@conference {838, title = {Estimating MPdist with SAX and Machine Learning}, booktitle = {New Trends in Database and Information Systems (Proceedings of ADBIS 2024, Short Papers, Workshops, Doctoral Consortium and Tutorials)}, year = {2024}, publisher = {Springer Cham}, organization = {Springer Cham}, abstract = {

MPdist is a distance measure which considers two time series to be similar if they share many similar subsequences. However, computing MPdist can be slow, especially for large time series. We propose a technique for the approximate computation of MPdist that uses the SAX representation of the time series to quickly estimate the Nearest Neighbor (NN) distance of each subsequence, and then applies a Machine Learning model to correct the accuracy loss incurred. Our method is orders of magnitude faster than the exact computation of MPdist; at the same time, our best approximation computes the NN of a time series with high accuracy. A thorough evaluation of our technique is provided.

}, keywords = {Distance metric, Machine Learning, MPdist, Random Forest, SAX, Time series}, doi = {https://doi.org/10.1007/978-3-031-70421-5_32}, author = {Mihalis Tsoukalos and Pantelis Chronis and Nikos Platis and Costas Vassilakis}, editor = {Joe Tekli and Johann Gamper and Richard Chbeir and Yannis Manolopoulos and Salma Sassi and Mirjana Ivanovic and Vargas-Solar, Genoveva and Ester Zumpano} } @conference {821, title = {RoG: A Pipeline for Automated Sensitive Data Identification and Anonymisation}, booktitle = {Proceedings of the 2023 IEEE CSR Workshop on Data Science for Cyber Security (DS4CS)}, year = {2023}, abstract = {

Nowadays, the amount of data available online is constantly increasing. This data may contain sensitive or private information that can expose the person behind the data or be misused by malicious actors for identity theft, stalking, and other nefarious purposes. There is thus, a growing need to protect individuals{\textquoteright} privacy and prevent data breaches in several application domains. Protecting data privacy though, is a complex and multifaceted issue that involves a range of legal, ethical, and technical considerations. In this paper, we discuss the challenges associated with data protection, the role of automated tools, and the effectiveness of identifying and anonymising sensitive data. We then, propose a fully-automated process for sensitive data identification and anonymisation, based on Natural Language Processing (NLP) techniques, that can be applied both in big diverse datasets and to a wide range of domains.

}, keywords = {anonymisation, automated process, k-anonymity, NER, NLP, pipeline, sensitive/private data}, author = {Sotiris Nikoletos and Stefanos Vlachos and Efstathios Zaragkas and Costas Vassilakis and Christos Tryfonopoulos and Paraskevi Raftopoulou} } @article {798, title = {On the Design of IoT Security: Analysis of Software Vulnerabilities for Smart Grids}, journal = {Energies}, volume = {14}, year = {2021}, month = {may}, pages = {2818}, abstract = {

The 5G communication network will underpin a vast number of new and emerging services, paving the way for unprecedented performance and capabilities in mobile networks. In this setting, the Internet of Things (IoT) will proliferate, and IoT devices will be included in many 5G application contexts, including the Smart Grid. Even though 5G technology has been designed by taking security into account, design provisions may be undermined by software-rooted vulnerabilities in IoT devices that allow threat actors to compromise the devices, demote confidentiality, integrity and availability, and even pose risks for the operation of the power grid critical infrastructures. In this paper, we assess the current state of the vulnerabilities in IoT software utilized in smart grid applications from a source code point of view. To that end, we identified and analyzed open-source software that is used in the power grid and the IoT domain that varies in characteristics and functionality, ranging from operating systems to communication protocols, allowing us to obtain a more complete view of the vulnerability landscape. The results of this study can be used in the domain of software development, to enhance the security of produced software, as well as in the domain of automated software testing, targeting improvements to vulnerability detection mechanisms, especially with a focus on the reduction of false positives.

