Thessaloniki, Greece

International Hellenic University
Thessaloniki, Greece

The International Hellenic University was established in October 2005, in accordance to Law No. 3391. The University consists of three Schools: The School of Economics and Business Administration, the School of Humanities and the School of Science and Technology. All degrees in IHU are taught exclusively in English. The IHU is financed by the European Union and the Greek state, and aims at providing higher education particularly to foreigners who are interested in studying in Greece. Wikipedia.

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Kanellakis M.,International Hellenic University | Martinopoulos G.,International Hellenic University | Zachariadis T.,Cyprus University of Technology
Energy Policy | Year: 2013

This article presents the implemented policies of the European Union in the broader field of energy and provides a picture of the Union's strategy on energy related issues. A brief historical background is provided, covering the period from the beginning of the Union's creation in 1951, when coal was considered as the heart of its economic growth, up to 2012. Policy development principles, as well as the consultations that take place before the proposal of each option are also discussed. Implemented policies are classified into seven broad categories: Renewable Energy, Energy Efficiency and Savings, Internal Energy Markets, Security of Energy Supply, Environmental Protection, Nuclear Energy and Research and Development. For each category, an introduction covering important milestones towards its development is followed by the presentation of the relevant policies and a description of their purpose. © 2013 Elsevier Ltd.

Koutitas G.,International Hellenic University | Karousos A.,Aircom International | Tassiulas L.,University of Thessaly
IEEE Transactions on Wireless Communications | Year: 2012

The energy efficiency of cellular networks is explored for different network deployment strategies and traffic conditions. The total network power consumption and the ratios Watts/kbps, Watts/user are used as metrics to quantify the performance and it is shown that efficiency depends on the deployment strategy and the state of operation of the network (underutilized-overutilized). As a general conclusion it is shown that a microcell based network, comprising a large number of low power stations, is the most efficient strategy but it does not present traffic proportional characteristics. For the purpose of the investigation, the paper presents a pre-processing of the database 3D ray tracing algorithm that is enhanced with an image test procedure and multiple slope diffraction mechanisms to achieve fast and accurate predictions. The algorithm is used for channel estimations over a real urban environment described in a vector format. In addition, a power control algorithm is developed that explicitly considers power levels of neighbor base stations and is used for the network power consumption estimation. Finally, network planning is achieved through an evolutionary optimization technique that combines the above mentioned algorithms. © 2012 IEEE.

Koutitas G.,International Hellenic University | Koutitas G.,University of Thessaly
IEEE Transactions on Smart Grid | Year: 2012

This paper investigates load control and demand response in a smart grid environment where a bidirectional communication link between the operator and the smart flexible devices supports command and data flow. Two control schemes are investigated that can provide energy management, taking into account user's comfort, via binary on-off policies of the smart flexible devices. A dynamic control algorithm is introduced that considers real time network characteristics and initiates command flow when critical parameters exceed predefined thresholds. To sustain fairness in the system, priority based and round robin scheduling algorithms are proposed. A continuous control algorithm is also explored to define the higher bounds of energy savings. To quantify the discomfort of users that participate in this type of services, a heuristic consumer utility metric is proposed and measurements with a flexible device (air conditioning unit) are performed to model empirically possible time intervals of the control scheme. Reciprocal fair energy management schemes are investigated being both operator and user centric. It is shown that great energy and cost savings can be achieved providing the required degrees of freedom to the smart grid to self-adapt during peak hours. © 2010-2012 IEEE.

Dergiades T.,International Hellenic University | Martinopoulos G.,International Hellenic University | Tsoulfidis L.,University of Macedonia
Energy Economics | Year: 2013

The objective of this paper is to contribute towards the understanding of the linear and non-linear causal linkages between energy consumption and economic activity, making use of annual time series data of Greece for the period 1960-2008. Two are the salient features of our study: first, the total energy consumption has been adjusted for qualitative differences among its constituent components through the thermodynamics of energy conversion. In doing so, we rule out the possibility of a misleading inference with respect to causality due to aggregation bias. Second, the investigation of the causal linkage between economic growth and the adjusted for quality total energy consumption is conducted within a non-linear context. Our empirical results reveal significant unidirectional both linear and non-linear causal linkages running from total useful energy to economic growth. These findings may provide valuable information for the contemplation of more effective energy policies with respect to both the consumption of energy and environmental protection. © 2012 Elsevier B.V.

