79 citations · 323 across the 15 of their papers we have counts for
16 papers
Integrable and Chaotic 4-Dimensional Lotka-Volterra Models and Population Sustainability
H. Christodoulidi, T. E. Kouloukas, L. B. Drossos +1
We examine a 4-dimensional generalization of predator-prey models describing interactions among four species. We show that these systems exhibit a rich variety of asymptotic behavi…
Measuring FPUT thermalization with Toda integrals
Helen Christodoulidi, Sergej Flach
We assess the ergodic properties of the Fermi-Pasta-Ulam-Tsingou- model for generic initial conditions using a Toda integral. It serves as an adiabatic invariant for the system…
Dynamics and Statistics of Weak Chaos in a 4--D Symplectic Map
Tassos Bountis, Konstantinos Kaloudis, Helen Christodoulidi
The important phenomenon of "stickiness" of chaotic orbits in low dimensional dynamical systems has been investigated for several decades, in view of its applications to various ar…
A new class of integrable Lotka-Volterra systems
H. Christodoulidi, A. N. W. Hone, T. E. Kouloukas
A parameter-dependent class of Hamiltonian (generalized) Lotka-Volterra systems is considered. We prove that this class contains Liouville integrable as well as superintegrable cas…
Stages of dynamics in the Fermi-Pasta-Ulam system as probed by the first Toda integral
H. Christodoulidi, C. Efthymiopoulos
We investigate the long term evolution of trajectories in the Fermi-Pasta-Ulam (FPU) system, using as a probe the first non--trivial integral in the hierarchy of integrals of t…
Extensive packet excitations in FPU and Toda lattices
H. Christodoulidi
At low energies, the excitation of low frequency packets of normal modes in the Fermi-Pasta-Ulam (FPU) and in the Toda model leads to exponentially localized energy profiles which…
The effect of long-range interactions on the dynamics and statistics of 1D Hamiltonian lattices with on-site potential
H. Christodoulidi, T. Bountis, L. Drossos
We examine the role of long--range interactions on the dynamical and statistical properties of two 1D lattices with on--site potentials that are known to support discrete breathers…
Dynamics and Statistics of the Fermi--Pasta--Ulam --model with different ranges of particle interactions
Helen Christodoulidi, Tassos Bountis, Constantino Tsallis +1
In the present work we study the Fermi--Pasta--Ulam (FPU) --model involving long--range interactions (LRI) in both the quadratic and quartic potentials, by introducing two indep…
Numerical integration of variational equations for Hamiltonian systems with long range interactions
Helen Christodoulidi, Tassos Bountis, Lambros Drossos
We study numerically classical 1-dimensional Hamiltonian lattices involving inter-particle long range interactions that decay with distance like 1/r^alpha, for alpha>=0. We demonst…
Fermi-Pasta-Ulam model with long-range interactions: Dynamics and thermostatistics
Helen Christodoulidi, Constantino Tsallis, Tassos Bountis
We introduce and numerically study a long-range-interaction generalization of the one-dimensional Fermi-Pasta-Ulam (FPU) model. The standard quartic interaction is generalized…
Phase Transitions in Models of Bird Flocking
H. Christodoulidi, K. van der Weele, Ch. G. Antonopoulos +1
The aim of the present paper is to elucidate the transition from collective to random behavior exhibited by various mathematical models of bird flocking. In particular, we compare…
Low-dimensional q-Tori in FPU Lattices: Dynamics and Localization Properties
Helen Christodoulidi, Christos Efthymiopoulos
This is a continuation of our study concerning q-tori, i.e. tori of low dimensionality in the phase space of nonlinear lattice models like the Fermi-Pasta-Ulam (FPU) model. In our…
The two-stage dynamics in the Fermi-Pasta-Ulam problem: from regular to diffusive behavior
Antonio Ponno, Helen Christodoulidi, Charalampos Skokos +1
A numerical and analytical study of the relaxation to equilibrium of both the Fermi-Pasta-Ulam (FPU) alpha-model and the integrable Toda model, when the fundamental mode is initial…
Weak chaos detection in the Fermi-Pasta-Ulam- system using -Gaussian statistics
Chris G. Antonopoulos, Helen Christodoulidi
We study numerically statistical distributions of sums of orbit coordinates, viewed as independent random variables in the spirit of the Central Limit Theorem, in weakly chaotic re…
Energy localization on q-tori, long term stability and the interpretation of FPU recurrences
H. Christodoulidi, C. Efthymiopoulos, T. Bountis
We focus on two approaches that have been proposed in recent years for the explanation of the so-called FPU paradox, i.e. the persistence of energy localization in the `low-q' Four…
Application of the GALI Method to Localization Dynamics in Nonlinear Systems
T. Bountis, T. Manos, H. Christodoulidi
We investigate localization phenomena and stability properties of quasiperiodic oscillations in degree of freedom Hamiltonian systems and coupled symplectic maps. In partic…