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This paper presents the requirements and specifications of videotelephony services and applications that are being developed or adapted to take advantage and demonstrate the potential of the broadband access networks based on the adaptation of CATV networks for interactive services. Furthermore, it emphasises the experience, problems and conclusions that are being acquired by using the Digital Audio-Visual Council (DAVIC) framework to implement such type of services and applications.

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A systematic investigation of erbium diffusion in lithium niobate (LiNbO3) crystal as a function of crystal cut-direction, diffusion process parameters (temperature and time), and initial film thickness is reported. Depth concentration profiles of erbium are obtained by secondary ion mass spectrometry (SIMS). Combining experimental data with diffusion theory, the relevant diffusion parameters are derived. Diffusion from an infinite source of erbium ions is studied to evaluate the solid solubility lower limit of Er in LiNbO3. A thin film diffusion regime, with complete depletion of ion source. is also investigated. A comparison of Er diffusion with Er/Ti codiffusion in LiNbO3 crystals is reported.

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Simulation is a useful tool which can significantly reduce resources invested during product development. The present paper describes the development of the Vector Control Signal Processing (VCSP) blockset for use with MATLAB/Simuhnk(R). The originality of this blockset consists on the extension of Simulink for design, simulation and prototyping of signal processing algorithms in power conversion systems. The VCSP blockset, consists on a number of newly developed blocks. Together with Real-Time WorkshopTM and a number of other generally available blocks, it takes advantage of the inherent visual programming techniques of Simulink to reach the above goals. Due to its open and flexible nature, this approach is also very useful as a tool for teaching. The work is focused on modelling and simulation for power conversion systems use in the drive of rotating AC machines with vector control methods. By concept, a simulation environment can be examined at different abstraction or hierarchy levels. The approach in this paper is so the formulation of a simulation task at different levels: component level, electric circuit level, functional description and implementation description. The basic blockset functions are presented and some examples of modelling techniques for both simple and complex drive structures are included. Simulation results are presented and discussed as well.

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This paper introduces the requirements for information systems supporting team work in manufacturing, under a Total Quality Management approach. The analysis and specification phases of a system in this category is described as well as the basic requirements for extending it beyond local shop-floors, towards networked enterprises.

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