@article {828,
	title = {Chatbots for Cultural Venues: A Topic-Based Approach},
	journal = {Algorithms},
	volume = {16},
	year = {2023},
	month = {jul},
	pages = {339},
	abstract = {<p>Digital assistants{\textemdash}such as chatbots{\textemdash}facilitate the interaction between persons and machines and are increasingly used in web pages of enterprises and organizations. This paper presents a methodology for the creation of chatbots that offer access to museum information. The paper introduces an information model that is offered through the chatbot, which subsequently maps the museum{\textquoteright}s modeled information to structures of DialogFlow, Google{\textquoteright}s chatbot engine. Means for automating the chatbot generation process are also presented. The evaluation of the methodology is illustrated through the application of a real case, wherein we developed a chatbot for the Archaeological Museum of Tripolis, Greece.</p>
},
	keywords = {chatbots, cultural venues, Museums, RDF triples, topics},
	doi = {10.3390/a16070339},
	url = {https://doi.org/10.3390/a16070339},
	author = {Vasilis Bouras and Dimitris Spiliotopoulos and Dionisis Margaris and Costas Vassilakis and Konstantinos Kotis and Angeliki Antoniou and George Lepouras and Manolis Wallace and Vassilis Poulopoulos}
}
@conference {799,
	title = {Cyber-Security Training Evaluation Metrics},
	booktitle = {Proceedings of the 2021 IEEE International Conference on Cyber Security and Resilience},
	year = {2021},
	publisher = {IEEE},
	organization = {IEEE},
	abstract = {<p>Cyber-security training has evolved into an imperative need, aiming to provide cyber-security professionals with the knowledge and skills required to confront cyber-attacks that are increasing in number and sophistication. Training activities are typically associated with evaluation means, aimed to assess the extent to which the trainee has acquired the knowledge and skills whose development is targeted by the training programme, while cyber-security awareness and skill level evaluation means may be used to support additional security-related aspects of organizations. In this paper, we review trainee performance assessment metrics in cyber-security training, aiming to assist designers of cyber-security training activities to identify the mostprominent trainee performance assessment means for their training programmes, while additional research directions involving cyber-security training evaluation metrics are also identified.</p>
},
	keywords = {Cyber-ranges, Cyber-security training, Evaluation, Gamification, Scoring},
	author = {Koutsouris, Nikolaos and Vassilakis, Costas and Kolokotronis, Nicholas}
}
@conference {717,
	title = {Citizen Engagement for Transparent and Accountable Policy Modelling},
	booktitle = {Proceedings of the 11th International Conference on Management of Digital EcoSystems (MEDES{\textquoteright}19)},
	year = {2019},
	publisher = {ACM},
	organization = {ACM},
	abstract = {In the modern information society, learning is no longer just about obtaining factual knowledge, but more about general skills on how and where to apply available knowledge and obtain new knowledge in order to solve new problems. Such skills include abilities to connect and organize ideas, fill gaps in knowledge structures, evaluate evidence, argue with new information, test and modify, predict, clarify, generate questions, learn new concepts, make unexpected connections, reflect, analyze, synthesize and loop back. This work presents the Immersion framework, a digital ecosystem for adaptive smart learning environments for interactive mixed reality driven methods to foster learners{\textquoteright} self-regulating skill development.},
	keywords = {Game-based Interaction, Learner Collaboration, Mixed Reality, Mobile Learning, Self-regulated Learning, Technology Enhanced Learning},
	author = {Dimitris Spiliotopoulos and Dionisis Margaris and Costas Vassilakis}
}
@conference {Antoniou_2019_Mytilene,
	title = {Cultural technologies: the case of the Tripolis archeological museum (in Greek; Greek title: "ΠΟΛΙΤΙΣΤΙΚΕΣ ΤΕΧΝΟΛΟΓΙΕΣ: Η ΠΕΡΙΠΤΩΣΗ ΤΟΥ ΑΡΧΑΙΟΛΟΓΙΚΟΥ ΜΟΥΣΕΙΟΥ ΤΡΙΠΟΛΗΣ")},
	booktitle = {Book of abstracts of the 2nd Conference of the School of Social Sciences of the University of the Aegean "Social sciences today: dilemmas and prospectives beyond the crisis"},
	year = {2019},
	abstract = {The Tripolis archeological museum hosts magnificent ancient art exhibits from the whole of the Arcadia county. However, a series of issues, including the old-style museological exhibition and the limited informational material offered to the visitor, combined with the lack of digital presence for the museum, lead to a low number of visitors. Culural technologies may offer solutions to these issues that the museum fronts, and to this end the museum was included in the CrossCult EU project (www.crosscult.eu). In the context of the project, the antecendents regarding the technological design for the particular museum were studied (staff, visitor and technological equipment needs), and the characteristics of the museum collections were examined. With the collaboration of the Ephorate of Antiquities of Arcadia, the most important and characteristic exhibits were identified, among those that were linked to the position of the woman in the ancient society. Using these exhibits as a basis, 7 thematic itineraries were created in both the English and the Greek language, which support the user in visiting the museum halls and