23,861 research outputs found
Experimental and numerical observation of dark and bright breathers in the band gap of a diatomic electrical lattice
We observe dark and bright intrinsic localized modes (ILMs), also known as discrete breathers, experimentally
and numerically in a diatomic-like electrical lattice. The experimental generation of dark ILMs by driving a
dissipative lattice with spatially homogenous amplitude is, to our knowledge, unprecedented. In addition, the
experimental manifestation of bright breathers within the band gap is also novel in this system. In experimental
measurements the dark modes appear just below the bottom of the top branch in frequency. As the frequency is
then lowered further into the band gap, the dark ILMs persist, until the nonlinear localization pattern reverses
and bright ILMs appear on top of the finite background. Deep into the band gap, only a single bright structure
survives in a lattice of 32 nodes. The vicinity of the bottom band also features bright and dark self-localized
excitations. These results pave the way for a more systematic study of dark breathers and their bifurcations in
diatomic-like chains.VI Plan Propio of the University of Seville, Spain (VI PPITUS)AEI/FEDER, UE MAT2016- 79866-
Experimentally observed evolution between dynamic patterns and intrinsic localized modes in a driven nonlinear electrical cyclic lattice
Locked intrinsic localized modes (ILMs) and large amplitude lattice spatial
modes (LSMs) have been experimentally measured for a driven 1-D nonlinear
cyclic electric transmission line, where the nonlinear element is a saturable
capacitor. Depending on the number of cells and electrical lattice damping a
LSM of fixed shape can be tuned across the modal spectrum. Interestingly, by
tuning the driver frequency away from this spectrum an LSM can be continuously
converted into ILMs and visa versa. The differences in pattern formation
between simulations and experimental findings are due to a low concentration of
impurities. Through this novel nonlinear excitation and switching channel in
cyclic lattices either energy balanced or unbalanced LSMs and ILMs may occur.
Because of the general nature of these dynamical results for nonintegrable
lattices applications are to be expected. The ultimate stability of driven aero
machinery containing nonlinear periodic structures may be one example.Comment: 7 pages 7 figure
Discrete breathers in a nonlinear electric line: Modeling, Computation and Experiment
We study experimentally and numerically the existence and stability
properties of discrete breathers in a periodic nonlinear electric line. The
electric line is composed of single cell nodes, containing a varactor diode and
an inductor, coupled together in a periodic ring configuration through
inductors and driven uniformly by a harmonic external voltage source. A simple
model for each cell is proposed by using a nonlinear form for the varactor
characteristics through the current and capacitance dependence on the voltage.
For an electrical line composed of 32 elements, we find the regions, in driver
voltage and frequency, where -peaked breather solutions exist and
characterize their stability. The results are compared to experimental
measurements with good quantitative agreement. We also examine the spontaneous
formation of -peaked breathers through modulational instability of the
homogeneous steady state. The competition between different discrete breathers
seeded by the modulational instability eventually leads to stationary
-peaked solutions whose precise locations is seen to sensitively depend on
the initial conditions
Nonlinear localized modes in two-dimensional electrical lattices
We report the observation of spontaneous localization of energy in two
spatial dimensions in the context of nonlinear electrical lattices. Both
stationary and traveling self-localized modes were generated experimentally and
theoretically in a family of two-dimensional square, as well as hon- eycomb
lattices composed of 6x6 elements. Specifically, we find regions in driver
voltage and frequency where stationary discrete breathers, also known as
intrinsic localized modes (ILM), exist and are stable due to the interplay of
damping and spatially homogeneous driving. By introduc- ing additional
capacitors into the unit cell, these lattices can controllably induce traveling
discrete breathers. When more than one such ILMs are experimentally generated
in the lattice, the interplay of nonlinearity, discreteness and wave
interactions generate a complex dynamics wherein the ILMs attempt to maintain a
minimum distance between one another. Numerical simulations show good agreement
with experimental results, and confirm that these phenomena qualitatively carry
over to larger lattice sizes.Comment: 5 pages, 6 figure
Power and momentum dependent soliton dynamics in lattices with longitudinal modulation
Soliton dynamics in a large variety of longitudinally modulated lattices are
studied in terms of phase space analysis for an effective particle approach and
direct numerical simulations. Complex soliton dynamics are shown to depend
strongly on both their power/width and their initial momentum as well as on
lattice parameters. A rish set of qualitatively distinct dynamical features of
soliton propagation that have no counterpart in longitudinally uniform lattices
is illustrated. This set includes cases of enhanced soliton mobility, dynamical
switching, extended trapping in several transverse lattice periods, and
quasiperiodic trapping, which are promising for soliton control applications
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