11,550 research outputs found
Knowledge web: realising the semantic web... all the way to knowledge-enhanced multimedia documents
The semantic web and semantic web services are major efforts in order to spread and to integrate knowledge technology to the whole web. The Knowledge Web network of excellence aims at supporting their developments at the best and largest European level and supporting industry in adopting them. It especially investigates the solution of scalability, heterogeneity and dynamics obstacles to the full development of the semantic web. We explain how Knowledge Web results should benefit knowledge-enhanced multimedia applications
Revisiting the optical -symmetric dimer
Optics has proved a fertile ground for the experimental simulation of quantum
mechanics. Most recently, optical realizations of -symmetric
quantum mechanics have been shown, both theoretically and experimentally,
opening the door to international efforts aiming at the design of practical
optical devices exploiting this symmetry. Here, we focus on the optical
-symmetric dimer, a two-waveguide coupler were the materials show
symmetric effective gain and loss, and provide a review of the linear and
nonlinear optical realizations from a symmetry based point of view. We go
beyond a simple review of the literature and show that the dimer is just the
smallest of a class of planar -waveguide couplers that are the optical
realization of Lorentz group in 2+1 dimensions. Furthermore, we provide a
formulation to describe light propagation through waveguide couplers described
by non-Hermitian mode coupling matrices based on a non-Hermitian generalization
of Ehrenfest theorem.Comment: 25 pages, 12 figure
A spatially-structured PCG method for content diversity in a Physics-based simulation game
This paper presents a spatially-structured evolutionary algorithm (EA) to procedurally generate game maps of di ferent levels of di ficulty to be solved, in Gravityvolve!, a physics-based simulation videogame that we have implemented and which is inspired by the n-
body problem, a classical problem in the fi eld of physics and mathematics. The proposal consists of a steady-state EA whose population is partitioned into three groups according to the di ficulty of the generated content (hard, medium or easy) which can be easily adapted to handle the automatic creation of content of diverse nature in other games. In addition, we present three fitness functions, based on multiple criteria (i.e:, intersections, gravitational acceleration and simulations), that were used experimentally to conduct the search process for creating a database of
maps with di ferent di ficulty in Gravityvolve!.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
Entanglement detection for electrons via witness operators
We discuss an implementation of the entanglement witness, a method to detect
entanglement with few local measurements, in systems where entangled electrons
are generated both in the spin and orbital degrees of freedom.
We address the efficiency of this method in various setups, including two
different particle-hole entanglement structures, and we demonstrate that it can
also be used to infer information on the possible dephasing afflicting the
devices.Comment: 12 pages, 5 figures; published versio
Vortex ratchet reversal: The role of interstitial vortices
Triangular arrays of Ni nanotriangles embedded in superconducting Nb films
exhibit unexpected dynamical vortex effects. Collective pinning with a vortex
lattice configuration different from the expected fundamental triangular
"Abrikosov state" is found. The vortex motion which prevails against the
triangular periodic potential is produced by channelling effects between
triangles. Interstitial vortices coexisting with pinned vortices in this
asymmetric potential, lead to ratchet reversal, i.e. a DC output voltage which
changes sign with the amplitude of an applied alternating drive current. In
this landscape, ratchet reversal is always observed at all magnetic fields (all
numbers of vortices) and at different temperatures. The ratchet reversal is
unambiguously connected to the presence of two locations for the vortices:
interstitial and above the artificial pinning sites.Comment: 21 pages, 4 figures, 1 Tabl
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