Multiscale Modeling of Thermomechanical Properties of Ceramic Pebbles (KIT Scientific Reports ; 7573)

Ceramic pebbles are foreseen to be used as tritium breeder in helium cooled pebble bed blankets in fusion reactors. The pebbles are subject to high temperature and irradiation. They may fail during thermomechanical loading. Failure of pebbles will influence the macroscopic thermomechanical response of pebble beds. Fragments of crushed pebbles can block the evacuation of purge gas. The influence of pebble failure, thermal stress and thermal conductivity is investigated to support blanket design

Keyword Search on RDF Graphs - A Query Graph Assembly Approach

Keyword search provides ordinary users an easy-to-use interface for querying RDF data. Given the input keywords, in this paper, we study how to assemble a query graph that is to represent user's query intention accurately and efficiently. Based on the input keywords, we first obtain the elementary query graph building blocks, such as entity/class vertices and predicate edges. Then, we formally define the query graph assembly (QGA) problem. Unfortunately, we prove theoretically that QGA is a NP-complete problem. In order to solve that, we design some heuristic lower bounds and propose a bipartite graph matching-based best-first search algorithm. The algorithm's time complexity is $O(k^{2l} \cdot l^{3l})$, where $l$ is the number of the keywords and $k$ is a tunable parameter, i.e., the maximum number of candidate entity/class vertices and predicate edges allowed to match each keyword. Although QGA is intractable, both $l$ and $k$ are small in practice. Furthermore, the algorithm's time complexity does not depend on the RDF graph size, which guarantees the good scalability of our system in large RDF graphs. Experiments on DBpedia and Freebase confirm the superiority of our system on both effectiveness and efficiency

Talents Oriented Strategy of Online Learning in Universities

This article argues online learning strategy and teaching characteristics in universities. First it introduces learning activities in EFL must be integrated with technology appropriately to develop talents effectively. Then it puts forward the idea of talents oriented integrative online learning. For incorporating active learning into online teaching it lists some active learning strategies that can be adapted for the online “classroom”. Finally it recommends the detailed talents oriented strategy of online learning design and analyzes effective and appropriate items for learning activity. Key words: Talents; Online Learning; Strategy; Universities; EFLRésumé: Cet article parle de la stratégie d'apprentissage en ligne et des caractéristiques de l'enseignement en ligne dans les universités. Premièrement, il introduit des activités d'apprentissage EFL (English as foreign language) qui doivent être intégrées avec la technologie appropriée pour développer les talents de façon efficace. Puis il met en avant l'idée de l'apprentissage en ligne. Pour incorporer l'apprentissage actif dans l'enseignement en ligne, il énumère quelques-unes des stratégies d'apprentissage actives qui peuvent être adaptées à la «classe» en ligne. Et finalement, il recommande la stratégie orientées vers les talents détaillée de la conception de l'apprentissage en ligne et analyse des éléments efficaces et appropriées pour les activités d'apprentissage.Mots-Clés: talents; apprentissage en ligne; stratégie; universités; EF