An hybrid approach based on neural networks and regression Tree Models for fast dynamic security assessment

This paper presents a new hybrid automatic learningapproach, which combines artificial neural networks (ANN) andregression trees (RT), to perform on-line dynamic securityassessment of power systems. In the proposed method, the RT isfirstly used to split the vast amount of knowledge data that describesa security problem into several less spread and disjoint problems.Then, an ANN is trained for each of these new smaller problems,resulting in a tree structure with an ANN predicting functionassociated to each leaf. Moreover, the capability of the RT to performfeature subset selection before ANN training is also tested. With thisnew method, the advantages of the two techniques are exploited inorder to obtained a more accurate model without compromisingprediction time. The quality of the approach is illustrated through itsapplication to a major security problem of the power system ofMadeira Island (Portugal)

Image segmentation for human motion analysis: methods and applications

Human motion analysis is closely connected with the development of computational techniques capable of automatically identify objects represented in image sequences, track and analyse its movement. Feature extraction is generally the first step in the study of human motion in image sequences which is strictly related to human motion modelling [1]. Next step is feature correspondence, where the problem of matching features between two consecutives image frames is addressed. Finally high level processing can be used in several applications of Computer Vision like, for instance, in the recognition of human movements, activities or poses. This work will focus in the study of image segmentation methods and applications for human motion analysis. Image segmentation methods related to human motion need to deal with several challenges such as: dynamic backgrounds, for instance when the camera is in motion; lighting conditions that can change along the image sequences; occlusion problems, when the subject does not remain inside the workspace; or image sequences with more than one subject in the workspace at the same time. It is not easy to develop methods which can deal with all thes

Methods to automatically build Point Distribution Models for objects like hand palms and faces represented in images

In this work we developed methods to automatically extract significant points of objects like hand palms and faces represented in images that can be used to build Point Distribution Models automatically. These models are further used to segment the modelled objects in new images, through the use of Active Shape Models or Active Appearance Models. These models showed to be efficient in the segmentation of objects, but had as drawback the fact that the labelling of the landmark points was usually manually made and consequently time consuming. Thus, in this paper we describe some methods capable to extract significant points of objects like hand palms and compare the segmentation results in new images

New implementation of the Tau method for PDEs

AbstractIn this work we propose an extension of the algebraic formulation for the Tau method for the numerical solution of partial differential problems set on domains in Rn,n>2. This extension is based on an appropriate choice of a basis for the space of polynomials in Rn and on the construction of the algebraic equivalent representation of the problem. Another feature of this implementation is related to the solution procedure for the necessarily large dimensional linear systems involved. We developed for this purpose an adapted LU factorization with a special pivoting strategy to build approximants in the sense of Tau method and to allow the solution of large problems.Numerical results for differential problems in 2D and 2D will be shown

Tourism environmental attitudes in Berlengas Biosphere Reserve, Portugal

Berlengas archipelago is located in the Atlantic Ocean, on the Portuguese continental shelf, on the western side of Iberian Peninsula. Berlengas is a marine reserve since 1981, a marine protected area since 1998 and, in 2011, it was included into the World Network of Biosphere Reserves (WNBR). As Berlengas is a relatively accessible archipelago from the west coast, it attracts all sorts of visitors during summer period. As a consequence, Berlengas has been facing a stronger demand for tourism activities each year that, in some cases, may conflict with the sustainable tourism principles desired for this kind of natural areas. The afflux of tourists is regulated by the management plan of the protected area, which defines a carrying capacity of 350 people daily but it is believed that this threshold is widely exceeded, by a factor of 2 or 3 during summer months. The delicate balance between the conservancy and human visitation can be obtained if tourism respects the natural values in Berlengas. Therefore, it is expected that the visitors of a biosphere reserve should demonstrate a high level of environmental concern and pro-ecological attitudes, especially those tourists who chose to visit such a location motivated by Berlengas’ worldwide recognized natural resources. In this work, the pro-ecological behavior and attitudes of tourists visiting Berlengas biosphere reserve are studied. A questionnaire was developed, using the New Ecological Paradigm (NEP) survey, and responded by 309 tourists visiting the islands in July and August 2014. The main results show that only 38% of the visitors are pro-ecological and most have mid-ecological views and 9% of the respondents showed anti-ecological views. These results suggest that a higher level of concern should be considered for the tourism industry in Berlengas, and that increasing the environmental awareness of visitors through education and information programs could contribute to a better environmental experience in this UNESCO Biosphere Reserve

