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2010 7th International Conference on the European Energy Market, EEM 2010

作者： El-Mabruk Saad, Yousef Ponnambalam, K. El-Shatshat, R.A. Department of Electrical and Computer Eng. University of Waterloo Waterloo ON N2L 3G1 Canada Systems Design Engineering Departmnet University of Waterloo Waterloo ON N2L 3G1 Canada

ISBN: (纸本)9781424468386

Recently in Ontario, Canada new installations of renewable distributed generation are being encouraged. Incentives are provided to producers directly by the government when energy is fed to the grid. This however has brought the attention of operators of local distribution companies to the issue of assuring the quality of supply to downstream customers when the grid receives this new and highly varying energy. As a result of these variations, the voltage may deviate from the standard levels. This paper investigates the impacts of installing a PV system, with considerable capacity compared to the network demand, on the voltage profile of an existing distribution network. Monte Carlo technique is applied focusing on the voltage profile by solving the steady state load flow model every 15-min time interval. A distribution system supplying a significant part of the region is considered as a case study. © 2010 IEEE.

关键词： Stochastic systems

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Convexification of optimal power flow problem

Convexification of optimal power flow problem

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Annual Allerton Conference on Communication, Control, and Computing

作者： Javad Lavaei Steven H. Low Department of Control and Dynamical Systems California Institute of Technology USA Computer Science and Electrical Engineering Departments California Institute of Technology USA

The optimal power flow (OPF) problem is nonconvex and generally hard to solve. We provide a sufficient condition under which the OPF problem is equivalent to a convex problem and therefore is efficiently solvable. Specifically, we prove that the dual of OPF is a semidefinite program and our sufficient condition guarantees that the duality gap is zero and a globally optimal solution of OPF is recoverable from a dual optimal solution. This sufficient condition is satisfied by standard IEEE benchmark systems with 14, 30, 57, 118 and 300 buses after small resistance (10 -5 per unit) is added to every transformer that originally assumes zero resistance. We justify why the condition might hold widely in practice from algebraic and geometric perspectives. The main underlying reason is that physical quantities such as resistance, capacitance and inductance, are all positive.

关键词： Optimized production technology Symmetric matrices Eigenvalues and eigenfunctions Transmission line matrix methods Resistance Null space

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Image synthesis using Conditional Random Fields

Image synthesis using Conditional Random Fields

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IEEE International Conference on Image Processing

作者： E. Ahmadi Z. Azimifar P. Fieguth Sh. Ayatollahi School of Electrical & Computer Engineering Shiraz University Shiraz Iran Systems Design Engineering University of Waterloo Waterloo Canada School of Petroleum & Chemical Engineering Shiraz University Shiraz Iran

Methods of scientific imaging and image analysis have become pervasive in a great variety of fields, including the properties of porous media. To study the large-scale morphological properties of porous media, high resolution random (Monte Carlo) samples are required. The purpose of this paper is to propose a novel approach for the statistical synthesis of scientific images, based on the concept of Conditional Random Fields. We explore two different sets of potential functions are used to model the pore-structure characteristics, and Monte Carlo Markov chain methods are also used to sample the high resolution images from the trained model. The resulting images are of high quality, and show the performance of the proposed framework.

关键词： Image resolution Media Pixel Image reconstruction Markov processes Computational modeling Imaging

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THREE DIMENSIONAL DEFECT RECONSTRUCTION USING STATE SPACE SEARCH AND WOODBURY’S SUBSTRUCTURE METHOD

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AIP Conference Proceedings 2010年第1期1211卷 790-797页

作者： X. Liu Y. Deng Y. Li L. Udpa S. S. Udpa aNDE Laboratory Department of Electrical and Computer Engineering Michigan State University East Lansing MI 48823 bElectrical Engineering University of Colorado Denver Denver CO 80217 cCadence Design Systems San Jose CA 95134

