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Various

1. J.A. Rohwer, C.T. Abdallah, and C. Christodoulou, "Least Squares Support Vector Machines for Fixed-Step and Fixed-Set CDMA Power Control", Proceedings of the 42nd IEEE Conference on Decision and Control, pp.5097-5102, Maui, HI, Dec. 2003.   [pdf]

   Abstract: This paper presents two machine learning based algorithms for CDMA power control. The Least Squares Support Vector Machine (LS-SVM) algorithms classify eigenvalues estimates into sets of power control commands. A binary LS-SVM algorithm generates fixed power control (FSPC) commands, while the one vs one multiclass LS-SVM algorithm generates estimates for fixed set power control.



2. P.F. Hokayem, and C.T. Abdallah, "Networked Control Systems: A Sampled-Data Approach", Proceedings of the 2003 IEEE International Symposium on Intelligent Control, pp.415-419, Houston, Tx, Oct. 2003.   [pdf]

   Abstract: In thfs paper we present a novel modelling method for networked control systems, motivated from a sampled-data approach. We study sufficient conditions that guarantee exponential stability for the closed-loop system and illustrate our results via a numerical example.



3. P.F. Hokayem, C. T. Abdallah, and P. Dorato, "Quasi-Monte Carlo Methods in Robust Control Design", Accepted, 11^th Mediterranean Conference on Control and Automation, Rhodes, Greece, June 2003.   [pdf]

   Abstract: Many practical control problems are so complex that traditional analysis and design methods fail to solve. Consequently, in recent years probabilistic methods that provide approximate solutions to such ’difficult’ problems have emerged. Unfortunately, the uniform random sampling process usually used in such techniques unavoidably leads to clustering of the sampled points in higher dimensions. In this paper we adopt the quasi-Monte Carlo methods of sampling to generate deterministic samples adequately dispersed in the sample-space. Such approaches have shown to provide faster solutions than probabilistic methods in fields such as Financial Mathematics.



4. F. Amato, M. Ariola, C. Cosentino, C.T. Abdallah, P. Dorato, "Necessary and Sufficient Conditions for Finite-Time Stability of Linear Systems", Proceedings of the American Control Conference, pp.4452-4456, Denver, Co, June 2003.   [pdf]

   Abstract: In this paper we consider the Finite-Time Stability and Finite-time Boundedness problems for linear systems subject to exogenous disturbances. The main results of the paper are some necessary and sufficient conditions, obtained by means of an approach based on operator theory; such conditions improve some recent results on this topic. An example is provided to illustrate the proposed technique.



5. P.F. Hokayem, C. T. Abdallah, and P. Dorato, "Quasi-Monte Carlo Methods in Robust Control Design", Submitted, IEEE CDC 2003, Maui, HI.   [pdf]

   Abstract: Many practical problems are so complex that traditional analysis and design methods fail to solve. Consequently, in recent years sampling methods that provide approximate solutions to such difficult problems have emerged. In this paper we address the deterministic quasi-Monte Carlo method of sampling and attempt to impose bounds on the error involved in the evaluation of the quality of performance of a specific controller over the whole plant parameter uncertainty space.



6. K.R. Horspool, R.S. Erwin, C.T. Abdallah, and P. Dorato, "A Randomized approach to the H2/H, Control Problem via Q-parameterization", Proceedings of the American Control Conference, pp.1400-1404, Chicago, Il, June 2000.   [pdf]

   Abstract: In this paper we show that the mixed H2/H, control problem can be efficiently solved using randomized algorithms. Q-parameterization provides a mechanism to search over all stabilizing controllers, and thus gives us the ability to search for H2 minimizing controllers, while still providing stability robustness. Finally, we are able to show that we can get results comparable to a more traditional approach such as gradient search, but in addition, we can solve more complex problems. With very little modification, we are able to deal with multiple objectives, plant uncertainty, and fixed order controllers.



7. P. Dorato, D. Famularo, and C.T. Abdallah, "Analytic Phase Margin Design", IEEE Transactions on Automatic Control, VOL. 44, NO.10, pp.1894-1900, Oct. 1999.   [pdf]

   Abstract: In [4] an algorithm is presented for analytic phase margin control design. Without special care, however, the compensator computed with this algorithm may not be a real rational function. The problem is evident when the plant has real unstable poles. In this case the algorithm in [4] requires a mapping of real points into complex values, and it is not clear that the resulting compensator has real coefficients. The purpose of this paper is to show how a complex mapping required in this algorithm can always be selected so that the compensator does have real coefficients.



8. K.R. Horspool, C.T. Abdallah, "On the Rotating Surge and Stall and the Polar Control Method", Proceedings of the American Control Conference, pp.2668-2672, San Diego, CA, June 1999.   [pdf]

   Abstract: In this paper, the polar controller is applied to the three-state, one-mode Moore-Greitzer Compressor model. A benchmark is first established with a backstepping controller. The polar control method is then explained, and compared to the backstepping controller. The polar controller is used successfully to control the surge and stall problem in the presence of both disturbances and uncertainties.



9. F. Amato, M. Ariola, C.T. Abdallah, P. Dorato, "Finite-Time Control for Uncertain Linear Systems with Disturbance Inputs", Proceedings of the American Control Conference, pp.1776-1780, San Diego, CA, June 1999.   [pdf]

   Abstract: In this paper we consider the static output feedback, finite-time disturbance rejection problem for linear systems with time-varying norm-bounded uncertaineties. The first result provided in the paper is a sufficient condition for finite-time state feedback disturbance rejection in the presence of constant disturbances. This condition requires the solution of an LMI. Then we consider the more general output feedback case, which is shown to be reducible to the solution of an optimization problem involving Bilinear Matrix Inequalities. Finally we deal with the case in which the disturbance is time-varying and generated by llinear system.



10. C. T. Abdallah, P. Dorato, D. Famularo and W. Yang, "Robust Nonlinear Feedback Design via Quantifier Elimination Theory", International Journal of Robust and Non-Linear Control, Vol. 9, pp.817-822, 1999.   [pdf]  [ps]

    Abstract: In this paper symbolic-computation methods are used to design simple, fixed-structure, robust controllers for nonlinear systems. Design specifications are reduced to logically quantified polynomial inequalities. The quantifier-elimination (QE) software package QEPCAD is used to eliminate quantifiers on state and plant parameters, to obtain regions of admissible controller parameters, and to guarantee robust stability and performance.

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