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Уважаемые сотрудники ИТФ,<br>
<br>
В четверг 7 мая 2018 (не в пятницу!!!) в 11:30 состоится онлайн
коллоквиум, на котором будет заслушан доклад:<br>
<br>
Paolo Maria Santini (Dept. of Physics, University of Roma "La
Sapienza")<br>
<font size="+1"><b>Towards an analytic description of periodic
anomalous waves in nature via the focusing NLS model </b>(joint
work with P. G. Grinevich)</font><br>
<br>
The focusing NLS equation is the simplest universal model describing
the modulation instability (MI) of quasi monochromatic waves in
weakly nonlinear media, and MI is considered the main physical
mechanism for the appearence of anomalous (rogue) waves (AWs) in
nature. We first show how the finite gap method adapts to the NLS
Cauchy problem for a generic periodic initial perturbation of the
unstable background solution, in the case of a finite number N of
unstable modes, allowing one to construct the solution, to leading
order, in terms of elementary functions of the initial data. In
particular, if N=1, one obtains the analytic quantitative
description of a Fermi-Pasta-Ulam recurrence of AWs already observed
in real (water wave and nonlinear optics) and numerical experiments.
Then we present the analytic description of the O(1) effect of a
small loss or gain on the dynamics of periodic AWs, in full
agreements with recent water wave and numerical experiments. If time
remains, we shall discuss analogies and differences with AWs in
other contexts: on the Ablowitz-Ladik lattice and in the massive
Thirring model relativistic field theory (with F. Coppini). <br>
<br>
Адрес для подключения - <a class=""
href="http://bbb2.itp.ac.ru/b/a-o-ytc-2k3">http://bbb2.itp.ac.ru/b/a-o-ytc-2k3</a>
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