Métodos de observação durante a execução de obras subterrâneas

Mestrado em Engenharia Geotécnica e Geoambiente

Typical load profiles in the smart grid context – a clustering methods comparison

The present research paper presents five different clustering methods to identify typical load profiles of medium voltage (MV) electricity consumers. These methods are intended to be used in a smart grid environment to extract useful knowledge about customer’s behaviour. The obtained knowledge can be used to support a decision tool, not only for utilities but also for consumers. Load profiles can be used by the utilities to identify the aspects that cause system load peaks and enable the development of specific contracts with their customers. The framework presented throughout the paper consists in several steps, namely the pre-processing data phase, clustering algorithms application and the evaluation of the quality of the partition, which is supported by cluster validity indices. The process ends with the analysis of the discovered knowledge. To validate the proposed framework, a case study with a real database of 208 MV consumers is used.

Technical and economic resources management in smart grids using heuristic optimization methods

Intensive use of Distributed Generation (DG) represents a change in the paradigm of power systems operation making small-scale energy generation and storage decision making relevant for the whole system. This paradigm led to the concept of smart grid for which an efficient management, both in technical and economic terms, should be assured. This paper presents a new approach to solve the economic dispatch in smart grids. The proposed methodology for resource management involves two stages. The first one considers fuzzy set theory to define the natural resources range forecast as well as the load forecast. The second stage uses heuristic optimization to determine the economic dispatch considering the generation forecast, storage management and demand response

Electricity markets: transmission prices methods

In the context of electricity markets, transmission pricing is an important tool to achieve an efficient operation of the electricity system. The electricity market is influenced by several factors; however the transmission network management is one of the most important aspects, because the network is a natural monopoly. The transmission tariffs can help to regulate the market, for this reason transmission tariffs must follow strict criteria. This paper presents the following methods to tariff the use of transmission networks by electricity market players: Post-Stamp Method; MW-Mile Method Distribution Factors Methods; Tracing Methodology; Bialek’s Tracing Method and Locational Marginal Price. A nine bus transmission network is used to illustrate the application of the tariff methods.

Comparison between deterministic and meta-heuristic methods applied to ancillary services dispatch

This paper proposes two meta-heuristics (Genetic Algorithm and Evolutionary Particle Swarm Optimization) for solving a 15 bid-based case of Ancillary Services Dispatch in an Electricity Market. A Linear Programming approach is also included for comparison purposes. A test case based on the dispatch of Regulation Down, Regulation Up, Spinning Reserve and Non-Spinning Reserve services is used to demonstrate that the use of meta-heuristics is suitable for solving this kind of optimization problem. Faster execution times and lower computational resources requirements are the most relevant advantages of the used meta-heuristics when compared with the Linear Programming approach.

Ancillary services market clearing simulation: a comparison between deterministic and heuristic methods

Electricity market players operating in a liberalized environment requires access to an adequate decision support tool, allowing them to consider all the business opportunities and take strategic decisions. Ancillary services represent a good negotiation opportunity that must be considered by market players. For this, decision support tool must include ancillary market simulation. This paper proposes two different methods (Linear Programming and Genetic Algorithm approaches) for ancillary services dispatch. The methodologies are implemented in MASCEM, a multi-agent based electricity market simulator. A test case based on California Independent System Operator (CAISO) data concerning the dispatch of Regulation Down, Regulation Up, Spinning Reserve and Non-Spinning Reserve services is included in this paper.

Reposição do sistema semi-automático Pyxis® num Hospital Central Universitário: avaliação do número de unidades repostas

