Abstract
We present an algorithm for optimal control problems producing a minimizing sequence of control processes which are solutions to the associated differential inclusion and that the limiting process satisfies necessary conditions of optimality of the Pontryagin type. Numerical experiments show a good robustness to control perturbations and a good precision near the optimal solution.

Abstract

Abstract
Multi-agent architectures are well suited for complex inherently distributed problem solving domains. From the many challenging aspects that arise within this framework, a crucial one emerges: how to incorporate dynamic and conflicting agent beliefs? While the belief revision activity in a single agent scenario is concentrated on incorporating new information while preserving consistency, in a multi-agent system it also has to deal with possible conflicts between the agents perspectives. To provide an adequate framework, each agent, built as a combination of an assumption based belief revision system and a cooperation layer, was enriched with additional features: a distributed search control mechanism allowing dynamic context management, and a set of different distributed consistency methodologies. As a result, a Distributed Belief Revision Testbed (DiBeRT) was developed. This paper is a preliminary report presenting some of DiBeRT contributions: a concise representation of external beliefs; a simple and innovative methodology to achieve distributed context management; and a reduced inter-agent data exchange format. © Springer-Verlag Berlin Heidelberg 1996.

Abstract
This paper reports a new approach in defining preventive control measures to assure transient stability relatively to one or several contingencies that may occur separately in a power system. Generation dispatch is driven not only by economic functions but also with the derivatives of the transient energy margin value; these derivatives are obtained directly from a trained Artificial Neural Network (ANN), using ri:al time monitorable system values. Results obtained from computer simulations, for several contingencies in the CIGRE test system, confirm the validity of the developed approach.

Abstract
The process of monitoring the machines or computing nodes in a network, and of monitoring the communication traffic between them, is very important to efficiently launch and execute parallel coarse-grained applications or even classical (serial-type) applications, taking advantage of machines in the network that are not heavily used. An experimental software system, named MONSYS, that is capable of monitoring the machines in a network, is presented. MONSYS can be used in the support of an Application Manager system capable of distributing parallel tasks (or classical programs) over the machines in a local area network with the objective of achieving load balancing. It can also be used as a tool in the administration of networks. MONSYS exhibits a highly decentralized and fault tolerant architecture based on the Peer-Model, which, together with its information diffusion algorithms, constitute its prime novelty. A set of experiments that investigate the performance and scalability of a prototype of MONSYS is presented and discussed. The experiments reported show that MONSYS offers a reasonably accurate picture of the internal state of the machines monitored, without being a burden to the network communication channels or to the machines themselves. In fact, the quantitative results obtained indicate that MONSYS can be several times more performant than an equivalent system using a multicast communication scheme for the exchange of machine state information.

Abstract
Perceptual audio coders rely on the efficient reduction of perceptually irrelevant components of the audio signal as well as on the removal of statistical signal redundancies to achieve good coding gains. In order to reach high compression ratios without reducing the subjective quality of the encoded audio signal, it is necessary to identify critically interdependent functional units of the encoding algorithm and to jointly optimize their performance. A flexible and interactive simulation and analysis environment has been programmed to assist the development and optimization of a new perceptual audio coder. The main features of this environment will be explained and the most relevant aspects that were found to limit the encoding performance will be presented.