Browsing by Issue Date, starting with "2013-07"
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- Embalagens Flexíveis: estudo do processo de reticulação de adesivos e do coeficiente de atritoPublication . Luís, Vânia Sofia Ferrás; Ribeiro, António Alfredo CrispimA dissertação foi realizada em ambiente industrial, mais precisamente na empresa Monteiro, Ribas – Embalagens Flexíveis, S.A.. Esta empresa dedica-se à impressão e laminagem de filmes, assim como à confeção de sacos. Os seus produtos são direcionados na sua maioria para a indústria alimentar, exportando mais de 50% da sua produção, e dizem respeito a complexos (dois ou mais filmes unidos pela presença de um adesivo) que podem possuir impressão ou não. Estes complexos podem ser enviados para o cliente em bobina ou já em saco. Os objetivos propostos pela empresa diziam respeito a estudos relacionados com a força de laminagem dos complexos, com o coeficiente de atrito dos mesmos e com a identificação dos espetros dos componentes dos adesivos, assim como o estudo do processo de reticulação dos mesmos por espetrofotometria de Infravermelho. Relativamente aos resultados obtidos verificou-se que tanto a tinta como os metalizados influenciam negativamente a força de laminagem. Por sua vez o coeficiente de atrito é afetado por vários fatores. Através dos ensaios experimentais verificou-se que o adesivo, a tinta e o verniz mate favorecem o aumento do valor do COF. Além disso, nos complexos em que se utilizaram filmes de polietileno de maior espessura obtiveram-se valores de COF mais baixos, e no que diz respeito à temperatura e à tensão de enrolamento, verificou-se que valores mais elevados e muito baixos da primeira traduzem-se num aumento do valor do COF e uma tensão de enrolamento maior também tem o mesmo efeito. Relativamente ao tipo de filme impresso, substratos com maior energia superficial atraem mais o agente de deslizamento (slip). Por último, não se conseguiu perceber qual o tipo de adesivo (com ou sem solvente) que tem maior impacto no COF uma vez que em 55% dos casos o valor do COF é superior nas amostras que foram complexadas com adesivo sem solvente e em 45% o COF era superior nas amostras complexadas com adesivo base solvente. No que diz respeito aos espetros obtidos verificou-se que a reticulação dos adesivos é identificada pela diminuição da extensão do pico correspondente à ligação N=C=O.
- Simulated Annealing Approach Applied to the Energy Resource Management Considering Demand Response for Electric VehiclePublication . Sousa, Tiago; Vale, Zita; Morais, HugoThe aggregation and management of Distributed Energy Resources (DERs) by an Virtual Power Players (VPP) is an important task in a smart grid context. The Energy Resource Management (ERM) of theses DERs can become a hard and complex optimization problem. The large integration of several DERs, including Electric Vehicles (EVs), may lead to a scenario in which the VPP needs several hours to have a solution for the ERM problem. This is the reason why it is necessary to use metaheuristic methodologies to come up with a good solution with a reasonable amount of time. The presented paper proposes a Simulated Annealing (SA) approach to determine the ERM considering an intensive use of DERs, mainly EVs. In this paper, the possibility to apply Demand Response (DR) programs to the EVs is considered. Moreover, a trip reduce DR program is implemented. The SA methodology is tested on a 32-bus distribution network with 2000 EVs, and the SA results are compared with a deterministic technique and particle swarm optimization results.
