998 resultados para electrical services


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During last decades there has been a trend to build collaboration platforms as enablers for groups of enterprises to jointly provide integrated services and products. As a result, the notion of business ecosystem is getting wider acceptance. However, a critical issue that is still open, despite some efforts in this area, is the identification of adequate performance indicators to measure and motivate sustainable collaboration. This work-in-progress addresses this concern, briefly presenting the state of the art of relevant contributing areas such as, collaborative networks, business ecosystems, enterprise performance indicators, social networks analysis, and supply chains. Complementarily, through an assessment of current gaps, the research challenges are identified and an approach for further development is proposed.

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Biometric recognition has recently emerged as part of applications where the privacy of the information is crucial, as in the health care field. This paper presents a biometric recognition system based on the Electrocardiographic signal (ECG). The proposed system is based on a state-of-the-art recognition method which extracts information from the frequency domain. In this paper we propose a new method to increase the spectral resolution of low bandwidth ECG signals due to the limited bandwidth of the acquisition sensor. Preliminary results show that the proposed scheme reveals a higher identification rate and lower equal error rate when compared to previous approaches.

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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

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Power systems have been through deep changes in recent years, namely due to the operation of competitive electricity markets in the scope the increasingly intensive use of renewable energy sources and distributed generation. This requires new business models able to cope with the new opportunities that have emerged. Virtual Power Players (VPPs) are a new type of player that allows aggregating a diversity of players (Distributed Generation (DG), Storage Agents (SA), Electrical Vehicles (V2G) and consumers) to facilitate their participation in the electricity markets and to provide a set of new services promoting generation and consumption efficiency, while improving players’ benefits. A major task of VPPs is the remuneration of generation and services (maintenance, market operation costs and energy reserves), as well as charging energy consumption. This paper proposes a model to implement fair and strategic remuneration and tariff methodologies, able to allow efficient VPP operation and VPP goals accomplishment in the scope of electricity markets.

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The power systems operation in the smart grid context increases significantly the complexity of their management. New approaches for ancillary services procurement are essential to ensure the operation of electric power systems with appropriate levels of stability, safety, quality, equity and competitiveness. These approaches should include market mechanisms which allow the participation of small and medium distributed energy resources players in a competitive market environment. In this paper, an energy and ancillary services joint market model used by an aggregator is proposed, considering bids of several types of distributed energy resources. In order to improve economic efficiency in the market, ancillary services cascading market mechanism is also considered in the model. The proposed model is included in MASCEM – a multi-agent system electricity market simulator. A case study considering a distribution network with high penetration of distributed energy resources is presented.

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Intelligent electrical grids can be considered as the next generation of electrical energy transportation. The enormous potential leads to worldwide focus of research on the technology of smart grids. This paper aims to present a review of the Brazilian electricity sector in context with the integration of communication technologies for smart grids. The work gives an overview of the generation, transmission and distribution of electrical energy in the Brazil and a brief summary of the current electricity market. Smart grid technologies are introduced and the requirements for the Brazilian power system are pointed out. Various technologies for communication within an intelligent network are presented and their characteristics, advantages and disadvantages are compared to the Brazilian conditions. In addition, a summary is given of current pilot projects for Smart Grid technologies within Brazil, as well as a presentation of individual selected projects.

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Dissertation presented at Faculdade de Ciências e Tecnologia of Universidade Nova de Lisboa to obtain the Master degree in Electrical Engineering and Computer Science

