

Preprint 56/2011
Stability result for abstract evolution problems
Alexander Ramm
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Submission date: 29. Aug. 2011
Pages: 9
published in: Mathematical methods in the applied sciences, 36 (2013) 4, p. 422-426
DOI number (of the published article): 10.1002/mma.2603
Bibtex
with the following different title: A stability result for abstract evolution problems
MSC-Numbers: 34E05, 35R30, 74J25
Keywords and phrases: stability, evolution problems
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Abstract:
Consider an abstract evolution problem in a Hilbert space H
<center class="math-display"> <img src="/fileadmin/preprint_img/2011/tex_1682a0x.png" alt="&#x02D9;u = A(t)u + G(t,u )+ f(t), u(0) = u0, " class="math-display"></center> | (1) |
where A(t) is a linear, closed, densely defined operator in H with domain independent of t ≥ 0, G(t,u) is a nonlinear operator such that ||G(t,u)||≤ a(t)||u||p, p = const > 1, ||f(t)||≤ b(t). We allow the spectrum of A(t) to be in the right half-plane Re(λ) < λ0(t), λ0(t) > 0, but assume that limt→∞λ0(t) = 0.
Under suitable assumption on a(t) and b(t) we prove boundedness of ||u(t)|| as t →∞. If f(t) = 0, the Lyapunov stability of the zero solution to problem (1) with u0 = 0 is established. For f≠0, sufficient conditions for Lyapunov stability are given. The novel point in the paper is the possibility for the linear operator A(t) to have spectrum in the half-plane ℜ(λ) < λ0(t) with λ0(t) > 0 and limt→∞λ0(t) = 0 at a suitable rate.