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American Control Conference (ACC)

作者： S. Lall C. Beck G. Dullerud Control and Dynamical Systems California Institute of Technology Pasadena CA USA Department of Electrical Engineering University of Pittsburgh Pittsburgh PA USA Department of Applied Mathematics University of Waterloo Waterloo Canada

Techniques are presented for the model reduction of linear time-varying and linear periodically-varying systems, including the formulation and proof of guaranteed upper bounds for the error. The commonly used method of balanced truncation for linear time-invariant systems is generalized to the time-varying case with explicit error bounds that are derived based on generalizations of the 'twice-the-sum-of-the-tail' formula. The development of these reduction results for time-varying systems relies on a new operator framework for analysis of linear time-varying systems, presented in Dullerad and Lall (1997), in combination with the model reduction methods for uncertain systems developed in Beck et al. (1996).

关键词： Reduced order systems Time varying systems Stability Upper bound Ear Controllability Observability Riccati equations Linear matrix inequalities Periodic structures

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A fuzzy approach to time-optimal control

A fuzzy approach to time-optimal control

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1998 IEEE International Conference on Fuzzy Systems, FUZZY 1998

作者： Kulczycki, Piotr Koczy, Laszlo T. Faculty of Electrical Engineering Cracow University of Technology ul.Warszawska 24 Cracow31-155 Poland Faculty of Applied Mathematics Academy of Mining and Metallurgy al. Mickiewicza 30 Cracow30-059 Poland Department of Telecommunications and Telematics Technical University of Budapest Sztoczek U.2 BudapestH-1521 Hungary

ISBN: (纸本)078034863X

The paper concerns the time-optimal control of objects described by a differential equation representing the second law of Newtonian mechanics and taking into account a discontinuous model of resistances to motion. Such a task has broad technical applications, especially in robotics. A fuzzy approach is used to design a suboptimal closed-loop control structure, convenient in practice thanks to its many advantages, especially in respect to robustness. © 1998 IEEE.

关键词： Differential equations

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Improved lightpath (wavelength) routing in large WDM networks

Improved lightpath (wavelength) routing in large WDM network...

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International Conference on Distributed Computing Systems

作者： Weifa Liang G. Havas Xiaojun Shen Department of Mathematics University of Queensland QLD Australia Centre for Discrete Mathematics and Computing Department of Computer Science and Electrical Engineering University of Queensland QLD Australia Computer Science Telecommunications Program University of Missouri Kansas City Kansas City USA

We address the problem of efficient circuit switching in wide area networks. The solution provided is based on finding optimal routes for lightpaths and semilightpaths. A lightpath is a fully optical transmission path, while a semilightpath is a transmission path constructed by chaining several lightpaths together, using wavelength conversion at their junctions. The problem thus is to find an optimal lightpath/semilightpath in the network in terms of the cost of wavelength conversion and the cost of using the wavelengths on links. We first present fast, efficient algorithms both for the general problem and for a natural restricted version. The new algorithms outperform earlier work, providing time improvements amounting to an almost linear time factor in most cases. Also, all our algorithms can be implemented on the network in a distributed way.

关键词： Wavelength routing Intelligent networks WDM networks Optical wavelength conversion Biomedical optical imaging Optical fiber networks Costs High speed optical techniques Bandwidth mathematics

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A fuzzy approach to time-optimal control

A fuzzy approach to time-optimal control

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IEEE International Conference on Fuzzy Systems (FUZZ-IEEE)

作者： P. Kulczycki L.T. Koczy Faculty of Applied Mathematics Academy of Mining and Metallurgy Cracow Poland Faculty of Electrical Engineering Cracow University of Technology Cracow Poland Department of Telecommunications and Telematics Technical University of Budapest Budapest Hungary

关键词： Fuzzy control Differential equations Adaptive control Telecommunication control Motion control Robust control Uncertainty Erbium Fuzzy systems Control systems

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Visualisation of heart rate variability data using topographic mappings

Visualisation of heart rate variability data using topograph...