Uma visão global sobre os pacemakers cardíacos: Ensino Baseado em Casos no 9º ano de escolaridade

Resumo Nas ultimas decadas, a pesquisa em Ensino de Ciencias tem evidenciado a relevancia do papel desempenhado pela Historia da Ciencia no ensino e aprendizagem das mesmas. E tao importante aprender ciencias como aprender sobre ciencias e esta compreensao sobre o que e a ciencia envolve tanto reconhecer a sua insercao num contexto social, como tambem ter uma ideia de como e construido o conhecimento cientifico e de que forma este se diferencia dos saberes do quotidiano. A metodologia de Ensino Baseado em Casos (EBC), rompeu decadas de ensino meramente transmissivo e enquadra-se na perspetiva socioconstrutivista da aprendizagem, onde o professor e mediador e os alunos trabalham em grupos e aprendem com os seus colegas. Esta metodologia de ensino parece assim vantajosa, uma vez que os alunos desenvolvem habilidades de trabalho colaborativo e resolucao de problemas, alem de dotar os alunos com ancoras mentais para os fatos, conceitos e principios a serem estudados e assimilados. Reconhecendo a potencialidade desta metodologia de ensino e a faculdade da HC no ensino das ciencias, foi proposto um caso que espelha a historia do avanco cientifico e tecnologico dos pacemakers cardiacos. O estudo, ainda em desenvolvimento, ira incidir numa amostra de conveniencia (n=26) constituida por alunos do 9o ano de escolaridade de uma escola publica de uma zona urbana do norte do pais. Palavras-chave: Historia da Ciencia; ensino baseado em casos; pacemakers cardiacosAbstract In recent decades, research in science education has highlighted the importance of the role played by HC in teaching and learning. As Matthews (1995), is so important to learn how to learn science as to learn science. This understanding of the Science involves both recognize the insertion in a social context, your as well as get an idea of how scientific knowledge is constructed and how this differs from knowledge of everyday life. The case-based teaching methodology broke decades of teaching merely transmissive and fits on social constructivism theory perspective of learning, where the teacher is a mediator and the students work in groups and learn from their colleagues. This teaching methodology seems so advantageous, since students develop job skills and collaborative problem-solving, in addition to providing students with mental anchors for the facts, concepts and principles to be studied and assimilated. Recognizing the potential of this methodology of teaching and the power of HC in science teaching, it was proposed a case that mirrors the history of scientific and technological advancement of pacemakers. This study, still under development, will focus on a convenience sample (n=26) consisting of students from the 9th grade level of a public school in an urban area in the north of the country. Keywords: history of science; case-based teaching; pacemakers.</jats:p

Analysis of tongue shape and motion in speech production using statistical modeling

The mechanisms of speech production are complex and have been raising attention from researchers of both medical and computer vision fields. In the speech production mechanism, the articulator’s study is a complex issue, since they have a high level of freedom along this process, namely the tongue, which instigates a problem in its control and observation. In this work it is automatically characterized the tongues shape during the articulation of the oral vowels of Portuguese European by using statistical modeling on MR-images. A point distribution model is built from a set of images collected during artificially sustained articulations of Portuguese European sounds, which can extract the main characteristics of the motion of the tongue. The model built in this work allows under standing more clearly the dynamic speech events involved during sustained articulations. The tongue shape model built can also be useful for speech rehabilitation purposes, specifically to recognize the compensatory movements of the articulators during speech production

Modelling and segmentation of the vocal track during speech production by using deformable models in magnetic resonance images

