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Dias F.,FEUP | Paiva A.C.R.,FEUP
Proceedings - 10th IEEE International Conference on Software Testing, Verification and Validation Workshops, ICSTW 2017 | Year: 2017

Usability is a critical aspect of software systems because poor user experience can lead users to choose other software. One way to improve usability is through testing. But, usability testing is a challenge because, most of the times, it can not be accomplished without the presence of real users, which is complex and requires a lot of effort. However, there are some aspects and usability guidelines that can be tested automatically. This paper presents a test approach that defines generic test strategies (test patterns) to test usability guidelines (or best practices). It is an extension to previous work on testing functional aspects of web applications through the GUI (PBGT - Pattern Based GUI Testing). The main goal of this work is to be the first step in extending PBGT's PARADIGM language with usability testing patterns, so that it is possible to build test models from which usability tests can be generated and automatically executed over a website. This paper presents a new usability test pattern, called 'Reachability Test Pattern', which is validated in a case study performed over an academic software system available on the web. © 2017 IEEE.

Marques B.P.,GILT ISEP | Villate J.E.,FEUP | Carvalho C.V.,GILT ISEP
Iberian Conference on Information Systems and Technologies, CISTI | Year: 2017

Higher Education (HE) teachers are aware that the evolution of technology changed the way students build their knowledge. New forms of access to information and new means of communication allowed creating specialized learning tools. It is now important to understand how the students' interaction with learning technologies influences their learning success. For that purpose, data referring to the use of a learning management system (LMS) supporting a specific course was collected and analyzed. Results indicate that a minor correlation exists between the effective use of those tools and student success. © 2017 AISTI.

Seabra M.R.R.,FEUP | Cesar De Sa J.M.A.,FEUP | Sustaric P.,C3M D.o.o. | Rodic T.,University of Ljubljana
Computational Mechanics | Year: 2012

TheXFEM is a powerful method to handle strong discontinuities in a finite element environment, especially in the study of the final stages of material failure, modelling the propagation of cracks, suppressing the need of remeshing. Nevertheless, for some materials undergoing large strain processes without noticeable volume changes, the discretization technique employed must not only describe the material behaviour but also correctly address the incompressibility constraints. In order to develop a robust formulation for this type of problems, an approach based on the analyses of the underlying sub-space of incompressible deformations embedded in the XFEM approximation is used, in the context of both infinitesimal and finite strains. This study motivated the extension of the conventional formulations of B-bar and F-bar to include the XFEM enrichment functions, whose performance is evaluated through some numerical examples and compared with competingmethods such as the enhanced strain formulation.

Seabra M.R.R.,FEUP | Sustaric P.,C3M D.o.o. | Cesar De Sa J.M.A.,FEUP | Rodic T.,C3M D.o.o. | Rodic T.,University of Ljubljana
Computational Mechanics | Year: 2013

Originally Continuum Damage Mechanics and Fracture Mechanics evolved separately. However, when it comes to ductile fracture, an unified approach is quite beneficial for an accurate modelling of this phenomenon. Ductile materials may undergo moderate to large plastic deformations and internal degradation phenomena which are well described by continuum theories. Nevertheless in the final stages of failure, a discontinuous methodology is essential to represent surface decohesion and macro-crack propagation. In this work, XFEM is combined with the Lemaitre ductile damage model in a way that crack initiation and propagation are governed by the evolution of damage. The model was built under a finite strain assumption and a non-local integral formulation is applied to avoid pathological mesh dependence. The efficiency of the proposed methodology is evaluated through various numerical examples. © 2012 Springer-Verlag Berlin Heidelberg.

Puga H.,University of Minho | Costa S.,University of Minho | Barbosa J.,University of Minho | Ribeiro S.,FEUP | Prokic M.,MP Interconsulting
Journal of Materials Processing Technology | Year: 2011

A novel MMM (Multi-frequency, Multimode, Modulated) ultrasonic (US) technology was used to refine the as cast microstructure and improve the mechanical properties of a AlSi9Cu3 alloy. Ultrasonic vibration was isothermally applied to the melt for 120 s at different temperatures slightly above the liquidus temperature of the alloy, using different electric power values, before pouring into a metallic mould. The microstructure of the cast samples was characterized by optical and scanning electron microscopy and energy dispersive spectrometry. Ultrasonic vibration promoted the formation of small α-Al globular grains, changed the size and morphology of intermetallic compounds and distributed them uniformly throughout the castings. Ultimate tensile strength and strain were increased to 332 MPa and 2.9%, respectively, which are 50% and 480% higher than the values obtained for castings produced without vibration. The microstructure morphology and the alloy mechanical properties were found to depend on the electric power and the melt temperature, and by using a suitable combination of these parameters it is possible to achieve high refinement efficiency by treating the melts in the liquid state. © 2011 Elsevier B.V. All rights reserved.

