Methods for a systematic analysis of power converters

This contribution aims at presenting fundamental principles and theoretical tools for a comprehensive study and systematic analysis of generic power conversion circuits. The contents are divided into three main parts. Part I presents a new graphical technique for the state analysis of the so-called ‘fundamental LCEI type circuit’, which is found in sequences of many practical power converter topologies. In Part II, this graphical technique is used within a straightforward sequence-by-sequence algorithm to study the intrinsic functionality of power converters and to describe the evolution in time of their main quantities (state variables) and the conditions governing switch commutations and state transitions. Part III is devoted to power converter modelling techniques, a major advance for stable control loop design

M-Payments in Brazil: Notes on How a Country\u27s Background May Determine Timing and Design of a Regulatory Model

Extended periods of high-inflation in Brazil have resulted in a sophisticated platform for payment methods and a vast network of banking correspondents all over the country. Social policies have encouraged increased access to telecommunications, with the number of mobile phones exceeding the nearly 200 million inhabitants. Governmental programs intend to combine such strengths to achieve massive financial inclusion and integrity, an effort that is expected to reach dozens of millions of new beneficiaries. In that endeavor, authorities wish to foster rapid popularization of mobile payments (m-payments) while keeping sound financial controls. Availability of current technological and legal platforms has allowed that a mature process develops in the selection of proper regulation. This Article discusses how Brazil’s background has determined the timing and design of a regulatory model, and points out a case of prudent approach by a developing country in the subject matter

Efeitos do treino dos músculos inspiratórios em remadores de competição

Introdução: A fadiga muscular compromete o funcionamento do sistema respiratório durante o exercício físico afetando os músculos respiratórios e podendo prejudicar a performance. Um programa de treino dos músculos inspiratórios (TMI) poderá trazer benefícios aos atletas, melhorando capacidades respiratórias e por consequência o seu desempenho. Objetivo: Investigar os efeitos do TMI na função pulmonar em remadores de competição e se este poderá influenciar a sua performance. Métodos: Participaram no estudo 14 atletas de remo, séniores, do sexo masculino. Foram avaliados antes e depois da aplicação do TMI, realizado durante seis semanas recorrendo a um threshold. Os atletas foram submetidos a duas séries de 30 repetições a 50% da pressão inspiratória máxima estimada (PIM). Nos dois momentos de avaliação foram registados, com recurso ao sistema BIOPAC MP36, os valores de: Capacidade Vital (CV), Volume Corrente (VC), Capacidade Pulmonar Total (CPT), Volume de Reserva Inspiratório (VRI), Volume de Reserva Expiratório (VRE), Volume Expiratório Forçado no primeiro segundo (FEV1) e Ventilação Voluntária Máxima (VVM). Resultados: Verificou-se um aumento significativo da VVM (p = 0,000), do VRI (p = 0,009) e do VC (p = 0,033) entre a primeira e segunda avaliação. Não se detetaram melhorias relevantes nos valores das capacidades e restantes volumes pulmonares que, no entanto, aumentaram ligeiramente, com a exceção do VRE, expressando a especificidade do TMI, corroborada pela melhoria nos valores do VRI. Conclusão: O TMI produz efeitos positivos na função pulmonar em remadores de competição aumentando a resistência muscular do atleta, que não entra em fadiga respiratória tão precocemente permitindo-lhe assim uma maior capacidade de resposta às exigências que o exercício requer

