Abstract
A detailed comparative experimental and theoretical study of nonlinear distortion in laser diodes is undertaken to provide practical proving of the effectiveness and utility of the Volterra series method. The observed harmonic and intermodulation distortion levels are compared with the results given by the Volterra series nonlinear laser model using intrinsic parameters extracted from reflection and small-signal frequency response measurements. Second-harmonic, two-tone and three-tone intermodulation distortion data are all found to be in good agreement with the theoretical results, providing endorsement of the Volterra series approach for the study of distortion in microwave subcarrier optical systems. © IEE, 1996.

Abstract
Distributed systems emerged in the last decade as a more efficient way of sharing networked resources, allowing cooperating processes to be executed in remote computers with possibly distinct architectures and operating systems. This paper presents the motivations that may lead to the usage of distributed architectures in the support of telecommunications services, particularly multimedia services. It also gives an overview of one distributed architecture, ANSA, which was used to implement a prototype of a distributed multimedia service, briefly described.

Abstract
A passive all-fibre technique for Bragg wavelength shift detection is presented which can be considered as the minimum configuration for fibre grating sensing demodulation. The scheme involves a light source with a particular spectral profile that allows the direct tracking of Bragg wavelength shifts. Referencing to source power fluctuations is also provided. This simple technique shows satisfactory resolution over a large dynamic range. Experimental results are presented for temperature and strain measurements. © 1996 IOP Publishing Ltd.

Abstract
Technical advances in communication networks and terminal equipment make possible the provision of a wide range of new and appealing telecommunication services. However, the increasing user demand and the strong market competition require that the creation of those services is efficient and fast, and that they have attractive interfaces. The complexity of networks and distributed systems, which support those services, renders the usage of formal specification languages, such as SDL, almost mandatory in their development. According to some authors, fifty percent of the total time necessary to develop applications is spent in building and testing graphical interfaces for different platforms. In this paper, an efficient methodology to create graphical interfaces for telecommunication services specified in SDL is presented.

Abstract
This paper presents an efficient information debugging methodology, using a dynamic state estimation algorithm which, through the use of a dynamic model for the time evolution of the system state, will meets simultaneously two objectives: the filtering of the incoming data and the forecasting of the state vector one step ahead. Based on this last characteristic a scheme for the detection of suspicious information is built.

Abstract
In this paper we present an evaluation of optical flow techniques applied to a case study in the perception of visual motion. This case study is being conducted in a project for the evaluation of human factors in road traffic, specifically, concerning the processing of visual information. We present the goals of the case study, discuss the need to apply optical flow techniques to synthesized image sequences and evaluate some limitations encountered in their use. © 1996 IEEE.