Temporal Evolution of the Migration-related Topics on Social Media?

This poster focuses on capturing the temporal evolution of migration-related topics on relevant tweets. It uses Dynamic Embedded Topic Model (DETM) as a learning algorithm to perform a quantitative and qualitative analysis of these emerging topics. TweetsKB is extended with the extracted Twitter dataset along with the results of DETM which considers temporality. These results are then further analyzed and visualized. It reveals that the trajectories of the migration-related topics are in agreement with historical events

Ontology-based end-user visual query formulation: Why, what, who, how, and which?

Value creation in an organisation is a time-sensitive and data-intensive process, yet it is often delayed and bounded by the reliance on IT experts extracting data for domain experts. Hence, there is a need for providing people who are not professional developers with the flexibility to pose relatively complex and ad hoc queries in an easy and intuitive way. In this respect, visual methods for query formulation undertake the challenge of making querying independent of users’ technical skills and the knowledge of the underlying textual query language and the structure of data. An ontology is more promising than the logical schema of the underlying data for guiding users in formulating queries, since it provides a richer vocabulary closer to the users’ understanding. However, on the one hand, today the most of world’s enterprise data reside in relational databases rather than triple stores, and on the other, visual query formulation has become more compelling due to ever-increasing data size and complexity—known as Big Data. This article presents and argues for ontology-based visual query formulation for end-users; discusses its feasibility in terms of ontology-based data access, which virtualises legacy relational databases as RDF, and the dimensions of Big Data; presents key conceptual aspects and dimensions, challenges, and requirements; and reviews, categorises, and discusses notable approaches and systems

Optical and magneto-optical characterization of TbFeCo thin films in trilayer structures

A series of TbFeCo films ranging in thickness from 100 to 800 Å have been deposited in trilayer structures on silicon wafer substrates, with S3N4 being employed as the dielectric material. These films have been characterized both optically and magneto-optically by variable angle of incidence spectroscopic ellipsometry, normal angle of incidence) reflectometry, and normal angle of incidence Kerr spectroscopy. From these measurements, the optical constants n and k have been determined for the TbFeCo films, as well as the magneto-optical constants Ql and Q2. Results are presented that demonstrate the lack of dependence of these constants on the thickness of the TbFeCo film, and which can be used for calculating the expected optical and magneto-optical response of any multilayer structure containing similar TbFeCo films

Magneto-optical Kerr effect and perpendicular magnetic anisotropy of evaporated and sputtered Co/Pt multilayer structures

Thin and ultrathin Co/Pt multilayered structures have been prepared on glass substrates by electron-beam evaporation at room temperature and by sputtering at various substrate temperatures and sputtering pressures. Perpendicular magnetic anisotropy was found in samples with Co/Pt bilayer thicknesses near 3 Å/l0 Å and total thicknesses of the layer stack of no greater than 300 Å. X-ray diffraction was performed on the samples to determine layer spacing and integrity, and possible crystallinity of films. Crystalline structures in the interface between the Co and Pt layers were found and identified. The effects of sputtering parameters, such as pressure and substrate temperature, on the magneto-optical Kerr effect were studied. The two deposition methods, electron-beam evaporation and sputtering, resulted in different magneto-optical properties in samples with the same nominal layer structures. We have also investigated optical properties (reflectance, index of refraction, and extinction coefficient) of these materials using ellipsometry

Knowledge graphs

18siIn this article, we provide a comprehensive introduction to knowledge graphs, which have recently garnered significant attention from both industry and academia in scenarios that require exploiting diverse, dynamic, large-scale collections of data. After some opening remarks, we motivate and contrast various graph-based data models, as well as languages used to query and validate knowledge graphs. We explain how knowledge can be represented and extracted using a combination of deductive and inductive techniques. We conclude with high-level future research directions for knowledge graphs.nonenoneHogan A.; Blomqvist E.; Cochez M.; D'Amato C.; Melo G.D.; Gutierrez C.; Kirrane S.; Gayo J.E.L.; Navigli R.; Neumaier S.; Ngomo A.-C.N.; Polleres A.; Rashid S.M.; Rula A.; Schmelzeisen L.; Sequeda J.; Staab S.; Zimmermann A.Hogan, A.; Blomqvist, E.; Cochez, M.; D'Amato, C.; Melo, G. D.; Gutierrez, C.; Kirrane, S.; Gayo, J. E. L.; Navigli, R.; Neumaier, S.; Ngomo, A. -C. N.; Polleres, A.; Rashid, S. M.; Rula, A.; Schmelzeisen, L.; Sequeda, J.; Staab, S.; Zimmermann, A