PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Nonlinear Dynamics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,351 records · Page 75Linked to original sources
PubMed2000

Bifurcations and transport barriers in the resistive-g paradigm

The so-called resistive-g (resistive pressure-gradient-driven turbulence) paradigm is a widely accepted and frequently investigated model for nonlinear plasma dynamics. The parameter dependences of the generated transport barriers as well as third order bifurcations will be discussed numerically and analytically in the present paper. First, using a Galerkin representation, bifurcating states (from the conductive states in a rectangular cell) are investigated for the cases when only one unstable mode dominates. The dependence of the bifurcation properties on the aspect ratio of the domain is discussed, leading to the conclusion that for vanishing (or small) magnetic shear the so-called low, high, and edge localized mode transitions do not occur for small aspect ratios of the domain. Including reasonable magnetic shear, the small-aspect-ratio cutoff disappears, and transport barriers may exist in a broad parameter range. Second, for small aspect ratios, interesting codimension-2 bifurcations occur. When unfolding the dynamics up to third order, e.g., a weakly nonlinear interaction of convection cells is observed. The analytical results are confirmed by numerical simulations.

Journal Article↗
PubMed2000

Shock wave dynamics in a discrete nonlinear Schrodinger equation with internal losses

Propagation of a shock wave (SW), converting an energy-carrying domain into an empty one, is studied in a discrete version of the normal-dispersion nonlinear Schrodinger equation with viscosity, which may describe, e.g., an array of optical fibers in a weakly lossy medium. It is found that the SW in the discrete model is stable, as well as in its earlier studied continuum counterpart. In a strongly discrete case, the dependence of the SWs velocity upon the amplitude of the energy-carrying background is found to obey a simple linear law, which differs by a value of the proportionality coefficient from a similar law in the continuum model. For the underdamped case, the velocity of the shock wave is found to be vanishing along with the viscosity constant. We argue that the latter feature is universal for long but finite systems, both discrete and continuum. The dependence of the SW's width on the parameters of the system is also discussed.

Journal Article↗
PubMed2003

Nonlinear stress and fluctuation dynamics of sheared disordered wet foam.

A sheared wet foam, which stores elastic energy in bubble deformations, relaxes stress through bubble rearrangements. The intermittency of bubble rearrangements in the foam leads to effectively stochastic drops in stress that are followed by periods of elastic increase. We investigate global characteristics of highly disordered foams over three decades of strain rate and almost two decades of system size. We characterize the behavior using a range of measures: average stress, distribution of stress drops, rate of stress drops, and a normalized fluctuation intensity. There is essentially no dependence on system size. As a function of strain rate, there is a change in behavior around shear rates of 0.07 s(-1).

Journal Article↗