3,046 research outputs found
Considerações sobre o ordenamento do território
O ordenamento do território é, fundamentalmente, a gestão da interacção homem/espaço natural. Consiste no planeamento das ocupações, no potenciar do aproveitamento das infra-estruturas existentes e no assegurar da preservação de recursos limitados.
Os diferentes planos, para serem eficazes, têm que ser enquadráveis a diversas escalas de análise, dependendo a efectividade de todos eles da coerência dos restantes. Um plano nacional de ordenamento do território tem que se basear na lógica dos planos das diferentes regiões; estes, por sua vez, têm por base planos municipais que definem o uso dos solos e estabelecem princípios para a gestão das cidades e das aldeias do local; os aglomerados deverão ser organizados por planos operativos que regulem e ordenem a sua estrutura construída, os seus edifícios, e que definam coerências para a localização das diferentes funções que neles coexistem – a indústria, o comércio, a habitação ou a agricultura. São os Planos de Urbanização, os de Pormenor ou de Salvaguarda que, e mais uma vez a escalas diversas, delimitam e desenham as malhas que estruturam e definem a urbe.
Spatial modulations for green heterogeneous networks
A rápida evolução dos sistemas de telecomunicações culminou numa necessidade cada vez mais
crescente por redes que permitam elevados débitos. Associado a esse throughput elevado está
o custo energético que gradualmente torna os sistemas pouco eficientes energeticamente. As
modulações espaciais generalizadas (Generalized Spatial Modulation -GSM) surgem da
necessidade de criar comunicações mais “verdes”, permitindo obter melhores eficiências
energéticas através da redução do número de cadeias de blocos radio-frequência (RF) utilizadas
no emissor.
O estudo apresentado neste trabalho pretende realçar, num primeiro ponto, a importância da
evolução dos sistemas de transmissão MIMO (Multiple-Input Multiple-Output) como forma de
aumento do throughput global de uma rede de telecomunicações mantendo uma eficiência
energética alta, com foco em GSM. O segundo ponto consiste no estudo de um algoritmo
baseado no método ADMM (Alternating Direction Method of Multipliers), como recetor de
baixa complexidade para esquemas GSM com desempenho próximo do ótimo, o detetor de
máxima verosimilhança (MLD).
O estudo do recetor ADMM foi efetuado em duas fases, sendo que a primeira é referente ao
estudo extensivo e exclusivo do recetor ADMM, com principal enfoque nos vários parâmetros
que o definem. Na segunda fase é feita uma comparação para vários cenários entre o recetor
ADMM e alguns dos recetores de baixa complexidade mais conhecidos, entre eles o OB-MMSE
(Ordered Block MMSE) e o BPDN (Basis Pursuit De-Noising), por exemplo.
A realização de simulações, com os vários recetores, em vários cenários permitiu concluir que
o ADMM, com recurso às suas técnicas de refinamento, representa uma alternativa eficiente, e
em certos casos superior, ao OB-MMSE principalmente para cenários com um elevado número
de bits por símbolo espacial.The fast evolution of telecommunications systems resulted in a growing need for networks that
support high transmission rates. Associated with this high throughput is the energy cost that
gradually makes this systems less energy-efficient . The Generalized Spatial Modulation
(GSM) arises from the need to create more "green" communication, allowing best energy
efficiencies.
The study presented in this thesis aims to highlight firstly, the importance of the development
of MIMO (Multiple-Input Multiple-Output) transmission systems capable of increasing the
overall throughput of a telecommunications network while maintaining high energy efficiency,
focusing on GSM. The second relevant aspect is the study of an algorithm based on the ADMM
(Alternating Direction Method of Multipliers) method, as a solution for a low complexity
receiver for GSM schemes with a performance close to the optimal one, the maximum
likelihood detector (MLD).
The ADMM receiver study was conducted in two phases, the first of which refers to the
extensive and unique study of the ADMM receiver, with main focus on the various parameters
that define it. In the second stage a comparison is made between the settings for various ADMM
receivers and some of the known low-complexity receivers, including OB-MMSE (Ordered
Block MMSE) and BPDN (Basis Pursuit De-noising), for example.
The results obtained from the evaluations performed several scenarios allow us to conclude that
the ADMM based receiver combined with refinement techniques, is an efficient alternative and
in some cases with better performance than the OB-MMSE receiver, especially for scenarios
with a large number of bits per spatial symbol
Prenegotiation and actual negotiation in electricity markets
Software agents have been successfully used in a vast range of applications. Agents have
been gradually designed to act in open environments and to manage their cooperative and
competitive interactions with other agents present in their environment. In a Multi-agent
System (MAS), involving different agents operating individually to meet their design goals,
conflict will be inevitable — it is not necessarily bad or good, but it is inevitable. Conflict is
the focal point of interaction, i.e. the driving force of negotiation. Furthermore, conflict is
the element that connects the individual and social behavior of agents.
