes is in observable canonical form. This allows the vector field to be discontinuous when the trajectories change mode. Necessary and sufficient conditions for well-posedness are given as a set of algebraic conditions and sign inequalities. It is shown that these conditions induce a joint structure for the system matrices of the two modes. This structure can be used for the classification of well-posed bimodal piecewise affine systems. Furthermore, it is also shown that, under certain conditions, well-posed Bimodal Piecewise Affine Systems in ℝn may have one or two equilibrium points or no equilibrium points.Article CMS Collaboration(Elsevier Ltd., 2014) CMS Collaboration; Karapınar, GülerArticle CMS Collaboration(Elsevier Ltd., 2014) CMS Collaboration; Karapınar, GülerArticle Citation - WoS: 6Citation - Scopus: 6Construction of Exact Solutions for Fractional-Type Difference-Differential Equations Via Symbolic Computation(Elsevier Ltd., 2013) Aslan, İsmailThis paper deals with fractional-type difference-differential equations by means of the extended simplest equation method. First, an equation related to the discrete KdV equation is considered. Second, a system related to the well-known self-dual network equations through a real discrete Miura transformation is analyzed. As a consequence, three types of exact solutions (with the aid of symbolic computation) emerged; hyperbolic, trigonometric and rational which have not been reported before. Our results could be used as a starting point for numerical procedures as well.