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5th International Latin American Networking Conference, LANC 2009

作者： De Pinho, Leonardo Bidese De Amorim, Claudio Luis Computer Engineering - Campus Bage UNIPAMPA - Federal University of Pampa P.O. Box 07 Bage RS 96400-970 Brazil COPPE - Systems Engineering Program UFRJ - Federal University of Rio de Janeiro P.O. Box 68.511 Rio de Janeiro RJ 21941-972 Brazil

ISBN: (纸本)9781605587752

In previous work we showed that Collocated Wireless Access Points coupled with appropriate management of their non-overlapping channels could be used for building Scalable Wireless Video-On-Demand (SWVoD) systems within a limited covered area. In this paper, we introduce the Grid of collocated Access Points or simply GAPS, a novel approach that uses clusters of Collocated Access Points as the basic blocks to efficiently build SWVoD systems for a wider covered area. In GAPS, each basic block is responsible for a distinct part of the covered area and the amount of APs per block can be set either statically or dynamically depending on the client concentration pattern (CCP). We present in details the framework of GAPS and report simulated performance results that indicated that GAPS could significantly decrease the blocking rate of video requests in comparison with previous design based on fixed distribution of basic blocks. In addition, GAPS had the advantage of sustaining the lower blockage rate over larger covered areas. Also, we showed that the higher setup cost of dynamic grids was fully compensated by handling changes on CCP much better than the static scheme so that GAPS could generate a higher monthly net income according to our cost metric. Copyright 2009 ACM.

关键词： Video on demand

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A neuromorphic head direction cell system

A neuromorphic head direction cell system

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IEEE International Symposium on Circuits and systems (ISCAS)

作者： Tarek M. Massoud Timothy K. Horiuchi Electrical and Computer Engineering Department Institute of Systems Research Neuroscience and Cognitive Science Program University of Maryland College Park MD USA

ISBN: (纸本)9781424438273

The head direction (HD) cell system in the brain of mammals is thought to be part of the neural circuitry supporting their spatial navigation capabilities. In this paper we present a neuromorphic VLSI system that mimics the operation of the HD system. Relying on spiking neurons and attractor dynamics, this system can be used to represent and retain the current estimate of head orientation in the environment and integrate angular velocity to update this estimate. The presented system is a first step towards more general odometry systems that could be used for modeling biological navigation systems.

关键词： Neuromorphics Neurons High definition video Navigation Very large scale integration Biological system modeling Brain Neuroscience Cognitive science Educational institutions

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Use of a step-response approximation for thermal transient modeling in power MOSFETs

Use of a step-response approximation for thermal transient m...

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ARFTG Conference

作者： Charles Baylis Joseph Perry Matthew Moldovan Robert J. Marks Lawrence Dunleavy Wireless and Microwave Circuits and Systems Program Department of Electrical and Computer Engineering Baylor University Waco Waco TX USA Center of Wireless and Microwave Information Systems Department of Electrical Engineering University of South Florida Tampa FL USA

In a previous ARFTG paper, we presented the measurement of the thermally-induced transient drain voltage response of a power Si MOSFET to a step excitation in gate voltage. The data was fit by assuming the drain voltage takes an exponential shape. This relies on the assumption that the drain current is a step function, which is actually only approximate due to the dependence of the drain current on temperature. In this work, we show that the exponential approximation actually possesses the same asymptotic behavior of a more accurate, model-based solution we have obtained that incorporates thermal feedback. We show that the more theoretically accurate solution and exponential approximation of the solution both provide excellent fits to measured data for the Si MOSFET.

关键词： MOSFETs Temperature Time measurement Electrothermal effects Thermal resistance Electrical resistance measurement Power measurement Voltage measurement Thermal engineering Power system modeling

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Comparison of threshold selection methods for microarray gene co-expression matrices

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BMC Research Notes 2009年第1期2卷 1-6页

作者： Borate, Bhavesh Chesler, Elissa Langston, Michael Saxton, Arnold Voy, Brynn Genome Science and Technology Program University of Tennessee Knoxville TN United States Department of Electrical Engineering and Computer Science University of Tennessee Knoxville TN United States Oak Ridge National Laboratory Systems Genetics Group Biosciences Division Oak Ridge TN United States Department of Animal Science University of Tennessee Knoxville TN United States

Background. Network and clustering analyses of microarray co-expression correlation data often require application of a threshold to discard small correlations, thus reducing computational demands and decreasing the number of uninformative correlations. This study investigated threshold selection in the context of combinatorial network analysis of transcriptome data. Findings. Six conceptually diverse methods - based on number of maximal cliques, correlation of control spots with expressed genes, top 1% of correlations, spectral graph clustering, Bonferroni correction of p-values, and statistical power - were used to estimate a correlation threshold for three time-series microarray datasets. The validity of thresholds was tested by comparison to thresholds derived from Gene Ontology information. Stability and reliability of the best methods were evaluated with block bootstrapping. Two threshold methods, number of maximal cliques and spectral graph, used information in the correlation matrix structure and performed well in terms of stability. Comparison to Gene Ontology found thresholds from number of maximal cliques extracted from a co-expression matrix were the most biologically valid. Approaches to improve both methods were suggested. Conclusion. Threshold selection approaches based on network structure of gene relationships gave thresholds with greater relevance to curated biological relationships than approaches based on statistical pair-wise relationships. © 2009 Saxton et al;licensee BioMed Central Ltd.

