Technical University of Crete

Voice: +30-28210-37415

Department of Electronic and Computer Engineering

Fax: +30-28210-37542

Room 141A.21 - Ktirio Epistimon

Email:

73100, Chania, Greece

 

Research Interests

 

·  Approximate Processing Techniques

·  Sensor Networks

·  Data Warehousing, OLAP

·  Data Streams

·  XML

 

Education

 

2001-May 2005

University of Maryland, Dept. of Computer Science
Ph.D. Computer Science, GPA: 4.00
Thesis: Accurate Data Approximation in Constrained Environments
Advisor: Prof. Nick Roussopoulos

1999-2001

University of Maryland, Dept. of Computer Science
M.Sc. Computer Science, GPA: 4.00
Advisor: Prof. Nick Roussopoulos

1994-1999

National Technical University of Athens
Dept. of Electrical and Computer Engineering
Diploma of Electrical and Computer Engineering,
GPA: 3.832, Rank in Class: 3rd
Thesis: SISYPHUS: A Chunk-Based Storage Manager for OLAP Data Cubes
Advisor: Prof. Timos Sellis

 

Honors and Awards

 

1999-2001

Recipient of one out of two UMIACS fellowships for first year graduate students
University of Maryland

1996-1999

Recipient of Annual National Fellowship Foundation (IKY)
Awards for academic excellence, Athens, Greece (4 times)

 

Research Experience

 

June-August, 2003

Research Intern, AT&T Labs - Research
Mentor: Dr. Yannis Kotidis

Worked on designing protocols for bandwidth-efficient data aggregation of continuous queries in sensor networks. Designed and implemented a versioning file system on top of a relational engine, optimized for lightweight cgi-bin processes. My libraries are at the core of the Virtual Integration Prototype (VIP), a search engine over AT&T's Legacy Applications (ordering, billing, provisioning, inventory). In 2003 VIP served around 25 million user queries.

September 2002

Visitor, AT&T Labs and Center for Discrete Mathematics & Theoritical Computer Science (DIMACS)

Worked on designing algorithms for the efficient approximation of multiple signals in sensor network and network management applications, by exploiting piece-wise correlations between parts of the collected signals.

2001-2005

Graduate Research Assistant
University of Maryland, Dept. of Computer Science

·  Approximate Processing Techniques

        My work on approximate processing techniques mainly involves the approximation of data sets containing multiple measures (multiple numeric entries for each table cell). Such data sets arise in many application domains, from network management and time-series analysis/correlation systems to On-Line Analytical Processing (OLAP) environments. I introduced the extended wavelet coefficients as a flexible storage technique for wavelet coefficients in such multi-measure data sets and proposed both optimal and provably approximate algorithms on selecting which extended wavelet coefficients to retain under a given storage constraint. These algorithms can be applied to minimize various error metrics, such as the weighted sum squared, relative and absolute error of the obtained approximation. While my techniques are developed for multi-measure data sets, the algorithms that I proposed for constructing probabilistic wavelet data synopses are significantly faster than previously proposed techniques even for the single-measure case.

·  Sensor Networks

        The first part of my work involved the design of protocols for bandwidth-efficient evaluation of aggregate continuous queries over sensor networks for applications that are willing to tolerate a specified maximum error on the obtained answer. I then studied the dual application, where the application specifies the desired average bandwidth consumption for the posed query, and the goal is to maximize the accuracy of the reported results. I also considered the case of periodic transmission of historical information in such networks. To exploit the correlations that are typically expected between different observed quantities, I proposed the Self-Based Regression (SBR) algorithm for efficiently compressing the transmitted measurements. The SBR algorithm constructs a base signal that contains prominent features of the data, and uses this base signal as a dictionary to encode the data using linear regression.

