English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Fermi, Pasta and Ulam observed, that the excitation of a low frequency normalmode in a nonlinear acoustic chain leads to localization in normal mode spaceon large time scales. Fast equipartition (and thus complete delocalization) inthe Fermi-Pasta-Ulam chain is restored if relevant intensive control parametersexceed certain threshold values. We compare recent results on periodic orbits(in the localization regime) and resonant normal forms (in a weakdelocalization regime), and relate them to various resonance overlap criteria.We show that the approaches quantitatively agree in their estimate of thelocalization-delocalization threshold. A key ingredient for this transition areresonances of overtones.

The Fermi-Pasta-Ulam problem: periodic orbits, normal forms and resonance overlap criteria