897 research outputs found
Self-organized criticality in the Kardar-Parisi-Zhang-equation
Kardar-Parisi-Zhang interface depinning with quenched noise is studied in an
ensemble that leads to self-organized criticality in the quenched
Edwards-Wilkinson (QEW) universality class and related sandpile models. An
interface is pinned at the boundaries, and a slowly increasing external drive
is added to compensate for the pinning. The ensuing interface behavior
describes the integrated toppling activity history of a QKPZ cellular
automaton. The avalanche picture consists of several phases depending on the
relative importance of the terms in the interface equation. The SOC state is
more complicated than in the QEW case and it is not related to the properties
of the bulk depinning transition.Comment: 5 pages, 3 figures; accepted for publication in Europhysics Letter
Comment on: "Roughness of Interfacial Crack Fronts: Stress-Weighted Percolation in the Damage Zone"
This is a comment on J. Schmittbuhl, A. Hansen, and G. G. Batrouni, Phys.
Rev. Lett. 90, 045505 (2003). They offer a reply, in turn.Comment: 1 page, 1 figur
Creep of a fracture line in paper peeling
The slow motion of a crack line is studied via an experiment in which sheets
of paper are split into two halves in a ``peel-in-nip'' (PIN) geometry under a
constant load, in creep. The velocity-force relation is exponential. The
dynamics of the fracture line exhibits intermittency, or avalanches, which are
studied using acoustic emission. The energy statistics is a power-law, with the
exponent . Both the waiting times between subsequent
events and the displacement of the fracture line imply complicated stick-slip
dynamics. We discuss the correspondence to tensile PIN tests and other similar
experiments on in-plane fracture and the theory of creep for elastic manifolds
Energy landscapes, lowest gaps, and susceptibility of elastic manifolds at zero temperature
We study the effect of an external field on (1+1) and (2+1) dimensional
elastic manifolds, at zero temperature and with random bond disorder. Due to
the glassy energy landscape the configuration of a manifold changes often in
abrupt, ``first order'' -type of large jumps when the field is applied. First
the scaling behavior of the energy gap between the global energy minimum and
the next lowest minimum of the manifold is considered, by employing exact
ground state calculations and an extreme statistics argument. The scaling has a
logarithmic prefactor originating from the number of the minima in the
landscape, and reads ,
where is the roughness exponent and is the energy fluctuation
exponent of the manifold, is the linear size of the manifold, and is
the system height. The gap scaling is extended to the case of a finite external
field and yields for the susceptibility of the manifolds . We also present a mean field argument
for the finite size scaling of the first jump field, .
The implications to wetting in random systems, to finite-temperature behavior
and the relation to Kardar-Parisi-Zhang non-equilibrium surface growth are
discussed.Comment: 20 pages, 22 figures, accepted for publication in Eur. Phys. J.
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