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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： O. Besson P. Stoica A.L.B. Gershman Department of Avionics and Systems ENSICA Toulouse France Department of Systems and Control University of Uppsala Uppsala Sweden Department of Electrical and Computer Engineering McMaster University Hamilton Canada

We consider the direction-of-arrival (DOA) problem for a wavefront whose amplitude and phase vary randomly along the array aperture. This phenomenon can for instance originate from propagation through an inhomogeneous medium. A simple and accurate DOA estimator is derived in the case of an uniform linear array of sensors. The estimator is based upon a reduced statistic obtained from the sub-diagonals of the covariance matrix of the array output. It only entails computing the Fourier transform of an (m-1)-length sequence where m is the number of array sensors. A theoretical expression for the asymptotic variance of the estimator is derived. Numerical simulations validate the theoretical results and show that the estimator has an accuracy very close to the Cramer-Rao bound.

关键词： Spatial coherence Sensor arrays Direction of arrival estimation Phased arrays Apertures Sensor phenomena and characterization Statistics Covariance matrix Fourier transforms Numerical simulation

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Recurrent neuro-fuzzy modeling of a biotechnological process

Recurrent neuro-fuzzy modeling of a biotechnological process

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European control Conference (ECC)

作者： G. I. Sainz M. J. Fuente P. Vega Department of Systems Engineering and Control University of Valladolid Science Faculty Valladolid Spain Department of Computer Sciences and Control University of Salamanca Béjar Salamanca Spain

This paper deals with the develop of a new recurrent neuro-fuzzy model for complex systems from input-output data. In this paper a recurrent fuzzy neural network, called RFasArt (Recurrent FasArt), has been applied to model a complex biotechnological process: a wastewater treatment plant. This network is based on the Adaptative Resonance Theory (ART) but introducing formalisms from the fuzzy set theory and taking into account the contextual information in its processing stage. In order to compare the results obtained with this fuzzy neural network, a classical recurrent neural network has been implemented and used to model the same process. The results shows the better behaviour of the RFasArt system. At the same time with this architecture it is possible to obtain a knowledge base of fuzzy rules where is stored all the knowledge of the plant learned by the fuzzy neural network.

关键词： Biomass Substrates Wastewater treatment Biological system modeling Mathematical model Modeling Subspace constraints

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SAR image construction from gapped phase-history data

SAR image construction from gapped phase-history data

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IEEE International Conference on Image Processing

作者： E.G. Larsson P. Stoica Jian Li Department of Systems and Control University of Uppsala Uppsala Sweden Department of Systems and Control the SwedishFoundation for Stmtegic Research SSF Uppsala University Uppsala Sweden Department of Electrical and Computer Engineering University of Florida Gainesville FL USA

We propose a method for estimating the amplitude spectrum of a 2D-signal from frequency domain (or phase history) data that contain gaps. This is a key problem in synthetic aperture radar (SAR) imaging with angular diversity. Our method is an extension of the well-known amplitude and phase estimation (APES) algorithm to the incomplete data case, and is called gapped-data APES (GAPES). It has recently been shown that APES minimizes a certain least-squares (LS) criterion, and our extension of APES is based on minimizing this criterion with respect to the missing data as well. We provide an example of the algorithm applied to SAR imaging from phase history data with angular diversity; and we also show the advantages of 2D data processing over 1D (row or column-wise) data processing that are enabled by our new algorithm.

关键词： Amplitude estimation Frequency estimation Phase estimation Noise level History Radar polarimetry Data processing Finite impulse response filter control systems Frequency domain analysis

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Assessment of the effects of wind farms connected in a power system

Assessment of the effects of wind farms connected in a power...

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Power Tech Conference

作者： M.A.B. Amora U.H. Bezerra NESC-Nucleus of Engineering in Supervision and Control of Systems Department of Electrical and Computer Engineering Federal University of Para Belem Para Brazil Department of Electrical and Computer Engineering Federal University of Para Belem Para Brazil

In this work, the authors present the results of transient stability studies, which are accomplished when assessing the effects of the connection of wind farms in a power system. For the execution of those studies, a software environment for stability simulation was developed in MATLAB/sup TM/ with a friendly user interface, that allows the execution of different cases studies, e.g. sudden disconnection of the wind farm or part of the wind farm, operation under turbulent wind, operation under wind gust, short circuits in the network, loss of conventional generation and reduction of loads. Results of simulation studies are shown to illustrate the use of the software developed and to evaluate the effects on the stability of a test power system, of the integration of a wind farm into the electric grid.

