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Location positioning techniques investigation in GSM networks

WSEAS Transactions on Communications 2006年第6期5卷 1159-1168页

作者： Deligiannis, N. Louvros, S. Ioannou, K. Garmpis, A. Kotsopoulos, S. Wireless Telecommunication Laboratory Department of Electrical and Computer Engineering University of Patras Rion 26500 Patras Greece Department of Applied Informatics in Management and Economy Technical Education Institute of Messologi Greece

Positioning algorithms are of great importance in recent years, as the means of providing location based services (LBS) including wireless emergency services. Telecommunication engineers are frequently puzzled by the accuracy of the implemented technique in contrast with the cost. In this paper, we introduce a novel Time of Arrivals (TOA) location positioning method in GSM networks using three Base Stations (BSs). In order to implement the proposed solution an analytical explanation of the signaling flow is provided. The algorithm's accuracy is improved by introducing an additional weight coefficient reflecting the LOS/nLOS propagation. Finally, the cost function is simulated in a microcellular city centre environment and compared to Turin's. Moreover a reference is provided regarding the other methods of positioning.

关键词： Global system for mobile communications

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Low HRV entropy is strongly associated with myocardial infarction

Low HRV entropy is strongly associated with myocardial infar...

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作者： Lau, Stephan Haueisen, Jens Schukat-Talamazzini, Ernst G. Voss, Andreas Goernig, Matthias Leder, Uwe Figulla, Hans-R. Institute of Computer Science Friedrich Schiller University Jena Jena Germany Biomagnetic Center Jena Friedrich Schiller University Jena Jena Germany Department of Medical Engineering University of Applied Sciences Jena Jena Germany Institute of Biomedical Engineering and Informatics Technical University of Ilmenau Ilmenau Germany Clinic of Internal Medicine I Friedrich Schiller University Jena Jena Germany Biomagnetic Center Jena Friedrich Schiller University Jena Erlanger Allee 101 07747 Jena Germany

Heart rate variability (HRV) is a marker of autonomous activity in the heart. An important application of HRV measures is the stratification of mortality risk after myocardial infarction. Our hypothesis is that the information entropy of HRV, a non-linear approach, is a suitable measure for this assessment. As a first step, to evaluate the effect of myocardial infarction on the entropy, we compared the entropy to standard HRV parameters. The entropy was estimated by compressing the tachogram with Bzip2. For univariate comparison, statistical tests were used. Multivariate analysis was carried out using automatically generated decision trees. The classification rate and the simplicity of the decision trees were the two evaluation criteria. The findings support our hypothesis. The meanNN-normalized entropy is reduced in patients with myocardial infarction with very high significance. One entropy parameter alone exceeds the discrimination strength of multivariate standards-based trees. ©2006 by Walter de Gruyter.

关键词： Cardiology

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Throughput and interference measurements in copper wires of xDSL type modems

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WSEAS Transactions on Information Science and Applications 2006年第2期3卷 352-357页

作者： Agapiou, G. Doukoglou, T. Georgiadis, P. Georgakopoulos, G. Plakidis, E. Rorris, P. Ioannou, K. Ioannou, A. Garmpis, A. Mobile and Radio Communications Research Laboratories OTE S.A. Athens Greece Wireless Telecommunication Laboratory Department of Electrical and Computer Engineering University of Patras Rion 26500 Patras Greece Department of Applied Informatics in Management and Economy Technical Education Institute of Messologi Messologi Greece

Crosstalk is an important factor that needs to be considered and study its effects in copper wires, especially when voice communication takes place. Its presence has proven to be an impaired factor in the performance of communication services. This paper measures the isolation losses and the crosstalk losses as a function of the frequency and the length of the copper wires. It also presents throughput results from modems designed in the context of an EU financed project that can provide a symmetric 100 Mbps over two pairs for reach up to 500m (5 times the existing reach of 100-BASE-T systems).

