27,822 research outputs found
Using P3P in a web services-based context-aware application platform
This paper describes a proposal for a privacy control architecture to be applied in the WASP project. The WASP project aims to develop a context-aware service platform on top of 3G networks, using web services technology. The proposed privacy control architecture is based on the P3P privacy policy description standard defined by W3C. The paper identifies extensions to P3P and its associated preference expression language APPEL that are needed to operate in a context-aware environment
Large time behavior for vortex evolution in the half-plane
In this article we study the long-time behavior of incompressible ideal flow
in a half plane from the point of view of vortex scattering. Our main result is
that certain asymptotic states for half-plane vortex dynamics decompose
naturally into a nonlinear superposition of soliton-like states. Our approach
is to combine techniques developed in the study of vortex confinement with weak
convergence tools in order to study the asymptotic behavior of a self-similar
rescaling of a solution of the incompressible 2D Euler equations on a half
plane with compactly supported, nonnegative initial vorticity.Comment: 30 pages, no figure
Superintegrability of the Fock-Darwin system
The Fock-Darwin system is analysed from the point of view of its symmetry
properties in the quantum and classical frameworks. The quantum Fock-Darwin
system is known to have two sets of ladder operators, a fact which guarantees
its solvability. We show that for rational values of the quotient of two
relevant frequencies, this system is superintegrable, the quantum symmetries
being responsible for the degeneracy of the energy levels. These symmetries are
of higher order and close a polynomial algebra. In the classical case, the
ladder operators are replaced by ladder functions and the symmetries by
constants of motion. We also prove that the rational classical system is
superintegrable and its trajectories are closed. The constants of motion are
also generators of symmetry transformations in the phase space that have been
integrated for some special cases. These transformations connect different
trajectories with the same energy. The coherent states of the quantum
superintegrable system are found and they reproduce the closed trajectories of
the classical one.Comment: 21 pages,16 figure
- …