Christos Bouras
Short CV: Christos Bouras is Professor in the University of Patras, Department of Computer Engineering and Informatics. Also he is a scientific advisor of Research Unit 6 in Computer Technology Institute and Press – Diophantus, Patras, Greece. His research interests include Analysis of Performance of Networking and Computer Systems, Computer Networks and Protocols, Mobile and Wireless Communications, Telematics and New Services, QoS and Pricing for Networks and Services, e-learning, Networked Virtual Environments and WWW Issues. He has extended professional experience in Design and Analysis of Networks, Protocols, Telematics and New Services. He has published more than 450 papers in various well-known refereed books, conferences and journals. He is a co-author of 9 books in Greek and editor of 2 in English. He has been member of editorial board for international journals and PC member and referee in various international journals and conferences. He has participated in R&D projects.
Book Chapters
Tsachrelias, Konstantinos; Katsigiannis, Chrysostomos-Athanasios; Kokkinos, Vasileios; Gkamas, Apostolos; Bouras, Christos; Pouyioutas, Philippos
Dynamic Resource Allocation in Future Cellular Networks: DUDe, MIMO, and Beyond Book Chapter
In: IntechOpen Cellurar Communication System - The Evolution from 1G to 6G, pp. 1-19 (Ed.): 2026, (to appear).
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title = {Dynamic Resource Allocation in Future Cellular Networks: DUDe, MIMO, and Beyond},
author = {Konstantinos Tsachrelias and Chrysostomos-Athanasios Katsigiannis and Vasileios Kokkinos and Apostolos Gkamas and Christos Bouras and Philippos Pouyioutas },
editor = {Cellurar Communication System - The Evolution from 1G to 6G, IntechOpen, pp. 1-19},
url = {https://telematics.upatras.gr/intechopen-revision-final/},
year = {2026},
date = {2026-01-19},
note = {to appear},
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Bouras, Christos; Kokkinos, Vasileios; Gkamas, Apostolos; Michos, Evangelos; Sina, Ioannis; Prokopiou, Ioannis; Allayiotis, Foivos
An Introduction of Upcoming Radio Resource Management Techniques for 5G Networks Book Chapter
In: Advances in Engineering Research, Nova Science Publishers, vol. 46, Chapter 3, pp. 147-188, 2022.
Abstract | Links | BibTeX | Tags: DUDe
@inbook{4569,
title = {An Introduction of Upcoming Radio Resource Management Techniques for 5G Networks},
author = {Christos Bouras and Vasileios Kokkinos and Apostolos Gkamas and Evangelos Michos and Ioannis Sina and Ioannis Prokopiou and Foivos Allayiotis},
url = {https://telematics.upatras.gr/978-1-68507-427-2-161-201/},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
booktitle = {Advances in Engineering Research, Nova Science Publishers},
volume = {46},
pages = {147-188},
chapter = {3},
abstract = {5G networks are the next generation of mobile internet connectivity, that are able to offer vastly increased speeds, more reliable connections, minimal latency and more supported devices. 5G networks are expected to supercharge Internet of Things (IoT) technology, so as to provide the infrastructure needed in order to support and transfer large data amounts that will enable a smarter and more connected world. To this direction, 5G incorporates many technologies and mechanisms that aid towards the overall goal, such as Multiple-Input and Multiple-Output (MIMO), Downlink (DL) and Uplink (UL) Decoupling (DUDe) and Machine Learning (ML). These technologies can significantly help towards more efficient resource allocation inside the next generation networks, offering increased spectral efficiency and data rates, better signal coverage, reduced latencies and many more. In this chapter, we will provide insights over the aforementioned technologies through firstly a literature review and later on by analyzing their architecture and their models. We will explain how these technologies can be taken advantage of in order to support the 5G networks and why they are core components of future networks, as it is expected that also 5G and Beyond networks will capitalize on them.},
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5G networks are the next generation of mobile internet connectivity, that are able to offer vastly increased speeds, more reliable connections, minimal latency and more supported devices. 5G networks are expected to supercharge Internet of Things (IoT) technology, so as to provide the infrastructure needed in order to support and transfer large data amounts that will enable a smarter and more connected world. To this direction, 5G incorporates many technologies and mechanisms that aid towards the overall goal, such as Multiple-Input and Multiple-Output (MIMO), Downlink (DL) and Uplink (UL) Decoupling (DUDe) and Machine Learning (ML). These technologies can significantly help towards more efficient resource allocation inside the next generation networks, offering increased spectral efficiency and data rates, better signal coverage, reduced latencies and many more. In this chapter, we will provide insights over the aforementioned technologies through firstly a literature review and later on by analyzing their architecture and their models. We will explain how these technologies can be taken advantage of in order to support the 5G networks and why they are core components of future networks, as it is expected that also 5G and Beyond networks will capitalize on them.
