35 citations · 128 across the 13 of their papers we have counts for
13 papers
Interpolating vector fields for near identity maps and averaging
Vassili Gelfreich, Arturo Vieiro
For a smooth near identity map, we introduce the notion of an interpolating vector field written in terms of iterates of the map. Our construction is based on Lagrangian interpolat…
Equilibration of energy in slow-fast systems
Kushal Shah, Dmitry Turaev, Vassili Gelfreich +1
Ergodicity is a fundamental requirement for a dynamical system to reach a state of statistical equilibrium. On the other hand, it is known that in slow-fast systems ergodicity of t…
Leaky Fermi accelerators
Kushal Shah, Vassili Gelfreich, Vered Rom-Kedar +1
A Fermi accelerator is a billiard with oscillating walls. A leaky accelerator interacts with an environment of an ideal gas at equilibrium by exchange of particles through a small…
Separatrix splitting at a Hamiltonian bifurcation
Vassili Gelfreich, Lev Lerman
We discuss the splitting of a separatrix in a generic unfolding of a degenerate equilibrium in a Hamiltonian system with two degrees of freedom. We assume that the unperturbed fixe…
Simplified normal forms near a degenerate elliptic fixed point in two-parametric families of area-preserving maps
Vassili Gelfreich, Natalia Gelfreikh
We derive simplified normal forms for an area-preserving map in a neighbourhood of a degenerate resonant elliptic fixed point. Such fixed points appear in generic two-parameter fam…
Oscillating mushrooms: adiabatic theory for a non-ergodic system
V. Gelfreich, V. Rom-Kedar, D. Turaev
Can elliptic islands contribute to sustained energy growth as parameters of a Hamiltonian system slowly vary with time? In this paper we show that a mushroom billiard with a period…