19 research outputs found
A closer look at sum-based embeddings for knowledge graphs containing procedural knowledge
While knowledge graphs and their embedding into low dimensional vectors are established fields of research, they mostly cover factual knowledge. However, to improve downstream models, e. g. for predictive quality in real-world industrial use cases, embeddings of procedural knowledge, available in the form of rules, could be utilized. As such, we investigate which properties of embedding algorithms could prove beneficial in this scenario and evaluate which established embedding methodologies are suited to form the basis of sum-based embeddings of different representations of procedural knowledge
PDPK: A Framework to Synthesise Process Data and Corresponding Procedural Knowledge for Manufacturing
Procedural knowledge describes how to accomplish tasks and mitigate problems.
Such knowledge is commonly held by domain experts, e.g. operators in
manufacturing who adjust parameters to achieve quality targets. To the best of
our knowledge, no real-world datasets containing process data and corresponding
procedural knowledge are publicly available, possibly due to corporate
apprehensions regarding the loss of knowledge advances. Therefore, we provide a
framework to generate synthetic datasets that can be adapted to different
domains. The design choices are inspired by two real-world datasets of
procedural knowledge we have access to. Apart from containing representations
of procedural knowledge in Resource Description Framework (RDF)-compliant
knowledge graphs, the framework simulates parametrisation processes and
provides consistent process data. We compare established embedding methods on
the resulting knowledge graphs, detailing which out-of-the-box methods have the
potential to represent procedural knowledge. This provides a baseline which can
be used to increase the comparability of future work. Furthermore, we validate
the overall characteristics of a synthesised dataset by comparing the results
to those achievable on a real-world dataset. The framework and evaluation code,
as well as the dataset used in the evaluation, are available open source
Towards models of conceptual and procedural operator knowledge
To increase the utility of semantic industrial information models we propose a methodology to incorporate extracted operator knowledge, which we assume to be present in the form of rules, in knowledge graphs. To this end, we present multiple modelling patterns that can be combined depending on the required complexity. Aiming to combine information models with learning systems we contemplate desired behaviours of embeddings from a predictive quality perspective and provide a suited embedding methodology. This methodology is evaluated on a real world dataset of a fused deposition modelling process
The Hanle Effect as a Diagnostic of Magnetic Fields in Stellar Envelopes IV. Application to Polarized P Cygni Wind Lines
The Hanle effect has been proposed as a new diagnostic of circumstellar
magnetic fields for early-type stars, for which it is sensitive to field
strengths in the 1-300 G range. In this paper we compute the polarized P-Cygni
line profiles that result from the Hanle effect. For modeling the polarization,
we employ a variant of the ``last scattering approximation''. For cases in
which the Sobolev optical depths are greater than unity, the emergent line
intensity is assumed to be unpolarized; while for smaller optical depths, the
Stokes source functions for the Hanle effect with optically thin line
scattering are used. For a typical P Cygni line, the polarized emission forms
in the outer wind, because the Sobolev optical depth is large at the inner
wind. For low surface field strengths, weak P Cygni lines are needed to measure
the circumstellar field. For high values of the surface fields, both the Zeeman
and Hanle diagnostics can be used, with the Zeeman effect probing the
photospheric magnetic fields, and the Hanle effect measuring the magnetic field
in the wind flow. Polarized line profiles are calculated for a self-consistent
structure of the flow and the magnetic geometry based on the WCFields model,
which is applicable to slowly rotating stellar winds with magnetic fields drawn
out by the gas flow. For surface fields of a few hundred Gauss, we find that
the Hanle effect can produce line polarizations in the range of a few tenths of
a percent up to about 2 percent.Comment: accepted to the Astrophysical Journa