169 research outputs found
Reconstruction of three-dimensional porous media using generative adversarial neural networks
To evaluate the variability of multi-phase flow properties of porous media at
the pore scale, it is necessary to acquire a number of representative samples
of the void-solid structure. While modern x-ray computer tomography has made it
possible to extract three-dimensional images of the pore space, assessment of
the variability in the inherent material properties is often experimentally not
feasible. We present a novel method to reconstruct the solid-void structure of
porous media by applying a generative neural network that allows an implicit
description of the probability distribution represented by three-dimensional
image datasets. We show, by using an adversarial learning approach for neural
networks, that this method of unsupervised learning is able to generate
representative samples of porous media that honor their statistics. We
successfully compare measures of pore morphology, such as the Euler
characteristic, two-point statistics and directional single-phase permeability
of synthetic realizations with the calculated properties of a bead pack, Berea
sandstone, and Ketton limestone. Results show that GANs can be used to
reconstruct high-resolution three-dimensional images of porous media at
different scales that are representative of the morphology of the images used
to train the neural network. The fully convolutional nature of the trained
neural network allows the generation of large samples while maintaining
computational efficiency. Compared to classical stochastic methods of image
reconstruction, the implicit representation of the learned data distribution
can be stored and reused to generate multiple realizations of the pore
structure very rapidly.Comment: 21 pages, 20 figure
A multiscale generative model to understand disorder in domain boundaries
A continuing challenge in atomic resolution microscopy is to identify
significant structural motifs and their assembly rules in synthesized materials
with limited observations. Here we propose and validate a simple and effective
hybrid generative model capable of predicting unseen domain boundaries in a
potassium sodium niobate thin film from only a small number of observations,
without expensive first-principles calculation. Our results demonstrate that
complicated domain boundary structures can arise from simple interpretable
local rules, played out probabilistically. We also found new significant
tileable boundary motifs and evidence that our system creates domain boundaries
with the highest entropy. More broadly, our work shows that simple yet
interpretable machine learning models can help us describe and understand the
nature and origin of disorder in complex materials
Topological Self-Organisation: Using a particle-spring system simulation to generate structural space-filling lattices
The problem being addressed relates to the filling of a certain volume with a structural
space frame network lattice consisting of a given number of nodes. A method is
proposed that comprises a generative algorithm including a physical dynamic simulation
of particle-spring system. The algorithm is able to arrange nodes in space and establish
connections among them through local rules of self-organisation, thus producing space
frame topologies. In order to determine the appropriateness of the method, an
experiment is conducted that involves testing the algorithm in the case of filling the
volume of a cube with multiple numbers of nodes. The geometrical, topological and
structural aspects of the generated lattices are analysed and discussed. The results
indicate that the method is capable of generating efficient space frame topologies that
fill spatial envelopes
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