Stavros Koubias | University of Patras (original) (raw)

Stavros A. KoubiasProfessor, Former RectorHead of the Department of Electrical and Computer EngineeringUniversity of Patraskoubias@ece.upatras.grProf. S. Koubias received his Engineering Diploma in Electrical Engineering and the Ph.D degree from the Department of Electrical and Computer Engineering, University of Patras, Greece, in 1976 and 1982, respectively. Since 1990 he has served as an Assistant Professor, Associate Professor and Full Professor in the Department of Electrical and Computer Engineering of the University of Patras and he has been Deputy Head and Head in the same department for the period 2001-2003 and 2015-2019. He has been elected as the Rector of the University of Patras for the period 2006-2010. His main current research interests include mainly embedded systems, real-time distributed systems, communication and routing protocols, wired and wireless interoperable industrial networking systems, wireless sensor and actors networks, distributed enterprise systems for C2Β, Β2Β applications (ontologies, web-services, industrial GRID etc.), vertical/horizontal enterprise integration, Internet of Things, advanced building networking and management systems, industrial machine vision systems, dynamic systems for industrial / business excellence, total quality. He has participated as coordinator or partner in many important national and European R

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Papers by Stavros Koubias

This paper presents a new loop structure and its associated protocol for a mini-micro computer co... more This paper presents a new loop structure and its associated protocol for a mini-micro computer communication network. The proposed structure consists of two loops, both of which are used for control and data transmission one in the clockwise direction and the other in the counter-clockwise direction. This topology has all the advantages of ring structures such as simplicity, cost modularity, space modularity, concurrent service and high reliability. In addition, it provides better line utilization and traffic regulation than previously proposed loops because a) it has a distributed control mechanism and b) it allows two stations to communicate for long periods of time without blocking completely communication between other stations. Furthermore, it allows limited communication in case that a break occurs in the line. The loop protocol is based on the SDLC frame format. This has made possible the use of the latest LSI technology that disasembles and reassembles the character of this frame.

Aim of this research is to propose an accurate model of measuring business excellence by applying... more Aim of this research is to propose an accurate model of measuring business excellence by applying the theory of System Dynamics. This theory defines the interaction of system variables giving the opportunity of a reliable and fair score as well as objective decision-making with regard to the areas that are susceptible of continuous improvement. This paper utilises the principles of

2016 23rd International Conference on Telecommunications (ICT), 2016

The aim of this paper is to measure the impact that web services have on wireless sensor networks... more The aim of this paper is to measure the impact that web services have on wireless sensor networks (WSN) when they are used for estimating the free size of parking places in smart cities. In particular, each wireless sensor mote (WSM) of these WSNs supports a fuzzy inference system (FIS)-based algorithm which predicts the aforementioned free sizes. Moreover, the inputs of this algorithm are the measurements acquired by the adjacent WSMs regarding the variation of magnetic fields caused by the chassis of vehicles. Well known web services technologies were used as the implementation vehicle for exchanging these measurements. Moreover, the well known network simulator 2 (NS-2) was used for acquiring simulation results concerning the energy consumption of the battery of the WSMs. These results have shown that Web services significantly increase the battery consumption. Furthermore, in order to model this consumption, a data fitting problem was solved and the cubic polynomial was fitted to the simulation data. This polynomial and the one obtained by modeling the error of the FIS were utilized in order to form a real-valued cost function. This function was minimized to get the optimal values for the distance between the WSMs and the sampling period based on which the output of the algorithm should be re-computed.

2009 International Symposium on Autonomous Decentralized Systems, 2009

International Journal of Structural Integrity, 2019

2016 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2016

Connectivity is crucial feature of every network and assuring it, is fundamental for the network ... more Connectivity is crucial feature of every network and assuring it, is fundamental for the network operation and efficiency. This work presents a connectivity evaluation algorithm based on graph theory methods, which can be used for simulation and analysis of the network regarding its connectivity in pre-deployment phase. For each network topology the following metrics can be computed: the number of the network parts, the number of the single critical node and the number of the double critical nodes, i.e., any node or combination of two nodes, which failure partitions the network. In case that the network is partitioned, the number of the isolated nodes, the number of the sub-network parts and the number of nodes belonging to each part are also calculated and enumerated.

EAI Endorsed Transactions on Pervasive Health and Technology, May 18, 2015

The ability to deploy efficient and versatile WSN networks in the home environment is and will re... more The ability to deploy efficient and versatile WSN networks in the home environment is and will remain in the years to come a cornerstone objective in wireless networking. Respective services are continuously expanding requiring novel design and implementation approaches able to cover all relative present and even more importantly future requirements. This paper aims to present and convey knowledge and experience gained from such an effort in the context of home monitoring. Respective discussion covers all relative aspects and analyzes all critical challenges addressed ranging from identification and specification of the main requirements, to possible implementation approaches considered and finally the actual development undertaken. The final outcome considering the WSN home monitoring infrastructure as well as extracted knowledge and practical conclusions can be proven useful for further extending such an endeavour or even pursuing a different approach.

