Página 1 dos resultados de 11 itens digitais encontrados em 0.126 segundos

The degree of nonlinearity and anisotropy of blood vessel elasticity

Zhou, J.; Fung, Y. C.
Fonte: The National Academy of Sciences of the USA Publicador: The National Academy of Sciences of the USA
Tipo: Artigo de Revista Científica
Publicado em 23/12/1997 EN
Relevância na Pesquisa
55.54%
Blood vessel elasticity is important to physiology and clinical problems involving surgery, angioplasty, tissue remodeling, and tissue engineering. Nonlinearity in blood vessel elasticity in vivo is important to the formation of solitons in arterial pulse waves. It is well known that the stress–strain relationship of the blood vessel is nonlinear in general, but a controversy exists on how nonlinear it is in the physiological range. Another controversy is whether the vessel wall is biaxially isotropic. New data on canine aorta were obtained from a biaxial testing machine over a large range of finite strains referred to the zero-stress state. A new pseudo strain energy function is used to examine these questions critically. The stress–strain relationship derived from this function represents the sum of a linear stress–strain relationship and a definitely nonlinear relationship. This relationship fits the experimental data very well. With this strain energy function, we can define a parameter called the degree of nonlinearity, which represents the fraction of the nonlinear strain energy in the total strain energy per unit volume. We found that for the canine aorta, the degree of nonlinearity varies from 5% to 30%, depending on the magnitude of the strains in the physiological range. In the case of canine pulmonary artery in the arch region...

Spatial solitons and light-induced instabilities in colloidal media

Matuszewski, Michal; Krolikowski, Wieslaw; Kivshar, Yuri
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Journal article; Published Version Formato: 6 pages
Relevância na Pesquisa
45.61%
We study nonlinear light propagation in colloidal nanosuspensions. We introduce a novel model for the nonlinear response of colloids which describes consistently the system in the regimes of low and high light intensities and low/large concentrations of colloidal particles. We employ this model to study the light-induced instabilities and demonstrate the formation of stable spatial solitons as well as the existence of a bistability regime.

Observation of surface gap solitons in semi-infinite waveguide arrays

Rosberg, Christian; Neshev, Dragomir; Krolikowski, Wieslaw; Mitchell, Arnan; Vicencio, Rodrigo; Molina, Mario I; Kivshar, Yuri
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Journal article; Published Version Formato: 4 pages
Relevância na Pesquisa
35.55%
We report on the observation of surface gap solitons found to exist at the interface between uniform and periodic dielectric media with defocusing nonlinearity. We demonstrate strong self-trapping at the edge of a LiNbO3 waveguide array and the formation of staggered surface solitons with propagation constant inside the first photonic band gap. We study the crossover between linear repulsion and nonlinear attraction at the surface, revealing the mechanism of nonlinearity-mediated stabilization of the surface gap modes.

Ring vortex solitons in nonlocal nonlinear media

Briedis, Dahliyani; Petersen, D; Edmundson, Darran; Krolikowski, Wieslaw; Bang, Ole
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Journal article; Published Version Formato: 9 pages
Relevância na Pesquisa
55.66%
We study the formation and propagation of two-dimensional vortex solitons, i.e. solitons with a phase singularity, in optical materials with a nonlocal focusing nonlinearity. We show that nonlocality stabilizes the dynamics of an otherwise unstable vortex beam. This occurs for either single or higher charge fundamental vortices as well as higher order (multiple ring) vortex solitons. Our results pave the way for experimental observation of stable vortex rings in other nonlocal nonlinear systems including Bose-Einstein condensates with pronounced long-range interparticle interaction.; Affiliation in article: Briedis, Dahliyani, Australian National University, Department of Mathematics.

Nonlinear diffusion and beam self-trapping in diffraction-managed waveguide arrays

Garanovich, Ivan; Sukhorukov, Andrey; Kivshar, Yuri
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Journal article; Published Version Formato: 6 pages
Relevância na Pesquisa
45.55%
We study nonlinear propagation of light in diffractionmanaged photonic lattices created by periodically-curved arrays of optical waveguides. We identify different regimes of the nonlinear propagation of light in such structures depending on the input power. We start from the regime of self-collimation at low powers and demonstrate that, as the beam power increases, nonlinearity destroys the beam self-imaging and leads to nonlinear diffusion. At higher powers, we observe a sharp transition to the self-trapping and the formation of discrete diffraction-managed solitons.

