88 research outputs found
Quantum tops as examples of commuting differential operators
We study the quantum analogs of tops on Lie algebras and
represented by differential operators.Comment: 24 p
Non-homogeneous systems of hydrodynamic type possessing Lax representations
We consider 1+1 - dimensional non-homogeneous systems of hydrodynamic type
that possess Lax representations with movable singularities. We present a
construction, which provides a wide class of examples of such systems with
arbitrary number of components. In the two-component case a classification is
given.Comment: 22 pages, latex, minor change
Atlas of two-dimensional irreversible conservative lagrangian mechanical systems with a second quadratic integral
This paper aims at the most comprehensive and systematic construction and
tabulation of mechanical systems that admit a second invariant, quadratic in
velocities, other than the Hamiltonian. The configuration space is in general a
2D Riemannian or pseudo-Riemannian manifold and the determination of its
geometry is a part of the process of solution. Forces acting on the system
include a part derived from a scalar potential and a part derived from a vector
potential, associated with terms linear in velocities in the Lagrangian
function of the system. The last cause time-irreversibility of the system. We
construct 41 multi-parameter integrable systems of the type described in the
title mostly on Riemannian manifolds. They are mostly new and cover all
previously known systems as special cases, corresponding to special values of
the parameters. Those include all known cases of motion of a particle in the
plane and all known cases in the dynamics of rigid body. In the last field we
introduce a new integrable case related to Steklov's case of motion of a body
in a liquid. Several new cases of motion in the plane, on the sphere and on the
pseudo-sphere or in the hyperbolic plane are found as special cases.
Prospective applications in mathematics and physics are also pointed out.Comment: Paper to be published in "Journal of Mathematical Physics", Vol. 48,
issue 7, July 200
Chaplygin ball over a fixed sphere: explicit integration
We consider a nonholonomic system describing a rolling of a dynamically
non-symmetric sphere over a fixed sphere without slipping. The system
generalizes the classical nonholonomic Chaplygin sphere problem and it is shown
to be integrable for one special ratio of radii of the spheres. After a time
reparameterization the system becomes a Hamiltonian one and admits a separation
of variables and reduction to Abel--Jacobi quadratures. The separating
variables that we found appear to be a non-trivial generalization of
ellipsoidal (spheroconical) coordinates on the Poisson sphere, which can be
useful in other integrable problems.
Using the quadratures we also perform an explicit integration of the problem
in theta-functions of the new time.Comment: This is an extended version of the paper to be published in Regular
and Chaotic Dynamics, Vol. 13 (2008), No. 6. Contains 20 pages and 2 figure
Specific features of the melting of poly(ethylene terephthalate) after its thermal and mechanical treatment
Effect of supermolecular structure on deformation and strength properties of low-pressure polyethylene
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