11 research outputs found
Study of intrinsic localized vibrational modes in micromechanical oscillator arrays
金沢大学大学院自然科学研究科物理学金沢大学理学部Intrinsic localized modes (ILMs) have been observed in micromechanical cantilever arrays, and their creation, locking, interaction, and relaxation dynamics in the presence of a driver have been studied. The micromechanical array is fabricated in a 300 nm thick silicon-nitride film on a silicon substrate, and consists of up to 248 cantilevers of two alternating lengths. To observe the ILMs in this experimental system a line-shaped laser beam is focused on the 1D cantilever array, and the reflected beam is captured with a fast charge coupled device camera. The array is driven near its highest frequency mode with a piezoelectric transducer. Numerical simulations of the nonlinear Klein-Gordon lattice have been carried out to assist with the detailed interpretation of the experimental results. These include pinning and locking of the ILMs when the driver is on, collisions between ILMs, low frequency excitation modes of the locked ILMs and their relaxation behavior after the driver is turned off. © 2003 American Institute of Physics
Experimental study of the robust global synchronization of Brockett oscillators
International audienceThis article studies the experimental synchronization of a family of a recently proposed oscillator model, i.e. the Brockett oscillator [Brockett, 2013]. Due to its structural property, Brockett oscillator can be considered as a promising benchmark nonlinear model for investigating synchronization and the consensus phenomena. Our experimental setup consists of analog circuit realizations of a network of Brockett oscillators. Experimental results obtained in this work correspond to the prior theoretical findings
Equilibrium and nonequilibrium properties of systems with long-range interactions
We briefly review some equilibrium and nonequilibrium properties of systems
with long-range interactions. Such systems, which are characterized by a
potential that weakly decays at large distances, have striking properties at
equilibrium, like negative specific heat in the microcanonical ensemble,
temperature jumps at first order phase transitions, broken ergodicity. Here, we
mainly restrict our analysis to mean-field models, where particles globally
interact with the same strength. We show that relaxation to equilibrium
proceeds through quasi-stationary states whose duration increases with system
size. We propose a theoretical explanation, based on Lynden-Bell's entropy, of
this intriguing relaxation process. This allows to address problems related to
nonequilibrium using an extension of standard equilibrium statistical
mechanics. We discuss in some detail the example of the dynamics of the free
electron laser, where the existence and features of quasi-stationary states is
likely to be tested experimentally in the future. We conclude with some
perspectives to study open problems and to find applications of these ideas to
dipolar media.Comment: 8 pages, 14 figures, Procs. of STATPHYS23, to be published on EPJ
Backward-wave propagation and discrete solitons in a left-handed electrical lattice
We study experimentally, analytically and numerically the backward-wave propagation, and formation of discrete bright and dark solitons in a nonlinear electrical lattice. We observe experimentally that a focusing (defocusing) effect occurs above (below) a certain carrier frequency threshold, and backward-propagating bright (dark) discrete solitons are formed. We develop a discrete model emulating the relevant circuit and benchmark its linear properties against the experimental dispersion relation. Using a perturbation method, we derive a nonlinear Schrödinger equation, that predicts accurately the carrier frequency threshold. Finally, we use numerical simulations to corroborate our findings and monitor the space-time evolution of the discrete solitons. © 2011 Elsevier B.V