Long-time analysis of nonlinearly perturbed wave equations via modulated Fourier expansions
نویسندگان
چکیده
A modulated Fourier expansion in time is used to show long-time nearconservation of the harmonic actions associated with spatial Fourier modes along the solutions of nonlinear wave equations with small initial data. The result implies the long-time near-preservation of the Sobolev-type norm that specifies the smallness condition on the initial data.
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