Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
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Article Citation - WoS: 23Citation - Scopus: 23Cold Sintering of Soda-Lime Glass(Elsevier Ltd., 2021) Karacasulu, Levent; Ögür, Ezgi; Pişkin, Cerem; Vakıfahmetoğlu, ÇekdarOrdinary recycled soda lime glass powder was densified via cold sintering process with the aid of concentrated NaOH solution. Increase in processing time, temperature and concentration of the NaOH solution resulted in the formation of monolithic glass artifacts with higher relative densities. The sample densified the most (95.2%) was obtained when the sintering was performed at 250˚C with a 20 min dwell time using 15 M NaOH solution.Article Citation - WoS: 7Citation - Scopus: 7Output Feedback Stabilization of the Linearized Korteweg-De Vries Equation With Right Endpoint Controllers(Elsevier Ltd., 2019) Batal, Ahmet; Özsarı, TürkerIn this paper, we prove the output feedback stabilization for the linearized Korteweg-de Vries (KdV) equation posed on a finite domain in the case the full state of the system cannot be measured. We assume that there is a sensor at the left end point of the domain capable of measuring the first and second order boundary traces of the solution. This allows us to design a suitable observer system whose states can be used for constructing boundary feedbacks acting at the right endpoint so that both the observer and the original plant become exponentially stable. Stabilization of the original system is proved in the L-2-sense, while the convergence of the observer system to the original plant is also proved in higher order Sobolev norms. The standard backstepping approach used to construct a left endpoint controller fails and presents mathematical challenges when building right endpoint controllers due to the overdetermined nature of the related kernel models. In order to deal with this difficulty we use the method of Ozsan and Batal, (2019) which is based on using modified target systems involving extra trace terms. In addition, we show that the number of controllers and boundary measurements can be reduced to one, with the cost of a slightly lower exponential rate of decay. We provide numerical simulations illustrating the efficacy of our controllers. (C) 2019 Elsevier Ltd. All rights reserved.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: 8Diffraction of Flexural-Gravity Waves by a Vertical Cylinder of Non-Circular Cross Section(Elsevier Ltd., 2020) Dişibüyük, Nazile Buğurcan; Korobkin, A. A.; Yılmaz, OğuzThe linear three-dimensional problem of flexural-gravity wave (hydro-elastic wave) diffraction by a vertical cylinder of an arbitrary smooth cross section is studied using an asymptotic approach combined with the vertical mode method for water of finite depth. The surface of the water is covered by an infinite, continuous elastic ice plate. The rigid cylinder extends from the sea bottom to the ice surface. The ice plate is frozen to the cylinder. The ice deflection is described by the equation of a thin elastic plate of constant thickness with clamped edge conditions at the cylinder. The flow under the ice is described by the linear theory of potential flows. The coupled problem of wave diffraction is solved in two steps. First, the problem is solved without evanescent waves similar to the problem of water waves diffracted by a vertical cylinder. This solution does not satisfy the edge conditions. Second, a radiation problem with a prescribed motion of the ice plate edge is solved by the vertical mode method. The sum of these two solutions solve the original problem. Both solutions are obtained by an asymptotic method with a small parameter quantifying a small deviation of the cylinder cross section from a circular one. Third-order asymptotic solutions are obtained by solving a set of two-dimensional boundary problems for Helmholtz equations in the exterior of a circle. Strains along the edge, where the ice plate is frozen to the cylinder, are investigated for nearly square and elliptic cross sections of the vertical cylinders depending on the characteristics of ice and incident wave. The strains are shown to be highest in the places of high curvatures of the cross sections. The derived asymptotic formulae can be used in design of vertical columns in ice. They directly relate the strains in ice plate to the shape of the column. © 2020 Elsevier LtdArticle Citation - WoS: 52Citation - Scopus: 56Study of Jet Quenching With Isolated-Photon+jet Correlations in Pbpb and Pp Collisions at Snn=5.02 Tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerMeasurements of azimuthal angle and transverse momentum (pT) correlations of isolated photons and associated jets are reported for pp and PbPb collisions at sNN=5.02 TeV. The data were recorded with the CMS detector at the CERN LHC. For events containing a leading isolated photon with pT γ>40 GeV/c and an associated jet with pT jet>30 GeV/c, the photon+jet azimuthal correlation and pT imbalance in PbPb collisions are studied as functions of collision centrality and pT γ. The results are compared to pp reference data collected at the same collision energy and to