Bouras, Christos; Barri, Eirini; Gkamas, Apostolos; Karacapilidis, Nikos; Karadimas, Dimitris; Kournetas, Georgios; Panaretou, Yiannis
In: Springer Book of SIMULTECH 2020, 2021.
Abstract | Links | BibTeX | Tags:
@inbook{4498,
title = {A Novel Approach to Energy Management in Large Passenger and Cruise Ships: Integrating Simulation and Machine Learning Models},
author = {Christos Bouras and Eirini Barri and Apostolos Gkamas and Nikos Karacapilidis and Dimitris Karadimas and Georgios Kournetas and Yiannis Panaretou},
url = {https://telematics.upatras.gr/simultech2020_id32_cameraready_aiscs_submitted-updated-final/},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
booktitle = {Springer Book of SIMULTECH 2020},
abstract = {It has been broadly admitted that the prediction of energy consumption in large passenger and cruise ships is a complex and challenging issue. Aiming to address it, this chapter reports on the development of a novel approach that builds on a sophisticated agent-based simulation model, which takes into account diverse parameters such as the size, type and behavior of the different categories of passengers onboard, the energy consuming facilities and devices of a ship, spatial data concerning the layout of a ship’s decks, and alternative ship operation modes. According to the proposed approach, outputs obtained from multiple simulation runs are then exploited by prominent Machine Learning algorithms to extract meaningful patterns between the composition of passengers and the corresponding energy demands in a ship. In this way, our approach is able to predict alternative energy consumption scenarios and trigger meaningful insights concerning the overall energy management in a ship. Overall, the proposed approach may handle the underlying uncertainty by blending the process centric character of a simulation model and the data-centric character of Machine Learning algorithms. The chapter also describes the overall architecture of the proposed solution, which is based on the microservices approach.},
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It has been broadly admitted that the prediction of energy consumption in large passenger and cruise ships is a complex and challenging issue. Aiming to address it, this chapter reports on the development of a novel approach that builds on a sophisticated agent-based simulation model, which takes into account diverse parameters such as the size, type and behavior of the different categories of passengers onboard, the energy consuming facilities and devices of a ship, spatial data concerning the layout of a ship’s decks, and alternative ship operation modes. According to the proposed approach, outputs obtained from multiple simulation runs are then exploited by prominent Machine Learning algorithms to extract meaningful patterns between the composition of passengers and the corresponding energy demands in a ship. In this way, our approach is able to predict alternative energy consumption scenarios and trigger meaningful insights concerning the overall energy management in a ship. Overall, the proposed approach may handle the underlying uncertainty by blending the process centric character of a simulation model and the data-centric character of Machine Learning algorithms. The chapter also describes the overall architecture of the proposed solution, which is based on the microservices approach.
Bouras, Christos; Barri, Eirini; Gkamas, Apostolos; Karacapilidis, Nikos; Karadimas, Dimitris; Kournetas, Giorgos; Panaretou, Yiannis
An agent-based simulation model for energy saving in large passenger and cruise ships Book Chapter
In: CRC Press, 2021.
