• Title/Summary/Keyword: logarithmic nonlinearity

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TWO NEW BLOW-UP CONDITIONS FOR A PSEUDO-PARABOLIC EQUATION WITH LOGARITHMIC NONLINEARITY

  • Ding, Hang;Zhou, Jun
    • Bulletin of the Korean Mathematical Society
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    • v.56 no.5
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    • pp.1285-1296
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    • 2019
  • This paper deals with the blow-up phenomenon of solutions to a pseudo-parabolic equation with logarithmic nonlinearity, which was studied extensively in recent years. The previous result depends on the mountain-pass level d (see (1.6) for its definition). In this paper, we obtain two blow-up conditions which do not depend on d. Moreover, the upper bound of the blow-up time is obtained.

GLOBAL SOLUTION AND BLOW-UP OF LOGARITHMIC KLEIN-GORDON EQUATION

  • Ye, Yaojun
    • Bulletin of the Korean Mathematical Society
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    • v.57 no.2
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    • pp.281-294
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    • 2020
  • The initial-boundary value problem for a class of semilinear Klein-Gordon equation with logarithmic nonlinearity in bounded domain is studied. The existence of global solution for this problem is proved by using potential well method, and obtain the exponential decay of global solution through introducing an appropriate Lyapunov function. Meanwhile, the blow-up of solution in the unstable set is also obtained.

BLOW UP OF SOLUTIONS FOR A PETROVSKY TYPE EQUATION WITH LOGARITHMIC NONLINEARITY

  • Jorge, Ferreira;Nazli, Irkil;Erhan, Piskin;Carlos, Raposo;Mohammad, Shahrouzi
    • Bulletin of the Korean Mathematical Society
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    • v.59 no.6
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    • pp.1495-1510
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    • 2022
  • This paper aims to investigate the initial boundary value problem of the nonlinear viscoelastic Petrovsky type equation with nonlinear damping and logarithmic source term. We derive the blow-up results by the combination of the perturbation energy method, concavity method, and differential-integral inequality technique.

EXISTENCE AND GENERAL DECAY FOR A VISCOELASTIC EQUATION WITH LOGARITHMIC NONLINEARITY

  • Ha, Tae Gab;Park, Sun-Hye
    • Journal of the Korean Mathematical Society
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    • v.58 no.6
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    • pp.1433-1448
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    • 2021
  • In the present work, we investigate a viscoelastic equation involving a logarithmic nonlinear source term. After proving the existence of solutions, we establish a general decay estimate of the solution using energy estimates and theory of convex functions. This result extends and complements some previous results of [9, 21].

ON SOLVABILITY OF A CLASS OF DEGENERATE KIRCHHOFF EQUATIONS WITH LOGARITHMIC NONLINEARITY

  • Ugur Sert
    • Journal of the Korean Mathematical Society
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    • v.60 no.3
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    • pp.565-586
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    • 2023
  • We study the Dirichlet problem for the degenerate nonlocal parabolic equation ut - a(||∇u||2L2(Ω))∆u = Cb ||u||βL2(Ω) |u|q(x,t)-2 u log |u| + f in QT, where QT := Ω × (0, T), T > 0, Ω ⊂ ℝN, N ≥ 2, is a bounded domain with a sufficiently smooth boundary, q(x, t) is a measurable function in QT with values in an interval [q-, q+] ⊂ (1, ∞) and the diffusion coefficient a(·) is a continuous function defined on ℝ+. It is assumed that a(s) → 0 or a(s) → ∞ as s → 0+, therefore the equation degenerates or becomes singular as ||∇u(t)||2 → 0. For both cases, we show that under appropriate conditions on a, β, q, f the problem has a global in time strong solution which possesses the following global regularity property: ∆u ∈ L2(QT) and a(||∇u||2L2(Ω))∆u ∈ L2(QT ).

THE CAUCHY PROBLEM FOR AN INTEGRABLE GENERALIZED CAMASSA-HOLM EQUATION WITH CUBIC NONLINEARITY

  • Liu, Bin;Zhang, Lei
    • Bulletin of the Korean Mathematical Society
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    • v.55 no.1
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    • pp.267-296
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    • 2018
  • This paper studies the Cauchy problem and blow-up phenomena for a new generalized Camassa-Holm equation with cubic nonlinearity in the nonhomogeneous Besov spaces. First, by means of the Littlewood-Paley decomposition theory, we investigate the local well-posedness of the equation in $B^s_{p,r}$ with s > $max\{{\frac{1}{p}},\;{\frac{1}{2}},\;1-{\frac{1}{p}}\},\;p,\;r{\in}[0,{\infty}]$. Second, we prove that the equation is locally well-posed in $B^s_{2,r}$ with the critical index $s={\frac{1}{2}}$ by virtue of the logarithmic interpolation inequality and the Osgood's Lemma, and it is shown that the data-to-solution mapping is $H{\ddot{o}}lder$ continuous. Finally, we derive two kinds of blow-up criteria for the strong solution by using induction and the conservative property of m along the characteristics.

