ESAIM: Control, Optimisation and Calculus of Variations

Research Article

Null controllability of the heat equation in unbounded domains by a finite measure control region

Cannarsa, Piermarcoa1, Martinez, Patricka2 and Vancostenoble, Juditha2

a1 Dipartimento di Matematica, Università di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy; cannarsa@mat.uniroma2.it.

a2 Laboratoire M.I.P., UMR CNRS 5640, Université Paul Sabatier Toulouse III, 118 route de Narbonne, 31062 Toulouse Cedex 4, France; martinez@mip.ups-tlse.fr.; cancoste@mip.ups.tlse.fr.

Abstract

Motivated by two recent works of Micu and Zuazua and Cabanillas, De Menezes and Zuazua, we study the null controllability of the heat equation in unbounded domains, typically $\mathbb R_+$ or  $\mathbb R^N$ . Considering an unbounded and disconnected control region of the form $\omega := \cup _n \omega _n$ , we prove two null controllability results: under some technical assumption on the control parts $\omega _n$ , we prove that every initial datum in some weighted L 2 space can be controlled to zero by usual control functions, and every initial datum in L 2(Ω) can be controlled to zero using control functions in a weighted L 2 space. At last we give several examples in which the control region has a finite measure and our null controllability results apply.

(Received May 20 2002)

(Revised July 18 2003)

(Online publication June 15 2004)

Key Words:

  • Null controllability;
  • weighted observability inequalities.

Mathematics Subject Classification:

  • 35K05;
  • 93B05;
  • 93B07