Tecnologia flextec aplicada ao sector da construção

Na primeira parte do presente estudo, são apresentadas, resumidamente, as tecnologias de adesivos e vedantes, que servem de base para a apresentação da tecnologia Flextec®, uma tecnologia que junta o melhor destes dois tipos de materiais. Relativamente aos adesivos apresentam-se algumas das teorias de adesão, a ligação adesiva ao longo dos tempos, as vantagens e desvantagens da utilização de adesivos e por fim, os diversos tipos de adesivos e suas principais aplicações. Relativamente aos vedantes, a introdução é semelhante, referindo-se os seus tipos, classificação e aplicações, nomeadamente a aplicação em juntas. Uma vez que a tecnologia em estudo, é um exclusivo Henkel, foi dedicada uma parte da introdução para a apresentação da empresa e do seu portfólio de produtos, destacando-se aqueles que se apresentam como soluções recentes e inovadores, nas suas gamas, dentro da divisão de construção. Após esta introdução, é apresentada a tecnologia Flextec®, com as suas vantagens, campos de aplicação e gama de produtos associados. Na segunda parte, apresentam-se os resultados do trabalho experimental realizado nas instalações da Henkel, com um dos produtos com tecnologia Flextec® - Sista Solyplast SP-301 Fachadas, em que foram elaborados 42 provetes com diferentes tipos de materiais utilizados em fachadas e o adesivo. Os provetes foram sujeitos a ensaios qualitativos de tracção e a maioria deles apresentou ruptura coesiva, resultado que garante que o produto cumpre os requisitos do certificado CIDEMCO apresentado pelo produto. Nesta segunda parte, são também apresentados outros trabalhos relacionados com utilização da tecnologia Flextec®, em novas soluções de construção

Speaking skills and communicative competence in EFL: relating theory to teachers’ and learners’ perceptions

Mastering the art of speaking is an undeniably essential aspect when learning any foreign language. At a functional level, speaking implies communicative competence, which is often seen as the knowledge of how one uses the linguistic system appropriately (Tarone, 1981). However, communicative competence does not stand alone. It requires strategic competence and interactive skills that involve making communication decisions, while maintaining desired relations with others (Bygate, 1987). With the bolstering situation of English as an international language, there is an increasing demand for communicative competence to be addressed more systematically. Taking the importance of developing EFL speaking skills into account, it is vital to understand what is implied in second language acquisition and learning, as well as to understand how the desired language proficiency should be boosted, in order to have learners efficiently conversing in real-life communicative contexts. Therefore, this study will be based on theory related to learning and teaching English as a foreign language and, in particular, on the communicative competence and speaking skills. This will be the basis for analysing the data gathered on the perspectives of Portuguese EFL learners and teachers, as far as speaking skills and oral communicative competences are concerned

CleanGraph - Graph viewing and editing for family trees and UML class diagrams

Traditionally, different types of diagrams are used to represent varying types of data in a fast and easy way to read. Their usage includes describing systems, understanding their features and presenting how different parts are interconnected, making them useful for many applications. Unfortunately, as the complexity of the data showed increases, so does the complexity of the diagram, making it more difficult to read and interpret. Since interactions are usually limited to panning and zooming, there is room for improvement with more interaction and different input methods. The goal is to tackle these issues in two types of diagrams -- Family Trees (FT) and Universal Modeling Language (UML) class diagrams. To achieve this, a new platform will be created, capable of generating diagrams and displaying them in a way where overlapping and unrelated data is minimised alongside having better methods for interacting with and manipulating information. These diagrams will prioritise visual clarity by grouping together elements with relevant or important information, as well as having new ways of interaction, such as selecting elements to receive more information and manually grouping them to better explore the data. Guaranteeing the viability of the solution will require two main issues to be addressed: (1) Defining a fitting diagram disposition and why it is the more advantageous; (2) Understanding the best way to create interactions with diagrams while making it intuitive and keeping them readable. Finding the best platform for the solution to reach its intended audience while providing the desired ease of use is one of the priorities. The evaluation of this work will be attained through previously defined metrics, to ensure that the generated diagram is adequate. The quality of the diagrams will be defined by characteristics such as overlapping connections between elements, related or unrelated data of adjacent elements to the selected one and the amount of displayed data at once. The result of the proposal aims to give a better tool to users seeking improved methods to view their ancestry data, as well as software architects, project managers and system analysts, who would benefit from a better platform for system representation. The developed features can help them convey their ideas easily to developers or anyone interested in the data represented, improving simplicity, workflow and potentially bringing new and improved methods of viewing and displaying information in these areas