关键词： Modems

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Experimental performance evaluation of the emerging WiMAX technology

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WSEAS Transactions on Information Science and Applications 2006年第2期3卷 322-327页

作者： Agapiou, G. Vali, D. Charalambakis, D. Georgiadis, P. Plakidis, E. Rorris, P. Ioannou, K. Garmpis, A. Mobile and Radio Communications Research Laboratories OTE S.A. Athens Greece Wireless Telecommunication Laboratory Department of Electrical and Computer Engineering University of Patras Rion 26500 Patras Greece Department of Applied Informatics in Management and Economy Technical Education Institute of Messologi Messologi Greece

The increasing demand for wireless broadband service offering in long distances is the major drive behind the emergence of the WiMAX technology. WiMAX is targeted to providing high bit data rates to the end users in a wireless manner, any time, in any location, even in harsh environmental conditions and at an acceptable quality. This paper presents the experimental results of a WiMAX system that follows the specifications of IEEE 802.16-2004 standard. Throughput and Bit Error Rate (BER) measurements, as well as voice and video service experiments are carried out, leading to useful conclusions for the performance evaluation of the WiMAX system under test and the WiMAX technology in general.

关键词： Wireless telecommunication systems

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Efficient SIE/VIE scattering analysis of ferroelectric inhomogeneous materials with high permittivity for microwave applications

Efficient SIE/VIE scattering analysis of ferroelectric inhom...

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European Conference on Antennas and Propagation: EuCAP 2006

作者： Avdikos, Georgios K. Zervos, Theodore Anastassiu, Hristos T. Uzunoglu, Nikolaos K. School of Applied Mathematics and Physics National Technical University of Athens Heroon Polytechniou 9 GR-15780 Zografou Greece Institute of Informatics and Telecommunications National Centre for Scientific Research Demokritos Athens 15310 Greece Hellenic Aerospace Industry Communications and Networks Design and Development Dept. PO Box 23 Schimatari - Tanagra Viotia Greece School of Electrical and Computer Engineering National Technical University of Athens Heroon Polytechniou 9 GR-15780 Zografou Greece

ISBN: (纸本)9290929375

Ferroelectric materials have been gaining much interest over the last decades due to the unique operational characteristics they demonstrate, when a dc electric field is applied. This paper investigates the scattering analysis of electromagnetic waves from materials with high permittivity that follows a linear spatial variation along one axis. The Surface Integral Equation (SIE) and Volume Integral Equation (VIE) methods are invoked to compute the currents and the radar cross section (RCS). The number of unknowns for the VIE is, as expected, larger than for the SIE method. The RCS and the induced current are associated in such a way that one can approximate the linear variation with relatively few elements (unknowns).

关键词： Ferroelectric materials

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Efficient SIE/VIE scattering analysis of ferroelectric inhomogeneous materials with high permittivity for microwave applications

Efficient SIE/VIE scattering analysis of ferroelectric inhom...

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European Conference on Antennas and Propagation, EuCAP

作者： Georgios K. Avdikos Theodore Zervos Hristos T. Anastassiu Nikolaos K. Uzunoglu School of Applied Mathematics and Physics National and Technical University of Athens Zografou Greece National Centre for Scientific Research Demokritos Institute of Informatics and Telecommunications Athens Greece Communications and Networks Design & Development Department Hellenic AeroSpace Industry SA Viotia Greece School of Electrical and Computer Engineering National and Technical University of Athens Zografou Greece

Ferroelectric materials have been gaining much interest over the last decades due to the unique operational characteristics they demonstrate, when a dc electric field is applied. This paper investigates the scattering analysis of electromagnetic waves from materials with high permittivity that follows a linear spatial variation along one axis. The surface integral equation (SIE) and volume integral equation (VIE) methods are invoked to compute the currents and the radar cross section (RCS). The number of unknowns for the VIE is, as expected, larger than for the SIE method. The RCS and the induced current are associated in such a way that one can approximate the linear variation with relatively few elements (unknowns).

关键词： Ferroelectric materials Permittivity Electromagnetic scattering Radar scattering Integral equations Electromagnetic analysis Radar cross section Linear approximation Dielectric materials Microwave antenna arrays

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An architecture for mobile-health care service provision

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WSEAS Transactions on computers 2005年第11期4卷 1502-1509页

作者： Votis, K. Vassiliadis, B. Tsaknakis, J. Stefani, A. Ioannou, K. Drossos, L. Dept. of Computer Engineering and Informatics University of Patras Patras Greece Department of Computer Science Hellenic Open University Greece Dept. of Electrical and Computer Engineering University of Patras Patras Greece Dept. of Applied Informatics in Management and Economy Technical Education Institute of Messologi Greece

This paper introduces the architecture of an open information and communication platform that integrates all relevant participants in health and social sector. The main concept of the proposed platform is based on concept introduced by new computing paradigms and the need of transformation of the existing internetworking and web technologies into a human resource pool that will be accessible by anyone, at anytime, and from everywhere in support of their needs. This platform intends to create the essential infrastructure for the provisioning of health and social services to individuals that receive residential care using Peer-to-Peer (P2P) networks over Internet, GSM and PSTN networks. The use of new computing models such as Service-Oriented computing, Grid, P2P and argumentation technologies are discussed. Furthermore, the functional requirements and the architecture of a complete solution are presented.

