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12th IFAC Symposium on Large Scale Systems: Theory and Applications, LSS 2010

作者： Ewald, Grzegorz Brdys, Mietek A. Department of Automatic Control Gdansk University of Technology ul. Narutowicza 11/12 80-233 Gdańsk Poland School of Electronic Electrical and Computer Engineering College of Engineering and Physical Sciences University of Birmingham Edgbaston Birmingham B15 2TT United Kingdom

ISBN: (纸本)9783902661913

control of the networked control systems is a crucial challenge. In the environment of shared communication media, data may be randomly delayed or even lost. As the shared communication links are used in the critical infrastructure systems, the problem becomes even more important. As opposed to network compensation, solutions presented in the paper integrate network with the controlled plant. The proposed networked control system employs the model predictive control technology and is based on the buffer in the actuator. Stability of the presented solution used to control a linear discrete time system is analyzed. A simulation example is also provided.

关键词： Networked control systems

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Modeling nonlinear medical ultrasound via a linearized contrast source method

Modeling nonlinear medical ultrasound via a linearized contr...

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作者： Demi, L. Verweij, M.D. De Jong, N. Van Dongen, K.W.A. Laboratory of Acoustical Imaging and Sound Control Faculty of Applied Sciences Delft University of Technology Netherlands Laboratory of Electromagnetic Research Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technology Netherlands Laboratory of Experimental Echocardiography Erasmus Medical Center Rotterdam Netherlands

ISBN: (纸本)9781457703829

Research on nonlinear medical ultrasound has been increased over the last decade and has resulted in a wide range of numerical methods for the modeling of the nonlinear distortion of a propagating pressure wave. However, when applied to realistic configurations, the majority of these methods are either computationally expensive or limited by the applied approximations. The Iterative Nonlinear Contrast Source (INCS) method is able to accurately compute the pulsed nonlinear pressure wave field that is generated in a large three-dimensional domain by an arbitrary transducer transmitting under a large steering angle. The method is based on the Neumann iterative solution of a nonlinear integral equation that is equivalent to the Westervelt equation. To improve the performance of the method, it would be beneficial to employ iterative schemes (e.g. Conjugate Gradient based schemes) that are efficient for solving linear integral equations. This motivates the development of a linearized version of the INCS method, as presented in this paper. To test the presented approach, a Bi-CGSTAB scheme is used to solve the linearized Westervelt equation. For the one-dimensional case, results are obtained and compared with the solution obtained with the original INCS method, and the Fubini solution. All the results have been obtained up to the third harmonic component and are in agreement with each other. © 2010 IEEE.

关键词： Numerical methods

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Modeling nonlinear acoustic wave fields in media with inhomogeneity in the attenuation and in the nonlinearity

Modeling nonlinear acoustic wave fields in media with inhomo...

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ISBN: (纸本)9781457703829

Biomedical tissues usually show inhomogeneity in their acoustic medium parameters. These inhomogeneities cause refraction and scattering of diagnostic and therapeutic ultrasound waves. A method that is able to model the effects of inhomogeneity in the attenuation and in the nonlinearity is essential for the design of transducers for new ultrasound modalities and the development of novel ultrasound applications. The Iterative Nonlinear Contrast Source (INCS) method has originally been designed for the accurate modeling of nonlinear acoustic wave fields in homogeneous media. It considers the nonlinear term from the Westervelt equation as a distributed contrast source, and the corresponding integral equation is solved using an iterative Neumann scheme. This paper presents an extension of the INCS method that can handle inhomogeneity in the attenuation and in the coefficient of nonlinearity. Results are presented for the one-dimensional case. These show that in this case the presented method correctly predicts the effects related to nonlinear propagation and scattering by inhomogeneities in the attenuation and the coefficient of non-linearity. © 2010 IEEE.

关键词： Integral equations

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High-performance sensorless vector control of induction motor drives using artificial intelligent technique

High-performance sensorless vector control of induction moto...

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International Conference on Methods and Models in Automation and Robotics (MMAR)

作者： Mokhtar Zerikat Abdelkader Mechernene Soufyane Chekroun Department of Electrical and Control Engineering Laboratory of Automatic and Systems Analysis ENSET of Oran Oran Algeria Department of Electrical Engineering University of Sciences and Technology Houari Boumediene Oran Algeria

This paper presents a sensorless speed observer method of an induction motor using an artificial intelligent technique in field-oriented control system. Speed and rotor flux are estimated from only measurable variables, the stator voltages and currents. The proposed estimation algorithm uses a deterministic state observer combined with an intelligent adaptive mechanism based on fuzzy logic, and using a knowledge base on human expertise. The introducing of fuzzy logic is applied to achieve high-performance, a low sensibility to parameter variations and external influences. The developed algorithm is robust and efficient, it also assures precise speed estimation, a good trajectory tracking with the different prescribed dynamics. In order to verify its performances test the behavior of the control algorithm, numerical simulations are achieved. The performances of the induction motor drive have been analyzed under steady state and transient conditions. The simulation results have shown a good estimate speed and flux and an excellent tracking performance of the proposed control system, and have demonstrated convincingly the usefulness of adaptive observer based on fuzzy logic in variable speed drives with high performance.

