Avaliação económica de sistemas solares fotovoltaicos residenciais

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica no Ramo de Energia

Reliable real-time communication in CAN networks

Controller area network (CAN) is a fieldbus network suitable for small-scale distributed computer controlled systems (DCCS), being appropriate for sending and receiving short real-time messages at speeds up to 1 Mbit/sec. Several studies are available on how to guarantee the real-time requirements of CAN messages, providing preruntime schedulability conditions to guarantee the real-time communication requirements of DCCS traffic. Usually, it is considered that CAN guarantees atomic multicast properties by means of its extensive error detection/signaling mechanisms. However, there are some error situations where messages can be delivered in duplicate or delivered only by a subset of the receivers, leading to inconsistencies in the supported applications. In order to prevent such inconsistencies, a middleware for reliable communication in CAN is proposed, taking advantage of CAN synchronous properties to minimize the runtime overhead. Such middleware comprises a set of atomic multicast and consolidation protocols, upon which the reliable communication properties are guaranteed. The related timing analysis demonstrates that, in spite of the extra stack of protocols, the real-time properties of CAN are preserved since the predictability of message transfer is guaranteed.

Integrating inaccessibility in response time analysis of CAN networks

Controller Area Network (CAN) is a fieldbus network suitable for small-scale Distributed Computer Controlled Systems, being appropriate for transferring short real-time messages. Nevertheless, it must be understood that the continuity of service is not fully guaranteed, since it may be disturbed by temporary periods of network inaccessibility [1]. In this paper, such temporary periods of network inaccessibility are integrated in the response time analysis of CAN networks. The achieved results emphasise that, in the presence of temporary periods of network inaccessibility, a CAN network is not able to provide different integrity levels to the supported applications, since errors in low priority messages interfere with the response time of higher priority message streams.

Programming atomic multicasts in CAN

In Distributed Computer-Controlled Systems (DCCS), a special emphasis must be given to the communication infrastructure, which must provide timely and reliable communication services. CAN networks are usually suitable to support small-scale DCCS. However, they are known to present some reliability problems, which can lead to an unreliable behaviour of the supported applications. In this paper, an atomic multicast protocol for CAN networks is proposed. This protocol explores the CAN synchronous properties, providing a timely and reliable service to the supported applications. The implementation of such protocol in Ada, on top of the Ada version of Real-Time Linux is presented, which is used to demonstrate the advantages and disadvantages of the platform to support reliable communications in DCCS.

Micro-generation Evaluation of the Zero Emissions Technologies in the Portuguese Market

Micro-generation is the small scale production of heat and/or electricity from a low carbon source and can be a powerful driver for carbon reduction, behavior change, security of supply and economic value. The energy conversion technologies can include photovoltaic panels, micro combined heat and power, micro wind, heat pumps, solar thermal systems, fuel cells and micro hydro schemes. In this paper, a small research of the availability of the conversion apparatus and the prices for the micro wind turbines and photovoltaic systems is made and a comparison between these two technologies is performed in terms of the availability of the resource and costs. An analysis of the new legal framework published in Portugal is done to realize if the incentives to individualspsila investment in sustainable and local energy production is worth for their point of view. An economic evaluation for these alternatives, accounting with the governmentpsilas incentives should lead, in most cases, into attractive return rates for the investment. Apart from the attractiveness of the investment there are though other aspects that should be taken into account and those are the benefits that these choices have to us all. The idea is that micro-generation will not only make a significant direct contribution to carbon reduction targets, it will also trigger a multiplier effect in behavior change by engaging hearts and minds, and providing more efficient use of energy by householders. The diversified profile of power generation by micro-generators, both in terms of location and timing, should reduce the impact of intermittency or plant failures with significant gains for security of supply.