exhibitions and learning certain aspects of women{\textquoteright}s lives in the antiquity (e.g. education, everyday life, social status, etc). Each exhibit is linked with different digital cultural artefacts (e.g. images from other collections, related videos, games, sound clips etc.), to create narratives that increase user engagement and stimulate reflection. In parallel, a series of games was deveped, aiming to disseminate the presence of the museum and the information sourced from it through the social networks, assist in creating user profiles and further promote the museum. Finally, user experience can continue after the visit, through the use of a specialized social network, created specifically for the needs of the museum. (Abstract in Greek follows: Το αρχαιολογικό μουσείο Τρίπολης στεγάζει καταπληκτικά δείγματα αρχαίας τέχνης από ολόκληρο τον νομό Αρκαδίας. Όμως μια σειρά προβλημάτων, όπως η παλαιού τύπου μουσειολογική έκθεση και το πολύ συνοπτικό πληροφοριακό υλικό που προσφέρεται στον επισκέπτη, μαζί με το γεγονός ότι το μουσείο δεν έχει ψηφιακή παρουσία, οδηγεί σε χαμηλή επισκεψιμότητα. Οι πολιτιστικές τεχνολογίες μπορούν να προσφέρουν λύσεις στα προβλήματα του μουσείου και έτσι το μουσείο εντάχθηκε στο Ευρωπαϊκό ερευνητικό έργο CrossCult (www.crosscult.eu). Μέσα στα πλαίσια του έργου, μελετήθηκαν τα προαπαιτούμενα σχεδιασμού τεχνολογιών για το συγκεκριμένο χώρο (ανάγκες προσωπικού, ανάγκες επισκεπτών, ανάγκες τεχνολογικού εξοπλισμού), καθώς και τα χαρακτηριστικά των συλλογών. Με τη βοήθεια της Εφορείας Αρχαιοτήτων Αρκαδίας, εντοπίστηκαν τα σημαντικότερα και χαρακτηριστικότερα εκθέματα, γύρω από το θέμα της θέσης της γυναίκας στον αρχαίο κόσμο. Με βάσει τα εκθέματα αυτά, δημιουργήθηκαν 7 θεματικές διαδρομές (σε Ελληνικά και Αγγλικά) όπου ο επισκέπτης μπορεί να περιηγηθεί στο μουσείο και να μάθει για συγκεκριμένες πτυχές της ζωής των γυναικών (π.χ. εκπαίδευση, καθημερινότητα, κοινωνική θέση, κλπ). Το κάθε έκθεμα συνδέεται με διαφορετικά ψηφιακά πολιτιστικά αντικείμενα (π.χ. εικόνες από εκθέματα άλλων συλλογών, σχετικά βίντεο, παιχνίδια, αρχεία ήχου, κλπ) για να δημιουργηθούν αφηγήσεις που να αυξάνουν τον προβληματισμό και την εμπλοκή του επισκέπτη. Παράλληλα, μια σειρά παιχνιδιών υλοποιήθηκε με σκοπό τη διάχυση στα μέσα κοινωνικής δικτύωσης για τη δημιουργία προφίλ επισκεπτών και την περαιτέρω διαφήμιση του μουσείου. Τέλος, η εμπειρία μπορεί να συνεχιστεί και μετά την επίσκεψη με τη χρήση εξειδικευμένου κοινωνικού δικτύου, φτιαγμένου ειδικά για τους επισκέπτες του μουσείου.)},
	url = {https://www.propobos.gr/?id=3247\&\&atfc=3250},
	author = {Angela Antoniou and Giorgos Lepouras and Costas Vassilakis and Manolis Wallace and Nikos Platis}
}
@inbook {DBLP:reference/db/Skiadopoulos18,
	title = {Cardinal Direction Relationships},
	booktitle = {Encyclopedia of Database Systems, Second Edition},
	year = {2018},
	doi = {10.1007/978-1-4614-8265-9_45},
	url = {https://doi.org/10.1007/978-1-4614-8265-9_45},
	author = {Spiros Skiadopoulos}
}
@conference {591,
	title = {A crawler architecture for harvesting the clear, social, and dark web for IoT-related cyber-threat intelligence},
	booktitle = {In Proceedings of the IEEE Workshop on Cyber Security \& Resilience in the Internet of Things (CSRIoT @ IEEE Services)},
	year = {2016},
	month = {July 2016},
	publisher = {IEEE},
	organization = {IEEE},
	address = {Milan, Italy},
	abstract = {The clear, social, and dark web have lately been identified as rich sources of valuable cyber-security information that {\textendash}given the appropriate tools and methods{\textendash} may be identified, crawled and subsequently leveraged to actionable cyber- threat intelligence. In this work, we focus on the information gathering task, and present a novel crawling architecture for transparently harvesting data from security websites in the clear web, security forums in the social web, and hacker fo- rums/marketplaces in the dark web. The proposed architecture adopts a two-phase approach to data harvesting. Initially a machine learning-based crawler is used to direct the harvesting towards websites of interest, while in the second phase state- of-the-art statistical language modelling techniques are used to represent the harvested information in a latent low-dimensional feature space and rank it based on its potential relevance to the task at hand. The proposed architecture is realised using exclusively open-source tools, and a preliminary evaluation with crowdsourced results demonstrates its effectiveness.},
	keywords = {crawling architecture, cyber-security, cyber-threat intelligence, IoT, language models, Machine Learning},
	url = {http://users.uop.gr/ trifon/papers/pdf/csriot19-KCTS.pdf},
	author = {Paris Koloveas and Thanasis Chantzios and Christos Tryfonopoulos and Spiros Skiadopoulos}
}
@conference {DBLP:conf/kcap/TsafaraTSZ15,
	title = {Cloud-Based Data and Knowledge Management for Multi-Centre Biomedical Studies},
	booktitle = {Proceedings of the 8th International Conference on Knowledge Capture, K-CAP 2015, Palisades, NY, USA, October 7-10, 2015},
	year = {2015},
	pages = {24:1{\textendash}24:4},
	doi = {10.1145/2815833.2816949},
	url = {https://doi.org/10.1145/2815833.2816949},
	author = {Amalia Tsafara and Christos Tryfonopoulos and Spiros Skiadopoulos and Lefteris Zervakis}
}
@conference {563,
	title = {Cloud-Based Data and Knowledge Management for Multi-Centre Biomedical Studies},
	booktitle = {Proceedings of the International Conference on Knowledge Capture (K-CAP)},
	year = {2015},
