Compact almost automorphic solutions for semilinear parabolic evolution equations

• Published in: Applicable analysis 2022-05, Vol.101 (7), p.2553-2579
• Main Authors: Es-sebbar, Brahim, Ezzinbi, Khalil, Khalil, Kamal
• Format: Article
• Language: English
• Subjects: Banach spaces; Compact almost automorphic solutions; Evolution; Mathematical analysis; nonlinear evolution equations; Primary 46T20-47J35; reaction-diffusion equations; Secondary 34C27-35K58; semigroup; Stepanov almost automorphic functions; subvariant functional method; unbounded forcing terms; Wave equations
• ISSN: 0003-6811; 1563-504X
• DOI: 10.1080/00036811.2020.1811979

In this paper, using the subvariant functional method due to Favard [Favard J. Sur les équations différentielles linéaires á coefficients presque-périodiques. ActaMathematica. 1928;51(1):31-81.], we prove the existence and uniqueness of compact almost automorphic solutions for a class of semilinear evolution equations in Banach spaces provided the existence of at least one bounded solution on the right half line. More specifically, we improve the assumptions in [Cieutat P, Ezzinbi K. Almost automorphic solutions for some evolution equations through the minimizing for some subvariant functional, applications to heat and wave equations with nonlinearities. J Funct Anal. 2011;260(9):2598-2634.], we show that the almost automorphy of the coefficients in a weaker sense (Stepanov almost automorphy of order ) is enough to obtain solutions that are almost automorphic in a strong sense (Bochner almost automorphy). For that purpose we distinguish two cases, and . The main difficulty in this work, is to prove the existence of at least one solution with relatively compact range while the forcing term is not necessarily bounded. Moreover, we propose to study a large class of reaction-diffusion problems with unbounded forcing terms.