Implementation of a sigma delta modulator for a class D audio power amplifier

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

Design of a power output stage for a class D audio power amplifier based on an 1.5-bit ∑ ∆ M

Dissertação apresentada para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Satisfação profissional dos dietistas nos hospitais do Serviço Nacional de Saúde : um primeiro estudo empírico

RESUMO - A satisfação no trabalho é entendida como um conjunto de sentimentos ou respostas afetivas relacionados com aspetos particulares do trabalho. Os autores não são unânimes na sua definição concetual. Neste estudo pretende-se compreender a satisfação profissional dos dietistas a exercer nos hospitais públicos em Portugal continental. A satisfação profissional foi avaliada através de um questionário (adaptado de Graça,1999) dividido em três partes. Foi aplicada uma escala de intervalos, na Discrepância entre as Expetativas (E) e Resultados (R), constituída por 8 dimensões e 44 itens. Mediu-se igualmente a importância motivacional que os dietistas atribuíram a cada uma das 8 dimensões, e foi feita a sua caraterização sociodemográfica da população estudada. De uma população inicial constituída por 42 elementos, contactada por email para responder ao questionário “on line”, tivemos 34 respondentes. Quatro respostas, por incompletas, não foram consideradas no tratamento. No final, temos uma amostra de conveniência constituída por 30 dietistas, todos eles a trabalhar atualmente em hospitais do SNS. A taxa de resposta válida é, pois, de 71,4%. Trata-se de um estudo descritivo, observacional e tipo transversal. A análise de dados baseou-se na estatística descritiva e analítica. O score médio global (2,59), indicador da discrepância E-R, permite classificar a amostra como estando “bastante satisfeita” em relação ao seu trabalho e à sua profissão. Em relação à ordenação das dimensões segundo a importância motivacional, a Realização pessoal e profissional & desempenho organizacional (1º) (2,57), é aquela que os inquiridos consideraram a mais importante, seguida da Relação profissional/utente (2º) (3,78) e finalmente a Autonomia & poder (3º) (3,96). Os melhores scores médios de cada dimensão são a Relação profissional/utente (1º) (1,36), seguida do Status e prestigio (2º) (1,51) e por último as Relações de trabalho e suporte social (3º) (2,39). Em conclusão, em relação à ordenação das dimensões segundo a importância motivacional, a Realização pessoal e profissional e desempenho organizacional foi considerada pelos dietistas a mais importante e a dimensão menos importante foi a do Status e prestígio. A Relação profissional/utente foi a dimensão com melhor score médio, ou seja, é a dimensão onde os dietistas se encontram mais satisfeitos, e a remuneração foi a dimensão onde a população se encontra menos satisfeita. A satisfação profissional dos dietistas que trabalham em hospitais públicos pode contribuir para melhorar a prestação de cuidados de saúde à população. Recomendamos por isso, mais investigação que aborde aquela temática, tornando mais visível a importância do dietista no contexto da saúde em Portugal.

Is Information Power? Using Mobile Phones and Free Newspapers during an Election in Mozambique*

African elections often reveal low levels of political accountability. We assess different forms of voter education during an election in Mozambique. Three interventions providing information to voters and calling for their electoral participation were randomized; an SMS-based information campaign, an SMS hotline for electoral misconduct, and the distribution of a free newspaper. To measure impact, we look at official electoral results, reports by electoral observers, behavioral and survey data. We find positive effects of all treatments on voter turnout. We observe that the distribution of the newspaper led to more accountability-based participation and to a decrease in electoral problems.

Study on the valorization routes of ashes from thermoelectric power plants working under mono-and co-combustion regimes

Thesis submitted to obtain the Doctoral degree in Energy and Bioenergy

Design of multidimensional compact constellations with high power efficiency

Dissertação apresentada para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

While the crisis proceeds: A world redistribution of economic power?