Abstract | Links | BibTeX | Tags:
@inbook{4497,
title = {An agent-based simulation model for energy saving in large passenger and cruise ships},
author = {Christos Bouras and Eirini Barri and Apostolos Gkamas and Nikos Karacapilidis and Dimitris Karadimas and Giorgos Kournetas and Yiannis Panaretou},
url = {https://telematics.upatras.gr/wp-content/uploads/2024/01/Chapter5.pdf},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
booktitle = {CRC Press},
abstract = {Undoubtedly, energy saving is of paramount importance in the shipping industry, as far as both the protection of environment and the reduction of the associated operating costs are concerned. In this direction, the
International Maritime Organization aims to reduce ship emissions by at least 50% by 2050, while ships to be built by 2025 are expected to be a massive 30% more energy efficient than those built some years ago [IMO,
2018].},
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Undoubtedly, energy saving is of paramount importance in the shipping industry, as far as both the protection of environment and the reduction of the associated operating costs are concerned. In this direction, the
International Maritime Organization aims to reduce ship emissions by at least 50% by 2050, while ships to be built by 2025 are expected to be a massive 30% more energy efficient than those built some years ago [IMO,
2018].
International Maritime Organization aims to reduce ship emissions by at least 50% by 2050, while ships to be built by 2025 are expected to be a massive 30% more energy efficient than those built some years ago [IMO,
2018].
Conferences
Bouras, Christos; Spirakis, Paul; Lampsas, P
In-Service Training through ODL Environments:From User Needs To Functional Specifications Conference
8th International Conference Society for Information Technology and Teacher Education-SITE 97, Orlando, USA, pp. 519-522, 1997.
@conference{2838,
title = {In-Service Training through ODL Environments:From User Needs To Functional Specifications},
author = {Christos Bouras and Paul Spirakis and P Lampsas},
url = {https://telematics.upatras.gr/5744275/},
year = {1997},
date = {1997-04-01},
urldate = {1997-04-01},
booktitle = {8th International Conference Society for Information Technology and Teacher Education-SITE 97, Orlando, USA, pp. 519-522},
pages = {519 - 522},
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Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Moiras, D; Ouzounis, V; Antoniou, I; Karageorgopoylos, D
Hermes Service: Distributed Hypermedia Educational Services on Demand Conference
ED-MEDIA/ED-TELECOM 97, Calgary, Canada, pp. 19-24, 1997.
Abstract | Links | BibTeX | Tags:
@conference{2840,
title = {Hermes Service: Distributed Hypermedia Educational Services on Demand},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and D Moiras and V Ouzounis and I Antoniou and D Karageorgopoylos},
url = {https://telematics.upatras.gr/6594271/},
year = {1997},
date = {1997-01-01},
urldate = {1997-01-01},
booktitle = {ED-MEDIA/ED-TELECOM 97, Calgary, Canada, pp. 19-24},
pages = {19 - 24},
abstract = {In this paper we present a distributed HypERMEdia SERVICE (HERMES SERVICE) which supports integrated capabilities for distance education and learning purposes. Hermes service consists of hermes servers and hermes browsers. The users are connected with the service using hermes browsers and retrieve hypermedia lessons organised in thematical units. The lessons are stored in various distributed Hermes servers which retrieve the requested lesson and transmit it to the corresponding browser on on-demand basis. The requested lesson is presented to the user according to a well defined presentation scenario. The media objects are rendered in a synchronized manner according to the spatio-temporal relationships existing among them. Finally, special monitoring mechanism controls the state of the network and adjusts the presentation process so as to improve presentation quality.},
keywords = {},
pubstate = {published},
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In this paper we present a distributed HypERMEdia SERVICE (HERMES SERVICE) which supports integrated capabilities for distance education and learning purposes. Hermes service consists of hermes servers and hermes browsers. The users are connected with the service using hermes browsers and retrieve hypermedia lessons organised in thematical units. The lessons are stored in various distributed Hermes servers which retrieve the requested lesson and transmit it to the corresponding browser on on-demand basis. The requested lesson is presented to the user according to a well defined presentation scenario. The media objects are rendered in a synchronized manner according to the spatio-temporal relationships existing among them. Finally, special monitoring mechanism controls the state of the network and adjusts the presentation process so as to improve presentation quality.
Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Moiras, D; Ouzounis, V; Tatakis, A
On-Demand Hypermedia/Multimedia Service over Broadband Networks Conference
5th IEEE International Symposium On High Performance Distributed Computing-HPDC-5, Syracuse, New York, USA, pp. 224-231, 1996.
