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International Conference on Information technology: Coding and Computing (ITCC)

作者： C. Makris E. Sakkopoulos S. Sioutas P. Triantafillou A. Tsakalidis B. Vassiliadis Computer Engineering & Informatics Department University of Patras Patras Greece Internet and Multimedia Technologies Research Unit RA Computer Technology Institute Patras Greece Computer Science Digital Systems & Media Computing Laboratory Hellenic Open University Patras Greece

Web services are becoming an important enabler of the semantic Web. Besides the need for a rich description mechanism, Web service information should be made available in an accessible way for machine processing. In this paper, we propose a new P2P based approach for Web services discovery. Peers that store Web services information, such as data item descriptions, are efficiently located using a scalable and robust data indexing structure for peer-to-peer data networks, NIPPERS. We present a theoretical analysis which shows that the communication cost of the query and update operations scale double-logarithmically with the number of NIPPERS nodes. Furthermore, we show that the network is robust with respect to failures fulfilling quality of Web services requirements.

关键词： Web services Peer to peer computing Robustness Costs Interpolation Tree data structures Web and internet services Multimedia systems Multimedia computing informatics

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A genetic algorithm-based approach to knowledge-assisted video analysis

A genetic algorithm-based approach to knowledge-assisted vid...

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IEEE International Conference on Image Processing

作者： N. Voisine S. Dasiopoulou F. Precioso V. Mezaris I. Kompatsiaris M.G. Strintzis Informatics and Telematics Institute Centre for Research and Technology Hellas Thessaloniki Greece Information Processing Laboratory Electrical and Computer Engineering Department Aristotle University of Thessaloniki Thessaloniki Greece

Efficient video content management and exploitation requires extraction of the underlying semantics, a non-trivial task associating low-level features of the image domain and high-level semantic descriptions. In this paper, a knowledge-assisted approach for extracting semantics of domain-specific video content is presented. Domain knowledge considers both low-level features (color, motion, shape) and spatial behavior (topological and directional information). During the preprocessing step, a set of over-segmented homogenous atom-regions is generated and their low-level and spatial descriptions are extracted. A genetic algorithm is then applied in order to find the optimal interpretation according to a specific domain conceptualization. The proposed approach was tested on the formula one, tennis and beach vacations domains showing promising results.

关键词： Algorithm design and analysis Data mining Ontologies Genetic algorithms Object detection Content management Feature extraction Knowledge representation Semantic Web Laboratories

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ON THE EQUIVALENCE OF A MINIMAL ORDER MPC AND A GTDOF CONTROL OF TIME-DELAY PLANTS

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IFAC Proceedings Volumes 2005年第1期38卷 183-188页

作者： L. Keviczky Cs. Bányász Computer and Automation Research Institute of the H. Ac. of Sc. Control Engineering Research Group of the H. Ac. of Sc. at the Department of Automation and Informatics TU of Budapest

It is shown that for open-loop stable plants the task of an MPC can be solved by identifying the plant model only instead of the redundant prediction model. Interesting structural considerations can be derived from comparison of the topologies and structural forms of regulators obtained by pole-placement design, the GTDOF scheme and the MPC . A new simple method is also introduced for adaptive and combined iterative identification and control for time-delay plants.

关键词： time-delay pole-placement model predictive control two-degree of freedom regulator

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Content-based decomposition of gesture videos

Content-based decomposition of gesture videos

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IEEE Workshop on Signal Processing Systems (SIPS)

作者： N.D. Doulamis A.D. Doulamis D.I. Kosmopoulos Department of Electrical and Computer Engineering National and Technical University of Athens Greece Institute of Informatics & Telecommunications National Centre for Scientific Research Demokritos

In this paper we present a novel method for gesture video decomposition based on the depicted content. From the initial content the key-frames are extracted and the neighboring frames are assigned to key-frames of similar content. The resulting frame groups are decomposed to binary trees, based on the energy of the depicted gestures. In case of reduced bandwidth we keep the original timeline but we send only a dynamically adapted video summary. The respective frames are obtained by moving appropriately across the hierarchy layers of the constructed tree. The hierarchically structured video can be used for purposes such as efficient video browsing and transmission of dynamically generated summaries over low bandwidth networks, for communication or human-computer interface applications.