关键词： Wind farms Power systems Power system stability Power system simulation Power system transients Circuit stability Circuit simulation MATLAB User interfaces Wind energy generation

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A 2D systems approach to iterative learning control based on nonlinear adaptive control techniques

A 2D systems approach to iterative learning control based on...

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IEEE International Symposium on Circuits and systems (ISCAS)

作者： M. French E. Rogers H. Wibowo D.H. Owens Department of Electronics and Computer Science University of Southampton Southampton UK Department of Automatic Control and Systems Engineering University of Sheffield Sheffield UK

ISBN: (纸本)0780366859

We consider the iterative learning control problem from a 2D systems/adaptive control viewpoint. In particular, it is shown how some fundamental results from nonlinear adaptive control can be successfully applied in the iterative learning control domain under very weak assumptions. Some areas for further research are also briefly discussed.

关键词： Iterative methods Nonlinear control systems control systems Adaptive control Automatic control Iterative algorithms computer science systems engineering and theory Robots Manipulators

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2D sinusoidal amplitude estimation with application to 2D system identification

2D sinusoidal amplitude estimation with application to 2D sy...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Hongbin Li Wei Sun P. Stoica Jian Li Department of Electrical and Computer Engineering Stevens Institute of Technology Hoboken NJ USA Department of Systems and Control University of Uppsala Uppsala Sweden Department of Electrical and Computer Engineering University of Florida Gainesville FL USA

We previously studied amplitude estimation of one-dimensional (1D) sinusoidal signals from measurements corrupted by possibly colored observation noise (see Stoica, P. et al., IEEE Trans. on Sig. Proc., vol. 48, p.338-52, 2000). We extend those results for two-dimensional (2D) amplitude estimation. In particular, we investigate the 2D sinusoidal amplitude estimation within the general frameworks of least squares (LS), weighted least squares (WLS), and MAtched FIlterbank (MAFI) estimation. A variety of 2D amplitude estimators are presented, which are all asymptotically statistically efficient. The performances of these estimators in finite samples are compared numerically with one another. Making use of amplitude estimation techniques, we introduce a new scheme for 2D system identification, which is shown to be computationally simpler and statistically more accurate than the conventional output error method (OEM), when the observation noise is colored.

关键词： Amplitude estimation System identification Noise level Least squares approximation Colored noise Additive noise Frequency estimation Application software Sun control systems

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Object-oriented modeling for remote monitoring of manufacturing processes

Object-oriented modeling for remote monitoring of manufactur...

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International Conference on Emerging Technologies and Factory Automation (ETFA)

作者： M. Marcos I. Calvo D. Orive I. Sarachaga J.M. Fuertes P. Marti R. Villa S. Buzoianu Department of Automatic Control and Systems Engineering University of Basque Country (UPV-EHU) Bilbao Spain Dept. of Automatic Control and Systems Engineering University of the Basque Country Bilbao SPAIN Dept. of Automatic Control and Computer Engineering Technical University of Catalonia Barcelona SPAIN

ISBN: (纸本)0780372417

Deals with the use of object oriented technologies in the modeling of industrial plants that have to be remotely monitored and/or controlled. The main goal is to propose a design methodology for obtaining the model of the so-called Virtual Plant, that a remote and certified user will use to access the real plant for performing command actions and/or monitoring. The type of applications and systems targeted must have autonomous behavior and be interconnected and accessible. Reliability, maintainability and flexibility are also required goals, as well as a high rate of reusability of the applications. The methodology has been applied to the remote process monitoring and control of manufacturing processes. The Virtual Plant Model is, in fact, the part of the plant that can be accessed by a certified remote client and thus it can be constituted by a set of sub-models, as many as different types of clients. The Virtual Plant resides inside the Application Server who is responsible of communicating with the cell controller and sends the image of the actual plant state (the Virtual Plant) as required by the remote client (monitoring) or sends the client commands to the cell controller.

