4,621 research outputs found
Highly-complex optical signal generation using electro-optical systems with non-linear, non-invertible transmission functions
We present a scheme whereby a static non-linear, non-invertible transmission
function performed by the electro-optic Mach-Zehnder modulator produces highly
complex optical chaos. The scheme allows the deterministic transformation of
low-dimensional band-limited chaotic signals into much higher-dimensional
structures with broadband spectra and without using any delay elements or
feedback. Standard benchmark tests show that all the considered complexity
indices are highly increased due to this transformation in a controlled
fashion. This mechanism allows the design of simple optoelectronic delayed
oscillators with extremely complex chaotic output.Comment: 4 pages, 5 figures. To appear in Applied Physics Letters (August
2012
A new battery-charging method suggested by molecular dynamics simulations
Based on large-scale molecular dynamics simulations, we propose a new
charging method that should be capable of charging a Lithium-ion battery in a
fraction of the time needed when using traditional methods. This charging
method uses an additional applied oscillatory electric field. Our simulation
results show that this charging method offers a great reduction in the average
intercalation time for Li+ ions, which dominates the charging time. The
oscillating field not only increases the diffusion rate of Li+ ions in the
electrolyte but, more importantly, also enhances intercalation by lowering the
corresponding overall energy barrier.Comment: 11 pages, 5 figure
Non-parametric Estimation of Stochastic Differential Equations with Sparse Gaussian Processes
The application of Stochastic Differential Equations (SDEs) to the analysis
of temporal data has attracted increasing attention, due to their ability to
describe complex dynamics with physically interpretable equations. In this
paper, we introduce a non-parametric method for estimating the drift and
diffusion terms of SDEs from a densely observed discrete time series. The use
of Gaussian processes as priors permits working directly in a function-space
view and thus the inference takes place directly in this space. To cope with
the computational complexity that requires the use of Gaussian processes, a
sparse Gaussian process approximation is provided. This approximation permits
the efficient computation of predictions for the drift and diffusion terms by
using a distribution over a small subset of pseudo-samples. The proposed method
has been validated using both simulated data and real data from economy and
paleoclimatology. The application of the method to real data demonstrates its
ability to capture the behaviour of complex systems
Classical properties of algebras using a new graph association
We study the relation between algebraic structures and Graph Theory. We have
defined five different weighted digraphs associated to a finite dimensional
algebra over a field in order to tackle important properties of the associated
algebras, mainly the nilpotency and solvability in the case of Leibniz
algebras
Computing coset leaders and leader codewords of binary codes
In this paper we use the Gr\"obner representation of a binary linear code
to give efficient algorithms for computing the whole set of coset
leaders, denoted by and the set of leader codewords,
denoted by . The first algorithm could be adapted to
provide not only the Newton and the covering radius of but also to
determine the coset leader weight distribution. Moreover, providing the set of
leader codewords we have a test-set for decoding by a gradient-like decoding
algorithm. Another contribution of this article is the relation stablished
between zero neighbours and leader codewords
1020 steel coated with Ti/TiN by Cathodic Arc and Ion Implantation
TiN coatings have been widely studied in order to improve mechanical properties of steels. In this work, thin Ti/TiN films were prepared by plasma based immersion ion implantation and deposition (PBII&D) with a cathodic arc on AISI 1020 steel substrates. Substrates were exposed to the discharge during 1 min in vacuum for the deposition of a Tiunderlayer with the aim of improving the adhesion to the substrate. Then, a TiN layer was deposited during 6 min in a nitrogen environment at a pressure of 3xl0-4 mbar. Samples were obtained at room temperature and at 300 °C, and with or without ion implantation in order to analyze differences between the effects of each treatment on the tribological properties. The mechanical and tribological properties of the films were characterized. The coatings deposited by PBII&D at 300 °C presented the highest hardness and young modulus, the best wear resistance and corrosion performance.Fil: Bermeo, Diego Fernando. Universidad Santiago de Cali; ColombiaFil: Quintana, Juan Pablo. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de FÃsica del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de FÃsica del Plasma; ArgentinaFil: Kleiman, Ariel Javier. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de FÃsica del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de FÃsica del Plasma; ArgentinaFil: Sequeda, F.. Universidad del Valle; ColombiaFil: Márquez, A.. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de FÃsica del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de FÃsica del Plasma; Argentin
Priming and the brain: an unexpected case of reverse priming with a prologue on the paradox of free will
The author describes results of conducting a research experiment observing what happens when people are confronted with two opposing primes simultaneously and exploring the mechanisms through which priming works in the brain
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