Lower semicontinuity of pullback attractors for a singularly nonautonomous plate equation

We show the lower semicontinuity of the family of pullback attractors for the singularly nonautonomous plate equation with structural damping $$ u_{tt} + a(t,x)u_{t} + (- Delta) u_{t} + (-Delta)^{2} u + lambda u = f(u), $$ in the energy space $H^2_0(Omega) imes L^2(Omega)$ under small perturbations of the damping term a.