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Attractors for Strongly Damped Wave Equations with Nonlinear Hyperbolic Dynamic Boundary Conditions

We establish the well-posedness of a strongly damped semilinear wave equation equipped with nonlinear hyperbolic dynamic boundary conditions. Results are carried out with the presence of a parameter distinguishing whether the underlying operator is analytic, $α>0$, or only of Gevrey class, $α=0$. We establish the existence of a global attractor for each $α\in[0,1],$ and we show that the family of global attractors is upper-semicontinuous as $α\rightarrow0.$ Furthermore, for each $α\in[0,1]$, we show the existence of a weak exponential attractor. A weak exponential attractor is a finite dimensional compact set in the weak topology of the phase space. This result insures the corresponding global attractor also possess finite fractal dimension in the weak topology; moreover, the dimension is independent of the perturbation parameter $α$. In both settings, attractors are found under minimal assumptions on the nonlinear terms.