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Controlled System (controlled + system)
Selected AbstractsAdaptive TS-FNN control for a class of uncertain multi-time-delay systems: The exponentially stable sliding mode-based approachINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 4 2009Tung-Sheng Chiang Abstract This paper presents an adaptive Takagi,Sugeno fuzzy neural network (TS-FNN) control for a class of multiple time-delay uncertain nonlinear systems. First, we develop a sliding surface guaranteed to achieve exponential stability while considering mismatched uncertainty and unknown delays. This exponential stability result based on a novel Lyapunov,Krasovskii method is an improvement when compared with traditional schemes where only asymptotic stability is achieved. The stability analysis is transformed into a linear matrix inequalities problem independent of time delays. Then, a sliding mode control-based TS-FNN control scheme is proposed to achieve asymptotic stability for the controlled system. Since the TS-FNN combines TS fuzzy rules and a neural network structure, fewer numbers of fuzzy rules and tuning parameters are used compared with the traditional pure TS fuzzy approach. Moreover, all the fuzzy membership functions are tuned on-line even in the presence of input uncertainty. Finally, simulation results show the control performance of the proposed scheme. Copyright © 2008 John Wiley & Sons, Ltd. [source] An indirect adaptive pole-placement control for MIMO discrete-time stochastic systemsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2005Wen-Shyong Yu Abstract In this paper, an indirect adaptive pole-placement control scheme for multi-input multi-output (MIMO) discrete-time stochastic systems is developed. This control scheme combines a recursive least squares (RLS) estimation algorithm with pole-placement control design to produce a control law with self-tuning capability. A parametric model with a priori prediction outputs is adopted for modelling the controlled system. Then, a RLS estimation algorithm which applies the a posteriori prediction errors is employed to identify the parameters of the model. It is shown that the implementation of the estimation algorithm including a time-varying inverse logarithm step size mechanism has an almost sure convergence. Further, an equivalent stochastic closed-loop system is used here for constructing near supermartingales, allowing that the proposed control scheme facilitates the establishment of the adaptive pole-placement control and prevents the closed-loop control system from occurring unstable pole-zero cancellation. An analysis is provided that this control scheme guarantees parameter estimation convergence and system stability in the mean squares sense almost surely. Simulation studies are also presented to validate the theoretical findings. Copyright © 2005 John Wiley & Sons, Ltd. [source] Composition cascade control for chemical reactorsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13 2002Jose Alvarez-Ramirez Abstract Eventhough the composition control of chemical reactors is an old, widely studied, and still relevant problem in chemical process control, it still presents some aspects that remain unexplored or unresolved. For instance, a unifying approach is needed to systematize the existing ad hoc controller constructions, to rigorously explain their remarkable robustness property, and to explore the possibility of improving their construction and functioning. In this paper, some aspects of these control problems are addressed by resorting to recently developed approaches in constructive non-linear control, yielding a systematic controller construction coupled to a simple tuning scheme that can be executed with standard tuning rules, a closed-loop stability criterion, and an explanation of the closed-loop dynamics behaviour. Specifically, a linear cascade (master/slave) control configuration is proposed, which leads to global internal stability of the controlled system with asymptotic regulation of the output-stream composition about a given desired setpoint. A simulation example is used to illustrate the results. Copyright © 2002 John Wiley & Sons, Ltd. [source] Fiscal institutions of Brazilian municipal borrowingPUBLIC ADMINISTRATION & DEVELOPMENT, Issue 1 2008Christine R. Martell Abstract In an effort to understand subnational borrowing, this article explores how three Brazilian institutions,the 1988 Constitution which mandates revenue and expenditure assignments among the levels of the federation; the national Law of Fiscal Responsibility, which imposes expenditure and debt limitations on all levels and branches of government; and various borrowing arrangements,affect the municipal borrowing environment. These institutions are examined in light of de Mello's (2001) policy recommendations for strengthening efficiency and fiscal discipline in subnational borrowing. The institutions of Brazilian borrowing were found to have some of de Mello's recommendations, with the new Constitution and the Law of Fiscal Responsibility making progress towards increased fiscal responsibility, but the current borrowing arrangements serving to maintain a controlled system that is not conducive to responsible municipal borrowing. Several recommendations are made to improve the borrowing environment and foster fiscal discipline and efficiency Copyright © 2008 John Wiley & Sons, Ltd. [source] Design of liveness-enforcing supervisors via transforming plant petri net models of FMS,ASIAN JOURNAL OF CONTROL, Issue 3 2010Chun-Fu Zhong Abstract This paper focuses on the deadlock prevention problems in a class of Petri nets, systems of simple sequential process with resources, S3PR for short. By structure analysis, we propose an approach that can transform a plant net model into a weighted S3PR (WS3PR) that is behaviorally equivalent to the plant model. The WS3PR is made to be live by properly reconfiguring its weight distribution such that its all strict minimal siphons are self-max'-controlled. The resulting WS3PR can serve as a liveness-enforcing Petri net supervisor for the plant model after removing some idle and operation places. A live controlled system can be accordingly obtained by synchronizing a plant model and the places whose weights are regulated. This research shows that a small number of monitors is obtained, leading to more permissive behavior of the controlled system. Examples are used to demonstrate the proposed concepts and methods. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Kinetic Simulations of Reversible Chain Transfer Catalyzed Polymerization (RTCP): Guidelines to Optimum Molecular Weight ControlMACROMOLECULAR THEORY AND SIMULATIONS, Issue 1 2010Philipp Vana Abstract Kinetic simulations of reversible chain transfer catalyzed polymerization (RTCP) were performed using the program package Predici. Mimicking the RTCP of styrene in bulk at 80,°C, the full molecular weight distributions, the polydispersities of resulting polymer and the time evolutions of monomer conversion and participating species were simulated. The influence of the kinetic coefficients governing the RTCP equilibrium , specifically, the rate coefficients of activation, ka, and deactivation, kda , on the controlled polymerization behavior was probed in detail by varying their respective simulation input values over five orders of magnitude. It was found that optimum results for molecular weight control are obtained for K,=,ka/kda in the range 1 to 10 and with ka and kda being of the order of 106 L,·,mol,1,·,s,1 or above. The influence of degenerative chain transfer on the process was found to be significant only in poorly controlled systems, but is small in well-controlled RTCP. Based on the finding that the catalyst is depleting during the polymerization due to cross-termination, guidelines for obtaining high molecular weight material via repeated addition of catalyst were developed. [source] | ||||||||||