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Publicações

2014

Visualization of red blood cells flowing through a PDMS microchannel with a microstenosis: An image analysis assessment

Autores
Monteiro, FC; Taboada, B; Lima, R;

Publicação
COMPUTATIONAL VISION AND MEDICAL IMAGE PROCESSING IV

Abstract
The present study aims to assess the motion of red blood cells (RBCs) under both shear and extensional flow using an image based technique. For this purpose, a microchannel having a smooth contraction was used and the images were captured by a standard high-speed microscopy system. An image processing and analyzing method has been developed in the MATLAB environment, to track the RBCs motion. The keyhole model, tested in this study, proved to be a promising technique to track individual RBCs in microchannels.

2014

Proposal of an Information System for an Adaptive Mixed Reality System for Archaeological Sites

Autores
Magalhaes, LG; Sousa, JJ; Bento, R; Adao, T; Pereira, F; Filipe, V; Peres, E;

Publicação
CENTERIS 2014 - CONFERENCE ON ENTERPRISE INFORMATION SYSTEMS / PROJMAN 2014 - INTERNATIONAL CONFERENCE ON PROJECT MANAGEMENT / HCIST 2014 - INTERNATIONAL CONFERENCE ON HEALTH AND SOCIAL CARE INFORMATION SYSTEMS AND TECHNOLOGIES

Abstract
The use of Augmented Reality (AR) techniques to visualize virtual archaeological sites is neither a new or recent issue. In those approaches the virtual models are only visualized using the existent in situ illumination, which does not allow a visitor to have a similar visual experience to that which he would have at the time the structures were built. In Augmented Virtuality (AV) approaches the virtual world prevails, which is augmented with information from the real world, which allows a better control over the parameters of the Mixed Reality (MR) environment created. In some cases, there is the need to use both approaches (AR or AV), depending on some context conditions. This paper proposes an architecture and an information system for an adaptive MR system which main goal is to visualize in situ virtual reconstructions of archaeological sites that are seamlessly merged with the real scene. In this context, a new adaptive methodology will be defined to manage the level of mixing between the real and the virtual scene, identifying in each instant the most proper approach to use (AR or AV), as well as defining the way how transitions between approaches are made. (C) 2014 The Authors. Published by Elsevier Ltd.

2014

Automatic simulation calibration: An evaluation of search-based metaheuristics applied to IEC 61131-3 based automation in the power systems domain

Autores
Silva, C; Rossetti, RJF; Pereira, JC;

Publicação
Modelling and Simulation 2014 - European Simulation and Modelling Conference, ESM 2014

Abstract
Industrial automation relies on PLC's to perform real-time critical tasks. These tasks are commonly implemented using IEC 61131-3 and tend to be very complex due to the current evolution of microprocessor capabilities. This complexity causes testing to be considered a very difficult task and the scope to be reduced to minimize effort. The application of automatic calibration techniques could allow the identification of optimal or near optimal solutions for the set of inputs to allow a better test coverage and simulation accuracy. This paper reviews current automatic simulation calibration methodologies and provides a description of an experiment of the application of search-based metaheuristics to IEC 61131-3 implemented algorithms in the context of power systems automation.

2014

Analysis of the performance of the teams in the portuguese football championship

Autores
Dias, L;

Publicação
PROCEEDINGS OF THE 2014 9TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI 2014)

Abstract

2014

Prototyping and analysing ubiquitous computing environments using multiple layers

Autores
Silva, JL; Campos, JC; Harrison, MD;

Publicação
INTERNATIONAL JOURNAL OF HUMAN-COMPUTER STUDIES

Abstract
If ubiquitous computing (ubicomp) is to enhance physical environments then early and accurate assessment of alternative solutions will be necessary to avoid costly deployment of systems that fail to meet requirements. This paper presents APEX, a prototyping framework that combines a 3D Application Server with a behaviour modeling tool. The contribution of this framework is that it allows exhaustive analysis of the behaviour models that drive the prototype while at the same time enabling immersive exploration of a virtual environment simulating the proposed system. The development of prototypes is supported through three layers: a simulation layer (using OpenSimulator); a modelling layer (using CPN Tools) and a physical layer (using external devices and real users). APEX allows movement between these layers to analyse different features, from user experience to user behaviour. The multi layer approach makes it possible to express user behaviour in the modelling layer, provides a way to reduce the number of real users needed by adding simulated avatars, and supports user testing of hybrids of virtual and real components as well as exhaustive analysis. This paper demonstrates the approach by means of an example, placing particular emphasis on the simulation of virtual environments, low cost prototyping and the formal analysis capabilities.

2014

Artificial neural networks for automatic modelling of the pectus excavatum corrective prosthesis

Autores
Rodrigues, PL; Moreire, AHJ; Rodrigues, NF; Pinho, ACM; Fonseca, JC; Correia Pinto, J; Vilaca, JL;

Publicação
MEDICAL IMAGING 2014: COMPUTER-AIDED DIAGNOSIS

Abstract
Pectus excavatum is the most common deformity of the thorax and usually comprises Computed Tomography (CT) examination for pre-operative diagnosis. Aiming at the elimination of the high amounts of CT radiation exposure, this work presents a new methodology for the replacement of CT by a laser scanner (radiation-free) in the treatment of pectus excavatum using personally modeled prosthesis. The complete elimination of CT involves the determination of ribs external outline, at the maximum sternum depression point for prosthesis placement, based on chest wall skin surface information, acquired by a laser scanner. The developed solution resorts to artificial neural networks trained with data vectors from 165 patients. Scaled Conjugate Gradient, Levenberg-Marquardt, Resilient Back propagation and One Step Secant gradient learning algorithms were used. The training procedure was performed using the soft tissue thicknesses, determined using image processing techniques that automatically segment the skin and rib cage. The developed solution was then used to determine the ribs outline in data from 20 patient scanners. Tests revealed that ribs position can be estimated with an average error of about 6.82 +/- 5.7 mm for the left and right side of the patient. Such an error range is well below current prosthesis manual modeling (11.7 +/- 4.01 mm) even without CT imagiology, indicating a considerable step forward towards CT replacement by a 3D scanner for prosthesis personalization.

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