	month = {October 7-10},
	address = {Palisades NY, USA},
	abstract = {Among the basic research tools for (bio)medical science are epidemiological studies that typically involve a number of hospitals, clinics, and research centres scattered around the world, and are often referred to as multi-centre studies. Clearly, the effectiveness and importance of a multi-centre study increases with the number of participating centres and enrolled patients, but at the same time this natural distribution in the production of research data requires sophisticated data management infrastructures to support the participating units. This kind of infrastructure is not only expensive to build and maintain, but also cannot be reused as it is often tailored to a specific study. In this work, we present a cloud-based system, coined CLOUDSTUDY, that allows users without any computer science background to design, deploy, and administer platforms aimed for managing, sharing, and analysing clinical data from multi-centre studies. The CLOUDSTUDY system provides a zero-administration, zero-cost online tool for creating multi- centre studies that (i) enhances re-usability by introducing study templates, (ii) supports (bio)medical needs through specialised data types, and (iii) emphasises data filtering/export through an expressive yet simple graphical query engine.},
	doi = {10.1145/2815833.2816949},
	url = {https://doi.org/10.1145/2815833.2816949},
	author = {Amalia Tsafara and Christos Tryfonopoulos and Spiros Skiadopoulos and Lefteris Zervakis}
}
@conference {marg15a,
	title = {A Collaborative Filtering Algorithm with Clustering for Personalized Web Service Selection in Business Processes},
	booktitle = {Proceedings of RCIS 2015},
	year = {2015},
	month = {5},
	abstract = {Recommender systems aim to propose items that are expected to be of interest to the users. As one of the most successful approaches to building recommender systems, collaborative filtering exploits the known preferences of a group of users to formulate recommendations or predictions of the unknown preferences for other users. In many cases, collaborative filtering algorithms handle complex items, which are described using hierarchical tree structures containing rich semantic information. In order to make accurate recommendations on such items, the related algorithms must examine all aspects of the available semantic information. Thus, when collaborative filtering techniques are employed to adapt the execution of business processes, they must take into account the services{\textquoteright} Quality of Service parameters, so as to generate recommendations tailored to the individual user needs. In this paper, we present a collaborative filtering-based algorithm which takes into account the web services{\textquoteright} QoS parameters in order to tailor the execution of business processes to the preferences of users. An offline clustering technique is also introduced for supporting the efficient and scalable execution of proposed algorithm under the presence of large repositories of sparse data.},
	keywords = {business processes, clustering, collaborative filtering, hierarchical tree, performance, Quality of service, Web services},
	doi = {10.1109/RCIS.2015.7128877},
	author = {Dionisis Margaris and P. Georgiadis and Costas Vassilakis}
}
@conference {570,
	title = {Constructing Subsumption Hierarchies of Web Queries},
	booktitle = {Proceedings of the International Workshop on Dataset PROFIling and fEderated Search for Linked Data (PROFILES @ ESWC)},
	year = {2015},
	month = {May},
	address = {Portoroz, Slovenia},
	author = {Alexander Prohaska and Christos Tryfonopoulos and Georgiana Ifrim}
}
@conference {DBLP:conf/bibe/TsafaraTS13,
	title = {CloudStudy: A cloud-based system for supporting multi-centre studies},
	booktitle = {13th IEEE International Conference on BioInformatics and BioEngineering, BIBE 2013, Chania, Greece, November 10-13, 2013},
	year = {2013},
	pages = {1{\textendash}4},
	doi = {10.1109/BIBE.2013.6701549},
	url = {https://doi.org/10.1109/BIBE.2013.6701549},
	author = {Amalia Tsafara and Christos Tryfonopoulos and Spiros Skiadopoulos}
}
@article {vassiliadis-hind2012,
	title = {Class-Based Weighted Fair Queuing Scheduling on Dual-Priority Delta Networks},
	journal = {Journal of Network and Computer Applications},
	volume = {2012},
	number = {XX},
	year = {2012},
	pages = {13 pages},
	abstract = {In this paper, we model, analyze and evaluate the performance of a 2-class priority architecture for finite-buffered Multistage Interconnection Networks (MINs). The MIN operation modelling is based on a state diagram, which includes the possible MIN states, transitions and conditions under which each transition occurs. Equations expressing state and transition probabilities are subsequently given, providing a formal model for evaluating the MIN{\textquoteright}s performance. The proposed architecture{\textquoteright}s performance is subsequently analyzed using simulations; operational parameters, including buffer length, MIN size, offered load and ratios of high priority packets which are varied across experiments to gain insight on how each parameter affects the overall MIN performance. The 2-class priority MIN performance is compared against the performance of single priority MINs, detailing the performance gains and losses for packets of different priorities. Performance is assessed by means of the two most commonly used factors, namely packet throughput and packet delay, while a performance indicator combining both individual factors is introduced, computed and discussed. The findings of this study can be used by network and interconnection system designers in order to deliver efficient systems while minimizing the overall cost. The performance evaluation model can also be applied to other network types, providing the necessary data for network designers to select optimal values for network operation parameters.},
