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International School for Advanced Studies
Applied Mathematics group
Geometric Control Course
January 2002
Andrei Fursikov
Moskow

     EXACT CONTROLLABILITY AND FEEDBACK STABILIZATION FOR PARABOLIC EQUATIONS AND FOR NAVIER-STOKES SYSTEM.

Exact controllability problem for evolution equations indicated in the title is formulated as follows: Let a solution $w(t,x), t\in (0,T), x\in G$ of this equation be given where $G$ is a bounded domain. Then for a prescribed initial value $v_0(x)\ne w(0,x) $ one have to find a boundary control $u(t,x), t\in (0,T), x\in \partial G$ such that the solution $v(t,x)$ of the boundary value problem supplied with initial and boundary conditions $v_0$ and  $u$ satisfies: $v(T,x)=w(T,x)$ Existence theorem for exact controllability problem will be discussed in the course. We will show that exact controllability problem is ill-posed and therefore its  calculation or ingeneering realization is difficult. We will consider so called stabilization problem which setting is close to exact controllability formulation. But stabilization problem will be solved with help of feedback control that damps fluctuations arising in calculations. This indicate on well-posedness of proposed resolving construction.