18,972 research outputs found
Nonlinear combining of laser beams
We propose to combine multiple laser beams into a single diffraction-limited
beam by the beam self-focusing (collapse) in the Kerr medium. The beams with
the total power above critical are first combined in the near field and then
propagated in the optical fiber/waveguide with the Kerr nonlinearity. Random
fluctuations during propagation eventually trigger strong self-focusing event
and produce diffraction-limited beam carrying the critical power.Comment: 5 pages, 5 figure
Norm Monitoring under Partial Action Observability
In the context of using norms for controlling multi-agent systems, a vitally
important question that has not yet been addressed in the literature is the
development of mechanisms for monitoring norm compliance under partial action
observability. This paper proposes the reconstruction of unobserved actions to
tackle this problem. In particular, we formalise the problem of reconstructing
unobserved actions, and propose an information model and algorithms for
monitoring norms under partial action observability using two different
processes for reconstructing unobserved actions. Our evaluation shows that
reconstructing unobserved actions increases significantly the number of norm
violations and fulfilments detected.Comment: Accepted at the IEEE Transaction on Cybernetic
Resolving Multi-party Privacy Conflicts in Social Media
Items shared through Social Media may affect more than one user's privacy ---
e.g., photos that depict multiple users, comments that mention multiple users,
events in which multiple users are invited, etc. The lack of multi-party
privacy management support in current mainstream Social Media infrastructures
makes users unable to appropriately control to whom these items are actually
shared or not. Computational mechanisms that are able to merge the privacy
preferences of multiple users into a single policy for an item can help solve
this problem. However, merging multiple users' privacy preferences is not an
easy task, because privacy preferences may conflict, so methods to resolve
conflicts are needed. Moreover, these methods need to consider how users' would
actually reach an agreement about a solution to the conflict in order to
propose solutions that can be acceptable by all of the users affected by the
item to be shared. Current approaches are either too demanding or only consider
fixed ways of aggregating privacy preferences. In this paper, we propose the
first computational mechanism to resolve conflicts for multi-party privacy
management in Social Media that is able to adapt to different situations by
modelling the concessions that users make to reach a solution to the conflicts.
We also present results of a user study in which our proposed mechanism
outperformed other existing approaches in terms of how many times each approach
matched users' behaviour.Comment: Authors' version of the paper accepted for publication at IEEE
Transactions on Knowledge and Data Engineering, IEEE Transactions on
Knowledge and Data Engineering, 201
A Probabilistic Approach to Classifying Supernovae Using Photometric Information
This paper presents a novel method for determining the probability that a
supernova candidate belongs to a known supernova type (such as Ia, Ibc, IIL,
\emph{etc.}), using its photometric information alone. It is validated with
Monte Carlo, and both space- and ground- based data. We examine the application
of the method to well-sampled as well as poorly sampled supernova light curves
and investigate to what extent the best currently available supernova models
can be used for typing supernova candidates. Central to the method is the
assumption that a supernova candidate belongs to a group of objects that can be
modeled; we therefore discuss possible ways of removing anomalous or less well
understood events from the sample. This method is particularly advantageous for
analyses where the purity of the supernova sample is of the essence, or for
those where it is important to know the number of the supernova candidates of a
certain type (\emph{e.g.}, in supernova rate studies).Comment: Version accepted for publication in Astrophysical Journa
Necessary conditions for linear noncooperative N-player delta differential games on time scales
We present necessary conditions for linear noncooperative N-player delta
dynamic games on a generic time scale. Necessary conditions for an open-loop
Nash-equilibrium and for a memoryless perfect state Nash-equilibrium are
proved.Comment: Partially presented at the "Fifth Symposium on Nonlinear Analysis"
(SNA 2007), Torun, Poland, September 10-14, 200
Nonlinear parity-time-symmetric transition in finite-size optical couplers
Parity-time-symmetric (-symmetric) optical waveguide couplers
offer a great potential for future applications in integrated optics. Studies
of nonlinear -symmetric couplers present new possibilities for
ultracompact configurable all-optical signal processing. Here, we predict
nonlinearly triggered transition from a full to a broken
-symmetric regime in finite-size systems described by smooth
permittivity profiles and, in particular, in a conventional discrete waveguide
directional coupler configuration with a rectangular permittivity profile.
These results suggest a practical route for experimental realization of such
systems
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