41 research outputs found
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Chess endgames: 6-man data and strategy
While Nalimov’s endgame tables for Western Chess are the most used today, their Depth-to-Mate metric is not the most efficient or effective in use. The authors have developed and used new programs to create tables to alternative metrics and recommend better strategies for endgame play
Antiferromagnetic effects in Chaotic Map lattices with a conservation law
Some results about phase separation in coupled map lattices satisfying a
conservation law are presented. It is shown that this constraint is the origin
of interesting antiferromagnetic effective couplings and allows transitions to
antiferromagnetic and superantiferromagnetic phases. Similarities and
differences between this models and statistical spin models are pointed out.Comment: 14 pages including 9 figure
Reflection of traveling waves near the onset of binary-fluid convection
The reflection coefficient of linear traveling waves in binary-fluid convection is calculated for the experimental situation of rigid, impermeable boundaries. Results for a range of parameters of interest to experiments in ethanol-water mixtures are displayed and compared with experiment
Derivation and Empirical Validation of a Refined Traffic Flow Model
The gas-kinetic foundation of fluid-dynamic traffic equations suggested in
previous papers [Physica A 219, 375 and 391 (1995)] is further refined by
applying the theory of dense gases and granular materials to the Boltzmann-like
traffic model by Paveri-Fontana. It is shown that, despite the
phenomenologically similar behavior of ordinary and granular fluids, the
relations for these cannot directly be transferred to vehicular traffic. The
dissipative and anisotropic interactions of vehicles as well as their
velocity-dependent space requirements lead to a considerably different
structure of the macroscopic traffic equations, also in comparison with the
previously suggested traffic flow models. As a consequence, the instability
mechanisms of emergent density waves are different. Crucial assumptions are
validated by empirical traffic data and essential results are illustrated by
figures.Comment: For related work see
http://www.theo2.physik.uni-stuttgart.de/helbing.htm
Time resolved particle dynamics in granular convection
We present an experimental study of the movement of individual particles in a
layer of vertically shaken granular material. High-speed imaging allows us to
investigate the motion of beads within one vibration period. This motion
consists mainly of vertical jumps, and a global ordered drift. The analysis of
the system movement as a whole reveals that the observed bifurcation in the
flight time is not adequately described by the Inelastic Bouncing Ball Model.
Near the bifurcation point, friction plays and important role, and the branches
of the bifurcation do not diverge as the control parameter is increased. We
quantify the friction of the beads against the walls, showing that this
interaction is the underlying mechanism responsible for the dynamics of the
flow observed near the lateral wall
Hydrodynamic Description of Granular Convection
We present a hydrodynamic model that captures the essence of granular
dynamics in a vibrating bed. We carry out the linear stability analysis and
uncover the instability mechanism that leads to the appearance of the
convective rolls via a supercritical bifurcation of a bouncing solution. We
also explicitly determine the onset of convection as a function of control
parameters and confirm our picture by numerical simulations of the continuum
equations.Comment: 14 pages, RevTex 11pages + 3 pages figures (Type csh
Thermal convection in fluidized granular systems
Thermal convection is observed in molecular dynamic simulation of a fluidized
granular system of nearly elastic hard disks moving under gravity, inside a
rectangular box. Boundaries introduce no shearing or time dependence, but the
energy injection comes from a slip (shear-free) thermalizing base. The top wall
is perfectly elastic and lateral boundaries are either elastic or periodic. The
observed convection comes from the effect of gravity and the spontaneous
granular temperature gradient that the system dynamically develops.Comment: 4 pages, 5 figure
A Continuum Description of Vibrated Sand
The motion of a thin layer of granular material on a plate undergoing
sinusoidal vibrations is considered. We develop equations of motion for the
local thickness and the horizontal velocity of the layer. The driving comes
from the violent impact of the grains on the plate. A linear stability theory
reveals that the waves are excited non-resonantly, in contrast to the usual
Faraday waves in liquids. Together with the experimentally observed continuum
scaling, the model suggests a close connection between the neutral curve and
the dispersion relation of the waves, which agrees quite well with experiments.
For strong hysteresis we find localized oscillon solutions.Comment: paper has been considerably extended (11 instead of 6 pages; 6
instead of 4 figures) much better agreement with experiment. obtain now
oscillons in 1 dimensio