8,001 research outputs found
Structural Flyby Characterization of Nanoporosity
Recently, Ferreira da Silva et al. [3] have performed a gradient pattern
analysis of a canonical sample set (CSS) of scanning force microscopy (SFM)
images of p-Si. They applied the so-called Gradient Pattern Analysis to images
of three typical p-Si samples distinguished by different absorption energy
levels and aspect ratios. Taking into account the measures of spatial
asymmetric fluctuations they interpreted the global porosity not only in terms
of the amount of roughness, but rather in terms of the structural complexity
(e.g., walls and fine structures as slots). This analysis has been adapted in
order to operate in a OpenGL flyby environment (the StrFB code), whose
application give the numerical characterization of the structure during the
flyby real time. Using this analysis we compare the levels of asymmetric
fragmentation of active porosity related to different materials as p-Si and
"porous diamond-like" carbon. In summary we have shown that the gradient
pattern analysis technique in a flyby environment is a reliable sensitive
method to investigate, qualitatively and quantitatively, the complex morphology
of active nanostructures
Gradient Pattern Analysis of Cosmic Structure Formation: Norm and Phase Statistics
This paper presents the preliminary results of the characterization of
pattern evolution in the process of cosmic structure formation. We are applying
on N-body cosmological simulations data the technique proposed by Rosa, Sharma
& Valdivia (1999) and Ramos et al. (2000) to estimate the time behavior of
asymmetries in the gradient field. The gradient pattern analysis is a well
tested tool, used to build asymmetrical fragmentation parameters estimated over
a gradient field of an image matrix able to quantify a complexity measure of
nonlinear extended systems. In this investigation we work with the high
resolution cosmological data simulated by the Virgo consortium, in different
time steps, in order to obtain a diagnostic of the spatio-temporal disorder in
the matter density field. We perform the calculations of the gradient vectors
statistics, such as mean, variance, skewness, kurtosis, and correlations on the
gradient field. Our main goal is to determine different dynamical regimes
through the analysis of complex patterns arising from the evolutionary process
of structure formation. The results show that the gradient pattern technique,
specially the statistical analysis of second and third gradient moment, may
represent a very useful tool to describe the matter clustering in the Universe.Comment: Accepted for publication in Physica
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