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18th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2007), vol.8

作者： George C. Alexandropoulos Kostas Berberidis Nikos C. Sagias Fotis I. Lazarakis Christos K. Datsikas Antonis A. Alexandridis Kostas P. Dangakis Department of Computer Engineering & Informatics University of Patras Greece Institute of Informatics and Telecommunications National Centre for Scientific Research Athens Greece

An infinite series representation for the moment generating function of the sum of squared arbitrarily correlated Rayleigh random variables is presented. Based on the derived formula, corresponding analytical expressions for the probability density and cumulative distribution functions are extracted. As an application for the aforementioned sum, exact analytical expressions for the outage and the average error probability, as well as, the channel average spectral efficiency of multi-branch maximal-ratio diversity receivers operating over identically distributed and arbitrarily correlated Rayleigh fading channels are obtained. Our analysis is verified by comparing numerically evaluated results with extensive computer simulation ones.

关键词： Diversity reception Fading Performance analysis Radiofrequency interference informatics Random variables Distribution functions Error probability computer simulation Land mobile radio

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Using a Grid Platform for Enabling Real Time User Modeling in On-line Campus

Using a Grid Platform for Enabling Real Time User Modeling i...

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International Conference on Complex, Intelligent and Software Intensive Systems, CISIS

作者： Santi Caballe Fatos Xhafa Thanasis Daradoumis Joan Esteve Leonard Barolli Arjan Durresi Universitat Oberta de Catalunya Barcelona Catalunya ES Dept. of Languages and Informatics Systems Polytechnic University of Catalonia Barcelona Spain Department of Computer Science Multimedia and Telecommunication Open University of Catalonia Barcelona Spain Department of Information and Communication Engineering Fukuoka Institute of Technology (FIT) Higashi-ku Fukuoka Japan Department of Computer Science Louisiana State University Baton Rouge LA USA

User modelling in on-line distance learning is an important research field focusing on two important aspects: describing and predicting students' actions and intentions as well as adapting the learning process to students' features, habits, preferences, and so on. The aim is to greatly stimulate and improve the learning experience. Indeed, on the one hand, students' intentions may change during the realization of learning activities and thus their actions evolve accordingly as the learning process moves forward. On the other hand, adaptive systems can effectively plan and design appropriate learning tasks according to students' features, habits and interests with the aim of facilitating the achievement of the learning goal. In this context, user modelling implies a continuous processing and analysis of user interaction data during long-term learning activities, which produces large and considerably complex information. As a consequence, processing this information is costly and could require computational capacity beyond that of a single computer. In this paper, we show how a grid approach can considerably decrease the processing time of log data of on-line distance educational Web-based systems. Our prototype is based on the master-worker paradigm and is implemented using a peer-to-peer platform running on the Planetlab nodes. The results of our study show the feasibility of using grid middleware to speed and scale up the processing of log data and thus achieve an efficient and dynamic user modeling in on-line distance learning

关键词： computer aided instruction Adaptive systems computer science Predictive models Context modeling Information analysis Peer to peer computing Software systems Application software Usability

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A multicast packet forwarding mechanism for WCDMA networks using routing lists

A multicast packet forwarding mechanism for WCDMA networks u...

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WMuNeP 2006: 2nd ACM International Workshop on Wireless Multimedia Networking and Performance Modeling

作者： Alexiou, Antonios Antonellis, Dimitrios Bouras, Christos Research Academic Computer Technology Institute Computer Engineering and Informatics Department Patras University GR 26500 Patras Greece

ISBN: (纸本)1595934855

This paper proposes a multicast scheme for the packet forwarding mechanism in the Universal Mobile Telecommunications System (UMTS). The scheme relies on the introduction of the Permanent Multicast Routing List (PMRL) and Temporary Multicast Routing List (TMRL) in each node of the network except UEs. In the PMRL we record the nodes of the next level that the messages for every multicast group should be forwarded. The TMRL is useful for the temporary record of information from the path from the mobile users to the GGSN. Additionally, a Multicast Group List (MGL) is kept in the GGSN which records the members of each multicast group. These lists lead to the decrement of the transmitted packets and the more efficient use of the network resources in the multicast routing in UMTS. We analyze the exact steps that the multicast packets are transmitted to the members of each multicast group. Furthermore, special issues such as joining/leaving a multicast service are described. Copyright 2006 ACM.

关键词： Code division multiple access

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Utilizing infrared pattern recognition features for indoor localization validated by future position restrictions

Utilizing infrared pattern recognition features for indoor l...

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2nd IET International Conference on Intelligent Environments, IE 06

作者： Petrellis, Nikos Konofaos, Nikos Alexiou, George Computer Engineering and Informatics Dept. Research Academic Computer Technology Institute University of Patras Greece

ISBN: (纸本)0863416632

In this paper we present a system that is capable of estimating the position of a moving target on a grid plane covered by a pair of infrared transmitters. The area of this plane can be up to 15m2, further expandable if multiple transmitters are used. The position estimation method is based on comparing the number of infrared patterns received to the expected ones in a specific time interval (success rate). Using this method, no signal strength or time of flight has to be precisely measured, leading to an ultra low cost architecture. A proper topology of the infrared transmitters that optimally cover the desired area is discussed. The history of movements of the target is utilized in order to reject false estimations. The error achieved is below the half of the grid node distance.

