arXiv subjects

Oleksiy O. Vakhnenko

Publications and source records attributed to Oleksiy O. Vakhnenko.

3 recordsLinked to original sources

arXiv2026

Integrable Twelve-Component Nonlinear Dynamical System on a Quasi-One-Dimensional Lattice

Bearing in mind the potential physical applicability of multicomponent completely integrable nonlinear dynamical models on quasi-one-dimensional lattices we have developed the novel twelve-component and six-component semi-discrete nonlinear inregrable systems in the framework of semi-discrete Ablowitz-Kaup-Newell-Segur scheme. The set of lowest local conservation laws found by the generalized direct recurrent technique was shown to be indispensable constructive tool in the reduction procedure from the prototype to actual field variables. Two types of admissible symmetries for the twelve-component system and one type of symmetry for the six-component system have been established. The mathematical structure of total local current was shown to support the charge transportation only by four of six subsystems incorporated into the twelve-component system under study. The twelve-component system is able to model the actions of external parametric drive and external uniform magnetic field via time dependencies and phase factors of coupling parameters.

nlin.SI↗

arXiv2020

Prototype and reduced nonlinear integrable lattice systems with the modulated pulson behavior

A multi-component semi-discrete nonlinear integrable system associated with the relevant third-order auxiliary linear problem is claimed to be the prototype system for several reduced integrable systems formulated in terms of true dynamical field variables. The main conservation laws related to the prototype system are found in the framework of generalized recurrent approach. The two-fold Darboux-Bäcklund dressing technique as applied to the integration of prototype system is developed in details. The novel reduced complex-valued nonlinear integrable system embracing three coupled dynamical subsystems on a quasi-one-dimensional lattice is proposed and its concise Lagrangian and Hamiltonian representations are written down. The essentially nontrivial couplings between the two complex-valued Toda-like subsystems are shown to be mediated by the intermediate subsystem both in their kinetic and potential parts. The explicit multi-component solution of a modulated pulson type related to the reduced integrable nonlinear ternary system is presented and analyzed.

nlin.SI↗

arXiv2004

Strain-induced kinetics of intergrain defects as the mechanism of slow dynamics in the nonlinear resonant response of humid sandstone bars

A closed-form description is proposed to explain nonlinear and slow dynamics effects exhibited by sandstone bars in longitudinal resonance experiments. Along with the fast subsystem of longitudinal nonlinear displacements we examine the strain-dependent slow subsystem of broken intergrain and interlamina cohesive bonds. We show that even the simplest but phenomenologically correct modelling of their mutual feedback elucidates the main experimental findings typical for forced longitudinal oscillations of sandstone bars, namely, (i) hysteretic behavior of a resonance curve on both its up- and down-slopes, (ii) linear softening of resonant frequency with increase of driving level, and (iii) gradual recovery (increase) of resonant frequency at low dynamical strains after the sample was conditioned by high strains. In order to reproduce the highly nonlinear elastic features of sandstone grained structure a realistic non-perturbative form of strain potential energy was adopted. In our theory slow dynamics associated with the experimentally observed memory of peak strain history is attributed to strain-induced kinetic changes in concentration of ruptured inter-grain and inter-lamina cohesive bonds causing a net hysteretic effect on the elastic Young's modulus. Finally, we explain how enhancement of hysteretic phenomena originates from an increase in equilibrium concentration of ruptured cohesive bonds that are due to water saturation.

physics.geo-ph↗