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Computers in Cardiology (CinC)

作者： B. Raymond R.E. Bogner J. Mazumdar M.F. Hilton Dept. of Electr. & Electron. Eng. Adelaide Univ. SA Australia Department of Electrical & Electronics Engineering University of Adelaide Australia Department of Applied Mathematics University of Adelaide Australia Department of Respiratory Physiology Birmingham Heartlands Hospital UK

Sammon's (1969) nonlinear mapping is applied to the visualisation of heart rate variability (HRV) spectral data. The mapping provides a graphical depiction of the relationships between the HRV spectra, and does not require the explicit subdivision of the spectra into the traditional low- and high-frequency fixed bands. Application of the mapping technique to HRV from physiological and pharmacological interventions and a cohort of sleep apnoea patients produced logical representations of the data sets. The method has application to the visualisation of a wide variety of biomedical signal data.

关键词： Data visualization Heart rate variability Frequency Signal mapping Signal processing Heart rate Euclidean distance Data engineering Information processing mathematics

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Providing multicast services in ATM switching. A solution for local area environments

Providing multicast services in ATM switching. A solution fo...

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Mediterranean Electrotechnical Conference (MELECON)

作者： J. Malgosa-Sanahuja J. Garcia-Haro C. Marin-Lasheras Dept. of Electr. Eng. & Commun. Zaragoza Univ. Spain Department of Applied Mathematics and Telematics Polytechnic University of Catalonia Barcelona Spain Department of Electrical Engineering and Communications Telematics Area Superior Polytechnic Center University of Zaragoza Zaragoza Spain

Most of the services that an ATM broadband integrated services digital network (B-ISDN) has to provide have a multicast and broadcast nature. For this type of services, a source of traffic transmits information to multiple destinations. In consequence, the ATM switching nodes have to support multi-point connections and therefore require some mechanism to allow the replication of ATM multicast cells to subsequently route them. A novel ATM switching architecture providing multicast capabilities is presented. This ATM switch operates in a very simple manner and achieves a notable reduction in the hardware complexity. However, the system becomes unstable for some range of operation values. To increase the stability margin of the system, along with the incorporation of speed-up techniques, a new cell selection policy adaptive to the input traffic is proposed. This cell selection algorithm improves the switch performance under bursty traffic and keeps low the hardware cost. Finally, the performance of the entire system is evaluated by using computer simulation.

关键词： Asynchronous transfer mode Switches Hardware Traffic control Computer architecture Telematics B-ISDN Stability Multicast algorithms Costs

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Robust Adaptive Control of Passive Systems with Unknown Disturbances

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IFAC Proceedings Volumes 1998年第17期31卷 841-846页

作者： Antonio Loria Elena Panteley Henk Nijmeijer Thor I. Fossen Dept. of Electrical Engineering University of California Santa Barbara CA 93106-9560 USA Faculty of Mechanical Engineering Technical University of Eindhoven P.O.Box 513 5600 MB Eindhoven The Netherlands Faculty of Applied Mathematics University of Twente P.O.Box 217 7500 AE Enschede The Netherlands Department of Engineering Cybernetics Norwegian Univ. of Sc. and Technology O.S. Bragstads plass 8 N 7034 Trondheim Norway

We address the problem of robust stabilisation of nonlinear systems affected by time-varying uniformly bounded affine perturbations. Our approach relies on the combination of sliding mode techniques and passivity-based control. Roughly speaking we show that under suitable conditions the sliding mode variable can be chosen as the output of the perturbed system in question. Then we show how to construct a controller which guarantees the global uniform convergence of the plant's outputs towards a time-varying desired reference, even in the presence of permanently exciting time-varying disturbances. As applications of our results we address the problems of tracking control of the van der Pol oscillator and ship dynamic positioning.