Software tools based on intelligent agents with negotiating capabilities have became important
and pervasive. Particularly, there is a growing demand to develop MAS featuring bilateral
contracts in liberalized Electricity Markets (EMs). This dissertation addresses, at least
in part, this challenge by presenting the computational tool NSEM – Negotiation Simulator
for Electricity Markets. NSEM features Belief-Desire-Intention agents able to effectively
plan actions, manage conflicts, and trade proposals to reach mutually beneficial agreements.
NSEM focuses on the preliminary activities that should come before negotiation, usually
referred to as prenegotiation. These activities include the definition of the issues at stake,
their prioritization, and the selection of an appropriate protocol and effective strategies. This
dissertation presents details of NSEM’s implementation and test. NSEM was developed with
the JAVA programming language and the JADE platform. Its test was performed by using a
case study, featuring prenegotiation and actual negotiation of bilateral contracts in liberalized
EMs.A tecnologia baseada em agentes computacionais autónomos tem vindo a ser utilizada
com sucesso numa vasta gama de aplicações. Num Sistema Multi-agente (SMA), composto
por diversos agentes atuando individualmente para alcançarr os seus objectivos de projecto,
os conflitos são inevitáveis. Os conflitos constituem o elemento que liga o comportamento
individual e social dos agentes, sendo normalmente a força motriz da negociação.
O desenvolvimento de agentes com capacidade negocial sofreu avanços significativos
ao longo dos últimos anos. Estes agentes apresentam diversas vantagens relativamente aos
negociadores humanos, sendo de realçar a capacidade de obterem acordos benéficos para
todas as partes envolvidas na negociação. Nesta perspectiva, salienta-se a procura crescente
de SMAs para simular a contratação bilateral de energia em mercados liberalizados.
Esta dissertação tenta responder a este desafio através do desenvolvimento da ferramenta
computacional NSEM: “Negotiation Simulator for Electricity Markets”. NSEM permite criar
agentes constituídos pelas atitudes mentais de crença, desejo e intenção, capazes de planear
ações de forma efectiva, gerir conflitos, e negociar acordos mutualmente beneficiáveis.
NSEM coloca a ênfase no conjunto de atividades preliminares a realizar antes da negociação,
referido usualmente como pré-negociação. Estas atividades incluem a definição dos itens
a negociar, as suas prioridades, a escolha de um protocolo apropriado, e a seleção de estratégias efetivas. Esta dissertação ao apresenta detalhes da implementação e teste do NSEM. A
implementação foi efetuada através do Java e do JADE. O teste foi realizado através do desenvolvimento
de um caso de estudo referente à contratação bilateral de energia em mercados
de eletricidade liberalizados
Heat fluxes from landsat images: a contribuition to Lisbon urban planning
The urban structure is a modeller of wind fields and an active modifier of radiation conditions, trapping, reflecting and shadowing much more than the rural areas. In a smaller scale the different albedos and the heat capacity of the materials are also able to modify the thermal patterns. The main purposes of this work are to create a land use/urban structure map for climatic purposes and to estimate heat fluxes with numerical modelling and Landsat images are. We also want to contribute to Lisbon's urban planning by creating several cartographic documents as part of the project: “Prescription of climatic principles in urban planning. Application to Lisbon".info:eu-repo/semantics/publishedVersio
Strategic Bidding of Retailers in Wholesale Markets: Continuous Intraday Markets and Hybrid Forecast Methods
ABSTRACT: The deregulation process of the electricity sector has led to competition in wholesale and retail markets. In particular, retailers submit bids to wholesale markets to satisfy the energy needs associated with portfolios of end-use customers. This paper describes a strategic process for retailers bidding in a wholesale market composed of a day-ahead market, an intraday market, and a balancing market. It considers a market design that involves a hybrid model for the intraday market, based on daily auctions and a continuous procedure. The paper also presents a computational study to illustrate and test both the market design and the strategic bidding process of retailers. The results confirm the advantages of considering a continuous intraday market, show that bidding in short-term markets is more beneficial than bidding in medium-term markets, and indicate important aspects to consider when selecting customers to add to the portfolios of retailers.info:eu-repo/semantics/publishedVersio
NetJets Europe: A perspective from a business jet operator
In the aeronautic sector, corrosion has been a severe and recurrent problem, mostly since the introduction of metals in aircraft structures and components. This type of damage can affect the structure's integrity, putting in question the airworthiness and safety of the aircraft. History shows us numerous, well-documented aviation accidents, where corrosion was a factor that led to a system failure. Even though improvements have been made, over the years, in the design and manufacturing of new aircrafts, including the use of more corrosion-resistant materials, operators should have a good Corrosion Prevention and Control Program (CPCP) in place throughout the life of the aircraft, achieved through the experience obtained by the operator during the operation of the aircraft.