	doi = {10.1155/2012/859694},
	author = {D.C. Vasiliadis and G.E. Rizos and Costas Vassilakis}
}
@article {vassiliadis-jpeds2012,
	title = {Class-based weighted fair queuing scheduling on quad-priority Delta Networks},
	journal = {International Journal of Parallel, Emergent and Distributed Systems},
	volume = {27},
	number = {5},
	year = {2012},
	month = {oct},
	pages = {435{\textendash}457},
	publisher = {Informa UK Limited},
	abstract = {Contemporary networks support multiple priorities, aiming to differentiate the QoS levels offered to individual traffic classes. Support for multiple priorities necessitates the introduction of a scheduling algorithm, to select each time the next packet to transmit over the data link. Class-based Weighted Fair Queuing (CBWFQ) scheduling and its variations, is widely used as a scheduling technique, since it is easy to implement and prevents the low-priority queues from starvation, i.e. receiving no service during periods of high-priority traffic. CBWFQ effectively thus offers low-priority queues the opportunity to transmit packets even though the high-priority queues are not empty. In this paper, we present the modeling and performance evaluation of a single-buffered, four-priority multistage interconnection network (MIN) operating under the CBWFQ scheduling policy. Performance evaluation is conducted through simulation, and the performance metrics obtained can be used by MIN designers to set the appropriate queue weights according to the expected traffic and the desired QoS levels for each priority class, delivering efficient thus systems.},
	doi = {10.1080/17445760.2012.712694},
	author = {D.C. Vasiliadis and G.E. Rizos and Costas Vassilakis}
}
@article {benou2012b,
	title = {A context management architecture for m-commerce applications},
	journal = {Central European Journal of Computer Science, Versita, co-published with Springer Verlag},
	volume = {2},
	number = {2},
	year = {2012},
	pages = {87{\textendash}117},
	abstract = {Mobile commerce applications operate in highly dynamic environments with diverse characteristics and interesting challenges. The characteristics and conditions of these environments {\textendash}called context{\textendash}, can be exploited to provide adaptive mobile services, in terms of user interface, functionality and content, in order to offer more effective m-commerce. Today, building adaptive mobile services is a complex and time-consuming task due to the lack of standardized methods, tools and architectures for the identification, representation and management of the context. Addressing some of these issues, recent works have provided formal extensions for various stages of the m-commerce application lifecycle, such as extended UML class diagrams for building design models and have used context parameters in order to offer adaptive applications. Using these works as the basis, in this paper we propose a context management architecture, which accommodates the requirements that have been identified for m-commerce applications. The proposed architecture is evaluated in terms of completeness, complexity, performance and utility, and compared against other approaches proposed in the literature regarding its suitability for supporting context-aware m-commerce applications.},
	keywords = {adaptivity, context, context management, context-awareness, mobile commerce, software architecture},
	doi = {10.2478/s13537-012-0010-z},
	url = {https://link.springer.com/article/10.2478/s13537-012-0010-z},
	author = {Poulcheria Benou and Costas Vassilakis}
}
@article {benou2012,
	title = {Context Management for m-Commerce Applications: Determinants, Methodology and the Role of Marketing},
	journal = {Information Technology and Management, Springer-Verlag},
	volume = {13(2)},
	year = {2012},
	pages = {91 {\textendash} 111},
	abstract = {Studying consumer behaviour and usage of environmental determinants in the mobile services domain contributes to the identification of context information which is critical for the effective operation of mobile commerce applications. Exploiting this information towards providing enhanced and innovative mobile services offers a competitive advantage within the highly demanding domain of m-commerce applications. However, in order to effectively exploit such context information, there is a need to design the necessary methods, software tools and information systems that will be employed for collecting, processing and disseminating this information. In this paper we develop a theoretical framework which defines the context information necessary for m-commerce applications, taking into account relevant marketing dimensions as well as privacy protection perspectives. Then, this framework is operationalized through the design of an appropriate software architecture which enables the standardization and management of context information.},
	doi = {10.1007/s10799-012-0120-2},
	author = {Poulcheria Benou and Costas Vassilakis and Adam Vrechopoulos}
}
@article {benou2010,
	title = {The Conceptual Model of Context for Mobile Commerce Applications},