关键词： Passivity Mechanical systems Sliding mode Tracking control

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Thermally Activated Relaxation Time of a Single Domain Ferromagnetic Particle Subjected to a Uniform Field at an Oblique Angle to the Easy Axis: Comparison with Experimental Observations

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Physical Review Letters 1998年第25期80卷 5655-5655页

作者： W. T. Coffey D. S. F. Crothers J. L. Dormann Yu. P. Kalmykov E. C. Kennedy W. Wernsdorfer Department of Electronic & Electrical Engineering Trinity College Dublin 2 Ireland Department of Applied Mathematics & Theoretical Physics The Queen's University of Belfast Belfast BT7 1NN Northern Ireland Laboratoire de Magnétisme et d'Optique CNRS Université de Versailles 45 Avenue des États Unis 76088 Versailles Cédex France Institute of Radio Engineering & Electronics of the Russian Academy of Sciences Vvedensky Square 1 Fryazino 141120 Russia Laboratoire de Magnétisme Louis Néel CNRS BP166 38042 Grenoble Cedex 09 France

New asymptotes of the relaxation time of the magnetic moment of a single domain particle with a uniform magnetic field applied at an oblique angle to the easy axis (in excellent agreement with exact numerical results from the Fokker-Planck equation for the Néel-Brown model) are used to model the experimental angular variation of the switching field for individual Co and BaFeCoTiO particles. Good agreement is obtained, justifying the Néel-Brown (in effect, the Kramers) conception of the superparamagnetic relaxation process and allowing one to deduce the value of the damping constant (hitherto almost unknown).

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An adaptive finite element procedure for the image segmentation problem

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International Journal for Numerical Methods in Biomedical engineering 1998年第7期14卷

作者： Fiana S. Yaacobson Dan Givoli Applied Mathematics Program Department of Aerospace Engineering Technion–Israel Institute of Technology Haifa 32000 Israel Department of Aerospace Engineering Technion-Israel Institute of Technology Haifa 32000 Israel

The image segmentation problem in computer vision is considered. Given a two-dimensional domain D and a function defined on it (the original image), the problem is to obtain a ‘cartoon’ associated with this function, namely to find a set of inner boundaries which divide D into subdomains (objects) in an optimal way. The optimality criterion used here is given by the Mumford–Shah (MS) and Blake–Zisserman model, which leads to a strongly non-linear problem. Related problems appear in multiphase continuum mechanics. An iterative procedure based on an h -adaptive finite element method is proposed for the solution of this problem. The mesh adaptivity enables an efficient solution technique, with the use of basic coarse discretization and a few local regions of high resolution where needed. © 1998 John Wiley & Sons, Ltd.

关键词： segmentation finite elements adaptive image

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Low-and-high gain design technique for linear systems subject to input saturation —a direct method

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International Journal of Robust and Nonlinear Control 1998年第12期7卷

作者： Zongli Lin Ali Saberi Department of Applied Mathematics and Statistics State University of New York at Stony Brook Stony Brook NY 11794-3600 U.S.A. School of Electrical Engineering and Computer Science Washington State University Pullman WA 99164-2752 U.S.A.

The low-and-high gain design technique, which was initiated for a chain of integrators and completed for general linear asymptotically null controllable with bounded controls systems, was conceived for semi-global control problems beyond stabilization and was related to the performance issues such as semi-global stabilization with enhanced utilization of the available control capacity and semi-global disturbance rejection. Although the low-and-high gain design technique, as initiated for a chain of integrators, is based on an explicit eigenstructure assignment algorithm, its full development is based on the solution of an algebraic Riccati equation (ARE) which is paramterized in an arbitrarily small scalar, called low gain, parameter. In this paper, we develop a new complete low-and-high gain design procedure which is based on an explicit eigenstructure assignment algorithm. The new design approach avoids the solution of the numerically stiff parametrized ARE. © 1997 by John Wiley & Sons, Ltd.

关键词： actuator saturation bounded control low-and-high gain disturbance rejection

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