10,047 research outputs found
Unsupervised Learning of Artistic Styles with Archetypal Style Analysis
In this paper, we introduce an unsupervised learning approach to
automatically discover, summarize, and manipulate artistic styles from large
collections of paintings. Our method is based on archetypal analysis, which is
an unsupervised learning technique akin to sparse coding with a geometric
interpretation. When applied to deep image representations from a collection of
artworks, it learns a dictionary of archetypal styles, which can be easily
visualized. After training the model, the style of a new image, which is
characterized by local statistics of deep visual features, is approximated by a
sparse convex combination of archetypes. This enables us to interpret which
archetypal styles are present in the input image, and in which proportion.
Finally, our approach allows us to manipulate the coefficients of the latent
archetypal decomposition, and achieve various special effects such as style
enhancement, transfer, and interpolation between multiple archetypes.Comment: Accepted at NIPS 2018, Montr\'eal, Canad
An application of machine learning to the organization of institutional software repositories
Software reuse has become a major goal in the development of space systems, as a recent NASA-wide workshop on the subject made clear. The Data Systems Technology Division of Goddard Space Flight Center has been working on tools and techniques for promoting reuse, in particular in the development of satellite ground support software. One of these tools is the Experiment in Libraries via Incremental Schemata and Cobweb (ElvisC). ElvisC applies machine learning to the problem of organizing a reusable software component library for efficient and reliable retrieval. In this paper we describe the background factors that have motivated this work, present the design of the system, and evaluate the results of its application
Are fossil groups a challenge of the Cold Dark Matter paradigm?
We study six groups and clusters of galaxies suggested in the literature to
be `fossil' systems (i.e. to have luminous diffuse X-ray emission and a
magnitude gap of at least 2 mag-R between the first and the second ranked
member within half of the virial radius), each having good quality X-ray data
and SDSS spectroscopic or photometric coverage out to the virial radius. The
poor cluster AWM4 is clearly established as a fossil system, and we confirm the
fossil nature of four other systems (RXJ1331.5+1108, RXJ1340.6+4018,
RXJ1256.0+2556 and RXJ1416.4+2315), while the cluster RXJ1552.2+2013 is
disqualified as fossil system. For all systems we present the luminosity
functions within 0.5 and 1 virial radius that are consistent, within the
uncertainties, with the universal luminosity function of clusters. For the five
bona fide fossil systems, having a mass range 2x10^13-3x10^14 M_Sun, we compute
accurate cumulative substructure distribution functions (CSDFs) and compare
them with the CSDFs of observed and simulated groups/clusters available in the
literature. We demonstrate that the CSDFs of fossil systems are consistent with
those of normal observed clusters and do not lack any substructure with respect
to simulated galaxy systems in the cosmological LambdaCDM framework. In
particular, this holds for the archetype fossil group RXJ1340.6+4018 as well,
contrary to earlier claims.Comment: Accepted for publication on MNRAS. Minor changes in sections 2.1 and
6. 13 pages, 4 eps figure
Knowledge-based zonal grid generation for computational fluid dynamics
Automation of flow field zoning in two dimensions is an important step towards reducing the difficulty of three-dimensional grid generation in computational fluid dynamics. Using a knowledge-based approach makes sense, but problems arise which are caused by aspects of zoning involving perception, lack of expert consensus, and design processes. These obstacles are overcome by means of a simple shape and configuration language, a tunable zoning archetype, and a method of assembling plans from selected, predefined subplans. A demonstration system for knowledge-based two-dimensional flow field zoning has been successfully implemented and tested on representative aerodynamic configurations. The results show that this approach can produce flow field zonings that are acceptable to experts with differing evaluation criteria
Automatic definition of engineer archetypes: A text mining approach
With the rapid and continuous advancements in technology, as well as the constantly evolving competences required in the field of engineering, there is a critical need for the harmonization and unification of engineering professional figures or archetypes. The current limitations in tymely defining and updating engineers' archetypes are attributed to the absence of a structured and automated approach for processing educational and occupational data sources that evolve over time. This study aims to enhance the definition of professional figures in engineering by automating archetype definitions through text mining and adopting a more objective and structured methodology based on topic modeling. This will expand the use of archetypes as a common language, bridging the gap between educational and occupational frameworks by providing a unified and up-to-date engineering professional figure tailored to a specific period, specialization type, and level. We validate the automatically defined industrial engineer archetype against our previously manually defined profile
Ridge Estimation of Inverse Covariance Matrices from High-Dimensional Data
We study ridge estimation of the precision matrix in the high-dimensional
setting where the number of variables is large relative to the sample size. We
first review two archetypal ridge estimators and note that their utilized
penalties do not coincide with common ridge penalties. Subsequently, starting
from a common ridge penalty, analytic expressions are derived for two
alternative ridge estimators of the precision matrix. The alternative
estimators are compared to the archetypes with regard to eigenvalue shrinkage
and risk. The alternatives are also compared to the graphical lasso within the
context of graphical modeling. The comparisons may give reason to prefer the
proposed alternative estimators
Learning Extremal Representations with Deep Archetypal Analysis
Archetypes are typical population representatives in an extremal sense, where
typicality is understood as the most extreme manifestation of a trait or
feature. In linear feature space, archetypes approximate the data convex hull
allowing all data points to be expressed as convex mixtures of archetypes.
However, it might not always be possible to identify meaningful archetypes in a
given feature space. Learning an appropriate feature space and identifying
suitable archetypes simultaneously addresses this problem. This paper
introduces a generative formulation of the linear archetype model,
parameterized by neural networks. By introducing the distance-dependent
archetype loss, the linear archetype model can be integrated into the latent
space of a variational autoencoder, and an optimal representation with respect
to the unknown archetypes can be learned end-to-end. The reformulation of
linear Archetypal Analysis as deep variational information bottleneck, allows
the incorporation of arbitrarily complex side information during training.
Furthermore, an alternative prior, based on a modified Dirichlet distribution,
is proposed. The real-world applicability of the proposed method is
demonstrated by exploring archetypes of female facial expressions while using
multi-rater based emotion scores of these expressions as side information. A
second application illustrates the exploration of the chemical space of small
organic molecules. In this experiment, it is demonstrated that exchanging the
side information but keeping the same set of molecules, e. g. using as side
information the heat capacity of each molecule instead of the band gap energy,
will result in the identification of different archetypes. As an application,
these learned representations of chemical space might reveal distinct starting
points for de novo molecular design.Comment: Under review for publication at the International Journal of Computer
Vision (IJCV). Extended version of our GCPR2019 paper "Deep Archetypal
Analysis
An Investigation of Semantic Links to Archetypes in an External Clinical Terminology through the Construction of Terminological Shadows
The two-level model based specifications for electronic health record communication EHRcom (ISO 13606) and openEHR both support the embedding of terminological references in Archetypes. This terminological binding can be created manually by a health terminology expert during Archetype design, and the binding is assessed during Archetype evaluation. There has also been some recent work on using lexical queries to generate term sets to represent concepts in Archetypes. This work created an information construct which we call a Terminological Shadow that links Archetype nodes to sets of candidate concepts from a terminology system. The coding scheme used for this work is SNOMED-CT. The proposed Shadows can be used to facilitate the mapping between an Archetype information model and terminological systems. A framework, which also acts as an analysis tool, has been created to construct Shadows from Archetypes. The work also demonstrates how the framework can be used to evaluate different searching algorithms by comparing the search results to the existing bound SNOMED codes
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