Blowup estimates for observability of a thermoelastic system


With observation restricted to a single component: displacement, velocity, or temperature, we consider observability of the nonscalar thermoelastic system [1-γΔ]w tt+Δ 2w-αΔθ=0, θ t-Δθ+αΔw t=0, coupling heat conduction with a Kirkhoff or Euler-Bernoulli plate model. One does have observability in arbitrarily short time here, but necessarily has blowup of the sensitivity as the observation time T→0 and also as the coupling coefficient α→0. In this paper we are able to examine the asymptotics of this blowup for two situations: global observation (i.e., on all of Ω) and, with significant restrictions, boundary observation. The blowup rates obtained are of optimal order: (T -5/2) for global observation, corresponding to what is known for 3-dimensional systems, and exponential in (1/T) for boundary observation, corresponding to what is known for scalar PDE problems. Our methods permit us also to obtain asymptotics as α→0 - a question which can only arise for systems. © 2006 - IOS Press and the authors. All rights reserved.

Publication Title

Asymptotic Analysis

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