Abstract | Links | BibTeX | Tags:
@conference{2848,
title = {On-Demand Hypermedia/Multimedia Service over Broadband Networks},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and D Moiras and V Ouzounis and A Tatakis},
url = {https://telematics.upatras.gr/8142358/},
year = {1996},
date = {1996-08-01},
urldate = {1996-08-01},
booktitle = {5th IEEE International Symposium On High Performance Distributed Computing-HPDC-5, Syracuse, New York, USA, pp. 224-231},
pages = {224 - 231},
abstract = {In this paper we present a uni ed approach for delivering hypermedia/multimedia objects over broadband networks. Documents are stored in various multimedia servers, while the inline data may reside in their own media servers, attached to the multimedia servers. The described service consists of several multimedia servers and a set of functions that intend to present to the end user interactive information in real-time. Users interact with the service requesting multimedia documents on demand. Various media streams are transmitted over di erent parallel connections according to their transmission requirements. The hypermedia documents are structured using a hypermedia markup language that keeps information of the spatiotemporal relationships among document’s media components. In order to deal with the variant network behavior, buffering manipulation mechanisms and grading of the transmitted media quality techniques are proposed to smooth presentation and synchronization anomalies.},
keywords = {},
pubstate = {published},
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In this paper we present a uni ed approach for delivering hypermedia/multimedia objects over broadband networks. Documents are stored in various multimedia servers, while the inline data may reside in their own media servers, attached to the multimedia servers. The described service consists of several multimedia servers and a set of functions that intend to present to the end user interactive information in real-time. Users interact with the service requesting multimedia documents on demand. Various media streams are transmitted over di erent parallel connections according to their transmission requirements. The hypermedia documents are structured using a hypermedia markup language that keeps information of the spatiotemporal relationships among document’s media components. In order to deal with the variant network behavior, buffering manipulation mechanisms and grading of the transmitted media quality techniques are proposed to smooth presentation and synchronization anomalies.
Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Tsakarissianos, G; Kastis, N
TRENDS: Training Educators through Networks and Distributed Systems Conference
EDEN Conference 1996, Futuroscope Poitiers, France, pp. 195-199, 1996.
Abstract | Links | BibTeX | Tags:
@conference{2851,
title = {TRENDS: Training Educators through Networks and Distributed Systems},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and G Tsakarissianos and N Kastis},
url = {https://telematics.upatras.gr/7831439/},
year = {1996},
date = {1996-07-01},
urldate = {1996-07-01},
booktitle = {EDEN Conference 1996, Futuroscope Poitiers, France, pp. 195-199},
pages = {195 - 199},
abstract = {The TRENDS project aims at the in-service, distance training of 2,400 school teachers in Secondary Education, and the use of Information Technology and Telematics in the learning process, by six countries (Greece, Italy, Spain, Portugal, France, and United Kingdom). The training process will be implemented by flexible and distance learning methods, through the development and use of an in-service school-based training system, which will be based on multimedia telematics and existing mature network technologies, and the establishment and operation of a European Teacher’s Training Network, consisted of six interconnected National Sites (Training Centre, schools and teachers per country). Each Training Centre in the Network will act as service provider to the schools and the teachers. The major aspect of the project is to provide the educator and their trainers, with various services including : e-mail contact with other educators and trainers, access to multimedia information, forums for the discussion and debate on educational projects, access to curriculum-related information for the educators, and multimedia teletraining for the conduction of lessons over the network. Due
to the nature of the planned services and applications, the network infrastructure that will be used for the realization of the TRENDS, must offer high speed, multicasting, trans-European interoperability and certified quality of services.},
keywords = {},
pubstate = {published},
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The TRENDS project aims at the in-service, distance training of 2,400 school teachers in Secondary Education, and the use of Information Technology and Telematics in the learning process, by six countries (Greece, Italy, Spain, Portugal, France, and United Kingdom). The training process will be implemented by flexible and distance learning methods, through the development and use of an in-service school-based training system, which will be based on multimedia telematics and existing mature network technologies, and the establishment and operation of a European Teacher’s Training Network, consisted of six interconnected National Sites (Training Centre, schools and teachers per country). Each Training Centre in the Network will act as service provider to the schools and the teachers. The major aspect of the project is to provide the educator and their trainers, with various services including : e-mail contact with other educators and trainers, access to multimedia information, forums for the discussion and debate on educational projects, access to curriculum-related information for the educators, and multimedia teletraining for the conduction of lessons over the network. Due
to the nature of the planned services and applications, the network infrastructure that will be used for the realization of the TRENDS, must offer high speed, multicasting, trans-European interoperability and certified quality of services.
to the nature of the planned services and applications, the network infrastructure that will be used for the realization of the TRENDS, must offer high speed, multicasting, trans-European interoperability and certified quality of services.
Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Lampsas, P; Tatakis, A; Kontogiannis, S; Fotakis, D; Kyriakou, K
An Interactive Cooperative Teleworking Environment-Tηλεµάθεια * Conference
ED-TELECOM 96, Boston, USA, pp. 37-42, 1996.
Abstract | Links | BibTeX | Tags:
@conference{2852,
title = {An Interactive Cooperative Teleworking Environment-Tηλεµάθεια *},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and P Lampsas and A Tatakis and S Kontogiannis and D Fotakis and K Kyriakou},
url = {https://telematics.upatras.gr/1055303/},
year = {1996},
date = {1996-06-01},
urldate = {1996-06-01},
booktitle = {ED-TELECOM 96, Boston, USA, pp. 37-42},
pages = {37 - 42},
abstract = {In this paper we present the design and the implementation of an interactive environment for cooperative teleworking. Telemathea offers tools that support the communication and the teleworking between tutor and trainee, who may reside in remote geographical regions. This environment offers audio communication over the network as well as support for joint editing of text documents and still images. It supports different audio coding techniques so as to adjust to the available bandwidth, and makes use of the RTP protocol in order to facilitate the exchange of audio and, in the future, video packets.},
keywords = {},
pubstate = {published},
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In this paper we present the design and the implementation of an interactive environment for cooperative teleworking. Telemathea offers tools that support the communication and the teleworking between tutor and trainee, who may reside in remote geographical regions. This environment offers audio communication over the network as well as support for joint editing of text documents and still images. It supports different audio coding techniques so as to adjust to the available bandwidth, and makes use of the RTP protocol in order to facilitate the exchange of audio and, in the future, video packets.
Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Tatakis, A; Fotakis, D; Balaouras, P; Chadelis, L; Palikarakis, N; Sandalatzopoulos, R
FINE:Implementation of a Distributed Telematics Environment for Clinical Engineers Conference
1996 Concurrent Engineering Europe, Cambridge, UK, pp. 56-60, 1996.
@conference{2850,
title = {FINE:Implementation of a Distributed Telematics Environment for Clinical Engineers},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and A Tatakis and D Fotakis and P Balaouras and L Chadelis and N Palikarakis and R Sandalatzopoulos},
url = {https://telematics.upatras.gr/8533438/},
year = {1996},
date = {1996-04-01},
urldate = {1996-04-01},
booktitle = {1996 Concurrent Engineering Europe, Cambridge, UK, pp. 56-60},
pages = {56 - 60},
keywords = {},
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Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Pantziou, G
Randomized adaptive video on demand Conference
15th ACM-PODC, Philadelphia PA, USA, pp. 179, 1996.
@conference{2849,
title = {Randomized adaptive video on demand},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and G Pantziou},
url = {https://telematics.upatras.gr/1232344/},
year = {1996},
date = {1996-01-01},
urldate = {1996-01-01},
booktitle = {15th ACM-PODC, Philadelphia PA, USA, pp. 179},
pages = {179},
keywords = {},
pubstate = {published},
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Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Lampsas, P; Tatakis, A; Kontogiannis, S; Fotakis, D
Multilingual Implementations of OSI Applications Conference
10th International Symposium on Computers and Information Sciences-ISCIS X, Izmir, Turkey, pp. 367-374, 1995.
