Semantic models for the modeling and management of big data in a smart city environment

The overall purpose of this research has been the building or the improve- ment of semantic models for the representation of data related to smart cities and smart industries, in such a way that it could also be possible to build context-rich, user-oriented, ecient and eective applications based on such data. In some more detail, one of the key purposes has been the modelling of structural and the functioning aspects of the urban mobility and the produc- tion of instances exploiting the Open Street Map, that once integrated with trac sensors data, it has lead to the building and displaying of real-time trac reconstructions at a city level. One second key purpose has been the modelling of the Internet of Things, that allows today to seamlessy and e- ciently identify sensing devices that are deployed in a given area or along a given path and that are of a given type, and also inspect real-time data that they produce, through a user-oriented Web application, namely the Service Map. A pragmatic approach to the modelling has been followed, always tak- ing into consideration the best practices of semantic modelling on one side for that a clean, comprehensive and understandable model could result, and the reality of the data at our hands and of the applicative requirements on the other side. As said, the identication of architectures and methods that could grant eciency and scalability in data access has also been a primary purpose of this research that has led to the denition and implementation of a federation of Service Maps, namely the Super Service Map. The archi- tecture is fully distributed: each Super Service Map has a local list of the actual Service Maps with relevant metadata, it exposes the same interface as actual Service Maps, it forwards requests and builds merged responses, also implementing security and caching mechanisms. As said, the identica- tion of technologies, tools, methods, for presenting the data in a user-friendly manner is also has been a relevant part of this research, and it has led among the other to the denition and implementation of a client-server architecture and a Web interface in the Snap4City platform for the building, manage- ment, and displaying of synoptic templates and instances thanks to which users can securely display and iteract with dierent types of data. In end, some eort has been made for the automatic classication of RDF datasets as for their structures and purposes, based on the computation of metrics through SPARQL queries and on the application of dimensionality reduc- tion and clustering techniques. A Web portal is available where directories, datasets, metrics, and computations can be inspected even at real-time.