Pedro Pimenta

Studies on on-line state and parameter estimation through a real-time process simulator

Abstract A PC-based simulator of non-linear multiple-input multiple-output dynamic systems was employed for studies concerning the on-line estimation of both ‘non-measured’ state variables and multiple specific growth rates of a virtual baker’s yeast fed-batch fermentation. The identification algorithms were implemented in an ‘Observer Computer’ which received, optionally in ‘real-time’, in ‘scaled time’ or in ‘simulation time’, the ‘measured’ state variables generated by the process simulator in the ‘Process Computer’. The state observer showed a robust behaviour under different situations where process parameters, operating variables and measuring characteristics (noise and delays) were changed in the process computer. The simulation package was seen to be an efficient and cheap tool for the simulation of non-linear processes with time varying parameters, providing a realistic environment for tests of identification, estimation and control strategies.

An Experiment in Collaborative Writing

In this article an experiment of collaborative work is described; it was held in an Internet environment of a Computer science discipline in the Accounting and Administration course of ISCAP, where 26 first-year students participated. This subject was lectured between September and December 2004 in a traditional class room, complemented with a distance developed collaborative work. Student’s easy access to the Internet was an essential condition for the success of this project’s implementation. The Institute has some rooms equipped with computers connected to the Internet, available for free access by the students. Nevertheless, an inquiry was carried out at the beginning of the semester to check the kind of technologies access the students had: 93% of the students had a computer at home and 73% of these had their computer connected to the Internet

Simulation of multiple-effect evaporators

Abstract A PC based simulator of the steady-state behaviour of multiple-effect calandria (or equivalent) evaporators is presented. The package, ‘MULTEVA’ can be applied in studies concerning thermodynamic design, in the analysis of alternative forms of operation and in the monitoring of unit efficiency. The latter is achieved through an option which performs the estimation of the heat transfer coefficients for given operation data. Three types of feed configurations are allowed, viz. - forward, mixed and backward. Up to 20 effects are accepted for analysis in each configuration. A database on the relevant thermodynamical and physical properties of the solute, solvent and solution has been created with read/write capacities. The simulator derives from the database all the necessary information to carry out the computations. The general model employed is based on theoretical heat and mass balances and on equilibrium considerations. It has already proved its efficiency in industrial applications of sugar liquor evaporation.

Real-time dynamic simulation of non-linear mimo systems

Abstract A PC based real-time simulator of the dynamic behaviour of non-linear MIMO (Multiple Input, Multiple Output) systems is presented. The strategy is developed in the time domain. Virtually all processes represented mathematically by sets of non-linear algebraic-differential equations can be described by the simulator. Exceptions, not yet found in our practice, may be cases of large number of ill-conditioned equations where the numerical strategies employed, albeit tested and robust, may experience difficulties. The User defines in very simple terms his own process (algebraic-differential) equations, control inputs, loads, measured variables and process parameters. The latter can be changed on-line during the simulation. Protocols for input/output are included for A/D, D/A and RS232 communications. Studies employing this simulator have been effectively conducted on penicillin and bakers yeast fed-batch fermentation, on sugar crystallization and on multiple-effect evaporation, among other systems.

Interoperability frameworks for competencies and learning outcomes: Databases vs ontologies

The changes introduced into the European Higher Education Area (EHEA) by the Bologna Process, together with renewed pedagogical and methodological practices, have created a new teaching-learning paradigm: Student-Centred Learning. In addition, the last few years have been characterized by the application of Information Technologies, especially the Semantic Web, not only to the teaching-learning process, but also to administrative processes within learning institutions. On one hand, the aim of this study was to present a model for identifying and classifying Competencies and Learning Outcomes and, on the other hand, the computer applications of the information management model were developed, namely a relational Database and an Ontology.