	journal = {Electronic Commerce Research, Springer-Verlag},
	volume = {10(2)},
	year = {2010},
	pages = {139-165},
	abstract = {Mobile commerce applications adhering to anytime and anywhere paradigm, required to be flexible. They should be able to adapt their interface, services and content towards a certain context. Several proposals for definition of context have been already proposed originating from various areas related to mobile commerce. However, an integrated, formal and methodological approach for the determination and representation of context, adjusted to special characteristics of mobile commerce applications, has not been insofar presented. This is the challenge we address in this paper, through a conceptual model that includes: i) a clear and formal definition of context, ii) the depiction of its specific characteristics as metadata, iii) a methodology for its determination and iv) the presentation of an extension of class diagrams of UML for its representation, all of them tailored to the special nature of mobile commerce applications.},
	doi = {10.1007/s10660-010-9050-4},
	author = {Poulcheria Benou and Costas Vassilakis}
}
@conference {torou2009a,
	title = {Capturing the historical research methodology: an experimental approach},
	booktitle = {Proceedings of International Conference of Education, Research and Innovation (ICERI 2009)},
	year = {2009},
	month = {11},
	abstract = {This paper presents the results of a study on how historians conduct research in a historical archive, and the methodologies they use while searching. Historic research involves finding, using, interpreting and correlating information within primary and secondary sources, in order to understand past events. The collection of historical data is accomplished through methodical and comprehensive research in primary and secondary sources. An important factor in our study was to understand what kind of data and/or information historians are looking for in a library/historical archive, either printed or digitized, and which research methodologies or research models they use while they investigate a historical archive. Since this issue has not been addressed insofar, and therefore there are no methods for elucidating research methodologies or research models that historians employ / use, we formulated a questionnaire comprising of seven information retrieval tasks commonly addressed in the context of historic research. History researchers were asked to describe in detail how they would proceed in searching for the information they need for completing these tasks. Through this procedure we aimed to investigate the different ways a historian can use to tackle a specific question, examine whether there exists a common research methodology, and the historic researchers? expectations and preferences. The insight gained from this investigation can be used for educational purposes, since it could be useful in the creation / development of a methodology for conducting research on historical information. Furthermore, the findings can be exploited in the context of organizing documents within historical source repositories, so as to facilitate the retrieval of documents by historians; finally the presented findings can serve as a preliminary requirement analysis phase for building tools that will enable historians to access more rapidly and fully the information they need.},
	author = {Elena Torou and Akrivi Katifori and Costas Vassilakis and Giorgos Lepouras and C. Halatsis}
}
@inbook {DBLP:reference/db/Skiadopoulos09,
	title = {Cardinal Direction Relationships},
	booktitle = {Encyclopedia of Database Systems},
	year = {2009},
	pages = {305{\textendash}308},
	doi = {10.1007/978-0-387-39940-9_45},
	url = {https://doi.org/10.1007/978-0-387-39940-9_45},
	author = {Spiros Skiadopoulos}
}
@article {DBLP:journals/tkde/SkiadopoulosSSK07a,
	title = {Correction to "A Family of Directional Relation Models for Extended Objects"},
	journal = {IEEE Trans. Knowl. Data Eng.},
	volume = {19},
	number = {10},
	year = {2007},
	pages = {1448},
	doi = {10.1109/TKDE.2007.190653},
	url = {https://doi.org/10.1109/TKDE.2007.190653},
	author = {Spiros Skiadopoulos and Nikos Sarkas and Timos K. Sellis and Manolis Koubarakis}
}
@conference {KatiforiGVLH07,
	title = {Creating an Ontology for the User Profile: Method and Applications},
	booktitle = {RCIS},
	year = {2007},
	month = {4/2007},
	pages = {407{\textendash}412},
	abstract = {User profiling is commonly employed nowadays to enhance usability as well as to support personalization, adaptivity and other user-centric features. Insofar, application designers model user profiles mainly in an ad-hoc manner, hindering thus application interoperability at the user profile level, increasing the amount of work to be done and the possibility of errors or omissions in the profile model. This work aims at creating a user profile ontology that incorporates concepts and properties used to model the user profile. Existing literature, applications and ontologies related to the domain of user context and profiling have been taken into account in order to create a general, comprehensive and extensible user model. This ontology can be used as a reference model, in order to alleviate the aforementioned issues. The model, available for download, is exemplified through its application in two different areas, personal information management and adaptive visualization.},