}, keywords = {Internet of Things, robustness, security, software vulnerabilities}, doi = {10.3390/en14102818}, author = {Christos-Minas Mathas and Costas Vassilakis and Nicholas Kolokotronis and Charilaos C. Zarakovitis and Michail-Alexandros Kourtis} } @conference {809, title = {Digital applications for the preservation of historic memory: the case of the Kalamata digital museum (greek title: Ψηφιακές εφαρμογές για τη διατήρηση της ιστορικής μνήμης: Η περίπτωση του ψηφιακού μουσείου Καλαμάτας)}, booktitle = {4th PanHellenic Conference on Digital Cultural Heritage-EuroMed 2021}, year = {2021}, abstract = {

The evolution in technology and informatics have changed all aspects of our lives, including civilization-related ones. And while interdisciplinary research involving the scientific disciplines of human sciences and informatics was underdeveloped for many years, it seems that informatics and technology can constitute the catalyst for the rapid advancement of certain areas in human sciences. This has become more than apparent during the last decade, especially in museums and venues related to civilization, where the application of technology, both for the improvement of the visitors{\textquoteright} experience and for the support of scientists (archaeologists, museologists etc), is now taken as granted. In particular, the measures that have been applied during the last two years of the COVID19 pandemic, further accelerate the developments towards digitalization and switching to an online world. The "Kalamata 1821: roads of freedom" project was the starting point for the creation of the first mixed digital museum in the region of the Peloponnese; this museum is strongly related to the history of Greece, starting from the Revolution of 1821 and its relationship with Kalamata. This paper analyses the process of design, preparation and implementation of digital multimedia applications that are installed on the digital museum infrastructure. The applications have been designed to maximize the information that can be perceived within the limited time frame during of a museum visit, offering in parallel means to obtain some of the information presented and store them on a mobile device.

