1,203 research outputs found
Genetic algorithm dynamics on a rugged landscape
The genetic algorithm is an optimization procedure motivated by biological
evolution and is successfully applied to optimization problems in different
areas. A statistical mechanics model for its dynamics is proposed based on the
parent-child fitness correlation of the genetic operators, making it applicable
to general fitness landscapes. It is compared to a recent model based on a
maximum entropy ansatz. Finally it is applied to modeling the dynamics of a
genetic algorithm on the rugged fitness landscape of the NK model.Comment: 10 pages RevTeX, 4 figures PostScrip
Evolutionary strategy based improved motion estimation technique for H.264 video coding
In this paper we propose an improved motion estimation algorithm based on evolutionary strategy (ES) for H.264 video codec applied to video. The proposed technique works in a parallel local search for macroblocks. For this purpose (mu+lambda) ES is used with an initial population of heuristically and randomly generated motion vectors. Experimental results show that the proposed scheme can reduce the computational complexity up to 50% of the motion estimation algorithm used in the H.264 reference codec at the same picture quality. Therefore, the proposed algorithm provides a significant improvement in motion estimation in the H.264 video codec
Multi-method-modeling of interacting galaxies. I. A unique scenario for NGC 4449?
(abridged) We combined several N-body methods in order to investigate the
interaction scenario between NGC 4449 and DDO 125, a close companion in
projected space. In a first step fast restricted N-body models are used to
confine a region in parameter space reproducing the main observational
features. In a second step a genetic algorithm is applied for a uniqueness test
of our preferred parameter set. We show that our genetic algorithm reliably
recovers orbital parameters, provided that the data are sufficiently accurate,
i.e. all the key features are included.
In the third step the results of the restricted N-body models are compared
with self-consistent N-body simulations. In the case of NGC 4449, the
applicability of the simple restricted N-body calculations is demonstrated.
Additionally, it is shown that the HI gas can be modeled here by a purely
stellar dynamical approach.
In a series of simulations, we demonstrate that the observed features of the
extended HI disc can be explained by a gravitational interaction between NGC
4449 and DDO 125. According to these calculations the closest approach between
both galaxies happened yr ago at a minimum distance of
kpc on a parabolic or slightly elliptic orbit. In the case of an
encounter scenario, the dynamical mass of DDO 125 should not be smaller than
10% of NGC 4449's mass. Before the encounter, the observed HI gas was arranged
in a disc with a radius of 35-40 kpc around the center of NGC 4449. It had the
same orientation as the central ellipsoidal HI structure. The origin of this
disc is still unclear, but it might have been caused by a previous interaction.Comment: 19 pages with 19 figures, accepted for publication in Astron. &
Astrophys., a full PostScript version is available at
http://www.astrophysik.uni-kiel.de/pershome/theis/pub.htm
Annealing schedule from population dynamics
We introduce a dynamical annealing schedule for population-based optimization
algorithms with mutation. On the basis of a statistical mechanics formulation
of the population dynamics, the mutation rate adapts to a value maximizing
expected rewards at each time step. Thereby, the mutation rate is eliminated as
a free parameter from the algorithm.Comment: 6 pages RevTeX, 4 figures PostScript; to be published in Phys. Rev.
An evolutionary strategy based motion estimation algorithm for H.264 video codecs
In this paper, we propose a new motion estimation algorithm based on evolutionary strategy (ES) for the H.264 video codec applied to monoscopic video. The proposed technique applies in macroblock basis and performs a parallel local search for the motion vector associated with the minimum motion compensated residue. For this purpose (/spl mu/+/spl lambda/)-ES is used with heuristically and randomly generated population of initial motion vectors. Experimental results show that the proposed scheme can reduce the computational complexity up to 50% of the motion estimation algorithm used in the H.264 reference codec at the same picture quality. Therefore, the proposed algorithm provides a significant improvement in motion estimation in the H.264 video codec
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