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Publications

Publications by CRAS

2017

A MoliZoft System Identification Approach of the Just Walk Data

Authors
Lopes dos Santos, PL; Freigoun, MT; Rivera, DE; Hekler, EB; Martin, CA; Romano, R; Perdicoulis, TP; Ramos, JA;

Publication
IFAC PAPERSONLINE

Abstract
A system identification approach is used estimate linear time invariant models from the data of physical activity gathered in the Just Walk intervention conducted by the Designing Health Lab and the Control Systems Laboratory at Arizona State University A class of identification algorithms proposed elsewhere by one of the authors, denoted as MoliZoft, was reformulated and adapted to estimate models from data gathered in this experience. In this paper, the identification algorithms are described and the best models estimated for a particular participant are analysed and used to improve the results in future experiments.

2017

PDE model for leakage detection in high pressure gas networks

Authors
Azevedo Perdicoúlis, TP; Almeida, R; Lopes dos Santos, P; Jank, G;

Publication
Lecture Notes in Electrical Engineering

Abstract
In this paper we design a model based method to locate a leakage and estimate its size in a gas network, using a linearised version of an hyperbolic PDE. To do this, the problem is reduced to two identical ODEs, allowing in this way for a representation of the pressure as well as the mass flow in terms of its system of fundamental solutions. Then using the available measurements at the grid boundary points, the correspondent coefficients can be determined. Assuming pressure continuity, we check for consistency of the coefficients in order to find faulty pipelines. Thence, the location of the leakage can be found either graphically or using a numerical method for a specific pipe. Next, its size can also be estimated. © Springer International Publishing Switzerland 2017.

2017

Monitoring and simulation of gas pipelines through quadripole models

Authors
Baltazar, ST; Perdicoúlis, TPA; dos Santos, PL;

Publication
Lecture Notes in Electrical Engineering

Abstract
In this paper we propose to model a high pressure gas network using a quadripole approach. Although being simple, the proposed model seems to be adequate to network analysis and control, and is directly extendible to more complex networks, i.e., networks with junctions and loops. The model is proven to be liable on a case study constructed from data supplied by REN Gasodutos, where we investigate the effect of a leakage on the mass flow and pressure along the pipeline with the final objective to define a model based methodology for leakage detection and location. © Springer International Publishing Switzerland 2017.

2017

Caracterização multidisciplinar de eflorescências salinas no Mosteiro da Batalha

Authors
Almeida, Fernando; Moura, Rui; Barraca, Nuno; Costa, Cristiana; Terroso, Denise; Matias, Manuel;

Publication
Congresso da Reabilitação do Património, crepat 2017

Abstract
O Mosteiro da Batalha é uma relevante obra da arquitectura gótica, resultou do cumprimento da promessa feita por D. João I, após vitória na batalha de Aljubarrota. O mosteiro esteve na posse dos dominicanos até à extinção das ordens religiosas, sendo actualmente dependência da DGPC e Património da Humanidade pela UNESCO. Recentemente a Universidade Aveiro caracterizou estrutural do monumento. Entre as técnicas testadas considera-se aqui o potencial espontâneo, anteriormente aplicados na Igreja da Graça em Santarém (Martinho et. al, 2014). Seleccionou-se uma parede com eflorescências na qual se sobrepôs uma grelha de eléctrodos (12×5) espaçados de 0.5m. O mapeamento do potencial espontâneo foi realizado tendo como referência um eléctrodo sobre eflorescências. Concluiu-se que as zonas da parede com sais estão ao mesmo potencial, enquanto as zonas onde as eflorescências não ocorrem apresentam um potencial mais elevado. A composição mineralógica dos sais foi estudada por Difracção de Raios X.

2017

High-Resolution geophysics in the investigation of the inner structure of walls and columns of batalha abbey

Authors
Senos, MJ; Almeida, F; Moura, R; Barraca, N;

Publication
23rd European Meeting of Environmental and Engineering Geophysics

Abstract
Knowledge of walls and other structural elements construction characteristics and techniques is mandatory in the maintenance and restoration of historical buildings. Such information is obtained from documents or by comparing with monuments of the same period. Documents are difficult to obtain and comparison with other buildings can be inaccurate. The use of direct invasive techniques may be considered but they are likely to damage structures or compromise buildings stability. Thus, indirect high-resolution methods are adapted to these investigations. This work describes a GPR and a Seismic Transmission Tomography survey to investigate the walls and columns of the 14th century Batalha Abbey (UNESCO heritage site). High-resolution GRP data revealed the dimensions and thicknesses of different walls and the structure and nature of materials inside them. The Seismic Transmission Tomography survey, supported by high-resolution photogrammetry scanning for accurate positioning of sources and geophones, was carried out to investigate the Abbey columns. Seismic velocities distribution inside the columns characterized their interior and clarified the nature of the materials used. Columns construction followed the same technique and used the same materials. However, each column depicts a different velocity zonation that could correspond to different stages of deterioration for each one.

2017

Contributions of Model-Based Learning to the Restructuring of Graduation Students' Mental Models on Natural Hazards

Authors
Moutinho, S; Moura, R; Vasconcelos, C;

Publication
EURASIA JOURNAL OF MATHEMATICS SCIENCE AND TECHNOLOGY EDUCATION

Abstract
Model-Based learning is a methodology that facilitates students' construction of scientific knowledge, which, sometimes, includes restructuring their mental models. Taking into consideration students' learning process, its aim is to promote a deeper understanding of phenomena's dynamics through the manipulation of models. Our aim was to ascertain whether the use of three different types of models, integrated into an intervention program whose goal was to teach the "seismic effects on soils and buildings", would influence the learning process of graduation students or not. For a better understanding of the results, the data were collected and analyzed through a combination of methods using, simultaneously, quantitative and qualitative method. And results not only confirmed the importance of the use of models, but also led us to the conclusion that despite the potential and limitations of all three models, mixed models are better for restructuring students' mental models and the development of meaningful learning.

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