Abstract
Solvent extraction is considered as a multi-criteria optimization problem, since several chemical species with similar extraction kinetic properties are frequently present in the aqueous phase and the selective extraction is not practicable. This optimization, applied to mixer-settler units, considers the best parameters and operating conditions, as well as the best structure or process flow-sheet. Global process optimization is performed for a specific flow-sheet and a comparison of Pareto curves for different flow-sheets is made. The positive weight sum approach linked to the sequential quadratic programming method is used to obtain the Pareto set. In all investigated structures, recovery increases with hold-up, residence time and agitation speed, while the purity has an opposite behaviour. For the same treatment capacity, counter-current arrangements are shown to promote recovery without significant impairment in purity. Recycling the aqueous phase is shown to be irrelevant, but organic recycling with as many stages as economically feasible clearly improves the design criteria and reduces the most efficient organic flow-rate.

Abstract
This paper presents the implementation of an algorithm for automatic identification of drops with different sizes in monochromatic digitized frames of a liquid-liquid chemical process. These image frames were obtained at our Laboratory, using a nonintrusive process, with a digital video camera, a microscope, and an illumination setup from a dispersion of toluene in water within a transparent mixing vessel. In this implementation, we propose a two-phase approach, using a Hough transform that automatically identifies drops in images of the chemical process. This work is a promising starting point for the possibility of performing an automatic drop classification with good results. Our algorithm for the analysis and interpretation of digitized images will be used for the calculation of particle size and shape distributions for modelling liquid-liquid systems.

Abstract
We have been working on a model for the shallow-layer settler, in a mixer-settler system, which is able to describe the hydrodynamic phenomena of the transient state of a liquid-liquid system. The mathematical model used includes parameters of the drop transport process as well as of the drop-drop and drop-interface coalescence with the active interface. The most adequate values of these parameters are unknown. In order to tune the model parameters we have linked the mixer-settler simulation algorithm to an optimization procedure. Due to its simplicity and robustness we've used the Hooke-Jeeves optimization algorithm to fit these parameters to given experimental results. © 2008 Civil-Comp Press.

Abstract
In this paper we describe a parameter optimization approach to a simulation algorithm of a mixer-settler system in the transient state. The model we are using for the shallow-layer settler, in a mixer-settler system, is able to describe the hydrodynamic phenomena of the transient state of a liquid liquid system. Its mathematical model includes parameters of the drop transport process as well as of the drop drop and drop-interface coalescence with the active interface. The most adequate values of these parameters are unknown. In order to tune the model parameters we have Linked the mixer-settler simulation algorithm to an optimization procedure. We have used the Hooke-Jeeves optimization algorithm to fit these parameters to given experimental results.

Abstract
An iterative numerical technique has been developed to simulate in detail the dynamics of a shallow-layer gravity settler. Currently acknowledged models apply only to specific equipments at steady-state and laboratory scale [Jeelani SAK, Hartland S. The continuous separation of liquid/liquid dispersions. Chem Eng Sci 1993;48(2):239-54]. To our knowledge, no study has ever addressed the dynamic simulation of a gravity settler. In this paper a direct numerical technique is presented for computing the thickness and drop-size composition of the dispersion band formed in a shallow-layer settler under steady-state and transient conditions. This technique is an extension for the settler of the one used on the stirred vessel by Ribeiro [Ribeiro LM. Simulacao Dinamica de Sistemas Liquido-Liquido, Urn novo Algoritmo com Potencialidades de Aplicao em Controlo. PhD thesis, Universidade do Minho, Portugal; 1995].

Abstract
We are developing a new method for the identification of rib boundaries in chest x-ray images. The identification of rib boundaries is important for radiologist diagnosis of lung diseases as TB. The radiologists use the ribs as reference for location and can be used to eliminate false positives in the detection of abnormalities. Our method automatically identifies rib boundaries from raw images through a sequence of steps using a combination of image processing techniques. Radiographs are still very relevant in practice because in Portugal and many other countries it is the first step for TB detection. We have access a large database of x-ray images provided by the pneumological screening centre (CDP) of Vila Nova de Gaia, in Portugal.