Human-robot teamwork: a knowledge-based solution

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

Perspectives of the Internal Public in a Cultural Event: the Case of Noc Noc, Guimarães - Portugal

Given the significant impact that cultural events may have in local communities and the inherent organization complexity, it is important to understand their specificities. Most of the times cultural events disregard marketing and often marketing is distant from art. Thus an analysis of an inside perspective might bring significant returns to the organization of such an event. This paper considers the three editions (2011, 2012 and 2013) of a cultural event – Noc Noc – organized by a local association in the city of Guimarães, Portugal. Its format is based in analogous events, as Noc Noc intends to convert everyday spaces (homes, commercial outlets and a number of other buildings) into cultural spaces, processed and transformed by artists, hosts and audiences. By interviewing a sample of people (20) who have hosted this cultural event, sometimes doubling as artists, and by experiencing the three editions of the event, this paper illustrates how the internal public understands this particular cultural event, analyzing specifically their motivations, ways of acting and participating, as well as their relationship with the public, with the organization of the event and with art in general. Results support that artists and hosts motivations must be identified in a timely and appropriate moment, as well as their views of this particular cultural event, in order to keep them participating, since low budget cultural events such as this one may have a key role in small scale cities.

Coastal sedimentary environments and sea-level changes

A detailed knowledge of the 3-D arrangement and lateral facies relationships of the stacking patterns in coastal deposits is essential to approach many geological problems such as precise tracing of sea level changes, particularly during small scale fluctuations. These are useful data regarding the geodynamic evolution of basin margins and yield profit in oil exploration. Sediment supply, wave-and tidal processes, coastal morphology, and accommodation space generated by eustasy and tectonics govern the highly variable architecture of sedimentary bodies deposited in coastal settings. But these parameters change with time, and erosional surfaces may play a prominent role in areas located towards land. Besides, lateral shift of erosional or even depositional loci very often results in destruction of large parts of the sediment record. Several case studies illustrate some commonly found arrangements of facies and their distinguishing features. The final aim is to get the best results from the sedimentological analysis of coastal units.

Interpretação tectónica de um conjunto de lineamentos WNW-ESE observados em imagens landsat da margem oeste ibérica

The existence of satellite images ofthe West Iberian Margin allowed comparative study of images as a tool applied to structural geology. Interpretation of LANDSAT images of the Lusitanian Basin domain showed the existence of a not previously described WNW-ESE trending set oflineaments. These lineaments are persistent and only observable on small scale images (e.g. approx. 11200000 and 11500 000) with various radiometric characteristics. They are approximately 20 km long, trend l200±15° and cross cut any other families oflineaments. The fact that these lineaments are perpendicular to the Quaternary thrusts of the Lower Tagus Valley and also because they show no off-set across them, suggests that they resulted from intersection oflarge tensile fractures on the earth's surface. It is proposed in this work that these lineaments formed on a crustal flexure of tens ofkm long, associated with the Quaternary WNW-ESE oriented maximum compressive stress on the West Iberian Margin. The maximum compressive stress rotated anticlockwise from a NW -SE orientation to approximately WNW-ESE, from Late Miocene to Quaternary times (RIBEIRO et aI., 1996). Field inspection of the lineaments revealed zones of norm~1.J. faulting and cataclasis, which are coincident with the lineaments and affect sediments of upper Miocene up to Quaternary age. These deformation structures show localized extension perpendicular to the lineaments, i.e. perpendicular to the maximum compressive direction, after recent stress data along the West Portuguese Margin (CABRAL & RIBEIRO, 1989; RIBEIRO et at., 1996). Also, on a first approach, the geographical distribution of these lineaments correlates well with earthquake epicenters and areas of largest Quaternary Vertical Movements within the inverted Lusitanian Basin (CABRAL, 1995).

