5 resultados para Eutrophication. Ecological modeling. Eutrophication model. Top-down control
em Universidade do Minho
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This paper presents a model predictive current control applied to a proposed single-phase five-level active rectifier (FLAR). This current control strategy uses the discrete-time nature of the active rectifier to define its state in each sampling interval. Although the switching frequency is not constant, this current control strategy allows to follow the reference with low total harmonic distortion (THDF). The implementation of the active rectifier that was used to obtain the experimental results is described in detail along the paper, presenting the circuit topology, the principle of operation, the power theory, and the current control strategy. The experimental results confirm the robustness and good performance (with low current THDF and controlled output voltage) of the proposed single-phase FLAR operating with model predictive current control.
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Publicado em "Information control in manufacturing 1998 : (INCOM'98) : advances in industrial engineering : a proceedings volume from the 9th IFAC Symposium, Nancy-Metz, France, 24-26 June 1998. Vol. 2"
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Tese de Doutoramento (Programa Doutoral em Engenharia Biomdica)
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Tese de Doutoramento em Geografia Humana.
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In 2008, the XVII Portuguese Constitutional Government launched the e.escolinha programme, within the Technological Plan for Education, which set out the distribution of a computer, called Magalhes, designed for chil-dren attending the 1st cycle of basic education. Suspended in 2011 by the XIX Government, this programme has allowed, however, almost 500 000 children to have access to a personal computer. It was expected that this political measure would revolutionise the national education system by bringing changes to the pedagogical practices of teachers and the learning processes of children and by achieving educational success, in general. Based on documental analysis and on a set of interviews with key decision-makers in conceiving, implementing and monitoring this governmental initiative, the rst part of this chapter presents and analyses the e.escolinha initiative and the policies be-hind that governmental programme, seeking to disassemble those objectives and provide some insights into the relationship between discourses, rhetoric, and reality. After that, the chapter focuses on childrens uses and practices with the Magalhes laptop, at school and at home. Based on the results of questionnaires lled in by approximately 1500 children from 32 First Cycle public schools of the municipality of Braga (north of Portugal) and also from questionnaires applied to their parents and teachers, this chapter intends to analyse the real impact of this initiative for children, family and school. It also seeks to discuss the contribution of this educational policy to childrens digital literacy and also to their own and their families social and digital inclusion. To understand if it represented an added value to teachers pedagogical practice is another of its aims. The ndings point out a major focus on technology and access rather than on uses and competences or even on social, educational and cultural change. In fact, a major conclusion is the existence of a strong gap between the policy and the practices, typical of a top-down policy design. This study is an integrant part of a research project titled Navigating with Magalhes: Study on the Impact of Digital Media in Schoolchildren conducted at the University of Minho, Portugal, nanced by the Portuguese Foundation for Science and Technology [PTDC/CCI-COM/101381/2008] and co-funded by the European Regional Development Fund [COMPETE: FCOMP-01-0124-FEDER-009056].
