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IEEE International symposium on Computer Aided control System Design (CACSD)

作者： F.J.P. Castelo R.F. Garcia Departamento Ingenieria Ind. Univ. de La Coruna Ferrol Spain Departmento Ingeniería Industrial Universidad de La Coruña Ferrol Spain

Classical PID controller tuning methods in the frequency domain have as their fundamental target the achievement of a certain phase margin or gain margin at a control frequency (w/sub c/). In both cases the task of w/sub c/ selection is key due to the fact that the control system stability and bandwidth are fully dependent on it.. The classical methodology can produce unstable systems if w/sub c/ is not adequately selected. When a precise process model is available, it is possible to select w/sub c/ to provide a controller that better satisfies the design specifications, but this task is not easy to implement when the process dynamics are unknown. A recursive procedure for the selection of w/sub c/ that guarantees system stability and the design specifications without the availability of a process model is presented in this work.

关键词： Frequency domain analysis Three-term control control systems control system synthesis Tuning Regulators Equations Frequency synthesizers Design engineering Stability

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Neural network based control of a cement mill by means of a VSS based training algorithm

Neural network based control of a cement mill by means of a ...

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IEEE International symposium on Industrial Electronics (ISIE)

作者： U. Yildiran M.O. Kaynak Bogazici Universitesi Istanbul TR

In this study, the authors investigate a neuro-control scheme proposed in the literature, which uses techniques from variable structure systems (VSS) theory in order to robustify learning dynamics, for control of nonlinear systems. A Gaussian radial basis function neural network (GRBFNN) is chosen as the neural network architecture because of its strong adaptation capabilities. By means of an instability analysis, it is shown that this scheme leads to unbounded evolution of the controller parameters in steady state due to presence of noise and uncertainties. A modification on the original adaptation algorithm is proposed in order to alleviate this problem. The simulation studies on a nonlinear cement mill circuit model show that the modified update rule stabilizes the learning dynamics and closed loop system becomes insensitive to parametric changes.

关键词： Training Heuristic algorithms Neural networks Mathematical model Uncertainty Steady-state process control

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Distributed simulation of multi-agent hybrid systems

Distributed simulation of multi-agent hybrid systems

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International symposium on Object-Oriented Real-Time Distributed Computing

作者： Yerang Hur Insup Lee Department of Computer and Information Science University of Pennsylvania Philadelphia USA

systems such as coordinating robot systems, automobiles, aircraft, and chemical process control systems can be modeled as interacting hybrid systems, where hybrid systems are finite state machines with continuous dynamics. The language CHARON and its simulator have been developed to model and analyze interacting hybrid systems as communicating agents. Simulations are widely used for the analyses of hybrid systems. The simulation of a complex system is, however usually very slow. This paper proposes four algorithms for distributed simulations of hybrid systems. The idea behind distributed simulations is to achieve a speedup by utilizing multiple computing resources. The agents of a modeled system are distributed over multiple processors to simulate the agents more efficiently. Since the state of the agent is affected by the input from other agents, they synchronize to update their local states. The challenge here is how to reduce the agent synchronization overhead. We present two approaches for resolving the problem: conservative and optimistic approaches. For the optimistic approach, we present three different algorithms for distributed simulations of hybrid systems, and compare them.

关键词： Computational modeling Analytical models Robot kinematics Automobiles Aircraft Aerospace control Chemical processes control system synthesis process control Automata

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Analytical modelling of transmit power control error process for S-UMTS

Analytical modelling of transmit power control error process...

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IEEE International symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： H.S.H. Gombachika S. Nourizadeh R. Tafazolli B.G. Evans Centre for Communication Systems Research (CCSR) University of Surrey UK

Transmit power control is indispensable in direct sequence code division multiple access (DS/CDMA) based systems such as the Satellite Universal Mobile Telecommunication System (S-UMTS). The performance of fixed step-size closed loop power control is significantly affected by command delay due to processing and propagation. This calls for insights into the dynamics of transmit power control taking into account the effects of delays. In this paper, therefore, we have developed an analytical model for the dynamic behaviour of the error process as a stochastic difference equation. We have modelled the effects of delays in the presence of random external disturbances as a random walk process. Using the stochastic difference equation, we have developed an expression for the steady-state pdf of the power control error process as a lognormal distribution. However, we demonstrate that in cases where the quantisation errors of the power control command are significant, the error process departs from the lognormal distribution approximation. This shows that the generally assumed lognormal distribution for power control error process may not always be valid.

关键词： Analytical models Power control Error correction Delay effects Stochastic processes Difference equations Power system modeling Direct-sequence code-division multiple access Multiaccess communication Artificial satellites

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A programmable diffuser circuit based on floating-gate devices

A programmable diffuser circuit based on floating-gate devic...

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Midwest symposium on Circuits and systems (MWSCAS)

作者： P.D. Smith P. Hasler Department of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

This paper presents a programmable diffuser using floating-gate circuits. We present the dynamics of classical diffuser circuits and show the differences between the classical and the programmable case. Programmable diffusers offer man), advantages including removing individual element mismatch and also giving the user the ability to reconfigure the overall system behavior Programmable diffusers can be used for spreading, just as in a resistive network, and they can also be used to create applications based on wave propagation. Experimental data is presented from circuits fabricated on a 0.5 /spl mu/m n-well CMOS process available through MOSIS.