Dispatch of distributed Energy Resources to Provide Energy and Reserve in Smart Grids using a Particle Swarm Optimization Approach

The smart grid concept is a key issue in the future power systems, namely at the distribution level, with deep concerns in the operation and planning of these systems. Several advantages and benefits for both technical and economic operation of the power system and of the electricity markets are recognized. The increasing integration of demand response and distributed generation resources, all of them mostly with small scale distributed characteristics, leads to the need of aggregating entities such as Virtual Power Players. The operation business models become more complex in the context of smart grid operation. Computational intelligence methods can be used to give a suitable solution for the resources scheduling problem considering the time constraints. This paper proposes a methodology for a joint dispatch of demand response and distributed generation to provide energy and reserve by a virtual power player that operates a distribution network. The optimal schedule minimizes the operation costs and it is obtained using a particle swarm optimization approach, which is compared with a deterministic approach used as reference methodology. The proposed method is applied to a 33-bus distribution network with 32 medium voltage consumers and 66 distributed generation units.

Vibration control with shape-memory alloys in civil engineering structures

Dissertação apresentada à Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Doutor em Engenharia Civil

Desenvolvimento de programação offline e de novos processos robotizados de lixamento

Atualmente a vantagem competitiva de uma empresa passa pela sua rápida adaptação às variações de procura do mercado, sendo necessário garantir elevados níveis de produtividade e, simultaneamente, grande flexibilidade, indispensável ao fabrico de pequenos lotes. A necessidade de ajuste do processo e a diminuição da média de vida do produto levam a paragens cada vez mais frequentes da célula de fabrico para programação e afinação, com consequentes perdas de produtividade. De forma a dar resposta a estes problemas, neste trabalho é testada a viabilidade da utilização da programação e simulação offline de tarefas de lixamento na Grohe Portugal, complementando a solução com o desenvolvimento de um novo método de afinação do programa, permitindo uma adaptação às flutuações do processo produtivo. Para isso foi necessário analisar o estado da arte dos robôs industriais na área de acabamento superficial e respetivos métodos de programação. Em seguida, após um trabalho prévio rigoroso de preparação e modelação da célula de trabalho, é possível fazer a programação offline das várias rotinas e trajetórias complexas que compõem um ciclo de lixamento de um produto, contribuindo para o aumento da qualidade do produto final sem comprometer os níveis de produtividade. Nesta dissertação são descritos e detalhados alguns dos procedimentos fulcrais no sucesso da aplicação deste método de programação. Por último é feita uma nova abordagem ao método de ajuste ponto-a-ponto convencional, desenvolvendo-se para isso um sistema de ajuste automático do programa, dotando o robô da capacidade de se adaptar às variações do processo, assegurando a consistência do mesmo. Foram realizados testes em pequena escala, extrapolando-se os resultados para a aplicação deste novo método no processo produtivo da Grohe Portugal, como forma de complemento ao método convencional de ajuste ponto-a-ponto do programa, reduzindo o tempo de paragem da célula de trabalho.

Correlation between the mechanical cycling behavior and microstructure in laser welded joints using NiTi memory shape alloys

Dissertação para obtenção do Grau de Mestre em Engenharia de Materiais

CHEMOPROPHYLAXIS TO CONTROL LEPROSY AND THE PERSPECTIVE OF ITS IMPLEMENTATION IN BRAZIL: A PRIMER FOR NON-EPIDEMIOLOGISTS

The occurrence of leprosy has decreased in the world but the perspective of its elimination has been questioned. A proposed control measure is the use of post-exposure chemoprophylaxis (PEP) among contacts, but there are still questions about its operational aspects. In this text we discuss the evidence available in literature, explain some concepts in epidemiology commonly used in the research on this topic, analyze the appropriateness of implementing PEP in the context of Brazil, and answer a set of key questions. We argue some points: (1) the number of contacts that need to receive PEP in order to prevent one additional case of disease is not easy to be generalized from the studies; (2) areas covered by the family health program are the priority settings where PEP could be implemented; (3) there is no need for a second dose; (4) risk for drug resistance seems to be very small; (5) the usefulness of a serological test to identify a higher risk group of individuals among contacts is questionable. Given that, we recommend that, if it is decided to start PEP in Brazil, it should start on a small scale and, as new evidence can be generated in terms of feasibility, sustainability and impact, it could move up a scale, or not, for a wider intervention.

Intention recognition, commitment and their roles in the evolution of cooperation

Dissertação para obtenção do Grau de Doutor em Informática