The crisis has drawn attention to the fact that not only emerging powers but other regions of the world as well may be offering different development models and may constitute into alternative, in some dimensions more positive agents, in the conduct of the present stage of globalisation. Notwithstanding, the traditional western powers have not lost a large amount of control of the world economy. And the crisis proceeds, reallocating world power as in a Hobbesian anarchy. It is difficult to foresee smooth developments in the near future. On the contrary, multilateralism seems to be losing ground to unilateral action or bilateral arrangements. More or less disguised currency wars may lead to serious disequilibria, and turf wars may become more frequent, with motives ranging from securing captive markets to control of specific commodities and energy goods, or targeted regulatory frameworks. As economic policy becomes even more involved with defence and security affairs, the feedbacks from each side to the other seem likely to keep dissent and animosity high, rather than contributing to peaceful and constructive approaches. A more trouble-prone world may be easily expected.

O quinto elemento da política externa portuguesa e o conceito de soft power

Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Ciência Política e Relações Internacionais, na área de especialização em Globalização e Ambiente

Exploring the predictive power of Google searches over the US stock market

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

Portuguese Ministers, 1851-1999: Social Background and Paths to Power

Disponível em: http://193.136.113.6/Opac/Pages/Search/Results.aspx?SearchText=UID=bb8aa8d5-c6b6-466a-81bb-fe8a67693cee&DataBase=10449_UNLFCSH

Design of a Continuous-Time (CT) Sigma-Delta modulator for class D audio power amplifiers

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

2D position system for a mobile robot in unstructured environments

Nowadays, several sensors and mechanisms are available to estimate a mobile robot trajectory and location with respect to its surroundings. Usually absolute positioning mechanisms are the most accurate, but they also are the most expensive ones, and require pre installed equipment in the environment. Therefore, a system capable of measuring its motion and location within the environment (relative positioning) has been a research goal since the beginning of autonomous vehicles. With the increasing of the computational performance, computer vision has become faster and, therefore, became possible to incorporate it in a mobile robot. In visual odometry feature based approaches, the model estimation requires absence of feature association outliers for an accurate motion. Outliers rejection is a delicate process considering there is always a trade-off between speed and reliability of the system. This dissertation proposes an indoor 2D position system using Visual Odometry. The mobile robot has a camera pointed to the ceiling, for image analysis. As requirements, the ceiling and the oor (where the robot moves) must be planes. In the literature, RANSAC is a widely used method for outlier rejection. However, it might be slow in critical circumstances. Therefore, it is proposed a new algorithm that accelerates RANSAC, maintaining its reliability. The algorithm, called FMBF, consists on comparing image texture patterns between pictures, preserving the most similar ones. There are several types of comparisons, with different computational cost and reliability. FMBF manages those comparisons in order to optimize the trade-off between speed and reliability.

Wind Power in the Portuguese Landscape: Global Concerns and Local Costs

Wind turbines and solar panels are becoming second nature in Portugal, as its occurrence in the country becomes ubiquitous. Somehow, one could argue that renewable energy in Portugal is in the process of ‘naturalisation’ as part of a new – mechanised, but environmentally benign – landscape. Portuguese Institute for the Conservation of Nature and Biodiversity (ICNB) has shown an ambiguous stance on this issue, defending global concerns towards renewable energy, while at the same time attempting to engage locals in the preservation of extensive ‘classified areas’. In the course of this research, we tried to focus on these incongruities and to analyse how they are impacting local communities during the process of wind power installation.

A marketing plan for Companhia das Quintas to strengthen its position in the Chinese wine market

Companhia das Quintas, Limited Company wishes to conquer the Chinese market with its wines. For that, it decided to enter in a partnership with a local importer and distributor. This project analyses the macroeconomic factors of the country, the local market and the consumer behavior, using on-site research that included interviews with professionals of the industry, unstructured observation of the consumer and existing statistical data analysis. Finally, the project presents a marketing plan to make this partnership a success.