Abstract | Links | BibTeX | Tags:
@conference{2854,
title = {Multilingual Implementations of OSI Applications},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and P Lampsas and A Tatakis and S Kontogiannis and D Fotakis},
url = {https://telematics.upatras.gr/4960440/},
year = {1995},
date = {1995-10-01},
urldate = {1995-10-01},
booktitle = {10th International Symposium on Computers and Information Sciences-ISCIS X, Izmir, Turkey, pp. 367-374},
pages = {367 - 374},
abstract = {In this work the problem of supporting multilingual environments over OSI applications is addressed. Initially a solution based on the idea of using multilingual structures and transcription techniques is presented. Another solution based on the major principles of the former follows, which exploits the coding of all of character sets uniformally.},
keywords = {},
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In this work the problem of supporting multilingual environments over OSI applications is addressed. Initially a solution based on the idea of using multilingual structures and transcription techniques is presented. Another solution based on the major principles of the former follows, which exploits the coding of all of character sets uniformally.
Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Lampsas, P; Tatakis, A; Fotakis, D; Papoutsopoulos, G
HIPPOCRATES: A multimedia tool for distance education Conference
ED-MEDIA 95, Gratz, Austria, pp. 103-108, 1995.
Abstract | Links | BibTeX | Tags:
@conference{2853,
title = {HIPPOCRATES: A multimedia tool for distance education},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and P Lampsas and A Tatakis and D Fotakis and G Papoutsopoulos},
url = {https://telematics.upatras.gr/2777305/},
year = {1995},
date = {1995-06-01},
urldate = {1995-06-01},
booktitle = {ED-MEDIA 95, Gratz, Austria, pp. 103-108},
pages = {103 - 108},
abstract = {In this paper we present a software tool for the realisation of the distance education service, that is the conduction of classes through the use of computers. The classes
are directed towards personnel in various areas and aim at the retraining and update of the personnel in subjects of special interest in their line of work. The conduction of
classes takes place, from and towards, remote regions with the aid of a computer network. Hippocrates is a flexible and easy-to-use application, which permits students, who sit in front of remotely situated workstations, to attend classes or seminars given by a teacher or expert, who can also be located in some remote geographical area. Hippocrates can be thought of as a distributed transparency projector. The teacher can project transparencies on the screens of the students’ workstations and can emphasize or indicate regions of interest on them by using the graphical tools offered by Hippocrates. Immediate results of the use of Hippocrates are the fast updating of the personnel in remote areas and the upgrading of the quality of the services they offer.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In this paper we present a software tool for the realisation of the distance education service, that is the conduction of classes through the use of computers. The classes
are directed towards personnel in various areas and aim at the retraining and update of the personnel in subjects of special interest in their line of work. The conduction of
classes takes place, from and towards, remote regions with the aid of a computer network. Hippocrates is a flexible and easy-to-use application, which permits students, who sit in front of remotely situated workstations, to attend classes or seminars given by a teacher or expert, who can also be located in some remote geographical area. Hippocrates can be thought of as a distributed transparency projector. The teacher can project transparencies on the screens of the students’ workstations and can emphasize or indicate regions of interest on them by using the graphical tools offered by Hippocrates. Immediate results of the use of Hippocrates are the fast updating of the personnel in remote areas and the upgrading of the quality of the services they offer.
are directed towards personnel in various areas and aim at the retraining and update of the personnel in subjects of special interest in their line of work. The conduction of
classes takes place, from and towards, remote regions with the aid of a computer network. Hippocrates is a flexible and easy-to-use application, which permits students, who sit in front of remotely situated workstations, to attend classes or seminars given by a teacher or expert, who can also be located in some remote geographical area. Hippocrates can be thought of as a distributed transparency projector. The teacher can project transparencies on the screens of the students’ workstations and can emphasize or indicate regions of interest on them by using the graphical tools offered by Hippocrates. Immediate results of the use of Hippocrates are the fast updating of the personnel in remote areas and the upgrading of the quality of the services they offer.
Bouras, Christos; Spirakis, Paul
ICCI’93, Sudbury, Ontario, Canada, pp. 403-407, 1993.
