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12th European Wireless Conference 2006 - Enabling Technologies for Wireless Multimedia Communications

作者： Ghadi Rayess Ioannis Tsirilakis Constantine G. Kakogiannis Antonis Kalis Athanassios G. Kanatas Philip Constantinou Athens Information Technology 19.5Km Markopoulo Ave. 19002 Greece Mobile Radio Communications Laboratory School of Electrical and Computer Engineering National Technical University of Athens 9 Iroon Polytechniou St. Zografos GR-157 73 Greece. Wireless Communications Laboratory Dept. of Technology Education & Digital Systems University of Piraeus 80 Karaoli & Dimitriou St. Piraeus GR-185 34 Greece

In this work, we present an event-based simulator for wireless networks using the Java programming language. Special focus has been placed on scalability and modularity of the implementation. Indeed, the new test-bed can support easily up to 10000 nodes; at the same time the different components interact with each other with well-defined interfaces permitting separate and independent modification. Even though the simulator can be used for any ad hoc wireless network, we have concentrated on the more energy-limited and constrained sensor networks. The supported physical model includes the use of directional antennas, enabling the switching of the antennas' lobe at will and the finding of direction of arrival (DoA) of the signal. Two variants of Aloha and one CSMA are the major MAC protocols implemented. At the network layer, emphasis was given on SPEED and its enhancements. Finally, the user is provided with a configuration file to set its inputs, an excel output file holding all the statistics of the simulation and an interactive GUI showing the flow of information across the sensor nodes. Finally, the simulator was tested in terms of speed and memory demands, and the results of our simulations were compared against those of other research groups.

关键词： Topology Baseband

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Enhanced UV emission by means of infrared optical pumping in UV light emitting diodes

Enhanced UV emission by means of infrared optical pumping in...

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43rd State-of-the-Art Program on Compound Semiconductors (SOTAPOCS XLIII)and Nitride and Wide Bandgap Semiconductors for Sensors, Photonics, and Electronics VI Symposium - 208th Meetingof the Electrochemical Society

作者： Batoni, P. Stokes, E.B. Leboeuf, S.F. Yang, N.V. Pagan, J.G. Hudgins, R.A. Electrical and Computer Engineering Dept. William States Lee College of Engineering The University of North Carolina at Charlotte 9201 University City Boulevard Charlotte NC 28223-0001 United States Center for Optoelectronics and Optical Communications Charlotte Research Institute University of North Carolina at Charlotte 9201 University City Boulevard Charlotte NC 28223-0001 United States Department of Physics and Optical Science College of Arts and Sciences University of North Carolina at Charlotte 9201 University City Boulevard Charlotte NC 28223-0001 United States GE Global Research General Electric Company Semiconductor Technology Lab One Research Circle Niskayuna NY 12309-0008 United States Dot Metrics Technologies Inc. Charlotte Research Institute 9201 University City Blvd Charlotte NC 28223 United States

ISBN: (纸本)9781607685395

In this paper we report the effects on both forward current and light output in ultraviolet (UV) III-nitride light emitting diodes (LEDs) optically pumped with mid-IR radiation. Furthermore, we demonstrate an enhanced UV light emission in the ultraviolet LEDs optically pumped at low bias in the mid-IR range, and we investigate their emission, and optoelectronic behavior at low temperature. © 2005 The Electrochemical Society.

关键词： Light emitting diodes

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Control of Communication Networks Using Infinitesimal Perturbation Analysis of Stochastic Fluid Models

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Lecture Notes in Control and Information Sciences 2005年 308卷 1-26页

作者： Panayiotou, Christos Cassandras, Christos G. Sun, Gang Wardi, Yorai Dept. of Electrical and Computer Engineering University of Cyprus Nicosia Cyprus Dept. of Manufacturing Engineering Center for Information and Systems Engineering Boston University Brookline MA 02446 United States School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA 30332 United States

