Abstract
Perceptual coders have proven to be highly efficient in the context of audio or video applications involving bit rate reduction. However, this efficiency is strongly limited in very low bit rate coding conditions. This paper studies the multiplicative effects of quantization in the frequency domain, when an overlapped filter bank (TDAC) is used to shape the quantization noise in a perceptually optimal way. The associated circular convolution operation generates aliased components in the time domain that are examined and subjected to minimization. A closed form expression is suggested to approximate an optimal transform window offering a desired tradeoff between the reduction of the time artifacts produced by a coarse quantization and the reduction of the stop-band leakage, relative to other transform windows commonly used.

Abstract
This article discusses the development of an Intelligent Distributed Environmental Decision Support System, built upon the association of a Multi-agent Belief Revision System with a Geographical Information System (GIS). The inherent multidisciplinary features of the involved expertises in the field of environmental management, the need to define clear policies that allow the synthesis of divergent perspectives, its systematic application, and the reduction of the costs and time that result from this integration, are the main reasons that motivate the proposal of this project. This paper is organised in two parts: in the first part we present and discuss the developed Distributed Belief Revision Test-bed — DiBeRT; in the second part we analyse its application to the environmental decision support domain, with special emphasis on the interface with a GIS. © Springer-Verlag Berlin Heidelberg 1996.

Abstract
Uncertainties in deviations of physical properties lead to a probabilistic failure analysis of the composite materials. The proposed optimization model for laminate composites is based on reliability analysis considering the ultimate failure state. To avoid difficulties associated with the complete analysis of the failure modes, bounds are established for the failure probability of the structural system. These bounds are related with the intact and degraded configurations of the structure. Using the first ply failure and the last ply failure theories and a degradation model for the mechanical properties with load sharing rules we obtain the failure probabilities corresponding to the two above configurations. The failure probability of each configuration is obtained using level 2 reliability analysis and the Lind-Hasofer method. The optimization algorithm is developed based on the problem decomposition into three subproblems having as objectives the maximization of the structural efficiency at intact and degraded configurations of the structure and weight minimization subjected to allowable values for the structural reliability. Additionally, the search for the initial design is performed introducing a weight minimization level. It is expected to explore the remaining load capacity of the structures after first ply failure as a function of the anisotropic properties of the composites. The design variables are the ply angles and the thicknesses of the laminates. The structural analysis for the model developed is performed through the finite element method mainly using the isoparametric degenerated shell finite element. The sensitivities are obtained using the discrete approach through the adjoint variable method. In order to show the performance of the analysis two examples are presented.

Abstract
Practical Prolog programs usually contain extra-logical features like cuts, side-effects, and database manipulating predicates. In order to exploit implicit parallelism from real applications while preserving sequential Prolog semantics, a parallel logic programming system should necessarily support these features. In this paper we show how Prolog's extra-logical features can be supported in an and-or parallel logic programming system. We show that to support extra-logical features an and-or parallel logic programming system should recompute the solutions to independent goals instead of sharing them. We describe an abstraction called the composition tree for representing and-or parallel execution with recomputation. We introduce the notion of ''local-leftmostness'' in the composition tree and use it for deriving complete and efficient methods for supporting extra-logical predicates in and-or parallel logic programming systems based on the composition tree abstraction.

Abstract
The FM intermodulation characteristics of directly modulated semiconductor lasers of relevance to the design of subcarrier multiplexed applications are investigated. "Adiabatic" chirp which has previously not been considered is shown to have a large impact on the reduction of the distortion levels at frequencies below half the resonance frequency of the laser. Results are presented showing that, in contrast to previous suggestions, FM modulation may be advantageous, imposing less requirements on laser linearity than IM modulation.

Abstract
The technique of genetic algorithms (GAs) is proposed as a means of auto-tuning PI Smith predictor controllers. The technique involves firstly using on-line data and the GA to identify a model of the process. Then the identified model, the GA and simulation methods, are used to off-line tune the PI Smith predictor controller, so as to minimise a time-domain based cost function. Finally, the genetically tuned controller is implemented on-line on the real process. The results of the auto-tuning of the PI Smith predictor controller technique are illustrated on a laboratory heat exchanger, and a comparison between this technique, and both the genetic PI auto-tuning technique and the Astrom PI auto-tuning technique are made.