Abstract
It has often been reported and is now well established that the traditional definition of Instantaneous Frequency (IFt) fails in the presence of multicomponent signals. New definitions of IFt have recently been proposed, in an attempt to cope with the difficulties of the traditional one. In this paper, we will address the reasons for failure of the traditional definition, show that it can also fail with monocomponent signals, and show how its behaviour can be predicted for any type of signal, thus generalizaing previous results. We will also analyse the performance in noise of one of the recently proposed definitions of IFt.

Abstract
This paper presents results concerning a full digital implementation of the KII and KIII model proposed by Freeman to explain the chaotic behavior of the mammalian's Olfactory Cortex. The environment used for the task is a commercial neural network package. The immediate goal is to offer a computational efficient alternative to Runge-Kutta methods of solving the system's differential equations. To accomplish the goal the differential equations impulse response were sampled and decomposed over the gamma basis. Both models, KII and KIII, are presently working as associative memories, where stored patterns can be recalled from an input pattern.

Abstract

Abstract
In this paper it is studied and analysed the transient stability of a test power network, considering the tripping of one or more generators. It was used the software package TRANsySTEM that the authors developed for transient security assessment of a multimachine power system. These computer programs use the extended equal area criteria formulation. The results obtained with this direct approach were compared with the solutions produced by the Runge-Kutta method. It is also analysed the influence of the sudden increase in the electromagnetic torque in the rotor shaft fatigue life of the remaining generators, when one or more power units are tripped. Finally, some conclusions that provide a valuable contribution to the understanding of the transient security assessment of a multimachine power system are pointed out.

Abstract
We propose a simple model of distribution for mobile processes, independent of the underlying calculus. Conventional processes compute within sites; inter-site computation is achieved by message sending and object migration, both obeying a lexical scope. We focus on the semantics of networks, on programming practice, and on physical realization with current technology. ©1998 Published by Elsevier Science B.V.

Abstract
A subspace-based on-line identification algorithm based on one specific technique, based on Van Overschee and De Moor's results, but can be adapted to other similar methods since they all recover from the state sequence and the observability matrix is presented. These results relate an estimated Kalman filter sequence with an oblique projection. With further improvements, the algorithm can adapt to the identification of time-variant systems.