We consider a coupled system of Kuramoto-Sivashinsky equations depending on a suitable parameter $\nu > 0$ and study its asymptotic behavior for $t$ large, as $\nu\rightarrow 0$. Introducing appropriate boundary conditions we show that the energy of the solutions decays exponentially uniformly with respect to the parameter $\nu$. In the limit, as $\nu\rightarrow 0$, we obtain a coupled system of Korteweg-de Vries equations known to describe strong interactions of two long internal gravity waves in a stratified fluid for which the energy tends to zero exponentially as well. The decay fails when the length of the space interval $L$ lies in a set of critical lengths.
"Uniform stabilization of a nonlinear coupled system of Korteweg-de Vries equations as a singular limit of the Kuramoto-Sivashinsky system." Differential Integral Equations 22 (1/2) 53 - 68, January/February 2009.