关键词： Bandwidth Telecommunication computing Video sequences informatics Binary trees Auditory system Speech Handicapped aids Compression algorithms MPEG 4 Standard

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Array factor measurements: A preliminary stage in a methodology for Smart Antenna characterization measurements

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WSEAS Transactions on Communications 2005年第10期4卷 1108-1115页

作者： Zervos, T. Alexandridis, A.A. Lazarakis, F. Dangakis, K. Soras, C. National Centre for Scientific Research Demokritos Institute of Informatics and Telecommunications Athens Greece University of Patras Department of Electrical and Computer Engineering Patras Greece

The huge expansion of mobile terminal users and the high data rate services leads to the need for more efficient use of the spectrum to increase the capacity in networks and enhance the quality of services. The adoption of Smart Antenna techniques in future wireless systems is expected to have a significant impact on the aforementioned needs. Following the proliferation of the use of Smart Antennas systems there is a growing need for characterization of such systems. In this work, a generalized methodology for Smart Antenna characterization measurements is introduced. A procedure for the measurement of antenna Array Factor (AF) is presented as the first phase of the introduced general measurement methodology. This measurement procedure is applied on a reference array prototype made for the evaluation of the proposed procedure. The results of the measurements are compared to those obtained both from theory and EM model simulation.

关键词： Antenna phased arrays

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Gesture-based video summarization

Gesture-based video summarization

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IEEE International Conference on Image Processing

作者： D.I. Kosmopoulos A. Doulamis N. Doulamis National Centre for Scientific Research Demokritos Institute of Informatics and Telecommunications Greece Department of Electrical and Computer Engineering National and Technical University of Athens Athens Greece

A novel method for summarizing videos of gestures is presented. The gestures performed by the hands and the head are extracted through skin color segmentation and represented through Zernike moments. The gesture energy is calculated using the norms of the Zernike moments and monitored through time for local minima and maxima that indicate distinctive visual events and thus key-frames. The proposed scheme is not threshold-dependent and therefore the number of extracted key-frames varies according to the complexity of gesture energy variation. The applicability of the method is verified experimentally in sign language videos.

关键词： Handicapped aids Head Data mining informatics Telecommunication computing Power engineering and energy Skin Monitoring Motion pictures Navigation

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Interaction Between GSM Handset Helical Antenna and User's Head: Theoretical Analysis and Experimental Results

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Environmentalist 2005年第2期25卷 215-221页

作者： A. Alexiou P. Kostarakis V. N. Christofilakis T. Zervos A. A. Alexandridis K. Dangakis C. Soras V. V. Petrović B. M. Kolundžija A. R. Dordević Physics Department University of Ioannina Ioannina Greece National Centre for Scientific Research “Demokritos” Institute of Informatics and Telecommunications Athens Greece Department of Electrical & Computer Engineering University of Patras Patras Greece Faculty of Electrical Engineering University of Belgrade Belgrade Serbia

The performance of a cellular phone commercial helical antenna at 900~MHz band, both in free space and in the presence of a human head phantom was studied. Numerical simulation of the phone model for the latter case has been performed giving 3D radiation diagrams. The effect of the phantom head on radiation diagrams is presented. The relative amount of the EM power absorbed in the head was obtained for several distances of the phone. Measurements were carried out in a RF anechoic chamber using standard horn antennas and a calibrated measuring system. Absolute radiation patterns of the antenna gain were obtained in the three principal planes. Significant reduction of the absorbed power could be achieved just by moving the phone 1 cm away from the head.

