Carlos F. Alastruey

Deformed systems for contextual postprocessing

In this paper a fuzzy method for contextual postprocessing, able to deal with the measurement level output that an isolated character classifier (ICC) can provide for every input letter, is introduced. The ICC information, is expressed as a fuzzy character which is then post-processed, by a deformed system, together with the rest of the fuzzy characters from a word. This deformed system implicitly contains the contextual knowledge provided by a dictionary and it is defined as an extension, for fuzzy inputs, of a classic automaton. Therefore, in the method, the classification of a character is postponed until the context is taken into account. This means that the classification and contextual processes are computed together. The formulation of the deformed systems makes possible the utilization of different strategies for the evidences composition. The method and also the composition strategies are evaluated in a text recognition experiment and high rates are obtained in correcting the characters miss-recognized by the ICC. Moreover, the results are compared with one of the best postprocessing methods and a clear improvement is achieved.

A distributed deadlock detection algorithm for the AND model

Abstract This paper ∗ introduces a simple and efficient distributed deadlock detection algorithm for a Distributed Database System with AND model. The algorithm is derived from a previous algorithm for the One-Resource model. By using a formal specification based on Automata Theory, the proof of correctness is provided: the algorithm reports all true deadlocks and does not report false deadlocks.

Interconnected systems with delays

This paper provides two simple results by which complex systems can be identified as sets of interconnected subsystems and their respective interconnections.

Kalman-Bucy filtering for stochastic Volterra models

Abstract In this paper a suboptimization procedure is formulated for Volterra-type equations by using the Kalman-Bucy filtering theory. The Volterra-type systems are, in general, of a time-varying and non-convolution nature, but we include the time-invariant and convolution cases

Stability of time-delay systems via Lyapunov functions

In this paper, a Lyapunov function candidate is introduced for multivariable systems with inner delays, without assuming a priori stability for the nondelayed subsystem. By using this Lyapunov function, a controller is deduced. Such a controller utilizes an input–output description of the original system, a circumstance that facilitates practical applications of the proposed approach.

A method to obtain sufficient conditions for the stability of a class of internally delayed systems under a Taylor series representation

A theorem due to Mori [9] guarantees asymptotic stability (AS) for a class of linear-time delay systems. Under a polynomial series representation, that theorem is reduced to a quite simple matrix relation, easy for evaluation. Practical aspects of this result are investigated.

ANALYTIC SOLUTION OF HOMOGENEOUS POINT-DELAY SYSTEMS. THE FIRST ORDER CASE

New fonnulae providing exact explicit solutions for a class of scalar delayed systems are given.

Neural Networks for Automatic Fuzzy Control System Design

In this paper, a method for the automatic design of Fuzzy Control Systems is introduced. The method is based on the identification of the inverse model of the process to be controlled by using a Neural Network. The Neural Network which models the inverse process, is used again to obtain a set of tuples representing the fuzzy variables of the fuzzy controller. In order to obtain the fuzzy linguistic variables involved in the fuzzy controller, a Neural Network is used with the DCL algorithm. Finally, the fuzzy controller is implemented by a decision table. The method has been applied to the automatic development of a fuzzy controller for a highly non linear process.

Advances in adaptive simulation of interconnected systems with delays

Abstract The present work presents two basic results especially adequated for adaptive simulation of interconnected systems with delays. The simulation here considered is via Taylor series representation. The results refer to the question of under what circumstances can an adaptive simulator describe in a suitable way the dynamics of a complex system by using information about its subsystems. The method has important applications in simulation of control systems.