154 research outputs found
Tools for analysis of Dirac structures on Hilbert spaces
In this paper tools for the analysis of Dirac structures on Hilbert spaces are developed. Some properties are pointed out and two natural representations of Dirac structures on Hilbert spaces are presented. The theory is illustrated on the example of the ideal transmission line. \u
Hamiltonian formulation of planar beams
This paper deals with the port-Hamiltonian formulation of planar beams. It is shown how this formulation can be related to the linear beams models: the Timoshenko beam model and the rod model
Harmonic oscillators in the Nos\'e - Hoover thermostat
We study the dynamics of an ensemble of non-interacting harmonic oscillators
in a nonlinear dissipative environment described by the Nos\'e - Hoover model.
Using numerical simulation we find the histogram for total energy, which agrees
with the analysis of the Nos\'e - Hoover equations effected with the method of
averaging. The histogram does not correspond to Gibbs' canonical distribution.
We have found oscillations at frequency proportional to ,
the dissipative parameter of thermostat and the characteristic
mass of particle, about the stationary state corresponding to equilibrium. The
oscillations could have an important bearing upon the analysis of simulating
molecular dynamics in the Nos\'e - Hoover thermostat.Comment: 7 pages, 4 figure
Title Stabilization of Membrane Pores by Packing
We present a model for pore stabilization in membranes without surface
tension. Whereas an isolated pore is always unstable (since it either shrinks
tending to re-seal or grows without bound til to membrane disintegration), it
is shown that excluded volume interactions in a system of many pores can
stabilize individual pores of a given size in a certain range of model
parameters. For such a multipore membrane system, the distribution of pore size
and associated pore lifetime are calculated within the mean field
approximation. We predict that, above certain temperature when the effective
line tension becomes negative, the membrane exhibits a dynamic sieve-like
porous structure.Comment: 4 pages, 4 figure
Symmetry breaking in low-dimensional SU(N) antiferromagnets
Consequences of explicit symmetry breaking in a physically motivated model of
SU(N) antiferromagnet in spatial dimensions one and two are studied. It is
shown that the case N=3, which can be realized in spin-1 cold atom systems,
displays special properties distinctly different from those for N>=4.
Qualitative form of the phase diagram depending on the model parameters is
given.Comment: 10 pages, 2 figures; added references, corrected fig.2; the final
version to appear in PR
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