#### Filter Results:

#### Publication Year

1994

2016

#### Publication Type

#### Co-author

#### Publication Venue

#### Key Phrases

Learn More

- S Flach, A E Miroshnichenko, M V Fistul
- Chaos
- 2003

We present a theoretical study of linear wave scattering in one-dimensional nonlinear lattices by intrinsic spatially localized dynamic excitations or discrete breathers. These states appear in various nonlinear systems and present a time-periodic localized scattering potential for plane waves. We consider the case of elastic one-channel scattering, when… (More)

- S Flach
- 1994

We consider time-periodic nonlinear localized excitations (NLEs) on one-dimensional translationally invariant Hamiltonian lattices with arbitrary finite interaction range and arbitrary finite number of degrees of freedom per unit cell. We analyse a mapping of the Fourier coefficients of the NLE solution. NLEs correspond to homoclinic points in the phase… (More)

- S Flach, O Yevtushenko, Y Zolotaryuk
- 2008

We consider the classical dynamics of a particle in a one-dimensional space-periodic potential U (x) under the influence of a time-periodic space-homogeneous external field E(t). This nonintegrable system allows for both quasiperiodic and chaotic solutions in time. If the field is neither symmetric E(t + t 0) = E(−t + t 0) for any t 0 nor antisymmetric… (More)

- S Flach, A E Miroshnichenko, V Fleurov, M V Fistul
- Physical review letters
- 2003

A theoretical study of linear wave scattering by time-periodic spatially localized excitations (discrete breathers) is presented. A peculiar effect of total reflection occurs due to a Fano resonance when a localized state originating from closed channels resonates with the open channel. For the discrete nonlinear Schrödinger chain, we give an analytical… (More)

- S Flach, M V Ivanchenko, O I Kanakov
- Physical review. E, Statistical, nonlinear, and…
- 2006

The Fermi-Pasta-Ulam (FPU) problem consists of the nonequipartition of energy among normal modes of a weakly anharmonic atomic chain model. In the harmonic limit, each normal mode corresponds to a periodic orbit in phase space and is characterized by its wave number q. We continue normal modes from the harmonic limit into the FPU parameter regime and obtain… (More)

- A E Miroshnichenko, S Flach, B Malomed
- Chaos
- 2003

We study the scattering of solitons in the nonlinear Schrödinger equation on local inhomogeneities which may give rise to resonant transmission and reflection. In both cases, we derive resonance conditions for the soliton's velocity. The analytical predictions are tested numerically in regimes characterized by various time scales. Special attention is paid… (More)

- S. Flach
- 1995

We present a numerical method for obtaining high-accuracy numerical solutions of spatially localized time-periodic excitations on a nonlinear Hamilto-nian lattice. We compare these results with analytical considerations of the spatial decay. We show that nonlinear contributions have to be considered, and obtain very good agreement between the latter and the… (More)

- A Ponno, H Christodoulidi, Ch Skokos, S Flach
- Chaos
- 2011

A numerical and analytical study of the relaxation to equilibrium of both the Fermi-Pasta-Ulam (FPU) α-model and the integrable Toda model, when the fundamental mode is initially excited, is reported. We show that the dynamics of both systems is almost identical on the short term, when the energies of the initially unexcited modes grow in geometric… (More)

- S. Flach, K. Kladko, C. R. Willis
- 1994

We analyze the origin and features of localized excitations in a discrete two-dimensional Hamiltonian lattice. The lattice obeys discrete translational symmetry, and the localized excitations exist because of the presence of non-linearities. We connect the presence of these excitations with the existence of local integrability of the original N degree of… (More)

- T. V. Laptyeva, S. Flach, K. Kladko
- IACR Cryptology ePrint Archive
- 2011

Vulnerabilities related to weak passwords are a pressing global economic and security issue. We report a novel, simple, and effective approach to address the weak-password problem. Building upon chaotic dynamics, criticality at phase transitions, CAPTCHA recognition, and computational round-off errors, we design an algorithm that strengthens the security of… (More)