This dissertation exposes the importance of periodic revisions of the aircraft’s CPCP in the fight against corrosion. This research comes from the need of a business jet aircraft operator, NetJets Europe, to reduce maintenance costs related to corrosion and improve aircraft availability.
In this work, a segmented and efficient methodology for a comprehensive CPCP revision is described, in order to improve the operator’s economic and operational status. A corrosion findings database was created for each NetJets Europe fleet, in order to obtain an overview of the most affected areas. A complementary study was also performed, in terms of maintenance costs and labor hours, with the objective of finding the most critical areas, structures or components, that needed to be selected for extensive root cause analyses. During the root cause analyses, the aircraft manufacturers and Original Equipment Manufacturers (OEMs) were contacted for a better assessment of the problems.
The results show the importance of these analyses in order to find the best countermeasures possible, which can reduce maintenance costs and improve aircraft availability, while maintaining or improving the safety level.No setor aeronáutico, a corrosão tem sido um problema severo e recorrente, principalmente desde a introdução de metais em estruturas e componentes nas aeronaves. Este tipo de dano pode afetar a integridade das estruturas, colocando em causa a aeronavegabilidade e a segurança da aeronave. A história mostra-nos numerosos e bem documentados acidentes de aviação, nos quais a corrosão foi um fator que levou a uma falha do sistema. Mesmo com importantes melhorias feitas, ao longo dos anos, na conceção e fabrico de novas aeronaves, incluindo o uso de materiais mais resistentes à corrosão, os operadores deveriam possuir um bom Corrosion Prevention and Control Program (CPCP) durante toda a vida da aeronave, alcançado através da experiência obtida pelo operador durante a operação da aeronave.
Esta dissertação expõe a importância de revisões periódicas do CPCP das aeronaves, no combate à corrosão. Esta pesquisa vem da necessidade de um operador de jatos executivos, a NetJets Europe, em reduzir custos de manutenção, relacionados com corrosão, e melhorar a disponibilidade das aeronaves.
Neste trabalho, é descrita uma metodologia segmentada e eficiente para uma revisão compreensiva do Corrosion Prevention and Control Program, a fim de melhorar a situação económica e operacional do operador. Foi criada uma base de dados com danos de corrosão, para cada frota da NetJets Europe, a fim de obter uma visão geral das áreas mais afetadas. Foi também realizado um estudo complementar, em termos de custos de manutenção e horas de trabalho, com o objetivo de encontrar as áreas mais críticas, estruturas ou componentes, que precisavam de ser selecionadas para uma extensa análise da causa do problema. Durante a análise da causa do problema, os fabricantes das aeronaves e os Original Equipment Manufacturers (OEMs) foram contactados para uma melhor avaliação dos problemas.
Os resultados obtidos mostram a importância destas análises, a fim de encontrar as melhores contramedidas possíveis, capazes de reduzir os custos de manutenção e melhorar a disponibilidade da aeronave, mantendo ou melhorando o nível segurança
Using peer-mentoring to increase clinical skills in physiotherapy education: a comparison of 3 approaches
Purpose / hypothesis:
The aim of this study was to compare 3 different approaches to Peer-Mentoring in relation to the perception of the students how Peer-Mentoring could promote the development of Physiotherapy clinical skills in undergraduate Physiotherapy students.
Subjects:
This Peer-Mentoring was developed among students of the 2nd and 3rd years of undergraduate Physiotherapy course
Material / Methods:
During one semester, the students of the second year were organized in small groups and distributed to them a group of mentors of the third year. Each mentor had a specific area and a specific mentoring style. Orientation support was given at least 3 times during this process. All the groups registered all the activities carried out in the meetings. An online questionnaire was developed and used to perceive perceptions about the outcomes and satisfaction of all participants in the mentoring process
Results:
The main results of the questionnaire showed great satisfaction with the mentoring process in both groups. The students refer to the importance that the tutor had in consolidating theoretical knowledge, clinical reasoning and practical skills. Both groups expressed that the process was very rewarding and are eager to repeat this experience. Regarding the comparison between mentoring styles, students preferred mentoring with more directed than free styles.
Conclusions:
Mentoring promotion facilitates learning opportunities for 2nd graders in the topics covered and can also increase the leadership and teaching skills of 3rd graders, both outcomes have the potential to benefit elements outside this process, including future work or patients. In relation to the process of Peer-Mentoring a good organization and objectives/tasks well established by the responsible teacher seems to be fundamental to the overall success. The promotion of peer-mentoring could facilitate peer-to-peer learning opportunities for students, and promote leadership and teaching skills.N/
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