- A influência do modelo pedagógico em variáveis psicológicas de estudantes do 1º ano da ESTSP-IPPPublication . Teixeira, Ricardo J.; Dores, Artemisa Rocha; Magalhães, Andreia; Barreto, João Francisco; Martins, HelenaA adaptação ao ensino superior reveste-se de experiências académicas que podem constituir fonte de stress para os estudantes. A implementação de novos modelos pedagógicos, no âmbito do processo de Bolonha, introduz novas variáveis cujo impacto, designadamente em termos de saúde, importa conhecer. Este estudo tem como objetivo analisar as associações entre modelo pedagógico (Problem Based Learning – PBL vs. modelos próximos do tradicional) e variáveis psicológicas (coping, desregulação emocional, sintomas psicossomáticos, perceção de stress e afeto). O estudo tem um design transversal. Foram usados os seguintes questionários online: Brief-COPE, Escala de Dificuldades de Regulação Emocional, Questionário de Manifestações Físicas de Mal-Estar, Escala de Stress Percebido e Escala de Afeto Positivo e Negativo. A amostra é constituída por 183 estudantes do primeiro ano (84% do género feminino) de cursos da Escola Superior de Tecnologia da Saúde do Porto – Instituto Politécnico do Porto (ESTSP-IPP). Resultados – Foram encontradas correlações significativas entre as variáveis demográficas e psicológicas. Considerando diferentes modelos pedagógicos, foram encontradas diferenças significativas nas variáveis psicológicas. Os principais preditores de stress na amostra foram: ser mulher, frequentar uma licenciatura no modelo PBL, ter maiores índices de desregulação emocional, apresentar mais sintomas psicossomáticos, menos afeto positivo e mais afeto negativo. As diferenças encontradas entre modelos pedagógicos são discutidas, possibilitando a reflexão sobre as implicações práticas e sugestões para futuras investigações.
- Comparison of methodologies of CSR index: application to the PSI 20 companiesPublication . Fernandes, Paula; Monte, Ana Paula; Pimenta, Rui; Afonso, SandraCorporate Social Responsibility (CSR) has assumed increasing importance over the past several decades, globally resulting from companies’ response to the demands of markets and society for responsible growth, both social and environmentally. At a European level, the CSR was initially boosted in 1993 by the former President of the European Commission, Jacques Delors, who called for more socially responsible action from companies, and culminated in 2001 with the publication of the Green Paper on CSR, by the European Commission in which the areas and guidelines for desirable social responsibility practices were defined. The measurement of social or CSR performance has not been consensual, which accounts for the existence of several methods. These use a variety of criteria ranging from expert evaluation to the analysis of reports and other documents or considerations of performance measures of pollution control. Each of these criteria is not exempt from criticism and limitations, as they are one-dimensional or do not reflect all aspects of CSR. Based on these measures, some evaluation CSR indices were developed, having been used in decision-making and positioning of the companies in their social and environmental performance. The most commonly used indices are those provided by the rating agency Kinder, Lindenberg and Domini index or reputation index of Fortune. This paper aims to compare the application of two methods in defining the levels of CSR from a CSR index, constructed for 19 of the 20 companies comprising the PSI-20, the Portuguese stock market index, the Euronext Lisbon. One of the methodologies defines five intervals of CSR using the cut-point method; the other considers a scale of 5 points (5 grades) with constant intervals. In order to construct the index, 247 items were considered, comprising the different dimensions of social responsibility suggested by the European Commission Green Paper on CRS of 2001 and the guidelines of the Global Reporting Initiative. We analyzed the contents of sustainability reports and financial reports of companies under research in order to assign a score (which will be 0 if the item is not observed, 0.5 if is only partially observed or 1 whether it is observed) for measurement of each item of responsibility, since there are no quantifiable and objective social responsibility indicators. The CSR index of a company, at any given time, is the sum of the scores across all 247 items. The categorization of companies in the CSR levels depends on the referred methodology to the definition of intervals. In brief, by using the two approaches, we found that the Portuguese companies which were analyzed denote a growing sensitivity in the adhesion and dissemination of their social responsibility practices, investing in a more specific and detailed disclosure and, in particular, complying with the guidelines of the Global Reporting Initiative.
- Determining the Adjustment Baseline Parameters to Define an Accurate Customer Baseline LoadPublication . Faria, Pedro; Vale, Zita; Antunes, PedroDemand response is an energy resource that has gained increasing importance in the context of competitive electricity markets and of smart grids. New business models and methods designed to integrate demand response in electricity markets and of smart grids have been published, reporting the need of additional work in this field. In order to adequately remunerate the participation of the consumers in demand response programs, improved consumers’ performance evaluation methods are needed. The methodology proposed in the present paper determines the characterization of the baseline approach that better fits the consumer historic consumption, in order to determine the expected consumption in absent of participation in a demand response event and then determine the actual consumption reduction. The defined baseline can then be used to better determine the remuneration of the consumer. The paper includes a case study with real data to illustrate the application of the proposed methodology.