}, author = {Poulopoulos, Vassileios and Wallace, Manolis and Antoniou, Antzela and Costas Vassilakis and Panagiotidi, Vayia and Zacharias, Nikolaos} } @article {589, title = {Efficient Continuous Multi-Query Processing over Graph Streams}, journal = {CoRR}, volume = {abs/1902.05134}, year = {2019}, url = {http://arxiv.org/abs/1902.05134}, author = {Lefteris Zervakis and Vinay Setty and Christos Tryfonopoulos and Katja Hose} } @conference {DBLP:conf/debs/ChantziosZST19, title = {Ping - A customizable, open-source information filtering system for textual data}, booktitle = {Proceedings of the 13th ACM International Conference on Distributed and Event-based Systems, DEBS 2019, Darmstadt, Germany, June 24-28, 2019.}, year = {2019}, pages = {228{\textendash}231}, doi = {10.1145/3328905.3332512}, url = {https://doi.org/10.1145/3328905.3332512}, author = {Thanasis Chantzios and Lefteris Zervakis and Spiros Skiadopoulos and Christos Tryfonopoulos} } @article {DBLP:journals/bmcbi/ZagganasVPVSD17, title = {BUFET: boosting the unbiased miRNA functional enrichment analysis using bitsets}, journal = {BMC Bioinformatics}, volume = {18}, number = {1}, year = {2017}, pages = {399:1{\textendash}399:8}, doi = {10.1186/s12859-017-1812-8}, url = {https://doi.org/10.1186/s12859-017-1812-8}, author = {Konstantinos Zagganas and Thanasis Vergoulis and Maria D. Paraskevopoulou and Ioannis S. Vlachos and Spiros Skiadopoulos and Theodore Dalamagas} } @book {DBLP:reference/gis/2017, title = {Encyclopedia of GIS}, year = {2017}, publisher = {Springer}, organization = {Springer}, isbn = {978-3-319-17884-4}, doi = {10.1007/978-3-319-17885-1}, url = {https://doi.org/10.1007/978-3-319-17885-1}, editor = {Shashi Shekhar and Hui Xiong and Xun Zhou} } @article {581, title = {Query Reorganisation Algorithms for Efficient Boolean Information Filtering}, journal = {IEEE Transactions on Knowledge and Data Engineering}, volume = {29}, year = {2017}, pages = {418{\textendash}432}, abstract = {In the information filtering paradigm, clients subscribe to a server with continuous queries that express their information needs and get notified every time appropriate information is published. To perform this task in an efficient way, servers employ indexing schemes that support fast matches of the incoming information with the query database. Such indexing schemes involve (i) main-memory trie-based data structures that cluster similar queries by capturing common elements between them and (ii) efficient filtering mechanisms that exploit this clustering to achieve high throughput and low filtering times. However, state-of-the-art indexing schemes are sensitive to the query insertion order and cannot adopt to an evolving query workload, degrading the filtering performance over time. In this paper, we present an adaptive trie-based algorithm that outperforms current methods by relying on query statistics to reorganise the query database. Contrary to previous approaches, we show that the nature of the constructed tries, rather than their compactness, is the determining factor for efficient filtering performance. Our algorithm does not depend on the order of insertion of queries in the database, manages to cluster queries even when clustering possibilities are limited, and achieves more than 96\% filtering time improvement over its state-of-the-art competitors. Finally, we demonstrate that our solution is easily extensible to multi-core machines.}, keywords = {dissemination, indexing methods, Information filtering, user profiles and alert services}, doi = {10.1109/TKDE.2016.2620140}, url = {https://doi.org/10.1109/TKDE.2016.2620140}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Spiros Skiadopoulos and Manolis Koubarakis} } @conference {DBLP:conf/esws/ZervakisTSK16, title = {Full-Text Support for Publish/Subscribe Ontology Systems}, booktitle = {The Semantic Web. Latest Advances and New Domains - 13th International Conference, ESWC 2016, Heraklion, Crete, Greece, May 29 - June 2, 2016, Proceedings}, year = {2016}, pages = {233{\textendash}249}, doi = {10.1007/978-3-319-34129-3_15}, url = {https://doi.org/10.1007/978-3-319-34129-3_15}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Spiros Skiadopoulos and Manolis Koubarakis} } @conference {DBLP:conf/edbt/ZervakisTSSS16, title = {Towards Publish/Subscribe Functionality on Graphs}, booktitle = {Proceedings of the Workshops of the EDBT/ICDT 2016 Joint Conference, EDBT/ICDT Workshops 2016, Bordeaux, France, March 15, 2016.}, year = {2016}, url = {http://ceur-ws.org/Vol-1558/paper13.pdf}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Vinay Setty and Stephan Seufert and Spiros Skiadopoulos} } @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 {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 {539, title = {DS4: Introducing Semantic Friendship in Distributed Social Networks.