Introdução: No Centro Hospitalar de São João, EPE a partir de 2008, foi implementado o sistema semi-automático de reposição de stocks nivelados de medicamentos, Pyxis®, atualmente implementado em 16 serviços clínicos. Atendendo ao crescimento verificado na implementação deste sistema automatizado na instituição, este trabalho pretende dar a conhecer a realidade de preparação da medicação para reposição no sistema semi-automático Pyxis®, por avaliação do número de unidades de medicamentos repostos diariamente e por dia da semana. Material e Métodos: Desenvolveu-se um estudo longitudinal retrospetivo onde se analisou a totalidade de serviços com implementação Pyxis® através do registo diário de reposição dos diferentes Serviços Clínicos num período de 41 dias consecutivos. Numa segunda fase, os dados foram sintetizados sob a forma de tabelas em Microsoft Office Excel®, tendo posteriormente sido construídos os respetivos gráficos para análise. Resultados: Os resultados, representados graficamente, mostram que a segunda-feira é o dia da semana com maior número de reposições de medicamentos, sendo os serviços com maior número de reposições totais UCI Geral, UCI Neurocríticos, Cirurgia Cardiotorácica e UCIPU. Discussão / Conclusões: Os resultados obtidos permitiram verificar uma sobrecarga de referências de medicamentos e unidades repostas às segundas-feiras, atingindo, em muitos serviços, valores de unidades repostas duas vezes superior à média de reposições do serviço (por ex. UCI Neurocíticos). Contudo, apesar do reduzido período de análise, os dados parecem evidenciar que o facto de haver reposições ao domingo agiliza o processo de reposição dos Pyxis® às segundas-feiras.

Online versus postal questionnaires: a comparison between two data collection methods

Objectives : The purpose of this article is to find out differences between surveys using paper and online questionnaires. The author has deep knowledge in the case of questions concerning opinions in the development of survey based research, e.g. the limits of postal and online questionnaires. Methods : In the physician studies carried out in 1995 (doctors graduated in 1982-1991), 2000 (doctors graduated in 1982-1996), 2005 (doctors graduated in 1982-2001), 2011 (doctors graduated in 1977-2006) and 457 family doctors in 2000, were used paper and online questionnaires. The response rates were 64%, 68%, 64%, 49% and 73%, respectively. Results : The results of the physician studies showed that there were differences between methods. These differences were connected with using paper-based questionnaire and online questionnaire and response rate. The online-based survey gave a lower response rate than the postal survey. The major advantages of online survey were short response time; very low financial resource needs and data were directly loaded in the data analysis software, thus saved time and resources associated with the data entry process. Conclusions : The current article helps researchers with planning the study design and choosing of the right data collection method.

Neurokinin-1 receptor, a new modulator of lymphangiogenesis in obese-asthma phenotype

Aims Obesity and asthma are widely prevalent and associated disorders. Recent studies of our group revealed that Substance P (SP) is involved in pathophysiology of obese-asthma phenotype in mice through its selective NK1 receptor (NK1-R). Lymphangiogenesis is impaired in asthma and obesity, and SP activates contractile and inflammatory pathways in lymphatics. Our aim was to study whether NK1-R expression was involved in lymphangiogenesis on visceral (VAT) and subcutaneous (SAT) adipose tissues and in the lungs, in obese-allergen sensitized mice. Main methods Diet-induced obese and ovalbumin (OVA)-sensitized Balb/c mice were treated with a selective NK1-R antagonist (CJ 12,255, Pfizer Inc., USA) or placebo. Lymphatic structures (LYVE-1 +) and NK1-R expression were analyzed by immunohistochemistry. A semi-quantitative score methodology was used for NK1-R expression. Key findings Obesity and allergen-sensitization together increased the number of LYVE-1 + lymphatics in VAT and decreased it in SAT and lungs. NK1-R was mainly expressed on adipocyte membranes of VAT, blood vessel areas of SAT, and in lung epithelium. Obesity and allergen-sensitization combined increased the expression of NK1-R in VAT, SAT and lungs. NK1-R antagonist treatment reversed the effects observed in lymphangiogenesis in those tissues. Significance The obese-asthma phenotype in mice is accompanied by increased expression of NK1-R on adipose tissues and lung epithelium, reflecting that SP released during inflammation may act directly on these tissues. Blocking NK1-R affects lymphangiogenesis, implying a role of SP, with opposite physiological consequences in VAT, and in SAT and lungs. Our results provide a clue for a novel SP role in the obese-asthma phenotype.

