Abstract
We discuss the cost of controlling parabolic equations of the formy t + δ2 y +kδy = 0 in a bounded smooth domain Ώ ofℝ d by means of a boundary control. More precisely, we are interested in the cost of controlling from zero initial state to a given final state (in a suitable approximate sense) at timeT > 0 and in the behavior of this cost ask → ∞. We introduce finite-dimensional Galerkin approximations and prove that they are exactly controllable. Moreover, we also prove that the cost of controlling converges exponentially to zero ask → ∞. This proves, roughly speaking, that when the system becomes more unstable it is easier to control. The system under consideration does not admit a variational formulation. Thus, in order to introduce its Galerkin approximation, we first approximate it by means of a singular perturbation. We also develop a method for the construction of special Galerkin bases well adapted to the control problem.
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References
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Dedicated to John E. Lagnese on his 60th Birthday.
Supported by project PB93-1203 of the DGICYT (Spain) and grant CHRX-CT94-0471 of the European Union.
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Lions, JL., Zuazua, E. On the cost of controlling unstable systems: The case of boundary controls. J. Anal. Math. 73, 225–249 (1997). https://doi.org/10.1007/BF02788145
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DOI: https://doi.org/10.1007/BF02788145