关键词： Feature extraction

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Comparison of seven approaches for holter ECG clustering and classification

Comparison of seven approaches for holter ECG clustering and...

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29th Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBS 2007), vol.10

作者： Vaclav Chudacek Milan Petrik George Georgoulas Miroslav Cepek Lenka Lhotska Chrysostomos Stylios Gerstner laboratory at Department of Cybernetics Czech Technical University Czech Republic Czech Republic Department of Cybernetics Center for Machine Perception Czech Technical University Czech Republic Intelligent Control Systems Laboratory Georgia Technology Research Institute Atlanta USA Czech Republic Department of Computer Science and Engineering Neural Computing Group Czech Technical University Czech Republic Czech Republic Department of Cybernetics Gerstner Laboratory Czech Technical University Czech Republic Department of Informatics and Communications Technology TEI Epirus Artas Greece

In this work we present a comparative study, testing selected methods for clustering and classification of holter electrocardiogram (ECG). More specifically we focus on the task of discriminating between normal 'N' beats and premature ventricular 'V' beats. Some of the tested methods represent the state of the art in pattern analysis, while others are novel algorithms developed by us. All the algorithms were tested on the same datasets, namely the MIT-BIH and the AHA databases. The results for all the employed methods are compared and evaluated using the measures of sensitivity and specificity.

关键词： Electrocardiography Testing Decision trees Laboratories Cybernetics Sensitivity and specificity Heart rate variability Clustering algorithms Spatial databases Computational complexity

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A slow start power control MAC protocol for mobile ad hoc networks

A slow start power control MAC protocol for mobile ad hoc ne...

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2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC

作者： Gkamas, Vasilis S. Varvarigos, Emmanouel A. University of Patras Computer Engineering and Informatics Research Academic Computer Technology Institute GR-26500 Rio-Patras Greece

ISBN: (纸本)1424403294

We propose a MAC protocol for mobile ad hoc networks that uses power control for the RTS/CTS and DATA frame transmissions in order to improve energy and capacity utilization efficiency. Unlike IEEE 802.11, in our scheme the RTS frames are not sent using the maximum transmission power to silence neighbouring nodes, and the CTS frames do not silence all receiving nodes to the same degree. In contrast, the transmission power of the RTS frames follows a slow start principle, while the CTS frames, which are sent at maximum transmission power, prevent the neighbouring nodes from transmitting their DATA frames with power more than a computed threshold, while allowing them to transmit at power levels less than that threshold. This is done by including in the RTS and the CTS frames additional information, such as the power of the transmissions, and the interference tolerance of the nodes. Moreover the DATA frames are sent at the minimum required transmission power increased by a small margin to ensure connectivity with the intended receiver, so as to cause minimal interference to neighbouring nodes and allow for future interference to be added to the receiver of the DATA frames. The power to be used by the transmitter is computed by the recipient of the RTS frame and is included in the CTS frame. It is expected that a network with such a power management scheme would achieve a better throughput performance and more power savings than a network without such a scheme. © 2006 IEEE.

关键词： Power control

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Evaluating different one to many packet delivery schemes for UMTS 06

Evaluating different one to many packet delivery schemes for...

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WoWMoM 2006: 2006 International Symposium on a World of Wireless, Mobile and Multimedia Networks

作者： Alexiou, Antonios Antonellis, Dimitrios Bouras, Christos Research Academic Computer Technology Institute Greece Computer Engineering and Informatics Dept. Univ. of Patras Greece

ISBN: (纸本)0769525938

It is known that multicasting is an efficient method of supporting group communication as it allows the transmission of packets to multiple destinations using fewer network resources. Thus, service providers are increasingly interested in supporting multicast communications over wireless networks and in particular over UMTS. Multicasting is a more efficient method of supporting group communication than unicasting or broadcasting, as it allows transmission and routing of packets to multiple destinations using fewer network resources. In this paper the three above mentioned methods of supporting group communication are analyzed in terms of their performance. © 2006 IEEE.

关键词： Packet networks

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Towards the development of a novel taxonomy of knowledge management systems from a learning perspective: An integrated approach to learning and knowledge infrastructures

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Journal of Knowledge Management 2006年第6期10卷 64-80页

作者： Lytras, Miltiadis D. Athanasia, Pouloudi Computer Engineering and Informatics Department Research Academic Computer Technology Institute University of Patras Patras Greece Department of Management Science and Technology ELTRUN Athens University of Economics and Business Athens Greece

