5,420 research outputs found
Robust Chaos
It has been proposed to make practical use of chaos in communication, in
enhancing mixing in chemical processes and in spreading the spectrum of
switch-mode power suppies to avoid electromagnetic interference. It is however
known that for most smooth chaotic systems, there is a dense set of periodic
windows for any range of parameter values. Therefore in practical systems
working in chaotic mode, slight inadvertent fluctuation of a parameter may take
the system out of chaos. We say a chaotic attractor is robust if, for its
parameter values there exists a neighborhood in the parameter space with no
periodic attractor and the chaotic attractor is unique in that neighborhood. In
this paper we show that robust chaos can occur in piecewise smooth systems and
obtain the conditions of its occurrence. We illustrate this phenomenon with a
practical example from electrical engineering.Comment: 4 pages, Latex, 4 postscript figures, To appear in Phys. Rev. Let
Matrix proof method in annotated paraconsistent logic
The matrix connection method (MCM) is an alternative procedure for theorem proving than the usual resolution technique. We already have used the MCM for finding models in a real-time knowledge-based system generator. In this paper, we adapt the MCM to the particular case of sorne annotated propositional paraconsistent logics. Further developments related to these ideas are also outlined.Eje: 2do. Workshop sobre aspectos teóricos de la inteligencia artificialRed de Universidades con Carreras en Informática (RedUNCI
Maximal correlation between flavor entanglement and oscillation damping due to localization effects
Localization effects and quantum decoherence driven by the mass-eigenstate
wave packet propagation are shown to support a statistical correlation between
quantum entanglement and damped oscillations in the scenario of three-flavor
quantum mixing for neutrinos. Once the mass-eigenstates that support flavor
oscillations are identified as three-{\em qubit} modes, a decoherence scale can
be extracted from correlation quantifiers, namely the entanglement of formation
and the logarithmic negativity. Such a decoherence scale is compared with the
coherence length of damped oscillations. Damping signatures exhibited by flavor
transition probabilities as an effective averaging of the oscillating terms are
then explained as owing to loss of entanglement between mass modes involved in
the relativistic propagation.Comment: 13 pages, 03 figure
Universality in active chaos
Many examples of chemical and biological processes take place in large-scale
environmental flows. Such flows generate filamental patterns which are often
fractal due to the presence of chaos in the underlying advection dynamics. In
such processes, hydrodynamical stirring strongly couples into the reactivity of
the advected species and might thus make the traditional treatment of the
problem through partial differential equations difficult. Here we present a
simple approach for the activity in in-homogeneously stirred flows. We show
that the fractal patterns serving as skeletons and catalysts lead to a rate
equation with a universal form that is independent of the flow, of the particle
properties, and of the details of the active process. One aspect of the
universality of our appraoch is that it also applies to reactions among
particles of finite size (so-called inertial particles).Comment: 10 page
Impact of substrate defects on the equilibrium one-dimensional island size distribution
As long as only first-neighbour interactions are considered, equilibrium island size distributions of monoatomic islands in one dimension follow an exponential law regardless of the strength and the repulsive or attractive character of the adsorbate–adsorbate interactions. However, one- dimensional atomic wires obtained via nucleation at the step edges have a monomodal island size distribution. In this paper, we present a simple one- dimensional Monte Carlo model that shows how the monomodal distribution observed experimentally can be obtained by including surface defects that only suppress the interaction between two successive adsorbates.Fil: Mirabella, D. A.. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y TecnologÃa de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de IngenierÃa; ArgentinaFil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y TecnologÃa de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de IngenierÃa; Argentin
Comparison of Clustering Algorithms for the Identification of Topics on Twitter
Topic Identification in Social Networks has become an important task when dealing with event detection, particularly when global communities are affected. In order to attack this problem, text processing techniques and machine learning algorithms have been extensively used. In this paper we compare four clustering algorithms – k-means, k-medoids, DBSCAN and NMF (Non-negative Matrix Factorization) – in order to detect topics related to textual messages obtained from Twitter. The algorithms were applied to a database initially composed by tweets having hashtags related to the recent Nepal earthquake as initial context. Obtained results suggest that the NMF clustering algorithm presents superior results, providing simpler clusters that are also easier to interpret.
 
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