6,639 research outputs found
“Soldiers for Sale: German “Mercenaries” with the British in Canada during the American Revolution, 1776-83 (Book Review)” by Jean-Pierre Wilhelmy
Review of Soldiers for Sale: German “Mercenaries” with the British in Canada during the American Revolution, 1776-83 by Jean-Pierre Wilhelm
Individual Expression Versus the Submissive Woman in France
While still in the midst of their study abroad experiences, students at Linfield College write reflective essays. Their essays address issues of cultural similarity and difference, compare lifestyles, mores, norms, and habits between their host countries and home, and examine changes in perceptions about their host countries and the United States. In this essay, Fatima Falcon Ontiveros describes her observations during her study abroad program at the Institut Américain Universitaire in Aix-en-Provence, France
Gravity wave turbulence revealed by horizontal vibrations of the container
We experimentally study the role of the forcing on gravity-capillary wave
turbulence. Previous laboratory experiments using spatially localized forcing
(vibrating blades) have shown that the frequency power-law exponent of the
gravity wave spectrum depends on the forcing parameters. By horizontally
vibrating the whole container, we observe a spectrum exponent that does not
depend on the forcing parameters for both gravity and capillary regimes. This
spatially extended forcing leads to a gravity spectrum exponent in better
agreement with the theory than by using a spatially localized forcing. The role
of the vessel shape has been also studied. Finally, the wave spectrum is found
to scale linearly with the injected power for both regimes whatever the forcing
type used
Simulations of vibrated granular medium with impact velocity dependent restitution coefficient
We report numerical simulations of strongly vibrated granular materials
designed to mimic recent experiments performed both in presence or absence of
gravity. The coefficient of restitution used here depends on the impact
velocity by taking into account both the viscoelastic and plastic deformations
of particles, occurring at low and high velocities respectively. We show that
this model with impact velocity dependent restitution coefficient reproduce
results that agree with experiments. We measure the scaling exponents of the
granular temperature, collision frequency, impulse, and pressure with the
vibrating piston velocity as the particle number increases. As the system
changes from a homogeneous gas state at low density to a clustered state at
high density, these exponents are all found to decrease continuously with the
particle number. All these results differ significantly from classical
inelastic hard sphere kinetic theory and previous simulations, both based on a
constant restitution coefficient.Comment: to be published in Phys. Rev.
Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient
We report two-dimensional simulations of strongly vibrated granular materials
without gravity. The coefficient of restitution depends on the impact velocity
between particles by taking into account both the viscoelastic and plastic
deformations of particles, occurring at low and high velocities respectively.
Use of this model of restitution coefficient leads to new unexpected behaviors.
When the number of particles N is large, a loose cluster appears near the fixed
wall, opposite the vibrating wall. The pressure exerted on the walls becomes
independent of N, and linear in the vibration velocity V, quite as the granular
temperature. The collision frequency at the vibrating wall becomes independent
of both N and V, whereas at the fixed wall, it is linear in both N and V. These
behaviors arise because the velocity-dependent restitution coefficient
introduces a new time scale related to the collision velocity near the cross
over from viscoelastic to plastic deformation.Comment: Final version - To be published in Powder Technolog
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