Purpose - The paper aims to discuss the critical issue of learning and knowledge convergence in knowledge-intensive organizations, and to provide practical guidelines for effective strategies. Design/methodology/approach - The paper brings together previous research in knowledge management and provides a critique for the lack of integration of previous studies with learning, a key process for efficient knowledge management. Stemming from this critique, an integrative framework for knowledge management support from a learning perspective is proposed. Findings - The major contribution is the framework for knowledge management support from a learning perspective, which can guide strategies of effective knowledge and learning management. This framework initiates an interesting discussion of technological issues that can enhance current knowledge management practices. research limitations/implications - The taxonomy of knowledge management systems provides the basis for an extensive specification of knowledge management strategies. Further research could focus on an instrumental approach to the integrative framework suggested in this paper, to illustrate how it can be used to enhance the integration of learning processes and products in the knowledge management process. Practical implications - The paper is a very useful source of information and impartial advice for strategists, knowledge management officers and people interested in implementing learning and knowledge management in a knowledge-intensive organization. Originality/value - This paper presents a novel taxonomy of knowledge management systems from a learning perspective. Unlike previous literature on knowledge management, this paper makes an explicit claim for integrating knowledge management and learning activities and illustrates how the two can be jointly supported by various knowledge management systems.

关键词： E-learning Knowledge management Learning

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Waters network's potential to transform environmental engineering education

Waters network's potential to transform environmental engine...

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114th Annual ASEE Conference and Exposition, 2007

作者： Eschenbach, Elizabeth Montgomery, Jami Johnson, James Brus, Chris Carlson, Patricia Giammar, Dan Grauer, Bette Hotaling, Liesl Oguntimein, Gbekeloluwa Safferman, Steven Wentling, Tim Humboldt State University United States Department of Environmental Resources Engineering Humboldt State University United States WATERS Network - CLEANER Project Office Network Howard University United States Department of Environmental Engineering College of Engineering Architecture and Computer Sciences Howard University United States American Academy of Environmental Engineers United States University of Iowa United States Program University of Iowa United States Rose-Hulman Institute of Technology United States Department of Rhetoric Rose-Hulman Institute of Technology United States National Research Council U. S. Air Force United States NASA's Classroom of the Future Wheeling WV United States Washington University United States Department of Energy Environmental and Chemical Engineering Washington University St. Louis United States Environmental Studies Program Center for Materials Innovation United States McPherson High School United States McPherson High School McPherson KS United States Stevens Institute of Technology United States Stevens Institute of Technology United States Morgan State University United States Michigan State University United States Biosystems and Agricultural Engineering Department Michigan State University United States University of Dayton United States Education Planning Committee National Center for Supercomputing Applications United States Department of Information Science Graduate School of Library and Information Science National Center for Supercomputing Applications University or Illinois United States Knowledge and Learning Systems Group NCSA United States

The WATERS Network (WATer and Environmental research Systems Network) will be an integrated real-time distributed observing system which will enable academic and government scientists, engineers, educators, and practitioners to advance effective management of our nation's water resources by understanding human interactions with water and the natural and built environment. WATERS will provide easily accessible real time environmental data as well as analysis tools to engineers, scientists, educators, K- graduate students and policymakers so they can better understand how water quantity, quality and related components of the hydrologic cycle are impacted by natural and human influences. The WATERS strategic plan will be completed by July 2007 and requires constituent input. This paper describes the draft Conceptual Design and the Education Plan of WATERS Network. This paper will highlight the potential impact of WATERS on undergraduate and graduate environmental engineering education in order to elicit input from the environmental engineering education community on how WATERS Network could better meet the future needs of undergraduate and graduate students and educators. More information can be found at ***. © American Society for engineering Education, 2007.

关键词： Water resources

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FISH Image Analysis Using a Modified Radial Basis Function Network

FISH Image Analysis Using a Modified Radial Basis Function N...

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International Symposium on Signals, Circuits and Systems (ISSCS)

作者： Ioannis N. Kasampalidis Ioannis Pitas Georgia Karayannopoulou Ioannis Kostopoulos Paolo Aretini Generoso Bevilacqua Andrea Cavazzana Michele Menicagli Antonina Starita Kleoniki Lyroudia Department of Informatics School of Applied Sciences Aristotle University of Thessaloniki Thessaloniki Greece Department of Pathology Medical School Aristotle University of Thessaloniki Thessaloniki Greece Research Institute for Networks and Communications Engineering Radio and Optical Communications Laboratory University of Pisa and Pisa University Hospital Pisa Italy Institute of Molecular Genetics and Medicine MGM Pisa Italy Department of Computer Science Dental School University of Pisa Pisa Italy Department of Endodontology Dental School Aristotle University of Thessaloniki Thessaloniki Greece

Fluorescent in situ hybridization (FISH) is a valuable method for determining Her-2/neu status in breast carcinoma samples, an important prognostic indicator. Visual evaluation of FISH images is a difficult task which involves manual counting of dots in multiple images, a procedure which is both time consuming and prone to human error. A number of algorithms have recently been developed dealing with (semi)-automated analysis of FISH images. These algorithms are quite promising but further improvement is required in improving their accuracy. Here, we present a novel method for analyzing FISH images based on the statistical properties of Radial Basis Functions. Our method was evaluated on a data set of 100 breast carcinoma cases provided by the Aristotle University of Thessaloniki and the University of Pisa, with promising results.

关键词： Marine animals Image analysis Radial basis function networks Breast Image segmentation Fluorescence Pathology Biomedical imaging Performance analysis Morphological operations

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