Volume 1, No. 2, April 2005        ISSN: 1743-9310

Title: NEW RESULTS ON RESILIENT CONTROL OF CONTINUOUS-TIME SYSTEMS WITH POLYTOPIC UNCERTAINTIES
Authors: Magdi S. Mahmoud, Hazem Nounou,.......................................................pp. 50-62
Abstract: A class of linear continuous-tune systems with convex-bounded parametric uncertainties in all system matrices and subject to additive controller gain perturbations is fully examined in this paper. The control objective is to design resilient feedback stabilization schemes using guaranteed cost control and control approaches. Initially, the case of state-variable measurements is considered, thereby leading to static feedback control. Then we move to examine the case of output-variable measurements to design dynamic output feedback control. The solution of the problem under consideration in all cases is cast as convex optimization over linear matrix inequalities which led to the derivation of sufficient conditions for closed-loop robust quadratic stability. Several system examples are provided throughout the paper to illustrate the theoretical developments.
Keywords: Quadratic Stability, Polytopic Uncertainties, Resilient Control, Additive Perturbations, Multiplicative Perturbations.

Title: FUZZY SUPERVISORY CONTROL AND OPTIMIZATION SYSTEM FOR A CASCADED RESERVOIRS HYDROPOWER PLANT
Authors: M. Mahmoud, K. Dutton, M. Denman, ....................................................pp. 63-73
Abstract: Cascaded reservoirs hydropower plants are complex nonlinear systems that involve interacting input and output nonlinear parameters and difficult optimization and scheduling tasks. For the purpose of minimizing the non hydraulic power production expenses by means of maximizing the cascaded reservoirs hydropower plant’s operational envelope, a fuzzy supervisory control and optimization system is designed and simulated so as it monitors the cascaded reservoirs’ rates of discharge/accumulation and alters the operational set points of the local fuzzy control systems which control the hydropower plant’s sub-systems, in real time, so that a maximized power plant operational envelope is always maintained.
Keywords: Cascaded Reservoirs, Hydropower Plants, Hydro Turbine Governor, Hydro Turbine Control, Fuzzy Control, Control Systems, Artificial Intelligence.

Title: ADAPTIVE CONTROL TECHNIQUE USING MULTILAYER FEEDFORWARD NEURAL NETWORKS
Authors: Hussain Al-Duwaish, ...............................................................................pp. 74-80
Abstract: This paper presents a new method for implementing adaptive controllers using multilayer feedforward neural networks (MFNN). The controlled process is approximated at each sampling time by a linear time-invariant (LTI) model. The proposed adaptive controller is a combination of a parameter estimation algorithm to estimate the parameters of the process and an adaptation algorithm for the connection weights of the neural network. An adaptation algorithm to adjust the connection weights of the neural network has been derived. Simulation results are included to demonstrate the feasibility and the adaptive properties of the proposed controller.
Keywords: Adaptive Control, Neural Networks, Nonlinear Control, Parameter Estimation.

Title: ROBUST INDUCTION MOTOR CONTROL WITH SLIDING MODE OBSEVER
Author: Moussa Boukhnifer, Boualem Hemici, Mohamed S. Boucherit,.....................pp.81-90
Abstract: In this paper, a robust control technique for an induction motor is presented. This motor is fed by five-level inverter controlled by the triangulo-sinusoidal strategy with four bipolar carriers. The control algorithm uses robust regulators designed by the H∞ loop shaping approach associated with indirect field oriented control. The sliding mode observer is used to observe the rotor flux in the induction motor. The simulation results show that the controllers stabilize the system and reject the disturbances when the system is subjected to uncertainties, which their norms are lower than the maximum stability margin.
Keywords: Induction Motor, Five Level Inverter, Field Oriented Control, Loop Shaping, Observer.

Title:  ON ELLIPTIC SYSTEMS INVOLVING SCHRODINGER OPERATORS
Author: H. M. Serag, A. H. Qamlo,........................................................................pp. 91-96
Abstract: In this paper some elliptic systems involving Schrodinger operators defined on an unbounded domain have been investigated. The necessary and sufficient conditions for having the maximum principle and existence of positive solutions for such systems have been obtained. It has been proved that these conditions ensure the existence of optimal control.
Keywords: Elliptic Systems, Variable Coefficients, Schrodinger Operators, Maximum Principle, Uniqueness of Solutions, Optimal Conditions.