predictions from several theoretical models for parton energy loss. No evidence of broadening of the photon+jet azimuthal correlations is observed, while the ratio pT jet/pT γ decreases significantly for PbPb data relative to the pp reference. All models considered agree within uncertainties with the data. The number of associated jets per photon with pT γ>80 GeV/c is observed to be shifted towards lower pT jet values in central PbPb collisions compared to pp collisions.Article Citation - WoS: 17Citation - Scopus: 23Search for R-Parity Violating Supersymmetry in Pp Collisions at S=13tev Using B Jets in a Final State With a Single Lepton, Many Jets, and High Sum of Large-Radius Jet Masses(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerResults are reported from a search for physics beyond the standard model in proton–proton collisions at a center-of-mass energy of s=13TeV. The search uses a signature of a single lepton, large jet and bottom quark jet multiplicities, and high sum of large-radius jet masses, without any requirement on the missing transverse momentum in an event. The data sample corresponds to an integrated luminosity of 35.9 fb−1 recorded by the CMS experiment at the LHC. No significant excess beyond the prediction from standard model processes is observed. The results are interpreted in terms of upper limits on the production cross section for R-parity violating supersymmetric extensions of the standard model using a benchmark model of gluino pair production, in which each gluino decays promptly via g˜→tbs. Gluinos with a mass below 1610 GeV are excluded at 95% confidence level.Article Citation - WoS: 155Citation - Scopus: 171Nuclear Modification Factor of D0 Mesons in Pbpb Collisions at Snn=5.02 Tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerThe transverse momentum (pT) spectrum of prompt D0 mesons and their antiparticles has been measured via the hadronic decay channels D0→K−π+ and D‾0→K+π− in pp and PbPb collisions at a centre-of-mass energy of 5.02 TeV per nucleon pair with the CMS detector at the LHC. The measurement is performed in the D0 meson pT range of 2–100GeV/c and in the rapidity range of |y|<1. The pp (PbPb) dataset used for this analysis corresponds to an integrated luminosity of 27.4 pb−1 (530 μb−1). The measured D0 meson pT spectrum in pp collisions is well described by perturbative QCD calculations. The nuclear modification factor, comparing D0 meson yields in PbPb and pp collisions, was extracted for both minimum-bias and the 10% most central PbPb interactions. For central events, the D0 meson yield in the PbPb collisions is suppressed by a factor of 5–6 compared to the pp reference in the pT range of 6–10GeV/c. For D0 mesons in the high-pT range of 60–100GeV/c, a significantly smaller suppression is observed. The results are also compared to theoretical calculations.Article Citation - WoS: 82Citation - Scopus: 119Search for New Physics in Events With Two Soft Oppositely Charged Leptons and Missing Transverse Momentum in Proton–proton Collisions at S=13 Tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerA search is presented for new physics in events with two low-momentum, oppositely charged leptons (electrons or muons) and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data collected using the CMS detector at the LHC correspond to an integrated luminosity of 35.9fb−1. The observed event yields are consistent with the expectations from the standard model. The results are interpreted in terms of pair production of charginos and neutralinos (χ˜1 ± and χ˜2 0) with nearly degenerate masses, as expected in natural supersymmetry models with light higgsinos, as well as in terms of the pair production of top squarks (t˜), when the lightest neutralino and the top squark have similar masses. At 95% confidence level, wino-like χ˜1 ±/χ˜2 0 masses are excluded up to 230 GeV for a mass difference of 20 GeV relative to the lightest neutralino. In the higgsino-like model, masses are excluded up to 168 GeV for the same mass difference. For t˜ pair production, top squark masses up to 450 GeV are excluded for a mass difference of 40 GeV relative to the lightest neutralino.Article Citation - WoS: 11Citation - Scopus: 11Search for Excited Quarks of Light and Heavy Flavor in ? +jet Final States in Proton–proton Collisions at S=13tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerA search is presented for excited quarks of light and heavy flavor that decay to γ+jet final states. The analysis is based on data corresponding to an integrated luminosity of 35.9fb−1 collected by the CMS experiment in proton–proton collisions at s=13TeV at the LHC. A signal would appear as a resonant contribution to the invariant mass spectrum of the γ+jet system, above the background expected from standard model processes. No resonant excess is found, and upper limits are set on the product of the excited quark cross section and its branching fraction as a function of its mass. These are the most stringent limits to date in the γ+jet final state, and exclude excited light quarks with masses below 5.5 TeV and excited b quarks with masses below 1.8 TeV, assuming standard model like coupling strengths.