Abstract
Neste artigo analisam-se em particular duas técnicas concebidas para apoiar o ensino da programação: a Animação de Programas e a Avaliação Automática de Programas. Com base na combinação destas técnicas e respetivas ferramentas, atualmente disponíveis, iremos enunciar duas possíveis abordagens. Serão apresentadas as conclusões retiradas de uma primeira experiência conduzida em sala de aula. Por fim, esboçaremos uma ferramenta que através da Web, implementará uma das abordagens propostas.

Abstract
Image processing of particulate phases can provide an important assistance for the estimation of particle size and shape distributions in multiphase systems. The knowledge of these distributions is of major importance in the modeling of agitated liquid-liquid systems either for hydrodynamic and mass transfer (with or without chemical reaction) simulation. Often, obtaining these distributions implies visual/manual techniques for identifying, counting and measuring the particles. This implies high costs, intensive labor, weariness build-up and consequent high error rates. A largely automated computational approach presents a great potential for better performance. In this paper we describe our technique in image processing for shape discrimination and size classification for liquid drops in monochromatic digitized frames. We empirically evaluate our approach on examples of images.

Abstract
Simulation of the dynamic behaviour of liquid-liquid systems is of prominent importance in many industrial fields. Algorithms for fast and reliable simulation of single stirred vessels and extraction columns have already been published by some of the present authors. In this work, we propose a methodology to develop a parallel version of a previously validated sequential algorithm, for the simulation of a liquid-liquid Kuhni column. We also discuss the algorithm implementation in a distributed memory parallel-computing environment, using MPI. Despite the difficulties encountered to preserve efficiency in the case of a heterogeneous cluster, the results demonstrate performance improvements that clearly indicate that the approach followed may be successfully extended to allow real-time plant control applications.

Abstract

Abstract
Design and control of mixer-settler batteries is very important for the technical and economical viability of the industrial processes of liquid-liquid extraction. Direct experimentation with these equipments is not always feasible, due to their complexity and cost. Computer simulation allows predicting the behaviour and optimizing the design of this type of equipments thus reducing costs. In previous works, we have already proposed a model to simulate the behaviour of a dispersion band in a gravitational settler unit of a mixer-settler system. Although the algorithm developed was able to simulate the band thickness for the transient state and the results obtained were in agreement with previously published results, some possible physical as well as conceptual limitations of this algorithm were detected. To overcome these problems, a new dynamic model using a kinetic formulation was proposed. This paper describes a new model for the shallow-layer settler unit which is able to describe the transient state of a liquid-liquid system, the hydrodynamic phenomena of drop-drop and drop-interface coalescence as well as the transport processes being explicitly taken into account. © 2006 Civil-Comp Press.

Abstract
In this paper we present an algorithm that identifies circular drops of different sizes in monochromatic digitized frames of a liquid-liquid chemical process. These image frames were obtained at our Laboratory, using a non-intrusive process, with a digital video camera, a microscope, and an illumination setup from a dispersion of toluene in water within a transparent mixing vessel. Here we describe in detail the two-phase approach used for the automatic identification of the drops in images of the chemical process, which employs a Hough transform. Empirical evaluation on an independent set of images shows promising results for the automatic classification of the drops. Copyright © 2010 by IJI (CESER Publications).