关键词： Circuits Filtering MOSFETs Resistors Computer networks Engineering profession Instruments Voltage control Signal to noise ratio Brain modeling

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A library of adaptive neural networks for control purposes

A library of adaptive neural networks for control purposes

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IEEE International symposium on Computer Aided control System Design (CACSD)

作者： G. Campa M.L. Fravolini M. Napolitano Department of Electronic and Information Engineering University of Perugia Perugia Italy Department of Mechanical and Aerospace Engineering West Virginia University Morgantown WV USA

In this paper, a library of adaptive neural networks to be used within the Simulink/spl reg/ environment is presented. The library has been developed by the authors with the intent of giving to the Simulink user an easy access to a variety of adaptive approximators. The neural networks contained in the library are ready to be used and interchanged within the user's application. Different from existing neural network collections and toolboxes, in this library, a neural network is strictly treated as a dynamic system with its inputs, outputs and states, and the "dynamics" of the approximation process are therefore considered as an essential part of this "system". The library is introduced and the featured network architectures are analyzed in detail. Finally, as an example, a comparison is performed between two of the presented networks.

关键词： Libraries Adaptive systems Programmable control Adaptive control Neural networks Mathematical model Artificial neural networks Airplanes Computer networks Aerospace electronics

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Steady-state operability characteristics of idealized reactors

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CHEMICAL ENGINEERING SCIENCE 2001年第17期56卷 5111-5130页

作者： Subramanian, S Georgakis, C Lehigh Univ Chem Proc Modelling & Control Res Ctr Bethlehem PA 18015 USA Lehigh Univ Dept Chem Engn Bethlehem PA 18015 USA

Operability analysis is one of the bridges that links process design and control. In this paper, we analyze the steady-state operability characteristics of classical reactors (CSTR and PER) in the framework of Vinson and Georgakis (DYCOPS-5. Fifth IFAC symposium on dynamics and control of process systems. 1998, pp. 700-709, J, Proc. control 10 (2000) 185). Reaction schemes vary from simple first-order A --> B to industrially relevant competing reactions. The nonlinear nature of reactors requires the use of special computational techniques for the determination of the operability index (OI). This study clearly brings out the potential of the OI framework. In addition to measuring the servo, regulatory, and overall operability of the systems studied. we were able to identify safe operating regions and tolerable disturbances with the available inputs. This analysis also points to optimized process conditions. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： process operability interaction of design and control reactor operability

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Tracking the predefined optimal policies for multiple-fraction batch distillation by using adaptive control

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COMPUTERS & CHEMICAL ENGINEERING 2001年第1期25卷 97-107页

作者： Li, P Wozny, G Tech Univ Berlin Inst Prozess & Anlagentech D-10623 Berlin Germany

Predefined optimal policies will be tracked with control systems to realize the optimum of multiple-fraction batch distillation. Adaptive control is proposed to carry out this task. Characteristics of batch distillation control are analyzed and a proper system is designed for controlling such processes. Besides tracking the optimal reflux ratio profile, the maximum vapor load will be maintained during the batch. In addition, a changing temperature profile of the condenser should be followed to reduce the operating energy with a possibly minimum subcooling. Recursive least square estimation (RLSE) with a variable forgetting factor is applied to the on-line identification of the plant to follow the changing dynamics of the process. Generalized predictive control (GPC) is used to track the predefined policies. The effectiveness of the control strategy is verified with a pilot batch column and the tracking performance is compared with that of PID controllers. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： multiple-fraction batch distillation tracking optimal policies adaptive control

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process control using a CFCM-based on-line adaptive neuro-fuzzy systems

Process control using a CFCM-based on-line adaptive neuro-fu...

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2001 IEEE International symposium on Industrial Electronics Proceedings (ISIE 2001)

作者： Kwak, K.-C. Lee, J. Kim, S.-S. Ryu, J.-W.

A conditional fuzzy c-means(CFCM)-based fuzzy adaptive neuro-fuzzy system(ANFS) by on-line learning is proposed in this paper. In the structure identification, the optimal or near optimal number of fuzzy rules is determined by a CFCM clustering with TSK-type fuzzy rules based on the criterion. In the parameter identification, The consequent parameters are tuned by least squares estimator (LSE) and the premise parameters are tuned by back-propagation algorithm in off-line learning, and then use on-line learning by recursive least squares estimator (RLSE) and back-propagation algorithm to cope with time varying plant dynamics. Finally, we will show its capability for a CFCM-based on-line ANFS to control the temperature of a water path.

关键词： process control

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Dynamic network model of control investment portfolio in continuous time 5

Dynamic network model of control investment portfolio in con...

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5th Korea-Russia International symposium on Science and Technology, KORUS 2001

作者： Dombrovsky, V.V. Gerasimov, E.S. Department of Mathematical Methods in Economics Tomsk State University Lenina ave 36 Tomsk634050 Russia

ISBN: (纸本)0780370082

In this paper we propose a method of description of the investment portfolio (IP) structure, composed of risk capital (ordinaries), and risk-free investment (account, bond), as dynamic stochastic net. The nodes of net represent financial assets, nested in given risk and risk-free asset, while arcs - direction and size finances, redistributed between assets in portfolio control process. The prices evolution of risk financial assets is described by stochastic differential equations. The equation set, describing dynamics IP belongs to the systems class with multiplicative noises. The management problem IP, is defined as dynamic tracing task for some sample portfolio with desired yield, assigned by investor. The approach of defining optimal control strategy with feedback on quadratic criterion is suggested. The numerical modeling results are presented. ©2001 IEEE.

关键词： Stochastic systems

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