ISBN: (纸本)3540228195

Managing and operating large scale communication networks is a challenging task and it is only expected to get worse as networks grow larger. The difficulties associated with network management stem from the fact that modeling and analysis of large scale communication networks is an excessively difficult task. On one hand, the enormous traffic volume in today's Internet makes packet-by-packet analysis infeasible. On the other hand, queueing systems (the natural modeling framework for packet-based communication networks) are largely based on Poisson processes and does not capture the bursty nature of realistic traffic. Moreover, the discovery of self-similar patterns in the Internet traffic distribution [1] and the resulting inadequacies of Poisson traffic models [2] further complicate queueing analysis. At the same time we need to account for the fact that the stochastic processes involved are time-varying, i.e., no stationarity assumptions hold. In addition, we need to explicitly model buffer overflow phenomena which typically defy tractable analytical derivations. Consequently, performance analysis techniques that do not depend on detailed traffic distributional information are highly desirable. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Telecommunication networks

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Usability and Interoperability of IEC 61499 based distributed automation systems

Usability and Interoperability of IEC 61499 based distribute...

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IEEE International Conference on Industrial Informatics (INDIN)

作者： Christoph Sunder Alois Zoitl James H. Christensen Valeriy Vyatkin Robert W. Brennan Antonio Valentini Luca Ferrarini Thomas Strasser Jose L. Martinez-lastra Franz Auinger Automation and Control Institute (ACIN) Vienna University of Technology Vienna Austria Holobloc Inc. Cleveland Heigths OH USA Dept. of Electrical and Computer Engineering The University of Auckland Auckland New Zealand Schulich School of Engineering University of Calgary Calgary Alberta Canada Centro di Ricerca e Innovazione Tecnologica Crit Srl Vignola (Mo) Italy Dipartimento di Elettronica e Informazione Politecnico di Milano Milano Italy Robotics and Adaptive Systems PROFACTOR Produktionsforschungs GmbH Steyr-Gleink Austria Institute of Production Engineering Tampere University of Technology Tampere Finland Upper Austrian University of Applied Science Automation Engineering University of Applied Science Wels Austria Automation Engineering Upper Austrian University of Applied Science Wels Austria

Since IEC 61499 has reached the state of an international standard and a substantial body of research results exists the question of the authors as main intention for this paper was: Do the models of IEC 61499 solve all problems when thinking of usability and interoperability in heterogeneous system environments? The main problems discussed within the paper concern to the execution model defined for basic function blocks and the scheduling of events within function block networks.

关键词： Usability IEC standards Automation Software tools Control systems Automatic control Robots Adaptive systems Production engineering Job shop scheduling

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Hybrid sensor networks: A small world

Hybrid sensor networks: A small world

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MOBIHOC 2005: 6th ACM International Symposium on Mobile Ad Hoc Networking and Computing

作者： Sharma, Gaurav Mazumdar, Ravi Center for Wireless Systems and Applications School of Electrical and Computer Engineering Purdue University Dept. of Electrical and Computer Engineering University of Waterloo

In this paper, we investigate the use of limited infrastructure, in the form of wires, for improving the energy efficiency of a wireless sensor network. We call such a sensor network - a wireless sensor network with a limited infrastructural support - a hybrid sensor network. The wires act as short cuts to bring down the average hop count of the network, resulting in a reduced energy dissipation per node. Our results indicate that adding a few wires to a wireless sensor network can not only reduce the average energy expenditure per sensor node, but also the non-uniformity in the energy expenditure across the sensor nodes. Copyright 2005 ACM.

关键词： computer networks

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Usability research challenges for cyberinfrastructure and tools

Usability research challenges for cyberinfrastructure and to...

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Conference on Human Factors in Computing systems, CHI EA 2006

作者： Procter, Rob Borgman, Christine Bowker, Geof Jirotka, Marina Olson, Gary Pancake, Cherri Rodden, Tom Schraefel, M.C. National Centre for E-Social Science Manchester University Manchester M13 9PL United Kingdom Dept. of Information Studies University of California Los Angeles CA 90095-1520 United States Center for Science Technology and Society Santa Clara University Santa Clara CA 95053-0470 United States Computing Laboratory Oxford University Oxford OX1 3QD United Kingdom Dept of Psychology University of Michigan Ann Arbor MI 48109-1092 United States School of Electrical Engineering and Computer Science Oregon State University Corvallis OR 97331-5501 United States School of Comp. Sc. and IT University of Nottingham Nottingham NG8 1BB United Kingdom School of Electronics and Comp Sci. University of Southampton Southampton SO17 1BJ United Kingdom

We summarize the motivation and aims for this workshop on usability research challenges for cyberinfrastructure and tools, and outline workshop preparations and program.