	author = {Akrivi Katifori and M. Golemati and Costas Vassilakis and Giorgos Lepouras and C. Halatsis}
}
@conference {1154709,
	title = {A Comparative Study of Four Ontology Visualization Techniques in Protege: Experiment Setup and Preliminary Results},
	booktitle = {IV {\textquoteright}06: Proceedings of the conference on Information Visualization},
	year = {2006},
	month = {7},
	pages = {417{\textendash}423},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Washington, DC, USA},
	abstract = {The continuing need for more effective information retrieval has lead to the creation of the notions of the semantic web and personalized information management, areas of study that very often employ ontologies to represent the semantic context of a domain. Consequently, the need for effective ontology visualization for design, management and browsing has arisen. There are several ontology visualizations available through the existing ontology management tools, but not as many evaluations to determine their advantages and disadvantages and their suitability for various ontologies and user groups. This work presents the preliminary results of an evaluation of four visualization methods in Protege.},
	isbn = {0-7695-2602-0},
	doi = {10.1109/IV.2006.3},
	author = {Akrivi Katifori and Elena Torou and C. Halatsis and Giorgos Lepouras and Costas Vassilakis}
}
@article {1412314,
	title = {Component reuse in electronic services development},
	journal = {J. Comp. Methods in Sci. and Eng.},
	volume = {6},
	number = {5,6 Supplement 2},
	year = {2006},
	pages = {229{\textendash}241},
	publisher = {IOS Press},
	address = {Amsterdam, The Netherlands, The Netherlands},
	abstract = {In the context of electronic government, e-services are a valuable instrument for offering high quality services to enterprises and individual citizens alike. While developing an e-service, it is usually possible to reuse elements that have already crafted for other e-services, such as personal detail forms or widgets for collecting social security numbers, decreasing thus both development effort and the time for deployment. A more generic framework for supporting reusability in development of e-services includes the identification of reusable objects, the creation and population of a repository containing such components, and the empowerment of developers with tools allowing for location, retrieval and adaptation of components for suiting their specific tasks. In this paper, we conduct an analysis to recognise e-service component that offer reusability opportunities and we present facilities and methods to enable e-service developers to exploit these opportunities while developing electronic services.},
	issn = {1472-7978},
	url = {http://content.iospress.com/articles/journal-of-computational-methods-in-sciences-and-engineering/jcm00134},
	author = {Costas Vassilakis and Giorgos Lepouras}
}
@conference {Golemati200662,
	title = {A context-based adaptive visualization environment},
	booktitle = {Proceedings of the International Conference on Information Visualisation},
	year = {2006},
	note = {cited By (since 1996) 0},
	month = {7},
	pages = {62-67},
	abstract = {Digital libraries and historical archives are increasingly employing visualization systems to facilitate the information retrieval and knowledge extraction tasks of their users. Typically, each organization employs a single visualization system, which may not suit best the needs of certain user groups, specific tasks, or properties of document collections to be visualized. In this paper we present a context-based adaptive visualization environment, which embeds a set of visualization methods into a visualization library, from which the most appropriate one is selected for presenting information to the user. Methods are selected by examining parameters related to the user profile, system configuration and the set of data to be visualized, and employing a set of rules to assess the suitability of each method. The presented environment additionally monitors user behavior and preferences to adapt the visualization method selection criteria. Β{\textcopyright} 2006 IEEE.},
	keywords = {(PL) properties, Adaptive systems, Adaptive visualization, Behavioral research, Digital libraries, document collections, Extraction, Information analysis, Information science, Information services, Information systems, Information visualization, Knowledge extraction, Libraries, Retrieval (MIR), Search engines, Selection criterion, Set of rules, Solvent extraction, Specific tasks, System configurations, User behaviors, User groups, user profiling, Visualization, visualization methods, Visualization systems},
	doi = {10.1109/IV.2006.5},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-45149121827\&partnerID=40\&md5=ec45ad555b132faaf0bd2ca53e3292dc},
	author = {M. Golemati and C. Halatsis and Costas Vassilakis and Akrivi Katifori and Giorgos Lepouras}
}
@conference {DBLP:conf/icdim/TorouKVLH06,
	title = {Creating an Historical Archive Ontology: Guidelines and Evaluation},
	booktitle = {ICDIM},
	year = {2006},
	month = {12},
	pages = {102-109},
	abstract = {Ontologies have been proven invaluable tools both for the semantic web and for personal information management. In the context of a historical archive an ontology may provide meaningful and efficient support for search tasks as well as be used as a tool for storage and presentation of historical data. The creation however of such an ontology is complex, since the digitized archive documents are not in text format and the concepts that must be captured may vary among different time periods. This work presents a user-centric methodological approach for extracting the ontology of an historical archive focusing on the evaluation issues related to this process. The approach is exemplified through cases from its application in the University of Athens Historical Archive.},
