Scheduling aircraft’s engines repair process: a mathematical model

In this talk, we discuss a scheduling problem that originated at TAP - Maintenance & Engineering - the maintenance, repair and overhaul organization of Portugal’s leading airline. In the repair process of aircrafts’ engines, the operations to be scheduled may be executed on a certain workstation by any processor of a given set, and the objective is to minimize the total weighted tardiness. A mixed integer linear programming formulation, based on the flexible job shop scheduling, is presented here, along with computational experiment on a real instance, provided by TAP-ME, from a regular working week. The model was also tested using benchmarking instances available in literature.

Modified Discrete PSO to Increase the Delivered Energy Probability in Distribution energy Systems

This paper proposes a PSO based approach to increase the probability of delivering power to any load point by identifying new investments in distribution energy systems. The statistical failure and repair data of distribution components is the main basis of the proposed methodology that uses a fuzzyprobabilistic modeling for the components outage parameters. The fuzzy membership functions of the outage parameters of each component are based on statistical records. A Modified Discrete PSO optimization model is developed in order to identify the adequate investments in distribution energy system components which allow increasing the probability of delivering power to any customer in the distribution system at the minimum possible cost for the system operator. To illustrate the application of the proposed methodology, the paper includes a case study that considers a 180 bus distribution network.

Cost Allocation Model for Distribution Networks Considering High Penetration of Distributed Energy Resources

The high penetration of distributed energy resources (DER) in distribution networks and the competitiveenvironment of electricity markets impose the use of new approaches in several domains. The networkcost allocation, traditionally used in transmission networks, should be adapted and used in the distribu-tion networks considering the specifications of the connected resources. The main goal is to develop afairer methodology trying to distribute the distribution network use costs to all players which are usingthe network in each period. In this paper, a model considering different type of costs (fixed, losses, andcongestion costs) is proposed comprising the use of a large set of DER, namely distributed generation(DG), demand response (DR) of direct load control type, energy storage systems (ESS), and electric vehi-cles with capability of discharging energy to the network, which is known as vehicle-to-grid (V2G). Theproposed model includes three distinct phases of operation. The first phase of the model consists in aneconomic dispatch based on an AC optimal power flow (AC-OPF); in the second phase Kirschen’s andBialek’s tracing algorithms are used and compared to evaluate the impact of each resource in the net-work. Finally, the MW-mile method is used in the third phase of the proposed model. A distributionnetwork of 33 buses with large penetration of DER is used to illustrate the application of the proposedmodel.