Menezes J.E.,FEUP
48th US Rock Mechanics / Geomechanics Symposium 2014 | Year: 2014

Discontinuity sample size influences the experimental shearing parameters of rock joints. To study how peak shear strength evaluation depends on sample size several shear tests were conducted on artificial joints prepared with molds used for encapsulating rock joints. Discontinuity surfaces were shaped with two different saw-tooth profiles. For each one three joint surface sizes were considered: 64, 100 and 144 cm2. The same series of shear tests with dry joint surfaces was repeated with wetted discontinuity samples. Some reduction was observed in peak shear strength values. Tests with dry surfaces were simulated in numerical calculations that reproduced satisfactorily experimental results. Size effect seems to be more important when normal stress is high. With low normal stress imbrication cohesion is influenced by sample size. Some reflection is advisable to propose a transition from one situation to the other. Calibration of numerical models with more laboratory tests will validate them to be used in later developments. Copyright © 2014 ARMA.

Menezes J.E.,FEUP
Numerical Methods in Geotechnical Engineering - Proceedings of the 8th European Conference on Numerical Methods in Geotechnical Engineering, NUMGE 2014 | Year: 2014

The simulation of mechanical behaviour of rock joints is a valuable contribution to the validation of shear strength criteria and to understand how experimental results can be influenced by scale effects and testing conditions. Two peak shear strength criteria are applied in numerical simulations of shear tests in order to understand how a geometrical predefined joint profile can be equivalent to applying specific shear criteria to a linear interface representing that joint. Saw-toothed and standard Barton's joint profiles were considered. It was found that numerical simulations can reproduce failure laws for peak shear strength calibrated from experimental results. The development of this study is expected to have a valuable contribution to joint roughness numerical modelling specially in post-peak behaviour. © 2014 Taylor & Francis Group.

Leite L.,FEUP
International Conference on Intelligent User Interfaces, Proceedings IUI | Year: 2012

Virtual Marionette is a research on digital puppetry, an interdisciplinary approach that brings the art of puppetry into the world of digital animation. Inspired in the traditional marionette technology our intention is to study novel interfaces as an interaction platform for creating artistic contents based on computer animated puppets. The overall goal of this thesis is to research and deploy techniques and methods for the manipulation of articulated puppets in real-time with low-cost interfaces to establish an interaction model for digital puppetry. Copyright © 2012 ACM.

Cabral A.L.,FEUP
Occupational Safety and Hygiene IV - Selected, Extended and Revised Contributions from the International Symposium Occupational Safety and Hygiene, 2016 | Year: 2016

The present study describes the anthropometrics data comparison between two studies made in the north of Portugal, the current study presents 11 body measurements taken in standing posture with workers of food and nutrition unit. In a total of 29 employees, 13 participated in this study, three male and 10 female. The study used the traditional method of anthropometric measurements and to ensure reliable, the measurements were made in pairs. The second study, which served as the comparison was the most significant Portuguese study conducted in 2004 by the Portuguese Institute of Health and Hygiene. This study were measured 891 workers, with 492 male and 399 female, through the method computer-aided measurement, this method was used assessment for photos to make the acquisition of 24 static body measurements in the standing and sitting posture of the samples. The measures compared in the study were stature (body straight), eye height, shoulder height, elbow height, hand center height (arm stretched), hand center height (raised arm), arm length (in horizontal, to hand center), body depth (at the level of the chest), width of shoulders, hip width and distance elbow-fist. Still, was compared the standard deviations and possible differences in the studies. The studies differ in their purposes, the current study aims to create a local database for further dimensioning of the workstation for the population under study. The Portuguese study conducted in 2004, had two objectives the first obtain anthropometric database of the Portuguese population and second objective was to evaluate a new method of acquisition of anthropometric measurements. The results of the comparison between the two studies were showed consistently, the Portuguese study showed higher values on measurements, but with little variation between studies. The current study shown that workers average weight was 7% higher than the Portuguese study. It can be said that the current study has approximate values even with number of samples were smaller than the Portuguese study, it shows necessary more anthropometric studies of the Portuguese population in order to update the previous study data and include workers from other sectors and regions of Portugal. © 2016 Taylor & Francis Group, London.

De Quay Y.,FEUP
Proceedings of the 5th International Conference on Tangible Embedded and Embodied Interaction, TEI'11 | Year: 2011

Who never whispered a secret to a wind chime, or saw it scare off evil spirits will have the opportunity to do so on a massive scale. The Espanta Espíritos is an interactive sculpture that embodies the spiritual and physical features of a wind chime. This piece presents itself as a giant wind chime made out of recyclable material, the size of a person, ready for outdoors or indoors. People can whisper secrets to the Espanta Espíritos, and through a microphone and a camera, it will register these secrets forever. Natural wind, or a specially designed reactive fan, will cause the Espanta Espíritos to move, and then play these recordings through different audio effects, recreating the secret as if said by spirits. To enhance the illusion, phantasmagoric videos of those who whispered will be projected on the sculpture.

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