22,611 research outputs found
Plastic Deformation of 2D Crumpled Wires
When a single long piece of elastic wire is injected trough channels into a
confining two-dimensional cavity, a complex structure of hierarchical loops is
formed. In the limit of maximum packing density, these structures are described
by several scaling laws. In this paper it is investigated this packing process
but using plastic wires which give origin to completely irreversible structures
of different morphology. In particular, it is studied experimentally the
plastic deformation from circular to oblate configurations of crumpled wires,
obtained by the application of an axial strain. Among other things, it is shown
that in spite of plasticity, irreversibility, and very large deformations,
scaling is still observed.Comment: 5 pages, 6 figure
Model inspired by population genetics to study fragmentation of brittle plates
We use a model whose rules were inspired by population genetics, the random
capability growth model, to describe the statistical details observed in
experiments of fragmentation of brittle platelike objects, and in particular
the existence of (i) composite scaling laws, (ii) small critical exponents \tau
associated with the power-law fragment-size distribution, and (iii) the typical
pattern of cracks. The proposed computer simulations do not require numerical
solutions of the Newton's equations of motion, nor several additional
assumptions normally used in discrete element models. The model is also able to
predict some physical aspects which could be tested in new experiments of
fragmentation of brittle systems.Comment: We have modified the text in order to make the description of the
model more clear. One Figure (Figure 1) was introduced showing the steps of
the dynamics of colonization. Twelve references were adde
T-Duality in 2-D Integrable Models
The non-conformal analog of abelian T-duality transformations relating pairs
of axial and vector integrable models from the non abelian affine Toda family
is constructed and studied in detail.Comment: 14 pages, Latex, v.2 misprints corrected, reference added, to appear
in J. Phys.
Structural properties of crumpled cream layers
The cream layer is a complex heterogeneous material of biological origin
which forms spontaneously at the air-milk interface. Here, it is studied the
crumpling of a single cream layer packing under its own weight at room
temperature in three-dimensional space. The structure obtained in these
circumstances has low volume fraction and anomalous fractal dimensions. Direct
means and noninvasive NMR imaging technique are used to investigate the
internal and external structure of these systems.Comment: 9 pages, 4 figures, accepted in J. Phys. D: Appl. Phy
Lorentz symmetry breaking in the noncommutative Wess-Zumino model: One loop corrections
In this paper we deal with the issue of Lorentz symmetry breaking in quantum
field theories formulated in a non-commutative space-time. We show that, unlike
in some recente analysis of quantum gravity effects, supersymmetry does not
protect the theory from the large Lorentz violating effects arising from the
loop corrections. We take advantage of the non-commutative Wess-Zumino model to
illustrate this point.Comment: 9 pages, revtex4. Corrected references. Version published in PR
Axial Vector Duality in Affine NA Toda Models
A general and systematic construction of Non Abelian affine Toda models and
its symmetries is proposed in terms of its underlying Lie algebraic structure.
It is also shown that such class of two dimensional integrable models naturally
leads to the construction of a pair of actions related by T-duality
transformationsComment: 9 pages, to appear in JHEP Proc. of the Workshop on Integrable
Theories, Solitons and Duality, IFT-Unesp, Sao Paulo, Brasil, one reference
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