Strong attractors for the strongly damped wave equations on time-dependent spaces

We examine the long-term behavior of strong solutions for the wave equation $ \varepsilon(t)u_{tt}-\Delta u_{t}-\Delta u+f(u) = g(x) $ and obtain the time-dependent attractor in $ \mathcal{H}_{t}^{1} = [H^{2}(\Omega)\cap H_{0}^{1}(\Omega)]\times H_{0}^{1}(\Omega) $. Moreover, the attractor is bounded in $ [H^{2}(\Omega)\cap H_{0}^{1}(\Omega)]\times[H^{2}(\Omega)\cap H_{0}^{1}(\Omega)] $.