Martinopoulos G.,International Hellenic University | Tsalikis G.,International Hellenic University
Energy and Buildings | Year: 2014

The purpose of this study is the technical and economic evaluation of a typical solar space and water heating system, utilized in an 88 m2 detached house that is designed according to the latest Greek Regulation on the Energy Performance of Buildings as a means toward Nearly Zero Energy Buildings (NZEB). The analysis was conducted for each of the four climatic zones designated in the Greek Regulation. A financial analysis was performed and the Net Present Value and the Discounted Payback Period (DPBP) were calculated and correlated with the solar systems collector area and the storage tank volume. Furthermore, the annual avoided emissions from the substituted fossil fuels are estimated for the solar systems considered. The analysis demonstrates that the typical solar space and water heating system can provide a viable solution toward NZEB with solar coverage and DPBP being strongly influenced by the climatic zone of the building and the type of fossil fuel substituted. In all cases the solar system covers at least 45% of the total heating loads while the payback period is as low as 4.5 years with an annual abatement of more than 50 t of CO2 in the worst case scenario. © 2013 Elsevier B.V.

Koutitas G.,International Hellenic University
IEEE Transactions on Broadcasting | Year: 2010

This paper investigates the network deployment of single frequency networks (SFN) based on OFDM schemes that are standardized for terrestrial broadcasting systems, for digital audio broadcasting (DAB) and for digital video broadcasting (DVB) systems. The concept of green network planning is presented. The term green refers to low carbon, energy efficiency and low exposure to radiation, parameters important for the sustainable growth. For the purpose of our investigation a mountainous area of Northern Greece is examined, that is described by a digital terrain elevation model (DTEM) and field computations are based on multi shape slope uniform theory of diffraction (UTD) technique. A genetic algorithm (GA) optimization method is developed for the network planning purposes. A comparison between various planning strategies is presented. It is shown that great Co2 reductions, cost savings and low exposure to radiation can be achieved when the network planning considers a 'green' strategy. © 2006 IEEE.

Koutitas G.,International Hellenic University
International Conference on Advanced Communication Technology, ICACT | Year: 2010

Based on OFDM and Single Frequency Network architecture (SFN), DVB-T systems can combine signals coming from several transmitters yielding to a diversity gain. The network planning for such systems has a great impact to quality of service and costs. This paper presents a network planning approach for DVB-T services and focuses the investigation on the optimisation of the network deployment in terms of energy efficiency. For the purpose of the investigation an evolution optimisation technique based on genetic algorithm method is developed and applied on a given network topology over a real Digital Elevation Map (DEM). The field computations are based on an accurate multiple diffraction model based on multi-shape Uniform Theory of Diffraction (UTD). Simulation results show a great energy consumption savings that yield to the green deployment of the network. Comparisons with the coverage and cost optimisation scenarios are also presented.

Koutitas G.,International Hellenic University
IEEE Antennas and Wireless Propagation Letters | Year: 2010

This letter investigates the channel variations in wireless body area networks (WBANs). For the purpose of the investigation, a ray solution for multiple closed surfaces is proposed that utilizes a modified slope uniform theory of diffraction (UTD) technique and can be applied to model scattering, radiation, coupling effects, or a combination of the three in a single formulation. The solution considers all possible ray paths and is valid at the transition boundaries of the scenario. The human bodies are represented as closed cylindrical surfaces with constitutive parameters based on the Muscle model. The proposed algorithm predicts channel variations in a ray format that requires less CPU and is characterized by lower complexity compared to full-wave techniques. Body-to-access point (BAP) and body-to-body networks are investigated. © 2010 IEEE.

Koutitas G.,International Hellenic University | Tassiulas L.,International Hellenic University
IEEE Communications Magazine | Year: 2014

This article explores smart grid technologies that can be applied to a telecommunication network to achieve energy-efficient networking, autonomous operation, and adaptation to realtime electricity pricing schemes. With the fast penetration of renewable energy sources within base stations and data centers, the telecommunication operator can establish an active role in the energy market by adjusting power consumption in real time. In the telecommunications sector, energy management technologies have recently emerged with BS management schemes and virtual machine migration/allocation strategies. In the energy sector, smart grid technologies and new standards enable real-time management and pricing. The only brick missing is the orchestration of the technologies in the two sectors to enable smart telecommunications network operation in terms of energy consumption. In this article, concepts such as demand response, supply load control, and the model of the "prosumer" in the smart grid are correlated to the operation of modern radio and data center networks. The main outcome of the research is to provide new ideas for net zero service delivery and explore the role of the telecommunication provider in the energy market where dynamic electricity pricing is expected to hold a critical role in decision making processes. Copyright © 2014 IEEE.

Koutitas G.,International Hellenic University
2010 European Wireless Conference, EW 2010 | Year: 2010

This paper investigates the deployment of single frequency terrestrial DVB networks in terms of their carbon footprint. A network optimization tool is presented that is based on evolution optimisation method, the genetic algorithm. The target of the investigation is to design the network considering the minimization of its carbon emissions. For the purpose of the investigation a real mountainous area is examined. The field computations are based on accurate multiple slope uniform theory of diffraction (UTD) approximations. Simulation results show a great reduction of CO2 emissions when carbon footprint is included in the optimization process. © 2010 IEEE.

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