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Publications

Publications by Elsa Ferreira Gomes

2022

Approaches to manage and understand student engagement in programming

Authors
Tavares, PC; Gomes, EF; Henriques, PR; Vieira, DM;

Publication
Open Education Studies

Abstract
Computer Programming Learners usually fail to get approved in introductory courses because solving problems using computers is a complex task. The most important reason for that failure is concerned with motivation; motivation strongly impacts on the learning process. In this paper we discuss how techniques like program animation, and automatic evaluation can be combined to help the teacher in Computer Programming courses. In the article, PEP system will be introduced to explain how it supports teachers in classroom and how it engages students on study sessions outside the classroom. To support that work, students' motivation was studied; to complement that study, a survey involving students attending the first year of Algorithms and Programming course of an Engineering degree was done. It is also presented a tool to analyse surveys, using association rules. © 2022 Paula Correia Tavares et al., published by De Gruyter.

2011

Image Processing for the Estimation of Drop Distribution in Agitated Liquid-Liquid Dispersion

Authors
Bras, LMR; Gomes, EF; Ribeiro, MMM;

Publication
NONLINEAR SCIENCE AND COMPLEXITY

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.

2001

A parallel algorithm for the simulation of the dynamic behaviour of liquid-liquid agitated columns

Authors
Gomes, EF; Ribeiro, LM; Regueiras, PFR; Cruz Pinto, JJC;

Publication
VECTOR AND PARALLEL PROCESSING - VECPAR 2000

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.

2009

Numerical Modelling of a Gravity Settler in Dynamic Conditions

Authors
Gomes, E; Madureira, C; Guimarães, M; Ribeiro, L;

Publication
Proceedings of the Fourth International Conference on Engineering Computational Technology

Abstract

2006

A dynamic model for a settler unit using a kinetic formulation

Authors
Gomes, EF; Guimaraes, MML; Pinto, GA; Ribeiro, LM;

Publication
Proceedings of the 5th International Conference on Engineering Computational Technology

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.

2010

Automatic identification of drops in images of agitated liquid-liquid dispersion

Authors
Gomes, EF; Bras, LMR; Ribeiro, MMM;

Publication
International Journal of Imaging

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).

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