15,449 research outputs found
noise on the brink of wet granular melting
The collective behavior of a two-dimensional wet granular cluster under
horizontal swirling motions is investigated experimentally. Depending on the
balance between the energy injection and dissipation, the cluster evolves into
various nonequilibrium stationary states with strong internal structure
fluctuations with time. Quantitative characterizations of the fluctuations with
the bond orientational order parameter reveal power spectra of the
form with the exponent closely related to the stationary
states of the system. In particular, type of noise with
emerges as melting starts from the free surface of the cluster, suggesting the
possibility of using noise as an indicator for phase transitions in
systems driven far from thermodynamic equilibrium.Comment: 13 pages, 4 figure
Clustering and melting in a wet granular monolayer
We investigate experimentally the collective behavior of a wet granular
monolayer under vertical vibrations. The spherical particles are partially wet
such that there are short-ranged attractive interactions between adjacent
particles. As the vibration strength increases, clustering, reorganizing and
melting regimes are identified subsequently through a characterization with the
bond-orientational order parameters and the mean kinetic energy of the
particles. The melting transition is found to be a continuous process starting
from the defects inside the crystal.Comment: 4 pages, 3 figures, accepted by Powders and Grains 201
Joint Syntacto-Discourse Parsing and the Syntacto-Discourse Treebank
Discourse parsing has long been treated as a stand-alone problem independent
from constituency or dependency parsing. Most attempts at this problem are
pipelined rather than end-to-end, sophisticated, and not self-contained: they
assume gold-standard text segmentations (Elementary Discourse Units), and use
external parsers for syntactic features. In this paper we propose the first
end-to-end discourse parser that jointly parses in both syntax and discourse
levels, as well as the first syntacto-discourse treebank by integrating the
Penn Treebank with the RST Treebank. Built upon our recent span-based
constituency parser, this joint syntacto-discourse parser requires no
preprocessing whatsoever (such as segmentation or feature extraction), achieves
the state-of-the-art end-to-end discourse parsing accuracy.Comment: Accepted at EMNLP 201
Dynamics of wet granular hexagons
The collective behavior of vibrated hexagonal disks confined in a monolayer
is investigated experimentally. Due to the broken circular symmetry, hexagons
prefer to rotate upon sufficiently strong driving. Due to the formation of
liquid bridges, short-ranged cohesive interactions are introduced upon wetting.
Consequently, a nonequilibrium stationary state with the rotating disks
self-organized in a hexagonal structure arises. The bond length of the
hexagonal structure is slightly smaller than the circumdiameter of a hexagon,
indicating geometric frustration. This investigation provides an example where
the collective behavior of granular matter is tuned by the shape of individual
particles.Comment: 5 pages, 5 figure
Role of defects in the onset of wall-induced granular convection
We investigate the onset of the wall-induced convection in vertically
vibrated granular matter by means of experiments and two-dimensional computer
simulations. In both simulations and experiments we find that the wall-induced
convection occurs inside the bouncing bed region of the parameter space in
which the granular bed behaves like a bouncing ball. A good agreement between
experiments and simulations is found for the peak vibration acceleration at
which convection starts. By comparing the results of simulations initialised
with and without defects, we find that the onset of convection occurs at lower
vibration strengths in the presence of defects. Furthermore, we find that the
convection of granular particles initialised in a perfect hexagonal lattice is
related to the nucleation of defects and the process is described by an
Arrhenius law.Comment: 7 pages, 6 figure
- …