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A correta ventilação de locais afetos a serviços técnicos elétricos, nomeadamente postos de transformação e salas de grupos geradores, reveste-se de extrema importância como garantia da continuidade e qualidade do serviço prestado, durabilidade dos materiais e equipamentos e da segurança das instalações e utilizadores. A ventilação dos locais afetos a serviços técnicos elétricos pode ser natural ou mecânica, dependendo das suas caraterísticas e das necessidades de ar para ventilação e combustão, quando aplicável. Os técnicos responsáveis pelo projeto de instalações elétricas não detém, em regra, um conhecimento muito profundo sobre este tema, sendo os seus projetos realizados com base em especificações e metodologias gerais disponibilizadas pelos fabricantes e comercializadores dos materiais e equipamentos. O projeto de uma solução de ventilação para um local afeto a serviços técnicos eléctricos exige o conhecimento de todos os ganhos térmicos no interior do espaço, o conhecimento das soluções técnicas e tecnológicas de ventilação bem como as metodologias de dimensionamento aplicáveis a cada situação. Sendo a fase de projeto elétrico, em regra, uma atividade com prazos apertados, pode conduzir ao menosprezar de certos aspetos particulares que carecem de investigação e tempo para serem desenvolvidos, o que pode resultar em projetos e mapas de quantidades que apresentam desvios da solução ideal para o cliente, podendo resultar em investimentos mais elevados, quer na fase de execução, quer na fase de exploração das instalações. Neste sentido, pretendeu-se com o presente trabalho, tratar o tema da ventilação de locais afetos a serviços técnicos, atendendo ao enquadramento normativo e regulamentar das instalações, às soluções técnicas e tecnológicas disponíveis no mercado e às metodologias de dimensionamento, apresentadas pelos documentos normativos e regulamentares. Pretendeu-se também desenvolver uma ferramenta informática de auxilio ao dimensionamento das soluções de ventilação de locais afetos a serviços técnicas eléctricos destinados a postos de transformação e grupos geradores de modo a reduzir o tempo normalmente exigido por esta tarefa, o que se traduzirá numa maior rentabilidade do tempo de projeto, assim como a normalizar as soluções apresentadas e minimizar a probabilidade de erro do dimensionamento das soluções, reduzindo assim a probabilidade de gastos em “trabalhos a mais” provenientes de erros em projeto, poupança em materiais presentes no mapa de quantidades, maior eficácia na execução da empreitada, poupança em gastos durante a exploração e desta forma numa proximidade entre as partes interessadas com o dimensionamento da ventilação do espaço técnico elétrico.

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Os crescentes custos ligados ao consumo elétrico, não apenas de cariz financeiro mas também ambiental, despertam cada vez mais para a importância da definição de estratégias de melhor utilização de recursos e eficiência energética. Esta importância tem sido reforçada pela definição de decretos-lei que vêm colocar metas e limites relativamente às despesas energéticas. Estes diplomas são também acompanhados por programas de incentivo para um setor ligado à eficiência energética. Em Portugal as medidas ligadas ao setor tem vindo a ser redirecionadas para o consumo final de energia, com a definição de metas para as instalações de maior consumo. As instalações hospitalares são grandes centros de consumo energético devido não só ao elevado número de utentes que recebem mas também pelos diversos tipos de equipamentos elétricos usados para a prestação dos serviços médicos. Como consequência disso, os investimentos e os custos operacionais são elevados, o que reforça a necessidade de gerir os gastos e consumos energéticos com a procura constante de melhoria na recolha de informação sobre todo o sistema e na adequação de intervenções com vista a uma maior eficiência energética. O Hospital Pedro Hispano vem desde algum tempo a investir no sentido de conhecer mais e melhor toda a instalação bem como os consumos energéticos a ela associados. Algumas medidas foram tomadas nesse sentido nomeadamente a instalação de analisadores de energia, de modo a obter um retrato mais fiel e fidedigno dos principais vetores de consumo. Neste momento a gestão técnica do hospital tem em análise uma grande parte da instalação recolhendo dados do consumo elétrico real do hospital. Nesta dissertação procurou-se fazer uma análise e enquadramento dos programas e metas ligados ao setor energético com ênfase nos diplomas que visão e abrangem as instalações hospitalares. Dos vários programas de incentivo à adoção de políticas de maior eficiência energética é dado especial destaque ao programa ECO.AP que visa a celebração de contratos para implementação de medidas de poupança energética ao setor público. Em colaboração com o HPH, iniciaram-se os trabalhos pelo estudo e identificação das principais fases e ferramentas utilizadas na gestão energética do edifício tendo como objetivo a reavaliação dos vetores energéticos já identificados no HPH e a criação e contabilização de novos grupos de consumo. Através de várias medições do consumo elétrico, num total superior a 650 horas de funcionamento, foi possível a criação do mapa de desagregação de consumos para o ano de 2013. A desagregação realizada conta com 3 novos vetores energéticos e com a reavaliação do peso relativo de mais 5 grupos de consumo. Das medições efetuadas destaca-se a reavaliação do consumo da central de bombagem onde a parcela considerada até à data estava 3 vezes acima do valor real medido. Com base na desagregação feita foram apontadas e estudadas medidas de implementação com o objetivo de reduzir os consumos energético em todo o hospital, destacando-se a solução apresentada para a central de bombagem. Esta medida traria um grande impacto em toda a fatura energética, não só pela sua viabilidade, mas também porque atuaria num grande centro de consumo onde até ao momento nenhuma ação do género foi implementada.