关键词： Spectral Cluster Maximal Clique Threshold Estimate Biological Relationship Spectral Graph

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GridRT: A Massively Parallel Architecture for Ray-Tracing Using Uniform Grids

GridRT: A Massively Parallel Architecture for Ray-Tracing Us...

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Euromicro Symposium on Digital System Design

作者： Alexandre Solon Nery Nadia Nedjah Felipe Maia Galvão Franca Systems Engineering and Computer Science Program Universidade Federal do Rio de Janeiro Brazil Department of Electronics Engineering and Telecommunications Universidade do Estado do Rio de Janeiro Brazil

In this paper, we propose an architecture, which we call GridRT, capable of dealing with the main features, such as shadows and reflections effects, of Ray Tracing used for rendering three-dimensional scenes. This architecture achieves an efficient overall performance yet using a simple and compact massively parallel design. The design exploits the usage of Xilinx ® Floating Point Operator IP Core and the spatial data structure of Regular Grids.

关键词： Parallel architectures Ray tracing Layout computer architecture Rendering (computer graphics) Optical reflection Data structures computer graphics Pipelines Pixel

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Modeling considerations for GaN HEMT devices

Modeling considerations for GaN HEMT devices

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IEEE Annual Conference on Wireless and Microwave Technology (WAMICON)

作者： Charles Baylis Lawrence Dunleavy Rick Connick Wireless and Microwave Circuits and Systems Program Department of Electrical and Computer Engineering Baylor University Waco TX USA Center of Wireless and Microwave Information Systems Department of Electrical Engineering University of South Florida Tampa FL USA Modelithics Inc. Tampa FL USA

The success of simulation-based design of power amplifiers for wireless communications is limited by the accuracy of nonlinear models that are used to represent the transistors. This paper provides some considerations that should be taken into account in measurement-based modeling of GaN transistors. With GaN modeling, particular attention needs to be paid to thermal and trapping issues. The use of pulsed measurements as part of the modeling process is critical to obtaining reliable GaN models. Established models such as EEHEMT, Angelov, and CFET can be successfully used in representing GaN devices.

关键词： Gallium nitride HEMTs Pulse measurements Equations Power system modeling Current measurement Power measurement Microwave devices Power amplifiers Testing

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Duty cycle dependent pulsed IV simulation and thermal time constant model fitting for LDMOS transistors

Duty cycle dependent pulsed IV simulation and thermal time c...

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ARFTG Conference

作者： Sivalingam Somasundaram Meena Charles Baylis Lawrence Dunleavy Marvin Marbell Center of Wireless and Microwave Information Systems Department of Electrical Engineering University of South Florida Tampa FL USA Wireless and Microwave Circuits and Systems Program Department of Electrical and Computer Engineering Baylor University Waco TX USA Modelithics Inc. Tampa FL USA

A pulsed simulation approach is demonstrated for prediction of duty-cycle dependent thermal effects in transistors. Also a novel method is shown for fitting and/or validating electro-thermal models using pulsed IV measurements and pulsed IV simulations. A commercial LDMOS device is used to demonstrate the new methods. After extracting the thermal time constant, good agreement is achieved between measured and simulated pulsed IV results under a wide range of different pulse conditions including DC, very short (<0.1%) duty cycles, and varied pulse widths between these extremes. A three-pole electro-thermal equivalent circuit model was shown to improve the model data fitting for intermediate pulse widths.

关键词： Pulse measurements Space vector pulse width modulation Predictive models MOSFETs Thermal resistance Heating Pulse circuits Circuit simulation computer simulation Thermal engineering

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Hardware Architecture for Particle Swarm Optimization Using Floating-Point Arithmetic

Hardware Architecture for Particle Swarm Optimization Using ...

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International Conference on Intelligent systems Design and Applications (ISDA)

作者： Daniel M. Muñoz Arboleda Carlos H. Llanos Leandro dos_S. Coelho Mauricio Ayala-Rincón Department of Mechanical Engineering University of Brasilia Brasília Brazil Industrial and Systems Engineering Graduate Program Pontificial Catholic University of Paraná Curitiba Brazil Departments of Computer Science and Mathematics University of Brasilia Brasília Brazil

High computational cost for solving large engineering optimization problems point out the design of parallel optimization algorithms. Population based optimization algorithms provide parallel capabilities that can be explored by their implementations done directly in hardware. This paper presents a hardware implementation of particle swarm optimization algorithms using an efficient floating-point arithmetic which performs the computations with high precision. All the architectures are parameterizable by bit-width, allowing the designer to choose the suitable format according to the requirements of the optimization problem. Synthesis and simulation results demonstrate that the proposed architecture achieves satisfactory results obtaining a better performance in therms of elapsed time than conventional software implementations.

