No abstract

Meeting citizens' requirements economically and efficiently is the most important objective of Smart Cities. As a matter of fact, they are considered a key concept both for future Internet and information and communications technology. It is expected that a wide range of services will be made available for residential users (e.g. intelligent transportation systems, e-government, e-banking, e-commerce and smart management of energy demand), public administration entities, public safety and civil protection agencies and so on with increased quality, lower costs and reduced environmental impact. In order to achieve these ambitious objectives, new technologies should be developed such as non-invasive sensing, highly parallel processing, smart grids and mobile broadband communications. This paper considers the communication aspects of Smart City applications, specifically, the role of the latest developments of Long-Term Evolution-Advanced standard, which forecast the increase of broadband coverage by means of small cells. We shall demonstrate that the novel concept of small cell fully meets the emerging communication and networking requirements of future Smart Cities. To this aim, a feasible network architecture for future Smart Cities, based on small cells, will be discussed in the framework of a future smarter and user-centric perspective of forthcoming 4G mobile technologies.

Knowledge Graphs (KGs) that publish RDF data modelled using ontologies in a wide range of domains have populated the Web. The SHACL language is a W3C recommendation that has been endowed to encode a set of either value or model data restrictions that aim at validating KG data, ensuring data quality. Developing shapes is a complex and time consuming task that is not feasible to achieve manually. This article presents two resources that aim at generating automatically SHACL shapes for a set of ontologies: (1) Astrea-KG, a KG that publishes a set of mappings that encode the equivalent conceptual restrictions among ontology constraint patterns and SHACL constraint patterns, and (2) Astrea, a tool that automatically generates SHACL shapes from a set of ontologies by executing the mappings from the Astrea-KG. These two resources are openly available at Zenodo, GitHub, and a web application. In contrast to other proposals, these resources cover a large number of SHACL restrictions producing both value and model data restrictions, whereas other proposals consider only a limited number of restrictions or focus only on value or model restrictions.

With the constant growth of Internet of Things (IoT) ecosystems, allowing them to interact transparently has become a major issue for both the research and the software development communities. In this paper we propose a novel approach that builds semantically interoperable ecosystems of IoT devices. The approach provides a SPARQL query-based mechanism to transparently discover and access IoT devices that publish heterogeneous data. The approach was evaluated in order to prove that it provides complete and correct answers without affecting the response time and that it scales linearly in large ecosystems.

Wireless Metropolitan Area Networks based on IEEE 802.16d/e standards are soon to be deployed in several countries. However, there is lack of published literature with results from actual testbeds. This paper introduces the work done in the EU Sixth Framework Programme Project WEIRD to design and set up WiMAX testbeds in four EU countries. We describe the methodlogy followed, detail our implementation and present results from the testbeds, as deployed in the first phase of WEIRD. The testbeds are used to demonstrate how WiMAX technology can be used to extend the connectivity of the panEuropean data communications network (GEANT2) to isolated and impervious areas and, furthermore, to assure end-to-end quality of service to novel applications.