2016
Autores
Romano, RA; dos Santos, PL; Pait, F; Perdicoulis, TP; Ramos, JA;
Publicação
2016 AMERICAN CONTROL CONFERENCE (ACC)
Abstract
In this paper an identification method for statespace LPV models is presented. The method is based on a particular parameterization that can be written in linear regression form and enables model estimation to be handled using Least-Squares Support Vector Machine (LS-SVM). The regression form has a set of design variables that act as filter poles to the underlying basis functions. In order to preserve the meaning of the Kernel functions (crucial in the LS-SVM context), these are filtered by a 2D-system with the predictor dynamics. A data-driven, direct optimization based approach for tuning this filter is proposed. The method is assessed using a simulated example and the results obtained are twofold. First, in spite of the difficult nonlinearities involved, the nonparametric algorithm was able to learn the underlying dependencies on the scheduling signal. Second, a significant improvement in the performance of the proposed method is registered, if compared with the one achieved by placing the predictor poles at the origin of the complex plane, which is equivalent to considering an estimator based on an LPV auto-regressive structure.
2016
Autores
Moutinho, SBG; Moura, RMM; Vasconcelos, CMdS;
Publicação
Terrae Didatica
Abstract
2016
Autores
Almeida, F; Barraca, N; Moura, R; Matias, MJS;
Publicação
22nd European Meeting of Environmental and Engineering Geophysics, Near Surface Geoscience 2016
Abstract
Modern and historical buildings may show some degree of subsidence resulting from foundation deterioration and local geological conditions. Hence, buildings stability can be affected and restoration plans must be envisaged. Resistivity methods have been used to investigate local conditions, providing 3D images of the soil under man made structures and hence contributing to the delimitation of hazardous areas and pathologies. However these techniques require the deployment of a grid of electrodes, which can be difficult to accomplish because of physical limitations and of the buildings nature that cannot be damaged. To overcome these problems special arrays have been used (L, Corner, Square arrays, etc). Here in it is proposed to use the "Odd-Even Pole-Pole Array" to study the ground under a contemporary building and under a high historical value XIV century Abbey, both showing evidence of subsidence. Field data quality is also addressed and it is proposed to identify low quality data to be expunged so that modelling is improved. It is also shown how to estimate resistivity values from data quality tests, to carry out further zonation, locate hazardous areas and to enhance modelling.
2016
Autores
Moutinho, S; Moura, R; Vasconcelos, C;
Publicação
Geoscience Education: Indoor and Outdoor
Abstract
Model-based learning is a teaching methodology that facilitates the learning process through the construction of models, which represent the conceptual models taught in geosciences lessons, promoting the construction of students’ scientific knowledge and the development of a meaningful learning. It is crucial that teachers know how to apply it in schools in order to support students’ learning process, but also because models are important tools for dissemination of science concepts. Having this in mind, it becomes relevant, beyond the analysis of its importance for both teaching and disseminating geosciences in Portuguese high schools, to provide some guidelines and recommendations about the use of models in geosciences teaching, based on the literature, seeking to prepare teachers to apply the methodology in science lessons and for making them more informed about the importance of dissemination of science. To achieve this purpose, the attitudes of Portuguese high school students towards the importance of model-based learning in teaching and disseminating the dependence of earthquakes effects on soils and buildings were analysed. The data were collected through a scale for model evaluation named Seismological Models’ Evaluation Scale (SMES), applied to 126 students who participated in Faculty of Sciences’ Open Days to Schools. This instrument was validated by two experts in geosciences teaching, and its fidelity was also determined. © Springer International Publishing Switzerland 2016.
2016
Autores
Moutinho, S; Moura, R; Vasconcelos, C;
Publicação
INTERNATIONAL JOURNAL OF SCIENCE AND MATHEMATICS EDUCATION
Abstract
Nowadays, meaningful learning takes a central role in science education and is based in mental models that allow the representation of the real world by individuals. Thus, it is essential to analyse the student's mental models by promoting an easier reconstruction of scientific knowledge, by allowing them to become consistent with the curricular models presented in the classroom. In this context, the study aims to examine, through the application of a diagnostic instrument (Two-Tier Diagnostic Test), what students consider to be the seismic effects on soils and buildings, to analyse and to compare their mental models about some of these issues related to seismology, applying a questionnaire to 52 students from a Portuguese University attending an undergraduate degree in Geology and a master course in Biology and Geology teaching. The analysis of the data allowed concluding that undergraduate students have more inconsistent mental models than master students, mainly concerning the factors which influence the seismic risk, such as hazard and vulnerability, and the soils characteristics which influence the intensity of earthquakes. During their academic formation in the university, teachers present some curricular models to students which allow them to reconstruct their mental models and turn them scientifically consistent, enhancing the educational implications of this study that points to the need for teachers to be aware of the importance of the diagnosis of the students' mental models and to promote meaningful learning and scientific literacy autonomously and dynamically.
2016
Autores
Dias, JC; Martins, MS; Ribeiro, S; Silva, MM; Esperanca, JMSS; Ribeiro, C; Botelho, G; Costa, CM; Lanceros Mendez, S;
Publicação
JOURNAL OF MATERIALS SCIENCE
Abstract
Actuators based on electroactive polymers are increasingly used in applications including microelectronic devices and artificial muscles, demanding low voltage operation and controllable switching response. This work reports on the preparation of electroactive actuators based on poly(vinylidene fluoride) (PVDF) composites with 10, 25, and 40 wt% N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulfonyl)imide ([N-1 1 1 2(OH)][NTf2]) and 1-Ethyl-3-methylimidazolium Ethylsulfate ([C(2)mim][C2SO4]) ionic liquids (ILs) prepared by solvent casting. Independent of the IL type, its presence leads to the crystallization of PVDF in the piezoelectric beta-phase. The degree of crystallinity and electrical conductivity of the samples strongly depends on ILs type and content. The highest electrical conductivity was found for PVDF/IL composites with 40 wt% of [N-1 1 1 2(OH)][NTf2]. The strain displacement and bending of the PVDF/IL composites were evaluated as a function of IL type and content under applied peak voltages of 2.0, 5.0, and 10.0 V at a frequency of 10 mHz. Strain displacement of the actuators depends more on IL content than on IL type, and the best strain bending response was found for the PVDF/IL composite with 25 wt% of [N-1 1 1 2(OH)][NTf2] at 5.0 V. Further, it is shown that [C(2)mim] [C2SO4]/PVDF composites do not show cytotoxic behavior, being suitable for biomedical applications.
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.