关键词： Hardware Particle swarm optimization Floating-point arithmetic computer architecture Design optimization Computational efficiency Design engineering Algorithm design and analysis High performance computing Computational modeling

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AAAI 2008 workshop reports

AAAI 2008 workshop reports

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作者： Anand, Sarabjot Singh Bunescu, Razvan Carvcdho, Vitor Chomicki, Jan Conitzer, Vincent Cox, Michael T. Dignum, Virginia Dodds, Zachary Dredze, Mark Furcy, David Gabrilovich, Evgeniy Göker, Mehmet H. Guesgen, Hans Hirsh, Haym Jannach, Dietmar Junker, Ulrich Ketter, Wolfgang Kobsa, Alfred Koenig, Sven Lau, Tessa Lewis, Lundy Matson, Eric Metzler, Ted Mihalcea, Rada Mobasher, Bamshad Pineau, Joelle Poupart, Pascal Raja, Anita Ruml, Wheeler Sadeh, Norman Shani, Guy Shapiro, Daniel Smith, Trey Taylor, Matthew E. Wagstaff, Kiri Walsh, William Zhou, Rong Department of Computer Science University of Warwick United Kingdom School of Electrical Engineering and Computer Science Ohio University United States Microsoft Live Labs United States computer science and engineering University at Buffalo United States Computer science and economics Duke University United States Intelligent Computing group of BBN Technologies Utrecht University Netherlands Department of Computer science Harvey Mudd College United States University of Pennsylvania United States University of Wisconsin United States Yahoo Research PricewaterhouseCoopers Center for Advanced Research United States Department of Computer science School of Engineering and Advanced Technology Massey University New Zealand Departent of Computer science Rutgers University United States Department of Computer Science Dortmund University of Technology. Germany ILOG Rotterdam School of Management Erasmus University Netherlands Donald Bren School of Information and Computer Sciences University of California Irvine United States Depatrment of Computer science University of Southern California United States IBM Almaden Research Center United States Department of Computer Information Technology Southern New Hampshire University United States Computer and Information Technology Program College of Technology Purdue University United States Hughes Program for Religion and Science Dialogue Oklahoma City University United States Department of Computer Science and Engineering University of North Texas United States School of Computing DePaul University United States Department of Computer Science McGill University Canada School of Computer Science University of Waterloo Canada Department of Software and Information Systems University of North Carolina Charlotte United States University of New Hampshire United States Microsoft Research Institute for the Study of Learning and Expertise Applied Reactivity Inc. United States NASA Ames Research Center Carnegie Mellon University West

AAAI was pleased to present the AAAI-08 Workshop program, held Sunday and Monday, July 13-14, in Chicago, Illinois, USA. The program included the following 15 workshops: Advancements in POMDP Solvers;AI Education Workshop Colloquium;Coordination, Organizations, Institutions, and Norms in Agent systems, Enhanced Messaging;Human Implications of Human-Robot Interaction;Intelligent Techniques for Web Personalization and Recommender systems;Metareasoning: Thinking about Thinking;Multidisciplinary Workshop on Advances in Preference Handling;Search in Artificial Intelligence and Robotics;Spatial and Temporal Reasoning;Trading Agent Design and Analysis;Transfer Learning for Complex Tasks;What Went Wrong and Why: Lessons from AI Research and Applications;and Wikipedia and Artificial Intelligence: An Evolving Synergy. Copyright © 2009, Association for the Advancement of Artificial Intelligence. All rights reserved.

关键词： Human robot interaction

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Time Series Mining Approach for Noninvasive Intracranial Pressure Assessment: An Investigation of Different Regularization Techniques

Time Series Mining Approach for Noninvasive Intracranial Pre...

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computer Science and Information engineering, CSIE, WRI World Congress on FLAGGED

作者： Shaozhi Wu Peng Xu Shadnaz Asgari Marvin Bergsneider Xiao Hu Biomedical Engineering Graduate Program Henry Samueli School of Engineering and Applied Science University of California Los Angeles USA Neural Systems and Dynamics Laboratory Department of Neurosurgery the David Geffen School of Medicine University of California Los Angeles USA School of Computer Science and Engineering University of Electronic Science and Technology Chengdu China

A data mining framework has been proposed to estimate intracranial pressure (ICP) non-invasively in our previous work. In the corresponding approach, the feature vector extracted from arterial blood pressure (ABP) and flow velocity (FV) is translated to the estimated errors by the mapping function for each entry in the database. In this paper, three different mapping function solutions, linear least squares (LLS), truncated singular value decomposition (TSVD) and standard Tikhonov regularization (STR) are systemically tested to compare the possible effects of different solutions on the non-invasive ICP estimation. The conducted comparison demonstrated that the selection of mapping function solution actually influences the estimation. Among the tested three solutions for mapping function, TSVD and STR show better ICP estimation performance with smaller ICP errors than LLS.

关键词： Cranial pressure Data mining Biomedical engineering Data engineering Spatial databases computer science Feature extraction Arterial blood pressure Biomedical measurements Laboratories

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