Uniform stabilization of a thermo piezoelectric/piezomagnetic model

We consider an evolution system describing an electro/magneto/thermoelastic phenomenon in a bounded domain of R³${\mathbb{R}}^3$. The resulting anisotropic model is a coupling between two hyperbolic equations, two elliptic equations and one parabolic equation. Assuming that a dissipative mechanism is present on the boundary and suitable boundary conditions are given we prove that the total energy decays exponentially as t?+∞$t?+\infty$ provided the region satisfies a geometric condition.