© 2003 by Institute of Mathematics and its Applications
A necessary and sufficient algebraic condition for the controllability of a thermoelastic plate equation
1 School of Mathematics-CDSNS, Georgia Tech, Atlanta, GA 30332, USA
In this paper we give a necessary and sufficient algebraic condition for the approximate controllability of the following thermoelastic plate equation with Dirichlet boundary conditions
wtt +
2w + 

= a1(x)u1 + ... + am(x)um, t
0, x
,
t ß

wt = d1(x)u1 + ... + dm(x)um, t
0, x
,
= w =
w = 0, t
0, x

,
where
0, ß > 0,
is a sufficiently regular bounded domain in RN, ai, di,
L2 (
; R), the control functions ui
L2 (0, t1; R); i = 1, 2, ..., m. This condition is easy to check and is given by
Rank [PjB
AjPjB
A2jPjB
... A3
j1jPjB] = 3
j,BU=b1U1+...+bmUm, bi=[0, ai, di], Aj=[0,
2j, 0, 1, 0, 
j, 0, 
j, ß
j] Pj, j
1,
where
j, S are the eigenvalues of
with Dirichlet boundary condition and Pj, S are the projections on the corresponding eigenspace.
Keywords: thermoelastic plate equation; algebraic condition; approximate controllability.