关键词： Intelligent agents

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Embedding advanced geometric techniques into SQL for efficient indexing of mobile objects

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WSEAS Transactions on computers 2005年第11期4卷 1517-1525页

作者： Sioutas, S. Drossos, L. Tsolis, D. Papatheodorou, T.S. Computer Engineering and Informatics Department University of Patras Building B University Campus 26500 Rion Patras Greece Technological Institute of Messolongi Department of Applied Informatics in Administration and Economics Technological Institute Campus 30200 Messolongi Greece

It is of great importance a trial to embed new geometric techniques into SQL in order to achieve more efficient indexing of objects moving on the plane and answer range queries about their future positions. This problem is motivated by real-life applications, such as allocating more bandwidth for areas where high concentration of mobile phones is imminent, or predicting future congestion areas in a highway Geographic Information System (GIS). We consider the problem in the external memory model of computation and present a variety of dynamic techniques.

关键词： Computational geometry

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The DILIGENT knowledge processes

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Journal of Knowledge Management 2005年第5期9卷 85-96页

作者： Vrandečić, Denny Pinto, Sofia Tempich, Christoph Sure, York University of Karlsruhe Institute of Applied Informatics and Formal Description Methods 76128 Karlsruhe Germany Department of Computer Science and Engineering Instituto Superior Tecnico Technical University of Lisbon Lisbon Portugal Institute of Applied Computer Science and Formal Description Methods University of Karlsruhe 76128 Karlsruhe Germany

Purpose - Aims to present the ontology engineering methodology DILIGENT, a methodology focussing on the evolution of ontologies instead of the initial design, thus recognizing that knowledge is a tangible and moving target. Design/methodology/approach - First describes the methodology as a whole, then detailing one of the five main steps of DILIGENT. The second part describes case studies, either already performed or planned, and what we learned (or expect to learn) from them. Findings - With the case studies it was discovered the strengths and weaknesses of DILIGENT. During the evolution of ontologies, arguments need to be exchanged about the suggested changes. Identifies those kind of arguments which work best for the discussion of ontology changes. Research implications - DILIGENT recognizes ontology engineering methodologies like OnToKnowledge or Methontology as proven useful for the initial design, but expands them with its strong focus on the user-centric further development of the ontology and the provided integration of automatic agents in the process of ontology evolution. Practical implications - With DILIGENT the experience distilled from a number of case studies and offers the knowledge manager a methodology to work in an ever-changing environment. Originality/value - DILIGENT is the first methodology to put focus not on the initial development of the ontology, but on the user and his usage of the ontology, and on the changes introduced by the user. We take the user's own view seriously and enable feedback towards the evolution of the ontology, stressing the ontology's role as a shared conceptualisation. © Emerald Group Publishing Limited.

关键词： computer applications Knowledge management systems Semantics User interfaces

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Using Semantic Web Mining technologies for personalized e-Learning experiences

Using Semantic Web Mining technologies for personalized e-Le...

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4th IASTED International Conference on Web-Based Education, WBE 2005

作者： Markellou, Penelope Mousourouli, Ioanna Spiros, Sirmakessis Tsakalidis, Athanasios Research Academic Computer Technology Institute 61 Riga Feraiou str. 26221 Patras Greece University of Patras Computer Engineering and Informatics Department 26504 Patras Greece Technological Education Institute of Messolongi Department of Applied Informatics in Administration and Economics 30200 Messolongi Greece

ISBN: (纸本)0889864802

The challenge of the Semantic Web Mining technologies in the e-Learning domain can relate to the provision of personalized experiences for the users. Particularly, these applications can take into consideration the individual needs and requirements of learners. In this paper, we propose a framework for personalised e-Learning based on aggregate usage profiles and a domain ontology. We have distinguished two stages in the whole process, one of offline tasks that includes data preparation, ontology creation and usage mining and one of online tasks that concerns the production of recommendations.

关键词： Ontology

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