This, the 40th issue of Transactions on Large-Scale Data- and Knowledge-Centered Systems, contains five revised selected regular papers. Topics covered include personalized social query expansion approaches, continuous query on social media streams, elastic processing systems, and semantic interoperability for smart grids and NoSQL environments.

Personalized Social Query Expansion Using Social Annotations.- A Data Services Composition Approach for Continuous Query on Social Media Streams.- DABS: A Data-Aware Approach for Elastic Stream Processing.- SSG: An Ontology-Based Information Model for Smart Grids.- Bridging the Semantic Web and NoSQL Worlds: Generic SPARQL Query Translation and Application to MongoDB.

The LNCS journal Transactions on Large-Scale Data- and Knowledge-Centered Systems focuses on data management, knowledge discovery, and knowledge processing, which are core and hot topics in computer science. Since the 1990s, the Internet has become the main driving force behind application development in all domains. An increase in the demand for resource sharing across different sites connected through networks has led to an evolution of data- and knowledge-management systems from centralized systems to decentralized systems enabling large-scale distributed applications providing high scalability. Current decentralized systems still focus on data and knowledge as their main resource. Feasibility of these systems relies basically on P2P (peer-to-peer) techniques and the support of agent systems with scaling and decentralized control. Synergy between grids, P2P systems, and agent technologies is the key to data- and knowledge-centered systems in large-scale environments.This,the 40th issue of Transactions on Large-Scale Data- and Knowledge-Centered Systems, contains five revised selected regular papers. Topics covered include personalized social query expansion approaches, continuous query on social media streams, elastic processing systems, and semantic interoperability for smart grids and NoSQL environments.

Covers a wide range of topics in the fields of social networks, data stream systems, and linked data Details personalized social query expansion approaches and continuous query on social media streams Includes in-depth papers on elastic stream processing and semantic interoperability for smart grids and NoSQL environments

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