This paper presents a new loop structure and its associated protocol for a mini-micro computer co... more This paper presents a new loop structure and its associated protocol for a mini-micro computer communication network. The proposed structure consists of two loops, both of which are used for control and data transmission one in the clockwise direction and the other in the counter-clockwise direction. This topology has all the advantages of ring structures such as simplicity, cost modularity, space modularity, concurrent service and high reliability. In addition, it provides better line utilization and traffic regulation than previously proposed loops because a) it has a distributed control mechanism and b) it allows two stations to communicate for long periods of time without blocking completely communication between other stations. Furthermore, it allows limited communication in case that a break occurs in the line. The loop protocol is based on the SDLC frame format. This has made possible the use of the latest LSI technology that disasembles and reassembles the character of this frame.

Aim of this research is to propose an accurate model of measuring business excellence by applying... more Aim of this research is to propose an accurate model of measuring business excellence by applying the theory of System Dynamics. This theory defines the interaction of system variables giving the opportunity of a reliable and fair score as well as objective decision-making with regard to the areas that are susceptible of continuous improvement. This paper utilises the principles of

2016 23rd International Conference on Telecommunications (ICT), 2016

The aim of this paper is to measure the impact that web services have on wireless sensor networks... more The aim of this paper is to measure the impact that web services have on wireless sensor networks (WSN) when they are used for estimating the free size of parking places in smart cities. In particular, each wireless sensor mote (WSM) of these WSNs supports a fuzzy inference system (FIS)-based algorithm which predicts the aforementioned free sizes. Moreover, the inputs of this algorithm are the measurements acquired by the adjacent WSMs regarding the variation of magnetic fields caused by the chassis of vehicles. Well known web services technologies were used as the implementation vehicle for exchanging these measurements. Moreover, the well known network simulator 2 (NS-2) was used for acquiring simulation results concerning the energy consumption of the battery of the WSMs. These results have shown that Web services significantly increase the battery consumption. Furthermore, in order to model this consumption, a data fitting problem was solved and the cubic polynomial was fitted to the simulation data. This polynomial and the one obtained by modeling the error of the FIS were utilized in order to form a real-valued cost function. This function was minimized to get the optimal values for the distance between the WSMs and the sampling period based on which the output of the algorithm should be re-computed.

2009 International Symposium on Autonomous Decentralized Systems, 2009

International Journal of Structural Integrity, 2019

2016 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2016

Connectivity is crucial feature of every network and assuring it, is fundamental for the network ... more Connectivity is crucial feature of every network and assuring it, is fundamental for the network operation and efficiency. This work presents a connectivity evaluation algorithm based on graph theory methods, which can be used for simulation and analysis of the network regarding its connectivity in pre-deployment phase. For each network topology the following metrics can be computed: the number of the network parts, the number of the single critical node and the number of the double critical nodes, i.e., any node or combination of two nodes, which failure partitions the network. In case that the network is partitioned, the number of the isolated nodes, the number of the sub-network parts and the number of nodes belonging to each part are also calculated and enumerated.

EAI Endorsed Transactions on Pervasive Health and Technology, May 18, 2015

The ability to deploy efficient and versatile WSN networks in the home environment is and will re... more The ability to deploy efficient and versatile WSN networks in the home environment is and will remain in the years to come a cornerstone objective in wireless networking. Respective services are continuously expanding requiring novel design and implementation approaches able to cover all relative present and even more importantly future requirements. This paper aims to present and convey knowledge and experience gained from such an effort in the context of home monitoring. Respective discussion covers all relative aspects and analyzes all critical challenges addressed ranging from identification and specification of the main requirements, to possible implementation approaches considered and finally the actual development undertaken. The final outcome considering the WSN home monitoring infrastructure as well as extracted knowledge and practical conclusions can be proven useful for further extending such an endeavour or even pursuing a different approach.

Abstract— This paper proposes “KATHODIGOS”, a novel smart parking system relying on wireless sens... more Abstract— This paper proposes “KATHODIGOS”, a novel smart
parking system relying on wireless sensor networks. More
specifically, its general architecture and desired properties are
presented while its differences from other related research
studies and projects are delineated. Based on the aforementioned
architecture, the interfaces and technical requirements between
the subsystems of “KATHODIGOS” are fully defined. Finally, a
promising property of these subsystems which is based on fuzzy
inference systems is studied and its preliminary results are
shown.
Keywords- Fuzzy inference system; Smart parking system;
Wireless sensor networks

The Wireless Sensor Networks (WSNs) have limited power and communication capabilities, combined w... more The Wireless Sensor Networks (WSNs) have limited power and communication capabilities, combined with the requirement for long network lifetime. To increase it, methods to reduce energy consumption are highly required. To achieve this goal, we study a data aggregation technique without size reduction, i.e. data merge. It is a generic technique, since it is also usable in applications with heterogeneous data and requirements for high accuracy. This study presents the impact of the data merge technique on WSNs applications executed under various realistic data flow scenarios, traffic loads and wait time intervals. Our results show significant reductions in both packet loss and radio energy consumption.