New three-layer-type hysteretic damper system and its damping capacity

  • Kim, Hyeong Gook;Yoshitomi, Shinta;Tsuji, Masaaki;Takewaki, Izuru
    • Earthquakes and Structures
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    • v.3 no.6
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    • pp.821-838
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    • 2012
  • This paper proposes a new three-layer pillar-type hysteretic damper system for residential houses. The proposed vibration control system has braces, upper and lower frames and a damper unit including hysteretic dampers. The proposed vibration control system supplements the weaknesses of the previously proposed post-tensioning vibration control system in the damping efficiency and cumbersomeness of introducing a post-tension. The structural variables employed in the damper design are the stiffness ratio ${\kappa}$, the ductility ratio ${\mu}_a$, and the ratio ${\beta}$ of the damper's shear force to the maximum resistance. The hysteretic dampers are designed so that they exhibit the targeted damping capacity at a specified response amplitude. Element tests of hysteretic dampers are carried out to examine the mechanical property and to compare its restoring-force characteristic with that of the analytical model. Analytical studies using an equivalent linearization method and time-history response analysis are performed to investigate the damping performance of the proposed vibration control system. Free vibration tests using a full-scale model are conducted in order to verify the damping capacity and reliability of the proposed vibration control system. In this paper, the damping capacity of the proposed system is estimated by the logarithmic decrement method for the response amplitudes. The accuracy of the analytical models is evaluated through the comparison of the test results with those of analytical studies.

Experimental Study on the Damping Estimation of the 5×5 Partial Fuel Assembly (5×5 부분핵연료 집합체의 감쇠추정을 위한 실험적 연구)

  • Lee, Kang-Hee;Yoon, Kyung-Ho;Song, Kee-Nam
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.2 s.107
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    • pp.163-168
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    • 2006
  • The PWR Nuclear Fuel assembly consists of more than 250 fuel rods that are supported by leaf springs in the cells of more than 10 Spacer Grids (SG) along the rod length. Since it is not easy to conduct mechanical tests on a full-scale model basis, the small-scaled rod bundle $(5\times5)$ which is called partial fuel assembly is generally used for various performance tests during the development stage. As one of the small-scaled tests, a flow test should be carried out in order to verify the performance of the spacer grid to obtain the Flow-Induced Vibration (FIV) characteristics of the scaled fuel assembly over the specified flow range. A vibration test should be also performed to obtain the modal parameters of the assembly prior to the flow test. In this study, we want to develop the estimation procedure of the damping ratio for the scaled test assembly. For the damping factor of the partial fuel assembly and the grid cage at the first vibration mode, as one of the vibration tests, a so-called pluck testing has been performed in air as a preliminary test prior to in-flow damping measurement test. Logarithmic decrement method is used for calculation of the damping ratio. Estimated damping ratio of the partial fuel assembly is about $0.7\%$ with reasonable error of $2\%$ for the previous results. Nonlinear behavior of the partial fuel assembly might be stem mainly from the rod-grid support configuration.

Experimental study on the damping estimation of the 5$\times$5 rod bundle (5$\times$5 봉다발의 감쇄추정을 위한 실험적 연구)

  • Lee, Kang-Hee;Yoon, Kyung-Ho;Song, Kee-Nam
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.503-506
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    • 2005
  • The PWR Nuclear Fuel assembly consists of more than 250 fuel rods that are supported by leaf springs in the cells of more than 10 Spacer Grids (SG) along the rod length. Since it is not easy to conduct mechanical tests on a full-scale model basis, the small-scaled rod bundle (5$\times$5) is generally used for various performance tests during the development stage. As one of the small-scaled tests, a flow test should be carried out in order to verify the performance of the spacer grid like the coolant mixing performance and to obtain the Flow-Induced Vibration (FIV) characteristics of the rod bundle over the specified flow range. A vibration test should be also performed to obtain the modal parameters of the bundle prior to the flow test. In this study, we want to develop the estimation procedure of the damping ratio for the small scaled test bundle. For the damping factor of the rod bundle and the grid case at the first vibration mode, as one of the vibration tests, a so-called pluck testing has been performed in air as a preliminary test prior to in-flow damping measurement test. Logarithmic decrement method is used for calculation of the damping ratio. Estimated damping ratio of the rod bundle is about 0.7% with reasonable error of 2% for the previous results. Nonlinear behavior of the rod bundle might be stem mainly Iron the rod-grid support configuration.

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