Derivative-free optimization and filter methods to solve nonlinear constrained problems

In real optimization problems, usually the analytical expression of the objective function is not known, nor its derivatives, or they are complex. In these cases it becomes essential to use optimization methods where the calculation of the derivatives, or the verification of their existence, is not necessary: the Direct Search Methods or Derivative-free Methods are one solution. When the problem has constraints, penalty functions are often used. Unfortunately the choice of the penalty parameters is, frequently, very difficult, because most strategies for choosing it are heuristics strategies. As an alternative to penalty function appeared the filter methods. A filter algorithm introduces a function that aggregates the constrained violations and constructs a biobjective problem. In this problem the step is accepted if it either reduces the objective function or the constrained violation. This implies that the filter methods are less parameter dependent than a penalty function. In this work, we present a new direct search method, based on simplex methods, for general constrained optimization that combines the features of the simplex method and filter methods. This method does not compute or approximate any derivatives, penalty constants or Lagrange multipliers. The basic idea of simplex filter algorithm is to construct an initial simplex and use the simplex to drive the search. We illustrate the behavior of our algorithm through some examples. The proposed methods were implemented in Java.

Navegação de um robô autónomo semi-industrial usando diferentes técnicas sensoriais

Mestrado em Engenharia Electrotécnica e de Computadores

Agrupamento de dados com restrições

Mestrado em Engenharia Informática

Construção de um robô trepador com locomoção através de rodas e adesão através de meios magnéticos

Mestrado em Engenharia Electrotécnica e de Computadores

Efeito da eletrolipólise na gordura abdominal em doentes cardíacos - fase manutenção

Objetivo: Verificar se a eletrolipólise pode ser um método coadjuvante na Reabilitação Cardíaca (RC) de modo a diminuir a gordura abdominal em indivíduos com Doença Cardiovascular (DCV). Métodos: Seis indivíduos, de ambos os sexos, da classe de RC do Centro Clinico de Gaia (CCG), foram distribuídos aleatoriamente em dois grupos, grupo controlo (GC) (n=3) e grupo experimental (GE) (n=3). O GE realizou 8 sessões (duas vezes por semana) de eletrolipólise por microcorrentes 30 minutos antes da classe de RC. Utilizaram-se como meios de avaliação a perimetria, adipometria, bioimpedância e ultrassonografia, análise sanguíneas, bem como a aplicação da Hospital Anxiety and Depression Scale (HADS), Questionário Internacional de Actividade Física (IPAQ) e Questionário Semi-Quantitativo de Frequência Alimentar (QSQFA). Resultados: Através do cálculo da mudança mínima detetável (MMD) verificou-se diminuição do perímetro ao nível do umbigo (3,7cm e 1,5cm) e barriga (4,2cm e 2,83cm) em dois indivíduos do GE e diminuição nas avaliações da ultrassonografia (de 1,3mm a 8,4mm) no GE. Conclusão: Do presente estudo foi possível concluir que nesta amostra existiu uma tendência para a diminuição da gordura abdominal localizada através dos dados obtidos pela perimetria e ultrassonografia.

Lipid content of frozen fish: comparison of different extraction methods and variability during freezing storage

In this work, a microwave-assisted extraction (MAE) methodology was compared with several conventional extraction methods (Soxhlet, Bligh & Dyer, modified Bligh & Dyer, Folch, modified Folch, Hara & Radin, Roese-Gottlieb) for quantification of total lipid content of three fish species: horse mackerel (Trachurus trachurus), chub mackerel (Scomber japonicus), and sardine (Sardina pilchardus). The influence of species, extraction method and frozen storage time (varying from fresh to 9 months of freezing) on total lipid content was analysed in detail. The efficiencies of methods MAE, Bligh & Dyer, Folch, modified Folch and Hara & Radin were the highest and although they were not statistically different, differences existed in terms of variability, with MAE showing the highest repeatability (CV = 0.034). Roese-Gottlieb, Soxhlet, and modified Bligh & Dyer methods were very poor in terms of efficiency as well as repeatability (CV between 0.13 and 0.18).