·  Data Warehousing, OLAP

       Calculating and storing data cubes for high-dimensional hierarchical data sets has long been a difficult task due to the dimensionality curse; the number of views in a data cube is exponential in the number of dimensions. I helped design Dwarf, a highly-compressed data structure for computing, storing and indexing data cubes. Dwarf identifies prefix and (most importantly) suffix structural redundancies and factors them out by coalescing their store. What makes Dwarf practical is the automatic discovery, in a single pass over the fact table, of the prefix and suffix redundancies without user involvement or knowledge of the value distributions, and their elimination before the redundant areas of the cube are computed.

1999-2001

University of Maryland Institute for Advanced Computer Studies (UMIACS) Fellow

1998-1999

Research and Teaching Assistant
National Technical University of Athens, Dept. of Electrical and Computer Engineering

Designed and helped implement the storage manager of the Eratosthenes OLAP system for hierarchical data sets, developed in the National Technical University of Athens. Worked as a research assistant to help develop a new tool for software testing.

 

Teaching Experience

 

1998-1999

Courses: "Introduction to Compilers" and "Introduction to Software Engineering", National Technical University of Athens
Gave lectures, designed projects and wrote 2 chapters in a book involving the use of the flex and bison tools.

2001-2004

DBChat organizer, University of Maryland
DBChat is a weekly seminar-type database group meeting. My duties included compiling the list of papers to be discussed, arranging class schedules, and putting the class material on the Web. DBChat was offered as a course in the Fall 2001 semester.

 

Publications

 

 

Talks and Conference Presentations

 

[12]

Query Processing for the Semantic Sensor Web [** Invited Talk **]
1st International Workshop on the Semantic Sensor Web (SemSensWeb 2009)

June 2009

[11]

Another Outlier Bites the Dust: Computing Meaningful Aggregates in Sensor Networks
25th International Conference on Data Engineering (IEEE ICDE)

Shanghai, China, April 2009

[10]

Efficient Query Processing in Sensor Networks
Technical University of Crete, May 2006

[9]

A Fast Approximation Scheme for Probabilistic Wavelet Synopses
4th Hellenic Data Management Symposium,

Athens, Greece, August 2005

[8]

Efficient Query Processing in Sensor Networks
4th Hellenic Data Management Symposium

Athens, Greece, August 2005

[7]

A Fast Approximation Scheme for Probabilistic Wavelet Synopses
17th International Conference on Scientific and Statistical Database Management (SSDBM)
Santa Barbara, June 2005

[6]

Sensor Networks: Applications and Ongoing Research
National Technical University of Athens, January 2005

[5]

Data Approximation in Multi-Measure Data Sets
National Technical University of Athens, July 2004

[4]

Hierarchical in-Network Data Aggregation with Quality Guarantees
9th Conference on Extending Database Technology (EDBT),
Chania, Greece, March 2004

[3]

Extended Wavelets for Multiple Measures
ACM SIGMOD International Conference on Management of Data,
San Diego, California, USA, June 2003

[2]

Data Reduction Techniques for Sensor Networks
AT&T Labs-Research, Florham Park, New Jersey, August 2003

[1]

Tutorial on Data Streams
University of Maryland, CMSC828G course, April 2002

 

Miscellaneous Talks

 

[8]

Tutorial on Sensor Networks: Applications and Ongoing Research
Database Chat (DBChat), University of Maryland, September 2004

[7]

Data Reduction Techniques for Sensor Networks
Database Chat (DBChat), University of Maryland, September 2003

[6]

Extended Wavelets for Multiple Measures
Database Chat (DBChat), University of Maryland, April 2003

[5]

Approximate Answering Techniques
Database Chat (DBChat), University of Maryland, October 2002

[4]

Tutorial on Approximation Techniques
Database Chat (DBChat), University of Maryland, February 2002

[3]

Overview of Data Streams
Database Chat (DBChat), University of Maryland, September 2001

[2]

On Materialized Views and Indexes in SQL Databases
Database Chat (DBChat), University of Maryland, February 2001

[1]

The Dynamic Data Cube
Database Chat (DBChat), University of Maryland, April 2000

 

Professional Service/Activities

 

·  Committee member at (sorted by year):