- MASCEM Restructuring: Ontologies For Scenarios Generation in Power Systems SimulatorsPublication . Santos, Gabriel; Pinto, Tiago; Vale, Zita; Morais, Hugo; Praça, IsabelThe electricity market restructuring, along with the increasing necessity for an adequate integration of renewable energy sources, is resulting in an rising complexity in power systems operation. Various power system simulators have been introduced in recent years with the purpose of helping operators, regulators, and involved players to understand and deal with this complex environment. This paper focuses on the development of an upper ontology which integrates the essential concepts necessary to interpret all the available information. The restructuring of MASCEM (Multi-Agent System for Competitive Electricity Markets), and this system’s integration with MASGriP (Multi-Agent Smart Grid Platform), and ALBidS (Adaptive Learning Strategic Bidding System) provide the means for the exemplification of the usefulness of this ontology. A practical example is presented, showing how common simulation scenarios for different simulators, directed to very distinct environments, can be created departing from the proposed ontology.
- Decision support tool for Virtual Power Players: Hybrid Particle Swarm Optimization applied to Day-ahead Vehicle-To-Grid SchedulingPublication . Soares, João; Vale, Zita; Morais, HugoThis paper presents a decision support tool methodology to help virtual power players (VPPs) in the Smart Grid (SGs) context to solve the day-ahead energy resource scheduling considering the intensive use of Distributed Generation (DG) and Vehicle-To-Grid (V2G). The main focus is the application of a new hybrid method combing a particle swarm approach and a deterministic technique based on mixedinteger linear programming (MILP) to solve the day-ahead scheduling minimizing total operation costs from the aggregator point of view. A realistic mathematical formulation, considering the electric network constraints and V2G charging and discharging efficiencies is presented. Full AC power flow calculation is included in the hybrid method to allow taking into account the network constraints. A case study with a 33-bus distribution network and 1800 V2G resources is used to illustrate the performance of the proposed method.
- Integration in MASCEM of the Joint Dispatch of Energy and Reserves Provided by Generation and Demand ResourcesPublication . Soares, Tiago; Santos, Gabriel; Faria, Pedro; Ppinto, Tiago; Vale, Zita; Morais, HugoThe provision of reserves in power systems is of great importance in what concerns keeping an adequate and acceptable level of security and reliability. This need for reserves and the way they are defined and dispatched gain increasing importance in the present and future context of smart grids and electricity markets due to their inherent competitive environment. This paper concerns a methodology proposed by the authors, which aims to jointly and optimally dispatch both generation and demand response resources to provide the amounts of reserve required for the system operation. Virtual Power Players are especially important for the aggregation of small size demand response and generation resources. The proposed methodology has been implemented in MASCEM, a multi agent system also developed at the authors’ research center for the simulation of electricity markets.
- Study of Factors Affecting the Long-term Spanish Electricity Price Formation and Corresponding Validation Using Long-term Forecast ModelsPublication . Ortiz, Maria; Ukar, Olatz; Azevedo, Filipe; Barrio, RubenThe deregulation of electricity markets has resulted on a competitive sector. The impossibility to store energy in large scale together with the constant balance between supply and demand is at the origin of high volatility of market clearing prices. The electricity market players use long-term contracts to practice the hedge against the price risk. The success of those contracts is directly related on the accuracy of long-term price forecast. This paper presents a study of the factors that affects long-term Spanish electricity price formation makes use of a neural network model applied to long-term forecast to validate that study. The use of correct input variables is essential for a forecast accurate. It is presented a case study with real data and the results are compared and discussed in detail.
- Contextual Intelligent Load Management Considering Real-Time Pricing in a Smart Grid EnvironmentPublication . Gomes, Luis; Fernandes, Filipe; Faria, Pedro; Vale, Zita; Ramos, Carlos; Morais, HugoThe use of demand response programs enables the adequate use of resources of small and medium players, bringing high benefits to the smart grid, and increasing its efficiency. One of the difficulties to proceed with this paradigm is the lack of intelligence in the management of small and medium size players. In order to make demand response programs a feasible solution, it is essential that small and medium players have an efficient energy management and a fair optimization mechanism to decrease the consumption without heavy loss of comfort, making it acceptable for the users. This paper addresses the application of real-time pricing in a house that uses an intelligent optimization module involving artificial neural networks.
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