Efeitos da contaminação na memória prospetiva: um estudo exploratório

The behavioural immune system is an adaptive disease avoidance system. It involves three different types of responses: emotional, behavioural, and cognitive. This study investigated this last type of response, focusing on memory. Previous studies have shown that we tend to memorize easier stimuli related to aspects of contamination, which focused essentially on retrospective memory. In this study, we focused on another type of memory: prospective memory, which allows us to remember to perform actions that need to be performed in the future. Thus, we tried to understand if humans tend to have a higher prospective memory performance when prospective stimuli are processed as sources of contamination, as happens in retrospective memory. During the experiment, participants responded to an ongoing task, in which they were presented with a face and an object, and had to indicate the category of the object, by pressing one of three possible keys. In some of the trials, prospective stimuli were presented (one with and the other without disease cues), and participants had to press the space key in these cases, simulating the delivery of an envelope. Results showed no significant differences in performance and response time values in both tasks (ongoing and PM task) between contaminated and non-contamination conditions. However, they showed significant higher ongoing task hit rate and response time values than in the PM task. This study was the first one to explore the contamination effects in prospective memory. Despite this, we point some limitation that can inspire future studies.O sistema imunológico comportamental é um sistema adaptativo que promove a prevenção de doenças. Envolve três tipos diferentes de respostas: emocional, comportamental e cognitiva. Este estudo investigou este último tipo de resposta, com foco na memória. Estudos prévios revelaram que tendemos a memorizar mais facilmente estímulos relacionados com aspetos de contaminação, focando-se essencialmente na memória retrospetiva. Neste estudo, focamo-nos noutro tipo de memória: a memória prospetiva, que nos permite lembrar de realizar ações que necessitam de ser realizadas no futuro. Assim, tentámos perceber se os humanos tendem a ter um desempenho de memória prospetiva mais alto quando os estímulos prospetivos são processados como podendo ser fontes de contaminação, tal como acontece na memória retrospetiva. Durante a realização da tarefa, os participantes responderam a uma tarefa decorrente, onde lhes eram apresentados uma face e um objeto, tendo de identificar a categoria do objeto, premindo uma de três possíveis teclas. Em alguns dos ensaios, eram apresentados os estímulos prospetivos (um com e outro sem pistas de doença), devendo o participante premir a tecla espaço nestes casos, simulando a entrega de um envelope. Os resultados revelaram a ausência de diferenças significativas na performance e nos tempos de resposta das tarefas (tarefa decorrente e prospetiva) entre os estímulos de contaminação e de não contaminação. Contudo, revelaram valores significativamente maiores de taxa de acerto e de tempo de resposta na tarefa decorrente (comparando com a tarefa de memória prospetiva). Este foi o primeiro estudo que explora os efeitos da contaminação na memória prospetiva. Apesar deste caracter inovador, apontamos algumas limitações que poderão inspirar estudos futuros.Mestrado em Psicologia da Saúde e Reabilitação Neuropsicológic

Modelling tourism demand in Madeira since 1946: and historical overview based on a time series approach

Tourism is the leading economic sector in most islands and for that reason market trends are closely monitored due to the huge impacts of relatively minor changes in the demand patterns. An interesting line of research regarding the analysis of market trends concerns the examination of time series to get an historical overview of the data patterns. The modelling of demand patterns is obviously dependent on data availability, and the measurement of changes in demand patterns is quite often focused on a few decades. In this paper, we use long-term time-series data to analyse the evolution of the main markets in Madeira, by country of origin, in order to re-examine the Butler life cycle model, based on data available from 1946 onwards. This study is an opportunity to document the historical development of the industry in Madeira and to introduce the discussion about the rejuvenation of a mature destination. Tourism development in Madeira has experienced rapid growth until the late 90s, as one of the leading destinations in the European context. However, annual growth rates are not within acceptable ranges, which lead policy-makers and experts to recommend a thoughtfully assessment of the industry prospects.info:eu-repo/semantics/publishedVersio