关键词： Observers Mathematical model Rotors Machine vector control Induction motor drives Torque

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An inventory of potentially habitable environments on Mars: Geological and biological perspectives

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Special Paper of the Geological Society of America 2011年 483卷 317-347页

作者： Dohm, J.M. Miyamoto, H. Ori, G.G. Fairén, A.G. Davila, A.F. Komatsu, G. Mahaney, W.C. Williams, J.-P. Joye, S.B. Di Achille, G. Oehler, D.Z. Marzo, G.A. Schulze-Makuch, D. Acocella, V. Glamoclija, M. Pondrelli, M. Boston, P. Hart, K.M. Anderson, R.C. Baker, V.R. Fink, W. Kelleher, B.P. Furfaro, R. Gross, C. Hare, T.M. Frazer, A.R. Ip, F. Allen, C.C.R. Kim, K.J. Maruyama, S. McGuire, P.C. Netoff, D. Parnell, J. Wendt, L. Wheelock, S.J. Steele, A. Hancock, R.G.V. Havics, R.A. Costa, P. Krinsley, D. Department of Hydrology and Water Resources University of Arizona Tucson AZ United States University Museum Tokyo Japan International Research School of Planetary Sciences Università d'Annunzio Pescara Italy Space Sciences and Astrobiology Division National Aeronautics and Space Administration Ames Research Center Moffett Field CA United States SETI Institute Mountain View CA United States Planetary Exploration Research Center Chiba Institute of Technology Chiba Japan Quaternary Surveys Toronto ON Canada Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA United States Ashima Research Pasadena CA United States Department of Marine Sciences University of Georgia Athens GA United States Laboratory for Atmospheric and Space Physics University of Colorado Boulder CO United States Astromaterials Research and Exploration Science NASA Johnson Space Center Houston TX United States Bay Area Environmental Research Institute Sonoma CA United States School of Earth and Environmental Sciences Washington State University Pullman WA United States Dipartimento Science Geologiche Università Roma Tre Rome Italy Geophysical Laboratory Carnegie Institution of Washington Carnegie WA United States Department of Earth and Environmental Science New Mexico Tech Socorro NM United States School of Chemical Sciences Dublin City University Dublin Ireland Jet Propulsion Laboratory California Institute of Technology Pasadena CA United States Division of Physics Mathematics and Astronomy California Institute of Technology Pasadena CA United States Departments of Electrical and Computer Engineering and Biomedical Engineering University of Arizona Tucson AZ United States Department of Aerospace and Mechanical Engineering University of Arizona Tucson AZ United States Institute of Geological Sciences-Planetary Sciences and Remote Sensing Freie Universität Berlin Malteserstrasse Berlin Germany U.S. Geological Survey Flagstaff

ISBN: (纸本)9780813724836

On Earth, biology, hydrology, and geology are interlinked such that certain types of life are often associated with specifi c conditions, including rock type, pressure, temperature, and chemistry. Life on Earth has established itself in diverse and extreme niches, presenting the possibility that Mars, too, may hold records of fossilized and/or extant life in diverse environments. Geologic, paleohydrologic, and climatic conditions through the evolution of Mars are similar in many respects to conditions occurring during the evolution of Earth and, as such, may point to environments on Mars with potential to have supported living systems. Here, we discuss examples of those Martian settings. Such extraterrestrial environments should be targeted by international robotic and/or manned missions to explore potential fossilized or extant life on Mars. © 2011 Geological Society of America.

关键词： Geology

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Disturbance and friction compensations in hard disk drives using neural networks

Disturbance and friction compensations in hard disk drives u...

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作者： Lai, Chow Yin Lewis, Frank L. Venkataramanan, Venkatakrishnan Ren, Xuemei Ge, Shuzhi Sam Liew, Thomas NUS Graduate School for Integrative Sciences and Engineering National University of Singapore Singapore 117456 Singapore Automation and Robotics Research Institute University of Texas at Arlington Fort Worth TX United States Data Storage Institute A STAR Singapore 117608 Singapore Department of Automatic Control Beijing Institute of Technology Beijing China Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore

In this paper, we show that by using two adaptive neural networks (NNs), each of which is tailored for a specific task, the tracking performance of the hard-disk-drive (HDD) actuator can be significantly improved. The first NN utilizes accelerometer signal to detect external vibrations and compensates for its effect on HDD position via feedforward action. The second NN is designed to compensate for pivot friction. The appealing advantage of the NN compensators is that the design does not involve any information on the plant, sensor, disturbance dynamics, and friction model. The stability of the proposed scheme is analyzed by the Lyapunov criterion. Experimental results show that the tracking performance of the HDDs can be improved significantly with the use of the NN compensators as compared to the case without compensation. © 2009 IEEE.

