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/

Global: Zendy Tools annual

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

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Using an ac driven asymmetric pulse we show how the Fermi acceleration(deceleration) can be controlled. A {\it deformed} sawtooth (Ratchetlike) pulserepresenting the moving wall in the static Fermi-Ulam model is considered. Thetime integral from the pulse over one period of oscillation must be negative toobtain deceleration and positive to obtain hyperacceleration. We show thatwhile the decelerated case is chaotic, for the hyperaccelerated case theLyapunov exponents converge to zero. Numerical simulations indicate that thehyperaccelerated case is ergodic in velocity space. Switching between differentpulse deformations we are able to control the particle acceleration. Resultsshould be valid for any pulse for which the time integral can be manipulatedbetween positive and negative values.

Ratchetlike pulse controlling the Fermi deceleration and hyperacceleration