Self-trapping of polychromatic light in nonlinear periodic photonic structures

Motzek, Christian; Sukhorukov, Andrey; Kivshar, Yuri
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Journal article; Published Version Formato: 6 pages
Relevância na Pesquisa
45.61%
We study dynamical reshaping of polychromatic beams due to collective nonlinear self-action of multiple-frequency components in periodic and semi-infinite photonic lattices and predict the formation of polychromatic gap solitons and polychromatic surface solitons due to light localization in spectral gaps. We show that the self-trapping efficiency and structure of emerging polychromatic solitons depend on the input spectrum due to the lattice-enhanced dispersion, including the effect of crossover from localization to diffraction in media with defocusing nonlinearity.; Article written under name Kristian Motzek.

Observation of polychromatic gap solitons

Sukhorukov, Andrey; Neshev, Dragomir; Dreischuh, Alexander; Krolikowski, Wieslaw; Bolger, J; Eggleton, Benjamin J; Bui, Lam; Mitchell, Arnan; Kivshar, Yuri
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Journal article; Published Version Formato: 6 pages
Relevância na Pesquisa
65.61%
We study theoretically and observe experimentally polychromatic gap solitons generated by supercontinuum light in an array of optical waveguides. The solitons are formed through a sharp transition from diffraction-induced broadening and color separation to the simultaneous spatio-spectral localization of supercontinuum light inside the photonic bandgap with the formation of the characteristic staggered phase structure for all colors.; Affiliation in article: Dreischuh, Alexander, also with Sofia University, Faculty of Physics, Bulgaria

Multi-Component Spatial Optical Solitons in Photorefractive Medium

Krolikowski, Wieslaw
Fonte: Polska Akademia Nauk (Polish Academy of Sciences) Publicador: Polska Akademia Nauk (Polish Academy of Sciences)
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.52%
We discuss properties of one- and two-dimensional multi-component spatial solitons. We present our recent results on formation and interaction of these solitons in photorefractive nonlinear crystal.

Magnetostatic spin waves and magnetic-wave chaos in ferromagnetic films. II. Numerical simulations of non-linear waves

Kuzovlev, Yu. E.; Medvedev, Yu. V.; Mezin, N. I.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 11/04/2012
Relevância na Pesquisa
45.42%
A method and some results of numeric simulations of magnetostatic spin waves in ferromagnetic films are exponded, in comparison with the theory earlier presented in arXiv preprint 1204.0200. In particular, roles of films finiteness (edges) and defects in formation of linear and non-linear magnetostatic wave patterns, excitation and evolution of two-dimensional solitons, and chaotic non-linear ferromagnetic resonance are considered.; Comment: 24 pages, 11 figures, latex2e revtex4

Soliton formation from a pulse passing the zero-dispersion point in a nonlinear Schr\"odinger equation

Clarke, S. R.; Grimshaw, R. H. J.; Malomed, Boris A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/01/2000
Relevância na Pesquisa
55.56%
We consider in detail the self-trapping of a soliton from a wave pulse that passes from a defocussing region into a focussing one in a spatially inhomogeneous nonlinear waveguide, described by a nonlinear Schrodinger equation in which the dispersion coefficient changes its sign from normal to anomalous. The model has direct applications to dispersion-decreasing nonlinear optical fibers, and to natural waveguides for internal waves in the ocean. It is found that, depending on the (conserved) energy and (nonconserved) mass of the initial pulse, four qualitatively different outcomes of the pulse transformation are possible: decay into radiation; self-trapping into a single soliton; formation of a breather; and formation of a pair of counterpropagating solitons. A corresponding chart is drawn on a parametric plane, which demonstrates some unexpected features. In particular, it is found that any kind of soliton(s) (including the breather and counterpropagating pair) eventually decays into pure radiation with the increase of the energy, the initial mass being kept constant. It is also noteworthy that a virtually direct transition from a single soliton into a pair of symmetric counterpropagating ones seems possible. An explanation for these features is proposed. In two cases when analytical approximations apply...

Optical Beams in Nonlocal Nonlinear Media

Krolikowski, Wieslaw; Bang, Ole; Wyller, John; Rasmussen, Per Dalgaard
Fonte: Polska Akademia Nauk (Polish Academy of Sciences) Publicador: Polska Akademia Nauk (Polish Academy of Sciences)
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.43%
We discuss propagation of optical beams in nonlocal Kerr-like media with the nonlocality of general form. We study the effect of nonlocality on modulational instability of the plane wave fronts, collapse of finite beams and formation of spatial solitons.