The first and second authors would like to thank the support of the PhD grants with references SFRH/BD/28817/2006 and SFRH/PROTEC/49517/2009, respectively, from Fundação para a Ciência e Tecnol ogia (FCT). This work was partially done in the scope of the project “Methodologies to Analyze Organs from Complex Medical Images – Applications to Fema le Pelvic Cavity”, wi th reference PTDC/EEA- CRO/103320/2008, financially supported by FCT.Since ancient times, speech production has attracted particularly interest aiming at reaching a deeper understanding of the mechanisms involved by considering both morphological and speech acoustic aspects. The central anatomical aspects and the physiology of the human vocal tract are common to all individuals. However, speech production is an exceptionally complex and individualistic process. Therefore, the modelling of the mechanisms involved in speech production implies the enclosing of adequate flexibility in order to consider individual variations accurately. In this work, the shape of vocal tract in the articulation of some European Portuguese (EP) sounds is evaluated by using deformable models applied in Magnetic Resonance (MR) images. Additionally, the deformable models built are afterwards used to automatically segment the modelled vocal tract in MR images. From the imaging modalities that have been take n into consideration in order to study the vocal tract shape and articulators, Magnetic Resonance Imaging (MRI) has been the most commonly accepted. Actually, the use of MRI allows the study of the entire human vocal tract and, in addition, the quality and resolution of soft-tissues and the use of non-ionizing radiation are key advantages presented by MRI. The deformable model used, commonly known as Point Distribution Model (PDM), was built from a set of training images acquired du ring artificially sustained articulations of 21 EP sounds. In a brief review, one can assert that PDM’s are obtained by a statistical analysis done on the co-ordinates of landmark points that represent the shape to be modelled: after aligning the training shapes, a Principal Component Analysis is performed in order to obtain the model mean shape and the modes of variation relatively to this mean shap e. Combining the geometrical information of the PDM with the grey levels of the landmark points us ed in its building one can build the Active Shape Models (ASM) and the Active Appearance Models (AAM). With these enhanced models is possible to segment the modelled shape in new images in a fully automated way. From the experimental results obtained in this work, one may conclude that the PDM built could efficiently characterize the behaviour of the voca l tract shape during the production of the EP sounds studied with MRI. Furthermore, one can ve rify that the ASM and the AAM built could be used to segment the modelled vocal tract in MR images in a successful manner. Therefore, the deformable models built should be considered towards the efficient and automatic study of the vocal tract during speech production with MRI, in particular for enhanced speech production simulation and speech rehabilitation therapies.Fundação para a Ciência e Tecnologia (FCT

Utilização de árvores de regressão híbridas na monitorização da segurança dinâmica de redes isoladas com grande produção eólica

Neste artigo descreve-se de forma sintética a metodologia adoptada para definir estruturasde avaliação rápida da segurança dinâmica de redes isoladas com elevados níveis deintegração de produção eólica. Estas metodologia recorre a árvores de regressão híbridas,permitindo quantificar o grau de robustez ligado ao comportamento dinâmico destas redesatravés da emulação do desvio mínimo de frequência que o sistema experimentará quandosujeito a uma perturbação pré-definida. Apresentam-se ainda novos procedimentos degeração automática de dados, explorados posteriormente na construção e medição dedesempenho das estruturas de avaliação. O caso teste aqui descrito corresponde a umcenário de funcionamento da rede da ilha Terceira no arquipélago dos Açores

Um estudo exploratório sobre evocações de estudantes universitários acerca do conceito de limite de uma função

Objetivamos com este trabalho apresentar resultados de uma investigação realizada junto a estudantes universitários acerca do conceito de limite de uma função. Os sujeitos investigados, que cursavam o 3º e o 4º semestre de licenciatura em matemática de duas universidades públicas do estado do Pará (Brasil), foram submetidos a duas etapas de investigação de uma pesquisa de mestrado, cujos resultados nos permitiram evidenciar os elementos que compõem suas imagens conceituais relativas ao conceito de limite de uma função. As considerações de Tall e Vinner (1981) e Vinner (1991) sobre imagem conceitual e definição conceitual compuseram a fundamentação teórica de nosso estudo, além de outras pesquisas relacionadas ao processo de ensino e aprendizagem de limite de função, tais como Jordaan (2005), Juter (2006), Nair (2009) e outras. Dentre as imagens conceituais evocadas pelos sujeitos investigados, ressaltamos aquelas voltadas para a ideia de que o valor do limite em determinado ponto não pode ser alcançado, ou seja, f(x) G L. Optamos por discutir nesse artigo os aspectos relacionados a tal interpretação, mobilizada pelos indivíduos de nossa pesquisa