Abstract | Links | BibTeX | Tags:
@conference{2857,
title = {The perfect and imperfect clocks approach to performance analysis of basic timestamp ordering in distributed databases},
author = {Christos Bouras and Paul Spirakis},
url = {https://telematics.upatras.gr/3253311/},
year = {1993},
date = {1993-05-01},
urldate = {1993-05-01},
booktitle = {ICCI’93, Sudbury, Ontario, Canada, pp. 403-407},
pages = {403 - 407},
abstract = {Locking and timestamping are two popular approaches to concurrency control in databases systems. Although more than a dozen analytic performance studies of locking techniques have recently appeared in the literature, analytic performance study of timestamp–based concurrency algorithms largely remains an unexplored area. This work presents a model of a distributed database system which provides the framework to study the performance of timestamp ordering concurrency control. We exhibit an analytical solution, which has been tested with extensive simulation. The accuracy seems to be very high. We assume perfect and also imperfect clocks for synchronization and quantify the way in which local clock inaccuracies affect the phenomenon of transaction conflicts. In particular, we derive a lot of interesting performance measures such as probability of abort, throughput and others.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Locking and timestamping are two popular approaches to concurrency control in databases systems. Although more than a dozen analytic performance studies of locking techniques have recently appeared in the literature, analytic performance study of timestamp–based concurrency algorithms largely remains an unexplored area. This work presents a model of a distributed database system which provides the framework to study the performance of timestamp ordering concurrency control. We exhibit an analytical solution, which has been tested with extensive simulation. The accuracy seems to be very high. We assume perfect and also imperfect clocks for synchronization and quantify the way in which local clock inaccuracies affect the phenomenon of transaction conflicts. In particular, we derive a lot of interesting performance measures such as probability of abort, throughput and others.
Bouras, Christos; Spirakis, Paul
Performance Models for Perfect and Imperfect Clocks on Timestamp Ordering in Distributed Databases Conference
MASCOTS’93, San Diego, California, USA, pp. 243-246, 1993.
Abstract | Links | BibTeX | Tags:
@conference{2856,
title = {Performance Models for Perfect and Imperfect Clocks on Timestamp Ordering in Distributed Databases},
author = {Christos Bouras and Paul Spirakis},
url = {https://telematics.upatras.gr/6258309/},
year = {1993},
date = {1993-01-01},
urldate = {1993-01-01},
booktitle = {MASCOTS’93, San Diego, California, USA, pp. 243-246},
pages = {243 - 246},
abstract = {This work presents a model of a distributed database system which provides the framework to study the performance of timestamp ordering concurrency control. We exhibit an analytical solution, which has been tested with extensive simulation. The accuracy seems to be very high. We assume perfect and also imperfect clocks for synchronization and quantify the way in which local clock inaccuracies affect the phenomenon of transaction conflicts.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
This work presents a model of a distributed database system which provides the framework to study the performance of timestamp ordering concurrency control. We exhibit an analytical solution, which has been tested with extensive simulation. The accuracy seems to be very high. We assume perfect and also imperfect clocks for synchronization and quantify the way in which local clock inaccuracies affect the phenomenon of transaction conflicts.
Bouras, Christos; Kapoulas, Vaggelis; Spirakis, Paul; Georgantas, T; Goutis, K
MIPL:An Image Processing Library for Medical Applications Conference
S/CAR’92, Baltimore, Maryland, USA, pp. 519-525, 1992.
@conference{2858,
title = {MIPL:An Image Processing Library for Medical Applications},
author = {Christos Bouras and Vaggelis Kapoulas and Paul Spirakis and T Georgantas and K Goutis},
url = {https://telematics.upatras.gr/3973306/},
year = {1992},
date = {1992-06-01},
urldate = {1992-06-01},
booktitle = {S/CAR’92, Baltimore, Maryland, USA, pp. 519-525},
pages = {519 - 525},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Bouras, Christos; Spirakis, Paul
The effect of clock drifts on the performance of distributed timestamp ordering Conference
3rd COMAD 91, Bombay, India, pp. 69-85, 1991.