ISBN: (纸本)1595932984

We summarize the motivation and aims for this workshop on usability research challenges for cyberinfrastructure and tools, and outline workshop preparations and program.

关键词： Collaboration Cyberinfrastructure Cybertools E-Science Grid Usability Virtual organizations

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Diversity performance of multi-code multi-carrier CDMA communications systems

Diversity performance of multi-code multi-carrier CDMA commu...

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2005 International Conference on Wireless Networks, Communications and Mobile Computing

作者： Ugweje, Okechukwu C. Lee, Jinwoo Efthymoglou, George Dept. of Electrical and Computer Engineering University of Akron Akron OH 44325 Dept. of Technology Education and Digital Systems University of Piraeus Greece

ISBN: (纸本)0780393058

A communication system combining multi-code and multi-carrier techniques is analyzed in this paper. The system is denoted as Multi-Code Multi-Carrier CDMA (MC/MC-CDMA). The analytical framework is presented and system performance is evaluated by means of Bit Error Rate (BER) for different system parameters and diversity techniques. The system is suitable for multi-rate services that use multi-codes and high data rate transmissions that employ multi-carriers, as it is proposed for the future generation wireless systems. The effect of changing the number of codes, carriers, users and diversity branches on system performance is investigated. Furthermore, the derived BER expressions quantify the amount of performance improvement achieved by using different diversity schemes. © 2005 IEEE.

关键词： Code division multiple access

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Estimation of phase constrained mimo transfer functions with application to flexible structures with mixed collocated and non-collocated actuators and sensors

Estimation of phase constrained mimo transfer functions with...

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作者： McKelvey, Tomas Moheimani, S. O. Reza Dept. of Signals and Systems Chalmers University of Technology SE-412 96 Gothenburg Sweden Dept. of Electrical and Computer Engineering University of Newcastle Newcastle Australia

ISBN: (纸本)008045108X

A computational scheme is proposed to estimate a state-space representation of MIMO transfer functions from frequency response measurements. The approach can constrain the phase curve of selected elements of the transfer function matrix to certain regions. Poles of the system are determined using a frequency domain subspace approach. The phase constraint is enforced by an LMI formulation based on the positive real lemma when the zeros of the system are estimated. The successful application of the algorithm to measurements from a cantilever beam with three collocated piezoelectric actuator/sensor pairs is demonstrated. Copyright © 2005 IFAC.

关键词： Transfer functions

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Discrete control for visual servoing the ODIS robot to parking lot lines

Discrete control for visual servoing the ODIS robot to parki...

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2005 IEEE International Conference on Robotics and Automation

作者： Berkemeier, Matthew D. Ma, Lili Dept. of Electrical and Computer Engineering Center for Self-Organizing and Intelligent Systems Utah State University Logan UT 84322-4120

ISBN: (纸本)078038914X

This paper contains 3 new contributions to our previous work: First, a continuous visual servoing model for the ODIS omni-directional robot is extended to consider rotation about the robot center, instead of the camera center. This is shown to lead to an undesirable limit cycle due to a Hopf bifurcation. Second, 2 new discrete controllers and models for visual servoing ODIS are derived, which are closer to the servoing methods used in experiments. It is shown that the resulting closed-loop systems are locally asymptotically stable. Finally, experiments are presented which demonstrate successful discrete visual servoing. ©2005 IEEE.

关键词： Mobile robots

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Self-organizing running in a quadruped robot model

Self-organizing running in a quadruped robot model

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2005 IEEE International Conference on Robotics and Automation

作者： Berkemeier, Matthew D. Sukthankar, Pranav Dept. of Electrical and Computer Engineering Center for Self-Organizing and Intelligent Systems Utah State University Logon UT 84322-4120

ISBN: (纸本)078038914X

In this paper it is demonstrated that pronking (or trotting or pacing) is the preferred mode of behavior of a fairly generic quadruped model. This gait often occurs even though no explicit control is used to force it, and thus the system is said to "self-organize." Further, it is demonstrated that, despite the complicated coupled nonlinear dynamics, the system is still amenable to analysis if certain parameters are assumed small, namely the leg masses and the hip spring constants. Explicit conditions are presented for a symmetric pronk. In one condition, the leg length and the hip spring constant determine the pronking height, which has implications for quadruped robot design. © 2005 IEEE.

关键词： Robot programming

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