	doi = {10.1109/ICDIM.2007.369337},
	author = {Elena Torou and Akrivi Katifori and Costas Vassilakis and Giorgos Lepouras and C. Halatsis}
}
@article {DBLP:journals/tkde/SkiadopoulosGSVSK05,
	title = {Computing and Managing Cardinal Direction Relations},
	journal = {IEEE Trans. Knowl. Data Eng.},
	volume = {17},
	number = {12},
	year = {2005},
	pages = {1610{\textendash}1623},
	doi = {10.1109/TKDE.2005.192},
	url = {https://doi.org/10.1109/TKDE.2005.192},
	author = {Spiros Skiadopoulos and Christos Giannoukos and Nikos Sarkas and Panos Vassiliadis and Timos K. Sellis and Manolis Koubarakis}
}
@proceedings {DBLP:conf/er/2005,
	title = {Conceptual Modeling - ER 2005, 24th International Conference on Conceptual Modeling, Klagenfurt, Austria, October 24-28, 2005, Proceedings},
	volume = {3716},
	year = {2005},
	publisher = {Springer},
	isbn = {3-540-29389-2},
	doi = {10.1007/11568322},
	url = {https://doi.org/10.1007/11568322},
	editor = {Lois M. L. Delcambre and Christian Kop and Heinrich C. Mayr and John Mylopoulos and Oscar Pastor}
}
@article {DBLP:journals/ai/SkiadopoulosK05,
	title = {On the consistency of cardinal direction constraints},
	journal = {Artif. Intell.},
	volume = {163},
	number = {1},
	year = {2005},
	pages = {91{\textendash}135},
	doi = {10.1016/j.artint.2004.10.010},
	url = {https://doi.org/10.1016/j.artint.2004.10.010},
	author = {Spiros Skiadopoulos and Manolis Koubarakis}
}
@article {DBLP:journals/ai/SkiadopoulosK04,
	title = {Composing cardinal direction relations},
	journal = {Artif. Intell.},
	volume = {152},
	number = {2},
	year = {2004},
	pages = {143{\textendash}171},
	doi = {10.1016/S0004-3702(03)00137-1},
	url = {https://doi.org/10.1016/S0004-3702(03)00137-1},
	author = {Spiros Skiadopoulos and Manolis Koubarakis}
}
@conference {DBLP:conf/edbt/SkiadopoulosGVSK04,
	title = {Computing and Handling Cardinal Direction Information},
	booktitle = {Advances in Database Technology - EDBT 2004, 9th International Conference on Extending Database Technology, Heraklion, Crete, Greece, March 14-18, 2004, Proceedings},
	year = {2004},
	pages = {329{\textendash}347},
	doi = {10.1007/978-3-540-24741-8_20},
	url = {https://doi.org/10.1007/978-3-540-24741-8_20},
	author = {Spiros Skiadopoulos and Christos Giannoukos and Panos Vassiliadis and Timos K. Sellis and Manolis Koubarakis}
}
@conference {Weir2004152,
	title = {Content enrichment through dynamic annotation},
	booktitle = {ICEIS 2004 - Proceedings of the Sixth International Conference on Enterprise Information Systems},
	year = {2004},
	note = {cited By (since 1996) 0},
	month = {4},
	pages = {152-157},
	abstract = {This paper describes a technique for interceding between users and the information that they browse. This facility, that we term {\textquoteright}dynamic annotation{\textquoteright}, affords a means of editing Web page content {\textquoteright}on-the-fly{\textquoteright} between the source Web server and the requesting client. Thereby, we have a generic way of modifying the content displayed to local users by addition, removal or reorganising any information sourced from the World-Wide Web, whether this derives from local or remote pages. For some time, we have been exploring the scope for this device and we believe that it affords many potential worthwhile applications. Here, we describe two varieties of use. The first variety focuses on support for individual users in two contexts (second-language support and second language learning). The second variety of use focuses on support for groups of users. These differing applications have a common goal which is content enrichment of the materials placed before the user. Dynamic annotation provides a potent and flexible means to this end.},
	keywords = {Content based retrieval, Content enrichment, Dynamic annotation, Information analysis, Knowledge based systems, Learning systems, Servers, Web browsers, World Wide Web},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-8444234304\&partnerID=40\&md5=1ba0d141296de4e5b8bbd76ba0d1d79a},
	author = {G.R.S. Weir and Giorgos Lepouras and Costas Vassilakis},
	editor = {I. Seruca and J. Filipe and S. Hammoudi and J. Cordeiro}
}
@conference {DBLP:conf/dawak/ManiatisVSV03,
	title = {CPM: A Cube Presentation Model for OLAP},
	booktitle = {Data Warehousing and Knowledge Discovery, 5th International Conference, DaWaK 2003, Prague, Czech Republic, September 3-5,2003, Proceedings},
	year = {2003},
	pages = {4{\textendash}13},
	doi = {10.1007/978-3-540-45228-7_2},
	url = {https://doi.org/10.1007/978-3-540-45228-7_2},
	author = {Andreas S. Maniatis and Panos Vassiliadis and Spiros Skiadopoulos and Yannis Vassiliou}
}
@conference {DBLP:conf/dolap/VassiliadisSS02,
	title = {Conceptual modeling for ETL processes},
	booktitle = {DOLAP 2002, ACM Fifth International Workshop on Data Warehousing and OLAP, November 8, 2002, McLean, VA, USA, Proceedings},
	year = {2002},
	pages = {14{\textendash}21},
	doi = {10.1145/583890.583893},
	url = {https://doi.org/10.1145/583890.583893},
	author = {Panos Vassiliadis and Alkis Simitsis and Spiros Skiadopoulos}
}
@conference {DBLP:conf/cp/SkiadopoulosK02,