2014

VLDB

ICDE

2013

VLDB

SIGMOD

2012

VLDB

ICDE

CIKM

International Conference on Advanced Geographic Information Systems, Applications, and Services (GEOProcessing)

2011

European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD)

International Conference on Mobile Data Management (MDM)

13th International Conference on Data Warehousing and Knowledge Discovery (DaWaK)

ACM Workshop on Data Engineering for Wireless and Mobile Access (MobiDE)

International Conference on Geosensor Networks (GSN)

International Conference on Advanced Geographic Information Systems, Applications, and Services (GEOProcessing)

Hellenic Data Management Symposium (HDMS)

2010

ACM Conference on Information and Knowledge Management (CIKM)

IEEE International Conference on Computational Science and Engineering (CSE)

East-European Conference on Advances in Databases and Information Systems (ADBIS)

ACM Workshop on Data Engineering for Wireless and Mobile Access (MobiDE)

International Workshop on Sensor Networks Technologies for Information Explosion Era (SeNTIE)

Hellenic Data Management Symposium (HDMS)

2009

International Conference on Data Engineering - Demo Program (ICDE)

SIAM International Conference on Data Mining (SDM)

International Conference on Geosensor Networks (GSN)

ACM Workshop on Data Engineering for Wireless and Mobile Access (MobiDE)

ACM International Workshop on Data Warehousing and OLAP (DOLAP)

International Workshop on Sensor Networks Technologies for Information Explosion Era (SeNTIE)

International Workshop on Data and Process Provenance (WDPP)

Hellenic Data Management Symposium (HDMS)

2008

ACM Workshop on Data Engineering for Wireless and Mobile Access (MobiDE)

ACM International Workshop on Data Warehousing and OLAP (DOLAP)

International Workshop on Networking Meets Databases (NetDB)

International Workshop on Sensor Networks Technologies for Information Explosion Era (SeNTIE)

Hellenic Data Management Symposium (HDMS)

2007

International Workshop on Data Intensive Sensor Networks (DISN)

2006

ACM International Workshop on Data Warehousing and OLAP (DOLAP)

 

·  Journal referee for (sorted by year):

2011

Journal of Computer and System Sciences (JCSS)

2010

ACM Transactions on Database Systems (TODS)

IEEE Transactions on Knowledge and Data Engineering (TKDE)

Parallel and Distributed Databases

ACM Transactions on Knowledge Discovery from Data (TKDD)

2009

IEEE Transactions on Knowledge and Data Engineering (TKDE)

IEEE Transactions on Computers

Pervasive and Mobile Computing

Sensors

Knowledge & Data Engineering

2008

ACM Transactions on Database Systems (TODS)

IEEE Transactions on Knowledge and Data Engineering (TKDE)

IEEE Transactions on Parallel and Distributed Systems (TPDS)

Communication Networks and Distributed Systems

2007

ACM Transactions on Database Systems (TODS)

IEEE Transactions on Knowledge and Data Engineering (TKDE)

2006

ACM Transactions on Database Systems (TODS)

2004

IEEE Transactions on Knowledge and Data Engineering (TKDE)

 

·  Conference referee for EDBT 2011, SIGMOD (2008), CIKM, ICDE, VLDB (2007), KDD (2007) and the Hellenic Data Management Symposium (HDMS)

·  Member of the ACM special interest group SIGMOD

·  DBChat organizer, University of Maryland

Departmental Service/Activities

·  Member of the graduate course committee at the Technical University of Crete (2008-2009)

·  Substitute Member of the under-graduate course committee at the Technical University of Crete (2008-2009)

·  Consultant in undergraduate studies (2nd semester courses, Spring 2009)

 

Programming Experience

 

·  Languages: C, C++, Pascal, Lisp, Basic, Fortran, Prolog, ADA, Java, XML, HTML

·  Environments: Unix/X-Windows, Linux, Microsoft Windows

·  Databases: Oracle, MySQL, Informix, SQL Server

·  Database Connection Tools: MySQL++

 

Personal Info

 

·  Single, citizen of Greece, currently on F1 student visa

·  Languages: English, Greek