This paper introduces a model‐based approach to reconstruct the three‐dimensional defect profiles using eddy‐current heat exchanger tube inspection signals. The method uses a Woodbury’s substructure finite element forward model to simulate the underlying physics, a state space defect representation, and a tree search algorithm to solve the inverse problem. The advantage of the substructure method is that it divides the whole solution domain into two substructures and only the region of interest (ROI) with dramatic material changes will be updated in each iterative step. Since the number of elements inside the ROI is very small compared with the number of elements in the entire mesh, the computational effort needed in both LU factorization and coefficient matrix assembly is reduced. Therefore, the execution time is reduced significantly making the inversion very efficient. The initial inversion results are presented to confirm the validity of the approach.

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Spectral variation constrained power spectral density estimation for wideband spectrum sensing

Spectral variation constrained power spectral density estima...

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International Symposium on Applied Sciences on Biomedical and Communication Technologies, ISABEL

作者： Xiao Yu Wang Alexander Wong Shao-Yu Lien Department of Electrical and Computer Engineering University of Waterloo Waterloo Canada Department of Systems Design Engineering University of Waterloo Waterloo Canada Graduate Institute of Communication Engineering National Taiwan University Taipei Taiwan

In this paper, a novel power spectrum density (PSD) estimation approach is proposed for accurate and efficient wideband spectrum sensing in Cognitive Radio (CR) systems. Based on the observed signal from a wideband receiver, the goal of determining the fluctuation-free signal PSD is formulated as a constrained Bayesian estimation problem, subject to spectral variation constraints between neighboring spectral frequencies. The extracted signal PSD obtained using the proposed approach can then used in the energy detection process to make informed decisions with regards to the identification of free spectrum resources for opportunistic access by the CR. Experimental results using Monte Carlo simulations and real terrestrial digital TV (DTV) signal acquisitions show that the proposed approach allows for accurate PSD computation using wideband receivers under unknown noise and fluctuation conditions. Therefore, there is great potential for integrating the proposed method into existing energy detection methods for more accurate and efficient wideband spectrum sensing in CR systems under unknown noise and channel conditions.

关键词： Estimation Sensors Wideband Digital TV Cognitive radio Signal to noise ratio

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Fuzzy-Bayesian network approach to genre-based recommender systems

Fuzzy-Bayesian network approach to genre-based recommender s...

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IEEE International Conference on Fuzzy systems (FUZZ-IEEE)

作者： Soheila Ashkezari-T Mohammad-R. Akbarzadeh-T Department of Computer Engineering Cognitive Computing Laboratory Center of Applied Research on Soft computing and Intelligent systems Ferdowsi University of Mashhad Mashhad Iran Departments of Electrical Engineering and Computer Engineering Cognitive Computing Laboratory Center of Applied Research on Soft computing and Intelligent systems Ferdowsi University of Mashhad Iran

The World Wide Web has created a new media for mass marketing that can also be highly customized to online customers' needs and expectations. Recommender systems (RS) play an important role in this area. Here, we aim to establish a genre-based collaborative RS to automatically suggest and rank a list of appropriate items (movies) to a user based on the user profile and the past voting patterns of other users with similar tastes. The contribution of this paper is using genre based information in a hybrid fuzzy-Bayesian network collaborative RS. The interest to the different genres is computed based on a hybrid user model. The similarity of like-minded users according to the fuzzy distance and also Pearson correlation coefficient is involved in a Bayesian network.

关键词： Motion pictures Mathematical model Collaboration Recommender systems Equations Computational modeling

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An iterative approach to the robust H∞ synthesis problem with a sequence of infeasible controllers

An iterative approach to the robust H∞ synthesis problem wi...