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Breakline detection embedded in a hybrid meshing scheme 31

Breakline detection embedded in a hybrid meshing scheme

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31st IAHR Congress 2005: Water engineering for the Future, Choices and Challenges

作者： Berkhahn, Volker Kaapke, Kai Rath, Sebastian Pasche, Erik Institute of Computer Science in Civil Engineering University of Hannover Callinstraße 34 Hannover30167 Germany Water Research Laboratory University of New South Wales King Street Sydney2093 Australia Department of River and Coastal Engineering University of Technology Hamburg Denickestraße 22 Hamburg21073 Germany

ISBN: (纸本)8987898245

In environmental and hydrodynamic engineering analysis, forecasts and assessments traditionally rely on measurements and experiments. In addition to this traditional approach, numerical simulations gained importance in the last decades. These numerical simulations are often based on the methods of finite elements, finite differences or finite volumes. For the application of these methods discrete element meshes of the considered topography are required. With respect to the applied method, these element meshes have to fulfil specific requirements regarding edge ratio, element angles and element size. In practice, these requirements vary between different areas of the domain. Therefore, a hybrid meshing scheme is presented by Rath et al. (2005) with the following key ideas: regular element meshes for river beds and slopes in order to specify edge ratio and element orientation;irregular triangle meshes for forelands. Element meshes have to approximate the topography with sufficient accuracy. All characteristic terrain features with an influence on the hydrodynamic behaviour have to be represented in the element meshes. Rath and Pasche (2004) and Rath et al. (2005) presented slope classification and breakline identification methods in detail. In this contribution the enhancements of these terrain feature analysis and the embedding in the hybrid meshing scheme are explained. The terrain analysis and meshing functionality is implemented in the software tool HybridMesh. © 31st IAHR Congress 2005: Water engineering for the Future, Choices and Challenges. All Rights Reserved.

关键词： Topography

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An e-learning system for improving learner study efficiency by stimulating learner volition

An e-learning system for improving learner study efficiency ...

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International Conference on Parallel and Distributed Systems (ICPADS)

作者： S. Takahama N. Nakamura L. Barolli A. Koyama A. Durresi K. Sugita Graduate School of Engineering Fukuoka Institute of Technology Fukuoka Japan Department of Information and Communication Engineering Fukuoka Institute of Technology Fukuoka Japan Department of Informatics Faculty of Engineering Yamagata University Yonezawa Yamagata Japan Department of Computer Science Louisiana State University Baton Rouge LA USA

Due to the opportunities provided by the Internet, more and more people are taking advantage of distance learning courses and during the last few years enormous research efforts have been dedicated to the development of distance learning systems. So far, many e-learning systems are proposed and used practically. However, in these systems the e-learning completion rate is about 30 percents. One of the reasons is the low study desire when the learner studies the learning materials. In this research, we propose an e-learning system, which includes three subsystems: the learning subsystem, learner support subsystem, and teacher support subsystem. The learning subsystem improves the learners study desire. The learner support subsystem supports the learner during the study, and the teacher support subsystem support the teacher to get the learner's study state. In the future work, we would like to add other functions to improve more the system performance.

关键词： Electronic learning computer aided instruction Electronic mail Internet computer science education informatics computer science System performance Control systems Costs

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A robust method for estimating multipath channel parameters in the uplink of a DS-CDMA system

A robust method for estimating multipath channel parameters ...

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IEEE Conference on Vehicular technology (VTC)

作者： V. Kekatos A.A. Rontogiannis K. Berberidis Department of Computer Engineering & Informatics and C.T.I.-Research and Development University of Patras Patras Greece Institute of Space Applications and Remote Sensing National Observatory of Athens Athens Greece

In this paper, the problem of estimating the multipath channel parameters of a new user entering the uplink of an asynchronous direct sequence-code division multiple access (DS-CDMA) system is addressed. The problem is described via a least squares (LS) cost function, which is non-linear with respect to the time delays and linear with respect to the gains of the multipath channel. This cost function is proved to be approximately decoupled in terms of the path delays, and thus an iterative procedure of one-dimensional searches turns out to be adequate for time delays estimation. The resulting method is computationally efficient and performs well even for a small number of training symbols. Simulation results show that the proposed technique offers a better estimation accuracy compared to existing related methods, and is robust to multiple access interference.

关键词： Robustness Parameter estimation Multipath channels Multiaccess communication Delay effects Cost function Delay estimation Least squares methods Least squares approximation Computational modeling

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