Análise de Integridade Estrutural de uma Flare Industrial

Para garantir que um equipamento opere com segurança e fiabilidade durante o seu ciclo de vida, desde a sua instalação ao desmantelamento, devem ser realizadas inspeções e/ou monitorizações que, dependendo dos dados recolhidos, podem implicar avaliações Fitness- For-Service (FFS) que definirão a necessidade de reparação ou alteração do equipamento ou das condições processuais. A combinação de inspeção ou monitorização com os melhores procedimentos e técnicas de avaliação atuais fazem sobressair insuficiências dos procedimentos mais antigos. Usando métodos mais avançados de avaliação, validados e suportados através de uma vasta experiência de campo, pode-se agora avaliar defeitos nos ativos (equipamentos) e determinar a adequação ao serviço com uma análise FFS. As análises FFS tornaram-se cada vez mais aceites em toda a indústria ao longo dos últimos anos. A norma API 579 - 1/ASME FFS-1: 2007 fornece diretrizes para avaliar os tipos de danos que afetam os equipamentos processuais e a norma API RP 571: 2011 descreve os mecanismos de degradação que afetam os equipamentos nas petroquímicas e refinarias, que incluem os danos por corrosão, desalinhamentos, deformações plásticas, laminações, fissuras, entre outros. Este trabalho consiste na análise de Integridade Estrutural de uma Flare Industrial que surgiu da necessidade real de análise do equipamento no âmbito da atividade profissional do candidato. O estudo realizado a nível profissional é de grande abrangência, incluindo a inspeção do equipamento, identificação da falha ou dano, recolha e registo de dados, definição de estratégia de atuação e seleção de técnicas de avaliação da condição para posterior alteração, reparação ou desmantelamento. Na presente dissertação de mestrado em Engenharia Mecânica, Ramo Construções Mecânicas, pretende-se efetuar o estudo aprofundado de uma das etapas de projeto, nomeadamente estudar a causa, avaliar a falha e implicações estruturais ou processuais devido à degradação interior do riser de uma flare, com base numa análise FFS, assumindo a operabilidade em segurança e garantindo resolutas condições de funcionamento. A presente análise FFS tem como finalidade validar ou não a integridade atual (avaliação técnica quantitativa) de modo a conhecer se o item em questão é seguro e confiável para continuar a operar em condições específicas durante um período de tempo determinado, tendo em consideração as condições verificadas no ato de inspeção e especificações de projeto, segundo os itens de verificação de segurança estabelecidos na norma EN 1990:2002/A1:2005/AC:2010 e com base na norma API 579-1/ASME FFS-1: 2007. No âmbito do presente trabalho foram realizadas as seguintes tarefas: - Identificar e analisar os mecanismos de degradação com base na norma API RP 571: 2011, face às condições processuais e geométricas que o equipamento em análise está sujeito de modo a perceber a evolução da degradação estrutural e quais as implicações na sua longevidade. - Avaliar e propor soluções de reparação e ou alterações processuais e ou geométricas do equipamento em análise de modo a permitir a continuidade em funcionamento sem afetar as condições de segurança e por conseguinte minimizar ou evitar o elevado custo económico associado a um novo equipamento e tempo de paragem processual. - Assumir limites estruturais face às condições processuais e ações externas ou adjacentes. - Garantir a segurança e qualidade da vida humana ou meio que o rodeia, do equipamento, das instalações, das infraestruturas envolventes e evitar o colapso económico, quer por motivos processuais, quer indeminizações ou agravamento do prémio do seguro. Verificou-se que os resultados serão a base para as alterações inerentes, tais como reforço estrutural, alteração da geometria do defletor, ajuste no tensionamento dos cabos e controlo da espessura mínima, de modo a alargar o período de vida útil da flare com segurança.

A molecularly imprinted sensor for sensitive detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) oxidative stress biomarker

6th Graduate Student Symposium on Molecular Imprinting

New and low cost plastic membrane electrode with low detection limits for sulfadimethoxine determination in aquaculture waters

Sulfadimethoxine (SDM) is one of the drugs, often used in the aquaculture sector to prevent the spread of disease in freshwater fish aquaculture. Its spread through the soil and surface water can contribute to an increase in bacterial resistance. It is therefore important to control this product in the environment. This work proposes a simple and low-cost potentiometric device to monitor the levels of SDM in aquaculture waters, thus avoiding its unnecessary release throughout the environment. The device combines a micropipette tip with a PVC membrane selective to SDM, prepared from an appropriate cocktail, and an inner reference solution. The membrane includes 1% of a porphyrin derivative acting as ionophore and a small amount of a lipophilic cationic additive (corresponding to 0.2% in molar ratio). The composition of the inner solution was optimized with regard to the kind and/or concentration of primary ion, chelating agent and/or a specific interfering charged species, in different concentration ranges. Electrodes constructed with inner reference solutions of 1 × 10−8 mol/L SDM and 1 × 10−4 mol/L chromate ion showed the best analytical features. Near-Nernstian response was obtained with slopes of −54.1 mV/decade, an extraordinary detection limit of 7.5 ng/mL (2.4 × 10−8 mol/L) when compared with other electrodes of the same type. The reproducibility, stability and response time are good and even better than those obtained by liquid contact ISEs. Recovery values of 98.9% were obtained from the analysis of aquaculture water samples.