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IEEE International Symposium on computer Aided Control System design (CACSD)

作者： Yasushi Kami Eitaku Nobuyama Department of Electrical and Computer Engineering Akashi National College of Technology Hyogo Japan Department of Systems Design and Informatics Kyushu Institute of Technology Fukuoka Japan

This paper aims to design a robust H ∞ control system against time invariant polytopic uncertainties. In general, such robust control problems are described by parameter dependent bilinear matrix inequality (PDBMI) problems which are not tractable numerically and there are few efficient methods for solving them. In this paper, we propose an iterative approach to the robust H ∞ controller synthesis problems, which constructs a sequence of infeasible controllers. The feature of our approach is to be able to use any controller variables which may not be a robust stabilizing controller as an initial point. The efficiency of our approach is shown by a numerical example.

关键词： Robustness Iterative methods Lyapunov method Linear matrix inequalities Symmetric matrices Eigenvalues and eigenfunctions Control systems

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An exterior-point approach to the robust regional pole placement control problem with fixed-order output feedback

An exterior-point approach to the robust regional pole place...

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International Conference on Modelling, Identification and Control (ICMIC)

This paper is concerned with the robust regional pole placement control problem against time invariant polytopic uncertainties. In this paper we propose an iterative approach to design a fixed-order output feedback controller achieving the robust regional pole placement. The features of our approach are to be able to use any controller variables as an initial point and to construct a controller sequence approaching a feasible region from the outside. Numerical examples are given to show the efficiency of our approach.

关键词： Robustness

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Multi-user diversity for secrecy in wireless networks

Multi-user diversity for secrecy in wireless networks

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Information Theory and Applications Workshop, ITA

作者： Sudarshan Vasudevan Stephan Adams Dennis Goeckel Zhiguo Ding Donald Towsley Kin Leung Computer Science Department University of Massachusetts Amherst MA USA Electrical and Computer Engineering Department University of Massachusetts Amherst MA USA Department of Communication Systems Lancaster University Lancaster UK Electrical and Electronic Engineering and Computing Departments Imperial College London London UK

The ability to transmit a message securely in the presence of eavesdroppers in a dense wireless network is considered. As with a number of recent schemes, system nodes other than the transmitter and receiver are chosen to generate noise that confuses the eavesdropper. By exploiting the dynamics of the fading, significantly improved performance is achieved beyond that generated from the standard multi-user diversity gain expected from opportunistic relaying. In particular, the node with the best fading characteristics takes responsibility for message relaying, while those whose fading will significantly reduce their impact on the desired communication play the role of noise generators. For a source transmitting to a destination using a set of intermediate relays, we consider the number of eavesdroppers that can be present without the interception of packets, in both the case where the eavesdroppers operate independently and in the case where they collude. The latter case also encompasses the more likely scenario of a single eavesdropper with a sophisticated receiver.

关键词： Wireless networks Relays Transmitters Fading Noise generators Interference cancellation Protocols Noise cancellation Jamming Diversity methods

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An accurate RTL power estimation considering power library unevenness

An accurate RTL power estimation considering power library u...

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IEEE International Symposium on Circuits and systems (ISCAS)

作者： Hirofomi Kawauchi Masanori Tsuzuki Ittetsu Taniguchi Masahiro Fukui Electrical Electronics and Computer Systems Course Graduate school of Science and Engineering Ritsumeikan University Kusatsu Shiga Japan Department of VLSI systems Design Ritsumeikan University Kusatsu Shiga Japan

Register transfer level power macro-modeling is a promising technique for accurate and efficient power estimation. This paper proposes an effective approach based on the table-based method of the RTL power macro-modeling. We propose the accurate table reference method which considers power library unevenness. The proposed method is applicable for various table-based estimation and outputs more proximal power value. The experimental results show the proposed methods reduces max error 46.48% in maximum for 8 benchmark circuits, comparing to conventional method. RMS (Root Mean Square) error is also improved 1.77% in maximum.

关键词： Libraries Table lookup Energy consumption Equations Data mining Parameter estimation Silicon compounds Tin Power engineering computing Educational institutions

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