	title = {Consistency Checking for Qualitative Spatial Reasoning with Cardinal Directions},
	booktitle = {Principles and Practice of Constraint Programming - CP 2002, 8th International Conference, CP 2002, Ithaca, NY, USA, September 9-13, 2002, Proceedings},
	year = {2002},
	pages = {341{\textendash}355},
	doi = {10.1007/3-540-46135-3_23},
	url = {https://doi.org/10.1007/3-540-46135-3_23},
	author = {Spiros Skiadopoulos and Manolis Koubarakis}
}
@conference {756327,
	title = {Controlled Caching of Dynamic WWW Pages},
	booktitle = {DEXA {\textquoteright}02: Proceedings of the 13th International Conference on Database and Expert Systems Applications},
	year = {2002},
	month = {9},
	pages = {9{\textendash}18},
	publisher = {Springer-Verlag},
	organization = {Springer-Verlag},
	address = {London, UK},
	abstract = {Web sites employ dynamically generated pages for content delivery more and more often, in order to increase their flexibility and provide up-to-date information. This practice, however, increases server load dramatically, since each request results to the execution of code, which may involve processing and/or access to information repositories. In this paper we present a scheme for maintaining a server-side cache of dynamically generated pages, allowing for cache consistency maintenance, without placing heavy burdens on application programmers. We also present insights to architecture scalability and some results obtained from conducted experiments.},
	isbn = {3-540-44126-3},
	doi = {10.1007/3-540-46146-9_2},
	url = {http://link.springer.com/chapter/10.1007\%2F3-540-46146-9_2},
	author = {Costas Vassilakis and Giorgos Lepouras}
}
@conference {DBLP:conf/ssd/SkiadopoulosK01,
	title = {Composing Cardinal Direction Relations},
	booktitle = {Advances in Spatial and Temporal Databases, 7th International Symposium, SSTD 2001, Redondo Beach, CA, USA, July 12-15, 2001, Proceedings},
	year = {2001},
	pages = {299{\textendash}320},
	doi = {10.1007/3-540-47724-1_16},
	url = {https://doi.org/10.1007/3-540-47724-1_16},
	author = {Spiros Skiadopoulos and Manolis Koubarakis}
}
@conference {790099,
	title = {A comparative study of temporal DBMS architectures},
	booktitle = {DEXA {\textquoteright}96: Proceedings of the 7th International Workshop on Database and Expert Systems Applications},
	year = {1996},
	month = {9},
	pages = {153},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Washington, DC, USA},
	abstract = {In the past years, a number of implementations of temporal DBMSs has been reported. Most of these implementations share a common feature, which is that they have been built as an extension to a snapshot DBMS. In this paper, we present three alternative design approaches that can be used for extending a snapshot DBMS to support temporal data,and evaluate the suitability of each approach, with respect to a number of design objectives.},
	isbn = {0-8186-7662-0},
	doi = {10.1109/DEXA.1996.558289},
	author = {Costas Vassilakis and P. Georgiadis and Anya Sotiropoulou}
}
@article {Spiliopoulou1996341,
	title = {A cost model for the estimation of query execution time in a parallel environment supporting pipeline},
	journal = {Computers and Artificial Intelligence},
	volume = {15},
	number = {4},
	year = {1996},
	note = {cited By (since 1996) 3},
	pages = {341-368},
	abstract = {We propose a model for the estimation of query execution time in an environment supporting bushy and pipelined parallelism. We consider a parallel architecture of processors having private main memories, accessing a shared secondary storage and communicating to each other via a network. For this environment, we compute the cost of query operators when processed in isolation and when in pipeline mode. We use those formulae to incrementally compute the cost of a query execution plan from its components. Our cost model can be incorporated to any optimizer for parallel query processing that considers parallel and pipelined execution of the query operators.},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33747804589\&partnerID=40\&md5=e04ec1604249525ebaf3dfb111a34f12},
	author = {M. Spiliopoulou and M. Hatzopoulos and Costas Vassilakis}
}
@conference {1993-kassapidis-hci,
	title = {Comparative Study of Protocols of the Transport Layer for Multimedia Applications},
	booktitle = {Proceedings of the 4th Hellenic Conference on Informatics},
	year = {1993},
	month = {12},
	pages = {105-118},
	abstract = {The forthcoming use of multimedia applications will require powerful computers and high performance networks. While great progress has been made to the physical layer of networks, the upper software layers of the OSI reference model have not kept up pace with them. This paper presents the demands imposed by multimedia applications on the underlying networks and their mapping to transport layer services, that protocols implementing it must provide. Four well-known transport layer protocols are briefly presented (TCP, TP4, VMTP, HSTP/XTP). The mechanisms employed by each one of those are studied and their suitability for demanding multimedia environments are evaluated. We conclude that much more effort needs to be made on the transport layer protocols so that high performance network architectures will be available to fullfill the diverse requirements of tomorrow{\textquoteright}s multimedia applications.},
	url = {http://cst.uop.gr/images/papers/1993-kassapidis-hci.pdf},
	author = {Kassapidis, P. and Costas Vassilakis and M. Nikolaidou and P. Georgiadis and Votsis, Gr. and Pronios, N.}
}
