Thanassis Tiropanis

Semantic Technologies for Learning and Teaching in the Web 2.0 Era

Deploying semantic tools and services over a field of linked data could be a way to address many current challenges of higher education. The strengths of semantic technologies for learning and teaching, and their benefits for digital libraries, virtual communities, and e-learning, have been a major topic of discussion during recent years. Experts argue that semantic technologies can enhance the advanced learning experience by using the expressive power of metadata to describe learning content, people, and services, and then matching these intelligently.

The Web Science Observatory

To understand and enable the evolution of the Web and to help address grand societal challenges, the Web must be observable at scale across space and time. That requires a globally distributed and collaborative Web Observatory.

The Web in education

The Web has spurred our imagination as to how education could be radically transformed and enhanced through the adoption of Information and Communication Technologies (ICTs). While there have been many significant innovations and successes over the last decade there have also been many unrealised aims. Beliefs in technology-driven change for education have been countered by shortcomings in technological understanding by educationalists and in turn by shortcomings in the understanding of educational theories and learning concepts by technologists. The use of the Web in education has revealed issues such as the distinction between formal and informal learning; the packaging and formatting of learning materials for online distribution and use; the management of learning materials and processes in virtual and managed learning environments; solutions offered by the semantic Web; and how the quality of experience in interactive learning environments relates to the quality of the Internet infrastructure. A comparison between the performance of early and current Web technologies from a user perspective is given for an interactive learning environment which has been in use for over a decade. Client, server, network and protocol components which contribute to the quality of experience for the end user are presented and analysed. In summary, this paper examines the use of the Web in education to date and looks forward to new challenges and aspirations such as MOOCs (massively online open coursewares) and the immersive 3D Web as the basis for the next generation of learning environments.

Web evolution and Web Science

This paper examines the evolution of the World Wide Web as a network of networks and discusses the emergence of Web Science as an interdisciplinary area that can provide us with insights on how the Web developed, and how it has affected and is affected by society. Through its different stages of evolution, the Web has gradually changed from a technological network of documents to a network where documents, data, people and organisations are interlinked in various and often unexpected ways. It has developed from a technological artefact separate from people to an integral part of human activity that is having an increasingly significant impact on the world. This paper outlines the lessons from this retrospective examination of the evolution of the Web, presents the main outcomes of Web Science activities and discusses directions along which future developments could be anticipated.

Grid-Based Virtual Laboratory Experiments for a Graduate Course on Sensor Networks

This paper presents the pedagogical and technical challenges the authors faced in developing a distributed laboratory for the execution of virtual scientific experiments (VSEs) superimposed on a Grid infrastructure, for a course on sensor networks that is part of the Masters in Information Networking (MSIN) program jointly offered by Carnegie Mellon University (CMU), USA and Athens Information Technology (AIT), Athens, Greece. The MSIN program utilizes virtual classroom technologies because of its strong distance learning component. Courses taught by CMU faculty are attended in real-time by students in Athens, Greece, via video-wall teleconferencing sessions. Vice versa, visiting CMU faculty to AIT teach classes that are attended by students at CMU. Students in both institutions enjoy full interactivity with their classmates on the other side of the Atlantic Ocean. A distributed shared virtual laboratory is needed for many of the more empirical courses. This paper describes the challenges and issues the authors faced in developing such a lab

The Web Observatory: a middle layer for broad data

The Web Observatory project is a global effort that is being led by the Web Science Trust, its network of WSTnet laboratories, and the wider Web Science community. The goal of this project is to create a global distributed infrastructure that will foster communities exchanging and using each others web-related datasets as well as sharing analytic applications for research and business web applications.3 It will provide the means to observe the digital planet, explore its processes, and understand their impact on different sectors of human activity.

Evaluating graph traversal algorithms for distributed SPARQL query optimization

Distributed SPARQL queries enable users to retrieve information by exploiting the increasing amount of linked data being published. However, industrial-strength distributed SPARQL query processing is still at its early stage for efficiently answering queries. Previous research shows that it is possible to apply methods from graph theory to optimize the performance of distributed SPARQL. In this paper we describe a framework that can simulate arbitrary RDF data networks to evaluate different approaches of distributed SPARQL query processing. Using this framework we further explore the graph traversal algorithms for distributed SPARQL optimization. We present an implementation of a Minimum-Spanning-Tree-based (MST-based) algorithm for distributed SPARQL processing, the performance of which is compared to other approaches using this evaluation framework. The contribution of this paper is to show that a MST-based approach seems to perform much better than other non graph-traversal-based approaches, and to provide an evaluation framework for evaluating distributed SPARQL processing.

Semantic-Based policy engineering for autonomic systems

This paper presents some important directions in the use of ontology-based semantics in achieving the vision of Autonomic Communications. We examine the requirements of Autonomic Communication with a focus on the demanding needs of ubiquitous computing environments, with an emphasis on the requirements shared with Autonomic Computing. We observe that ontologies provide a strong mechanism for addressing the heterogeneity in user task requirements, managed resources, services and context. We then present two complimentary approaches that exploit ontology-based knowledge in support of autonomic communications: service-oriented models for policy engineering and dynamic semantic queries using content-based networks. The paper concludes with a discussion of the major research challenges such approaches raise.

EXPRESS: EXPressing REstful Semantic Services Using Domain Ontologies

Existing approaches to Semantic Web Services (SWS) require a domain ontology and a semantic description of the service. In the case of lightweight SWS approaches, such as SAWSDL, service description is achieved by semantically annotating existing web service interfaces. Other approaches such as OWL-S and WSMO describe services in a separate ontology. So, existing approaches separate service description from domain description, therefore increasing design efforts. We propose EXPRESS a lightweight approach to SWS that requires the domain ontology definition only. Its simplicity stems from the similarities between REST and the Semantic Web such as resource realization, self describing representations, and uniform interfaces. The semantics of a service is elicited from a resources semantic description in the domain ontology and the semantics of the uniform interface, hence eliminating the need for ontologically describing services. We provide an example that illustrates EXPRESS and then discuss how it compares to SA-REST and WSMO.

Rethinking measurements of social media use by charities: a mixed methods approach

Increasingly, the utilisation of social media services are helping charities continue to operate, as they provide unique opportunities of low-cost, easily targeted and viral marketing that have never been seen before to this scale. However, without knowing exactly how and why they are being used, analysis of their performance that could be used to indicate areas of improvement will continue to be insufficient. An innovative mixed methods approach was followed in order to address the issue, and this paper presents the results of a study that sought to determine the reasons why charities use social media, and the strategies they employ in an attempt to succeed. Three main contributions are presented -- firstly, by combining the qualitative and quantitative data it was discovered that social media are currently intended to be used primarily as relationship building tools, with little focus on fundraising; secondly, an overview of how successful charities perceive social media to be is shown and methods of measurement are mapped to a previously designed framework; and thirdly, future requirements for revising the measurement framework are discussed, demonstrating the importance of this work for grounding future developments.