Almost periodic functions serve as a powerful conceptual framework in analysing differential equations whose coefficients or forcing terms exhibit recurrent behaviour over time. Rooted in the ...

The aim of this paper is to consider the radially-symmetric periodic-Dirichlet problem on [0, T] × Bn[a] for the equation utt - Δ u = f(t, |x|, u), where Δ is the classical Laplacian operator, and ...