The main difficulty is to prove the Observability estimate for the linearized system corresponding to the control by a single force which in avery different way from the case that two control force localized on the same subdomain.

• 控制只加在一个方程上,而对一个系统施加最小数目的控制或使其中的控制满足一定条件是我们在控制领域经常讨论的问题。 本文证明的难点是线性化系统的观测估计,这比控制加在系统的两个方程更加复杂。