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In today’s highly competitive market, it is critical to provide customers services with a high level of configuration to answer their business needs. Knowing in advance the performance associated with a specific choreography of services (e.g., by taking into account the expected results of each component service) represents an important asset that allows businesses to provide a global service tailored to customers’ specific requests. This research work aims at advancing the state-of-the-art in this area by proposing an approach for service selection and ranking using services choreography, predicting the behavior of the services considering customers’ requirements and preferences, business process constraints and characteristics of the execution environment.

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Assistimos à queda de um serviço, que em muitos países, figurava como um serviço de um modelo social europeu, passando de um monopólio para um sistema de mercado liberalizado e concorrencial: o mercado energético. (EURO COOP, 2014) Em maio de 2014, o mercado livre chegou a ultrapassar os 2,8 milhões de consumidores, tendo um crescimento face a maio de 2013 de 64%, com uma taxa média mensal de 4,2%. (Entidade Reguladora dos Energéticos - ERSE, 2009). Perante a crescente adesão de consumidores para o mercado liberalizado, e suas possíveis futuras mudanças, e tendo em conta com os potenciais clientes a aderirem, foi proposto então construir a plataforma MelhorTarifa.pt . Apesar da já existência de simuladores, estes demonstram-se a ser pouco intuitivos e a não demonstrar toda a informação que o utilizador pretende bem como não existir uma imagem de marca associada a um apoio à mudança de tarifário, tendo sido estas umas das razões que levaram ao desenvolvimento do MelhorTarifa.pt. O âmbito principal deste trabalho, é fornecer uma plataforma informática grátis, imparcial, com o acréscimo até à data, em relação a outros simuladores, da disponibilização de faturas detalhadas sobre o produto que o cliente pretende adquirir, serviços de consultoria, tudo isto de forma rápida e de simples acesso. Com este trabalho pretende-se também definir o atual estado de arte de simuladores idênticos em Portugal e no estrangeiro, pretendendo-se também dar conhecimento do trabalho desenvolvido para esta dissertação, denominado como MelhorTarifa.pt.