A framework for using real data with distributed low cost sensors

Currently, due to the widespread use of computers and the internet, students are trading libraries for the World Wide Web and laboratories with simulation programs. In most courses, simulators are made available to students and can be used to proof theoretical results or to test a developing hardware/product. Although this is an interesting solution: low cost, easy and fast way to perform some courses work, it has indeed major disadvantages. As everything is currently being done with/in a computer, the students are loosing the “feel” of the real values of the magnitudes. For instance in engineering studies, and mainly in the first years, students need to learn electronics, algorithmic, mathematics and physics. All of these areas can use numerical analysis software, simulation software or spreadsheets and in the majority of the cases data used is either simulated or random numbers, but real data could be used instead. For example, if a course uses numerical analysis software and needs a dataset, the students can learn to manipulate arrays. Also, when using the spreadsheets to build graphics, instead of using a random table, students could use a real dataset based, for instance, in the room temperature and its variation across the day. In this work we present a framework which uses a simple interface allowing it to be used by different courses where the computers are the teaching/learning process in order to give a more realistic feeling to students by using real data. A framework is proposed based on a set of low cost sensors for different physical magnitudes, e.g. temperature, light, wind speed, which are connected to a central server, that the students have access with an Ethernet protocol or are connected directly to the student computer/laptop. These sensors use the communication ports available such as: serial ports, parallel ports, Ethernet or Universal Serial Bus (USB). Since a central server is used, the students are encouraged to use sensor values results in their different courses and consequently in different types of software such as: numerical analysis tools, spreadsheets or simply inside any programming language when a dataset is needed. In order to do this, small pieces of hardware were developed containing at least one sensor using different types of computer communication. As long as the sensors are attached in a server connected to the internet, these tools can also be shared between different schools. This allows sensors that aren't available in a determined school to be used by getting the values from other places that are sharing them. Another remark is that students in the more advanced years and (theoretically) more know how, can use the courses that have some affinities with electronic development to build new sensor pieces and expand the framework further. The final solution provided is very interesting, low cost, simple to develop, allowing flexibility of resources by using the same materials in several courses bringing real world data into the students computer works.

High-Accuracy Low-Cost RTK-GPS for an Unmanned Surface Vehicle

This work presents a low cost RTK-GPS system for localization of unmanned surface vehicles. The system is based on the use of standard low cost L1 band receivers and in the RTKlib open source software library. Mission scenarios with multiple robotic vehicles are addressed as the ones envisioned in the ICARUS search and rescue case where the possibility of having a moving RTK base on a large USV and multiple smaller vehicles acting as rovers in a local communication network allows for local relative localization with high quality. The approach is validated in operational conditions with results presented for moving base scenario. The system was implemented in the SWIFT USV with the ROAZ autonomous surface vehicle acting as a moving base. This setup allows for the performing of a missions in a wider range of environments and applications such as precise 3D environment modeling in contained areas and multiple robot operations.

Cost allocation model for distribution networks considering high penetration of distributed energy resources

The high penetration of distributed energy resources (DER) in distribution networks and the competitive environment of electricity markets impose the use of new approaches in several domains. The network cost allocation, traditionally used in transmission networks, should be adapted and used in the distribution networks considering the specifications of the connected resources. The main goal is to develop a fairer methodology trying to distribute the distribution network use costs to all players which are using the network in each period. In this paper, a model considering different type of costs (fixed, losses, and congestion costs) is proposed comprising the use of a large set of DER, namely distributed generation (DG), demand response (DR) of direct load control type, energy storage systems (ESS), and electric vehicles with capability of discharging energy to the network, which is known as vehicle-to-grid (V2G). The proposed model includes three distinct phases of operation. The first phase of the model consists in an economic dispatch based on an AC optimal power flow (AC-OPF); in the second phase Kirschen's and Bialek's tracing algorithms are used and compared to evaluate the impact of each resource in the network. Finally, the MW-mile method is used in the third phase of the proposed model. A distribution network of 33 buses with large penetration of DER is used to illustrate the application of the proposed model.

Multi-criteria optimisation approach to increase the delivered power in radial distribution networks

This study proposes a new methodology to increase the power delivered to any load point in a radial distribution network, through the identification of new investments in order to improve the repair time. This research work is innovative and consists in proposing a full optimisation model based on mixed-integer non-linear programming considering the Pareto front technique. The goal is to achieve a reduction in repair times of the distribution networks components, while minimising the costs of that reduction as well as non-supplied energy costs. The optimisation model considers the distribution network technical constraints, the substation transformer taps, and it is able to choose the capacitor banks size. A case study based on a 33-bus distribution network is presented in order to illustrate in detail the application of the proposed methodology.