关键词： Object oriented modeling Remote monitoring Manufacturing processes Automatic control Internet Process control systems engineering and theory Paper technology Industrial plants computerized monitoring

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Skid to turn control of the APKWS missile using trajectory linearization technique

Skid to turn control of the APKWS missile using trajectory l...

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American control Conference (ACC)

作者： M.C. Mickle J.J. Zhu Guidance Navigationa and Control Department Ratheon Missile Systems USA School of Electrical Engineering and Computer Science Ohio University USA

This paper presents the design and simulation results of an autopilot for the US Army's APKWS missile. The concept is to add on a guidance section to the existing Hydra 70 unguided rocket airframe. The guidance section is to be mounted onto existing hardware using a deroll bearing which permits the motor to roll freely while the guidance section is roll stabilized. The Hydra 70 has unusual dynamic and aerodynamic characteristics, which include a very large intentional induced roll moment which is heavily influenced by down wash effects on the rear spin inducing fins from large aerodynamic angles and the displacement of the control canards. Moreover, angle of attack tracking with control canards makes the problem nonminimum phase. The autopilot consists of a nonlinear inverse subsection which places the missile on the nominal commanded trajectory, and a linear time varying trajectory regulating controller. The regulating controller is formulated using a new parallel differential eigenvalue stability concept. An advantage of the proposed design method is that the controller gains are computed symbolically such that a full flight envelope autopilot can be designed without resorting to pointwise gain scheduling. Simulation results are shown to demonstrate the effectiveness of the trajectory linearization control technique.

关键词： Missiles Aerodynamics Rockets Hardware Displacement control Eigenvalues and eigenfunctions Stability Design methodology Processor scheduling Computational modeling

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On some aspects of discrete equivalents of differential linear repetitive processes

On some aspects of discrete equivalents of differential line...

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IEEE Conference on Decision and control

作者： J. Gramacki A. Gramacki K. Galkowski E. Rogers D.H. Owens Department of Electronics and Computer Science University of Zielona Góra Poland Department of Electronics and Computer Science University of Southampton UK Department of Automatic Control and Systems Engineering University of Sheffield UK

ISBN: (纸本)0780370619

Differential linear repetitive processes are a distinct sub-class of 2D continuous-discrete linear systems which pose problems that cannot (except in a few very restrictive special cases) be solved by the direct application of standard (1D) systems theory and hence by the direct use of a large number of currently-available tools for computer-aided analysis/design. One such area is the construction of discrete approximations to their dynamics. In this paper, we investigate some problems which arise during the discretization of differential linear repetitive processes and develop solutions to them.

关键词： computer science Linear systems computer aided analysis Orbital robotics Robotics and automation Software engineering Automatic control systems engineering and theory Stability

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Robust /spl Hscr//sub /spl infin// filtering for uncertain discrete-time state-delayed systems

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IEEE Transactions on Signal Processing 2001年第8期49卷 1696-1703页

作者： R.M. Palhares C.E. de Souza P.L. Dias Peres Graduate Program in Electrical Engineering Pontifical Catholic University of Minas Gerais Belo Horizonte Brazil Department of Systems and Control Brazil School of Electrical and Computer Engineering State University of Campinas-UNICAMP Campinas Brazil

This paper addresses the problem of robust /spl Hscr//sub /spl infin// filtering for linear discrete-time systems subject to parameter uncertainties in the system state-space model and with multiple time delays in the state variables. The uncertain parameters are supposed to belong to a given convex bounded polyhedral domain. A methodology is developed to design a stable linear filter that assures asymptotic stability and a prescribed /spl Hscr//sub /spl infin// performance for the filtering error, irrespective of the uncertainty and the time delays. The proposed design is given in terms of linear matrix inequalities, which has the advantage in that it can be implemented numerically very efficiently.

关键词： Filtering Nonlinear filters Delay effects Uncertainty Noise robustness Uncertain systems Linear matrix inequalities Signal design Riccati equations Context modeling

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