}, booktitle = {Proceedings of the 21st International Conference on Cooperative Information Systems (CoopIS)}, year = {2013}, month = {September}, address = {Graz, Austria}, author = {Paraskevi Raftopoulou and Christos Tryfonopoulos and E.G.M. Petrakis and Nikos Zevlis} } @article {DBLP:journals/corr/ZervakisTPKS13, title = {Full-text Support for Publish/Subscribe Ontology Systems}, journal = {CoRR}, volume = {abs/1307.2015}, year = {2013}, url = {http://arxiv.org/abs/1307.2015}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos} } @proceedings {DBLP:conf/pkdd/2013-3, title = {Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2013, Prague, Czech Republic, September 23-27, 2013, Proceedings, Part III}, volume = {8190}, year = {2013}, publisher = {Springer}, isbn = {978-3-642-40993-6}, doi = {10.1007/978-3-642-40994-3}, url = {https://doi.org/10.1007/978-3-642-40994-3}, editor = {Hendrik Blockeel and Kristian Kersting and Siegfried Nijssen and Filip Zelezn{\'y}} } @conference {554, title = {Full-text Support for Publish/Subscribe Ontology Systems}, booktitle = {Proceedings of the Extended Semantic Web Conference (ESWC)}, year = {2012}, month = {May}, address = {Crete, Greece}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos} } @conference {586, title = {Approximate Information Filtering in Peer-to-Peer Networks}, booktitle = {Proceedings of the 9th Web Information Systems Engineering (WISE) Conference}, year = {2008}, month = {September}, address = {Auckland, New Zealand}, author = {Christian Zimmer and Christos Tryfonopoulos and Klaus Berberich and Manolis Koubarakis and Gerhard Weikum} } @conference {574, title = {Exploiting Correlated Keywords to Improve Approximate Information Filtering}, booktitle = {Proceedings of the 31st Annual International ACM SIGIR Conference}, year = {2008}, month = {July}, address = {Singapore}, author = {Christian Zimmer and Christos Tryfonopoulos and Gerhard Weikum} } @conference {566, title = {P2P Information Retrieval and Filtering with MAPS}, booktitle = {Proccedings of the IEEE International Conference on Peer-to-Peer Computing (P2P)}, year = {2008}, month = {September}, address = {Aachen, Germany}, author = {Christian Zimmer and Johannes Heinz and Christos Tryfonopoulos and Gerhard Weikum} } @proceedings {DBLP:conf/ssd/2007, title = {Advances in Spatial and Temporal Databases, 10th International Symposium, SSTD 2007, Boston, MA, USA, July 16-18, 2007, Proceedings}, volume = {4605}, year = {2007}, publisher = {Springer}, isbn = {978-3-540-73539-7}, doi = {10.1007/978-3-540-73540-3}, url = {https://doi.org/10.1007/978-3-540-73540-3}, editor = {Dimitris Papadias and Donghui Zhang and George Kollios} } @article {557, title = {Architectural Alternatives for Information Filtering in Structured Overlay Networks}, journal = {IEEE Internet Computing}, volume = {11}, year = {2007}, pages = {24-34}, author = {Christos Tryfonopoulos and Christian Zimmer and Manolis Koubarakis and Gerhard Weikum} } @conference {543, title = {Efficient Search and Approximate Information Filtering in a Distributed Peer-to-Peer Environment of Digital Libraries}, booktitle = {Proceedings of the DELOS Conference on Digital Libraries}, year = {2007}, month = {February}, address = {Pisa, Italy}, author = {Christian Zimmer and Christos Tryfonopoulos and Gerhard Weikum} } @conference {548, title = {MinervaDL: An Architecture for Information Retrieval and Filtering in Distributed Digital Libraries}, booktitle = {Proceedings of the 11th European Conference on Research and Advanced Technology for Digital Libraries (ECDL)}, year = {2007}, month = {September}, address = {Budapest, Hungary}, author = {Christian Zimmer and Christos Tryfonopoulos and Gerhard Weikum} } @conference {564, title = {Node Behavior Prediction for Large-Scale Approximate Information Filtering}, booktitle = {Proceedings of the International Workshop on Large-Scale Distributed Systems for Information Retrieval (LSDS-IR @ SIGIR)}, year = {2007}, month = {July}, address = {Amsterdam, The Netherlands}, author = {Christian Zimmer and Christos Tryfonopoulos and Klaus Berberich and Gerhard Weikum and Manolis Koubarakis} } @proceedings {DBLP:conf/www/2007, title = {Proceedings of the 16th International Conference on World Wide Web, WWW 2007, Banff, Alberta, Canada, May 8-12, 2007}, year = {2007}, publisher = {ACM}, isbn = {978-1-59593-654-7}, editor = {Carey L. Williamson and Mary Ellen Zurko and Peter F. Patel-Schneider and Prashant J. Shenoy} } @conference {adpuc06-BKTWZ, title = {MAPS: Approximate Publish/Subscribe Functionality in Peer-to-Peer Networks}, booktitle = {Proceedings of Advanced Data Processing in Ubiquitous Computing Workshop (ADPUC @ Middleware)}, year = {2006}, month = {November}, pages = {1{\textendash}6}, address = {Melbourne, Australia}, author = {Klaus Berberich and Manolis Koubarakis and Christos Tryfonopoulos and Gerhard Weikum and Christian Zimmer} }