Adaptive Penalty and Barrier function based on Fuzzy Logic

Optimization methods have been used in many areas of knowledge, such as Engineering, Statistics, Chemistry, among others, to solve optimization problems. In many cases it is not possible to use derivative methods, due to the characteristics of the problem to be solved and/or its constraints, for example if the involved functions are non-smooth and/or their derivatives are not know. To solve this type of problems a Java based API has been implemented, which includes only derivative-free optimization methods, and that can be used to solve both constrained and unconstrained problems. For solving constrained problems, the classic Penalty and Barrier functions were included in the API. In this paper a new approach to Penalty and Barrier functions, based on Fuzzy Logic, is proposed. Two penalty functions, that impose a progressive penalization to solutions that violate the constraints, are discussed. The implemented functions impose a low penalization when the violation of the constraints is low and a heavy penalty when the violation is high. Numerical results, obtained using twenty-eight test problems, comparing the proposed Fuzzy Logic based functions to six of the classic Penalty and Barrier functions are presented. Considering the achieved results, it can be concluded that the proposed penalty functions besides being very robust also have a very good performance.

Escolas do concelho de Matosinhos com estrutura de betão armado

O presente trabalho pretende contribuir para a gestão das intervenções de reparação e de reforço das escolas do concelho de Matosinhos com estrutura de betão armado. Apresenta-se uma síntese sobre a história do edifício escolar e do seu desenvolvimento em território nacional. Desenvolve-se uma pesquisa bibliográfica sobre metodologias de inspeção adotadas em território nacional e internacionalmente. Identificaram-se diferentes tipologias estruturais e arquitetónicas das escolas de Matosinhos, selecionou-se a mais representativa e, aparentemente, a que envolve casos com estados de conservação mais deficientes, definiu-se uma metodologia de inspeção estrutural e desenvolveram-se as respetivas fichas de inspeção. Selecionou-se e inspecionou-se visualmente um corpo da Escola Básica da Portela, de tipologia P3 e realizaram-se diferentes ensaios de diagnóstico. Comparam-se os respetivos resultados com os obtidos na inspeção da Escola da Amieira, do mesmo concelho e com a mesma tipologia. Propõem-se soluções de reparação com base no resultado da inspeção visual, nos ensaios de diagnóstico e na norma NP EN 1504-9. Estima-se o respetivo custo e sugere-se uma metodologia de extrapolação das conclusões e do estabelecimento de uma estimativa orçamental das intervenções de reparação das restantes escolas tipo P3 deste concelho e de outras com idênticas tipologias, localizações e condições ambientais envolventes.

Ensaio para a implementação de procedimentos de um plano de manutenção das juntas de dilatação do estádio do Dragão

No Estádio do Dragão existem doze juntas de dilatação localizadas simetricamente, que separam o estádio em doze corpos independentes, com o objetivo de minimizar a fendilhação provocada pelas movimentações da estrutura resultantes da solicitação de ações diretas e, principalmente, indiretas nessa mesma estrutura. Neste relatório explicar-se-á a importância, causas e objetivos que levam à necessidade de utilização destas juntas de dilatação em geral nas edificações, e no caso particular do estádio referido. Este elemento estrutural é considerado pela empresa responsável pela manutenção do Estádio do Dragão como a causa de um dos principais problemas recorrentes no estádio que necessitam de uma exigente atenção. Esta consideração deve-se ao fato das intervenções nas juntas de dilatação terem um custo de manutenção bastante oneroso e também pelo frequente aparecimento de novas patologias associadas a este elemento, tais como infiltrações de água, que necessitam de uma reparação urgente. Portanto, no sentido de resolver estas patologias decorrentes do mau funcionamento dos sistemas de juntas existentes no Estádio do Dragão, foi proposto pela PortoEstádio a elaboração de procedimentos de um plano de manutenção das juntas de dilatação que permitisse planear as intervenções e mitigar o aparecimento dessas patologias, com o objetivo principal de minimizar os custos inerentes à manutenção das juntas de dilatação. Estes procedimentos solicitados e demais elementos complementares são apresentados no presente trabalho, com a classificação dos sistemas de juntas do Estádio do Dragão, identificação das principais patologias nos diversos sistemas de juntas, escolha de novos sistemas para substituição dos existentes no estádio e finalmente, a criação de uma calendarização de intervenções nas juntas para a implementação de um plano de manutenção preventiva neste elemento de grande importância estrutural.