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All over the world, the liberalization of electricity markets, which follows different paradigms, has created new challenges for those involved in this sector. In order to respond to these challenges, electric power systems suffered a significant restructuring in its mode of operation and planning. This restructuring resulted in a considerable increase of the electric sector competitiveness. Particularly, the Ancillary Services (AS) market has been target of constant renovations in its operation mode as it is a targeted market for the trading of services, which have as main objective to ensure the operation of electric power systems with appropriate levels of stability, safety, quality, equity and competitiveness. In this way, with the increasing penetration of distributed energy resources including distributed generation, demand response, storage units and electric vehicles, it is essential to develop new smarter and hierarchical methods of operation of electric power systems. As these resources are mostly connected to the distribution network, it is important to consider the introduction of this kind of resources in AS delivery in order to achieve greater reliability and cost efficiency of electrical power systems operation. The main contribution of this work is the design and development of mechanisms and methodologies of AS market and for energy and AS joint market, considering different management entities of transmission and distribution networks. Several models developed in this work consider the most common AS in the liberalized market environment: Regulation Down; Regulation Up; Spinning Reserve and Non-Spinning Reserve. The presented models consider different rules and ways of operation, such as the division of market by network areas, which allows the congestion management of interconnections between areas; or the ancillary service cascading process, which allows the replacement of AS of superior quality by lower quality of AS, ensuring a better economic performance of the market. A major contribution of this work is the development an innovative methodology of market clearing process to be used in the energy and AS joint market, able to ensure viable and feasible solutions in markets, where there are technical constraints in the transmission network involving its division into areas or regions. The proposed method is based on the determination of Bialek topological factors and considers the contribution of the dispatch for all services of increase of generation (energy, Regulation Up, Spinning and Non-Spinning reserves) in network congestion. The use of Bialek factors in each iteration of the proposed methodology allows limiting the bids in the market while ensuring that the solution is feasible in any context of system operation. Another important contribution of this work is the model of the contribution of distributed energy resources in the ancillary services. In this way, a Virtual Power Player (VPP) is considered in order to aggregate, manage and interact with distributed energy resources. The VPP manages all the agents aggregated, being able to supply AS to the system operator, with the main purpose of participation in electricity market. In order to ensure their participation in the AS, the VPP should have a set of contracts with the agents that include a set of diversified and adapted rules to each kind of distributed resource. All methodologies developed and implemented in this work have been integrated into the MASCEM simulator, which is a simulator based on a multi-agent system that allows to study complex operation of electricity markets. In this way, the developed methodologies allow the simulator to cover more operation contexts of the present and future of the electricity market. In this way, this dissertation offers a huge contribution to the AS market simulation, based on models and mechanisms currently used in several real markets, as well as the introduction of innovative methodologies of market clearing process on the energy and AS joint market. This dissertation presents five case studies; each one consists of multiple scenarios. The first case study illustrates the application of AS market simulation considering several bids of market players. The energy and ancillary services joint market simulation is exposed in the second case study. In the third case study it is developed a comparison between the simulation of the joint market methodology, in which the player bids to the ancillary services is considered by network areas and a reference methodology. The fourth case study presents the simulation of joint market methodology based on Bialek topological distribution factors applied to transmission network with 7 buses managed by a TSO. The last case study presents a joint market model simulation which considers the aggregation of small players to a VPP, as well as complex contracts related to these entities. The case study comprises a distribution network with 33 buses managed by VPP, which comprises several kinds of distributed resources, such as photovoltaic, CHP, fuel cells, wind turbines, biomass, small hydro, municipal solid waste, demand response, and storage units.

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Sol-gel chemistry allows the immobilization of organic molecules of biological origin on suibtable solid supports, permitting their integration into biosensing devices widening the possibility of local applications. The present work is an application of this principle, where the link between electrical receptor platform and the antibody acting as biorecognition element is made by sol-gel chemistry. The immunosensor design was targeted for carcinoembryonic antigen (CEA), an important biomarker for screening the colorectal cancer, by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SVW). The device displayed linear behavior to CEA in EIS and in SWV assays ranging from 0.50 to 1.5ng/mL, and 0.25 to 1.5ng/mL, respectively. The corresponding detection limits were 0.42 and 0.043 ng/mL. Raman spectroscopy was used to characterize the surface modifications on the conductive platform (FTO glass). Overall, simple sol-gel chemistry was effective at the biosensing design and the presented approach can be a potential method for screening CEA in point-of-care, due to the simplicity of fabrication, short response time and low cost. - See more at: http://www.eurekaselect.com/127192/article#sthash.m1AWhINx.dpuf

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Workshop on ns-3 (WNS '15). 13, May, 2015. Castelldefels, Spain.

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The internal impedance of a wire is the function of the frequency. In a conductor, where the conductivity is sufficiently high, the displacement current density can be neglected. In this case, the conduction current density is given by the product of the electric field and the conductance. One of the aspects the high-frequency effects is the skin effect (SE). The fundamental problem with SE is it attenuates the higher frequency components of a signal. The SE was first verified by Kelvin in 1887. Since then many researchers developed work on the subject and presently a comprehensive physical model, based on the Maxwell equations, is well established. The Maxwell formalism plays a fundamental role in the electromagnetic theory. These equations lead to the derivation of mathematical descriptions useful in many applications in physics and engineering. Maxwell is generally regarded as the 19th century scientist who had the greatest influence on 20th century physics, making contributions to the fundamental models of nature. The Maxwell equations involve only the integer-order calculus and, therefore, it is natural that the resulting classical models adopted in electrical engineering reflect this perspective. Recently, a closer look of some phenomas present in electrical systems and the motivation towards the development of precise models, seem to point out the requirement for a fractional calculus approach. Bearing these ideas in mind, in this study we address the SE and we re-evaluate the results demonstrating its fractional-order nature.