6,441 research outputs found
Application of compressed sensing to the simulation of atomic systems
Compressed sensing is a method that allows a significant reduction in the
number of samples required for accurate measurements in many applications in
experimental sciences and engineering. In this work, we show that compressed
sensing can also be used to speed up numerical simulations. We apply compressed
sensing to extract information from the real-time simulation of atomic and
molecular systems, including electronic and nuclear dynamics. We find that for
the calculation of vibrational and optical spectra the total propagation time,
and hence the computational cost, can be reduced by approximately a factor of
five.Comment: 7 pages, 5 figure
Simplified model for the non-linear behaviour representation of reinforced concrete columns under biaxial bending
In the present paper a simplified model is proposed for the force-deformation behaviour of reinforced concrete members under biaxial loading combined with axial force. The starting point for the model development was an existing fixed-length plastic hinge element model that accounts for the non-linear hysteretic behaviour at the element end-sections, characterized by trilinear moment-curvature laws. To take into account the section biaxial behaviour, the existing model was adopted for both orthogonal lateral directions and an interaction function was introduced to couple the hysteretic response of both directions.
To calibrate the interaction function it were used numerical results, obtained from fibre models, and experimental results. For the parameters identification, non-linear optimization approaches were adopted, namely: the gradient based methods followed by the genetic, evolutionary and nature-inspired algorithms.
Finally, the simplified non-linear model proposed is validated through the analytical simulation of biaxial test results carried out in full-scale reinforced concrete columns
Efficient formalism for large scale ab initio molecular dynamics based on time-dependent density functional theory
A new "on the fly" method to perform Born-Oppenheimer ab initio molecular
dynamics (AIMD) is presented. Inspired by Ehrenfest dynamics in time-dependent
density functional theory, the electronic orbitals are evolved by a
Schroedinger-like equation, where the orbital time derivative is multiplied by
a parameter. This parameter controls the time scale of the fictitious
electronic motion and speeds up the calculations with respect to standard
Ehrenfest dynamics. In contrast to other methods, wave function orthogonality
needs not be imposed as it is automatically preserved, which is of paramount
relevance for large scale AIMD simulations.Comment: 5 pages, 3 color figures, revtex4 packag
Walks on Apollonian networks
We carry out comparative studies of random walks on deterministic Apollonian
networks (DANs) and random Apollonian networks (RANs). We perform computer
simulations for the mean first passage time, the average return time, the
mean-square displacement, and the network coverage for unrestricted random
walk. The diffusions both on DANs and RANs are proved to be sublinear. The
search efficiency for walks with various strategies and the influence of the
topology of underlying networks on the dynamics of walks are discussed.
Contrary to one's intuition, it is shown that the self-avoiding random walk,
which has been verified as an optimal strategy for searching on scale-free and
small-world networks, is not the best strategy for the DAN in the thermodynamic
limit.Comment: 5 pages, 4 figure
Antropologia e arte contemporânea: parodia e estereótipos na obra de Sandow Birk
Ensayo Visual "Antropología y arte contemporáneo: parodia y estereotipos en la obra de Sandow Birk"Visual essay "Anthropology and Contemporary Art: Parody and Stereotypes in the Work of Sandow Birk"Ensaio visual "Antropologia e arte contemporânea: parodia e estereótipos na obra de Sandow Birk
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