Abstract | Links | BibTeX | Tags:
@conference{2860,
title = {The effect of clock drifts on the performance of distributed timestamp ordering},
author = {Christos Bouras and Paul Spirakis},
url = {https://telematics.upatras.gr/7832887/},
year = {1991},
date = {1991-12-01},
urldate = {1991-12-01},
booktitle = {3rd COMAD 91, Bombay, India, pp. 69-85},
pages = {69 - 85},
abstract = {Timestamp–based algorithms have been proposed to protect distributed database from inconsistencies during concurrent access. In such algorithms, transactions may reach a paricular site out of the order of their timestamps, due to unexpected network delays. This causes conflicts which the distributed concurrency control mechanism has to cope with. In this paper we analyze the essential features of the conflict phenomenon under the realistic assumption of the local site clocks out of total synchrony. We quantify the way in which local clock inaccuracies affect the phenomenon of transaction conflicts. In particular, we express the probability of order–reverse as a particular increasing function of the maximum clock drift.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Timestamp–based algorithms have been proposed to protect distributed database from inconsistencies during concurrent access. In such algorithms, transactions may reach a paricular site out of the order of their timestamps, due to unexpected network delays. This causes conflicts which the distributed concurrency control mechanism has to cope with. In this paper we analyze the essential features of the conflict phenomenon under the realistic assumption of the local site clocks out of total synchrony. We quantify the way in which local clock inaccuracies affect the phenomenon of transaction conflicts. In particular, we express the probability of order–reverse as a particular increasing function of the maximum clock drift.
Bouras, Christos; Spirakis, Paul; Garofalakis, J; Papoutsopoulos, G; Basiroglou, P
RECPHONE: A new environment for medical remote expert consultation Conference
EuroPACS’91, 9th International Meeting, Berlin, Germany, pp. 22-23, 1991.
@conference{2859,
title = {RECPHONE: A new environment for medical remote expert consultation},
author = {Christos Bouras and Paul Spirakis and J Garofalakis and G Papoutsopoulos and P Basiroglou},
url = {https://telematics.upatras.gr/7799recphone_bouras/},
year = {1991},
date = {1991-07-01},
urldate = {1991-07-01},
booktitle = {EuroPACS’91, 9th International Meeting, Berlin, Germany, pp. 22-23},
pages = {22 - 23},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Bouras, Christos; Spirakis, Paul
5th International Symposium on Computers and Information Sciences- ISCIS V, Volume II, Cappadocia, Nevsehir, Turkey, pp. 719-727, 1990.
@conference{2861,
title = {Simplified performance models of the reordering issue in timestamp ordering concurrency control in distributed databases},
author = {Christos Bouras and Paul Spirakis},
url = {https://telematics.upatras.gr/8684simplified_bouras/},
year = {1990},
date = {1990-10-01},
urldate = {1990-10-01},
booktitle = {5th International Symposium on Computers and Information Sciences- ISCIS V, Volume II, Cappadocia, Nevsehir, Turkey, pp. 719-727},
pages = {719 - 727},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Bouras, Christos; Spirakis, Paul; Triantafillou, Vasilis; Garofalakis, J
Queueing Delays in Buffered Multistage Interconnection Networks Conference
ACM SIGMETRICS Conference 1987, Banff, Alberta, Canada, pp. 111-121, 1987.
Abstract | Links | BibTeX | Tags:
@conference{2862,
title = {Queueing Delays in Buffered Multistage Interconnection Networks},
author = {Christos Bouras and Paul Spirakis and Vasilis Triantafillou and J Garofalakis},
url = {https://telematics.upatras.gr/5267queueing_delays_bouras/},
year = {1987},
date = {1987-05-01},
urldate = {1987-05-01},
booktitle = {ACM SIGMETRICS Conference 1987, Banff, Alberta, Canada, pp. 111-121},
pages = {111 - 121},
abstract = {Our Work with the analysis of the queueing delays of buffered multistage banyan networks of multiprocessors. We provide tight upper bounds on the mean delays of the second stage and beyond, in the case of infinite buffers. Our results are validated by simulations performed on a network simulator constructed by us. The analytic work for network stages beyond the first, provides a partial answer to open problems posed by previous research. },
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Our Work with the analysis of the queueing delays of buffered multistage banyan networks of multiprocessors. We provide tight upper bounds on the mean delays of the second stage and beyond, in the case of infinite buffers. Our results are validated by simulations performed on a network simulator constructed by us. The analytic work for network stages beyond the first, provides a partial answer to open problems posed by previous research.