Reviewer\Organizer on the following journals and conferences

• 1998, 2004: Information Processing Letters (IPL) – Reviewer

• 1998: Algorithmica – Reviewer

• 1999. Acta Informatica – Reviewer

• 2000: Journal of Algorithms – Reviewer

• 2002: ESA (European Symposium on Algorithms) – Reviewer

• 2002: ICALP (International Colloquium on Automata, Languages and Programming) – Reviewer

• 2003: AWOCA (Australasian Workshop on Combinatorial Algorithms) – Reviewer

• 2005: WEA (Workshop on Experimental Algorithms) – Reviewer

• 2005:  Program Committee: Algorithmic Techniques for Handling Spatiotemporal and Environmental Data,  http://www.worldses.org/conferences/2005/greece/iccomp/spatio.htm

• 2005: Organizing and Program Committee: Sixteenth ACM Conference on Hypertext and Hypermedia (ACM HyperText 2005), 6.-9.Sept. 2005, Salzburg, International Workshop on Peer to Peer and Service Oriented Hypermedia: Techniques and Systems

• 2006: Organizing and Program Committee: Seventeenth ACM Conference on Hypertext and Hypermedia, (ACM HyperText 2006), Odense, Denmark, 20-23 August, International Workshop on Architectures, Models and Infrastructures to Generate Semantics in Peer to Peer and Hypermedia Systems

• 2007, 2009: JPDC (Journal of Parallel and Distributed Computing) - Reviewer

• 2008, 2009: JSS (Journal of Systems and Software, Elsevier) - Reviewer

• 2008, 2009: DKE (Data and Knowledge Engineering, Elsevier) - Reviewer

• 2008: IEEE PCI, http://www.icsd.aegean.gr/pci2008/  - Reviewer

• 2008: Organizing Committee, 2nd Workshop of Informatics Dept., Ionian University,June 2008.

• 2008: IADIS Data Mining, http://www.datamining-conf.org/committees.asp - Reviewer

• 2008,2009 :Organizing and Program Committee on ICICTE, http://www.icicte.org/

• 2009 : ICDE (Reviewer)

• 2009: IEEE PCI  (pci2009.ionio.gr) - Organizing and Program Committee

• 2010: PSD (Privacy in Statistical Databases) - Organizing and Program Committee

• 2010: Computer Journal – Reviewer

• 2011: IEEE Networks – Special Issue on Cloud Computing (Reviewer)

• 2011: AIAI / EANN 2011 (Organizing and Program Committee)

• 2011: Computer Journal – Reviewer

• 2012: AIAI 2012 (Workshop Chair)

• 2013: EANN/MHDW (Workshop Chair)

• 2014: AIAI 2014 (Workshop Chair)

• 2015: ICDM 2015 (Reviewer)

• 2015: EANN/MHDW (Workshop Chair)

• 2015: ALGO 2015 / ALGOCLOUD 2015 (Workshop Chair)

• 2016: EANN/MHDW (Workshop Chair)

• 2016: ALGO 2016 / ALGOCLOUD 2016 (Workshop Chair – ALGOCLOUD  Steering Committee)

• 2016: Journal of Algorithms, Special Issue in Mining Humanistic Data, Guest Editor: http://www.mdpi.com/journal/algorithms/special_issues/data_processing

• 2016: INNS BIG DATA, Springer, Program Committee.

• 2016: Journal of Computation, Special Issue in natural-unconventional-and-bio-inspired-algorithms-and-computation-methods, Guest Editor.

• MEDI (LNCS) 2015, 2016: Program Committee.

• 2016: Journal of Computers and Electrical Engineering, Elsevier, Special Issue on new-trends in-humanistic informatics, Guest Editor:

• http://www.journals.elsevier.com/computers-and-electrical-engineering/call-for-papers/special-section-on-new-trends-in-humanistic-informatics

• 2017: ACM/IEEE CCGRID 2017 Program Committee.