关键词： Tribology

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Model Predictive Direct Torque control of permanent magnet synchronous motors

Model Predictive Direct Torque Control of permanent magnet s...

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IEEE Energy Conversion Congress and Exposition, ECCE

作者： Tobias Geyer Giovanni A. Beccuti Georgios Papafotiou Manfred Morari Department of Electrical and Computer Engineering University of Auckland New Zealand ABB Corporate Research Center Baden-Dattwil Switzerland Automatic Control Laboratory Department of Information Technology and Engineering ETH Zurich Zurich Switzerland

Model Predictive Direct Torque control (MPDTC) is a recent computational control methodology that combines the merits of Model Predictive control (MPC) with the ones of Direct Torque control (DTC). Specifically, with respect to standard DTC, the converter's switching frequency and/or losses are considerably reduced, while at the same time the Total Harmonic Distortion (THD) levels of the phase currents and the torque are improved. Moreover, DTC's favorable dynamic and robustness properties are preserved. This paper presents an MPDTC scheme for a permanent magnet synchronous motor that achieves long prediction horizons in the range of up to 150 time-steps through the use of extrapolation and bounds. A discrete-time internal controller model of the drive system is derived from the physical equations. Simulation results for a three-level voltage source inverter indicate that such an MPDTC scheme, compared to an industry standard controller, is capable of reducing the switching losses and the switching frequency by up to 50%, and the torque THD by 25%, while leaving the current THD unchanged.

关键词： Switches Inverters Stators Switching frequency Mathematical model Predictive models

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Model Predictive controller for Networked control Systems

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IFAC Proceedings Volumes 2010年第8期43卷 274-279页

作者： Grzegorz Ewald Mietek A. Brdys Department of Automatic Control Gdansk University of Technology ul. Narutowicza 11/12 80-233 Gdańsk Poland School of Electronic Electrical and Computer Engineering College of Engineering and Physical Sciences University of Birmingham Edgbaston Birmingham B15 2TT UK

关键词： control system design model predictive control stability analysis networked control system dynamic models networks.

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Robust Performance Issues in Tracking control over Networks

Robust Performance Issues in Tracking Control over Networks

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International Conference on Intelligent Systems, Modelling and Simulation (ISMS)

作者： Leonidas Dritsas Vasilis N. Tsoulkas Athanasios A. Pantelous Antony Tzes Division of Automatic Control Hellenic Air Force Academy Athens Greece General Secretariat for Research and Technology Athens Greece Department of Mathematical Sciences University of Liverpool UK Electrical and Computer Engineering Department University of Patras Greece

ISBN: (纸本)9781424459841;9780769539737

This paper is concerned with the investigation of robust performance of linear tracking controllers affected by unmodelled delays acting in the loop. The incentive comes from the area of Networked control System (NCS) where the inevitable network-induced (transmission) delays are either time-varying or constant. The main contribution (based on extensive simulation work rather than strict mathematical proof) is that the tracking performance of (typical or more sophisticated) linear tracking control laws is drastically reduced when applied to NCS. The provided simulation results (i) demonstrate the impact of the network-induced delays on the tracking performance of single-input single-output NCS, (ii) provide initial guidelines for the tuning of the controllers and (iii) pave the road for further work to be done.

关键词： Robust control control systems Networked control systems Protocols Robust stability Stability analysis Tracking loops automatic control Force control Communication system control

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Modeling Nonlinear Acoustic Wave Fields in Media with Inhomogeneity in the Attenuation and in the Nonlinearity

Modeling Nonlinear Acoustic Wave Fields in Media with Inhomo...

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2010 IEEE International Ultrasonics Symposium

作者： L. Demi M.D. Verweij N. de Jong K.W.A. van Dongen Laboratory of Acoustical Imaging and Sound Control Faculty of Applied Sciences Delft University of Technology The Netherlands Laboratory of Electromagnetic Research Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technology The Netherlands Laboratory of Experimental Echocardiography Erasmus Medical Center Rotterdam The Netherlands

ISBN: (纸本)9781457703829

关键词： Inhomogeneities nonlinearity Attenuation wave fields Attenuation Acoustic Wave Ultrasonic applications Scattering Ultrasonic Therapy

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