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About

About

First degree in Mechanical Engineering by FEUP (1982). Master of Science (1984) in Engineering Production and Management and Doctor of Philosophy (1989) in Engineering Production and Management in the scientific area of Quality, Reliability and Maintenance by the University of Birmingham (UK). Assistent Professor of the Faculty of Engineering in the Industrial Engineering and Management Department since 1982. Between the years of 2001 until 2011 I was in an Extraordinary Service Commission in IPB (Polytechnic  Institute of Bragança) as Coordenator Professor and where, among others functions, I was the Head of the Industrial Engineering Department and the  Coordenator of the  Erasmus Program of ESTIG. Since 1990 I have been  involved with several institutions (University Lusíada, ISEE, University Minho, University Nova, ISQ) where I teach subjects in the scientific area of Operations Management and Quantitative Methods with particular relevence to Reliability and Maintenance field. I have conducted several research work in these areas as well as business consulting.

Interest
Topics
Details

Details

  • Name

    Armando Leitão
  • Role

    Senior Researcher
  • Since

    01st February 2014
006
Publications

2024

Performance evaluation and benchmarking to inform dispatching rules for hydropower plants

Authors
Barbosa, F; Casacio, L; Bacalhau, ET; Leitao, A; Guimaraes, L;

Publication
UTILITIES POLICY

Abstract
Hydropower currently generates more than all other renewable energies combined. Considering the challenges of climate change and the transition to green energy, it is expected to remain the world's largest source of renewable electricity generation. This paper proposes a tool for performance evaluation and benchmarking of hydropower generation to inform dispatching. Through them, strengths and weaknesses of asset operations can be set, identifying areas with the best performance, gathering insights from their strategies and best practices, and comprehending factors that lead to variations in performance levels. The results allow for optimising energy resource use by indicating the dispatching rules with maximum power production and minimum wearand-tear impact. This framework allows the formulation of practical guidelines for dispatching policies. The proposed methodology is applied to analyse two real-world case studies: the Vogelgr & uuml;n run of river hydropower plant (France) and the Frades 2 pump-storage powerplant (Portugal).

2023

Multiobjective Evolutionary Clustering to Enhance Fault Detection in a PV System

Authors
Yamada, L; Rampazzo, P; Yamada, F; Guimaraes, L; Leitao, A; Barbosa, F;

Publication
OPERATIONAL RESEARCH, IO 2022-OR

Abstract
Data clustering combined with multiobjective optimization has become attractive when the structure and the number of clusters in a dataset are unknown. Data clustering is the main task of exploratory data mining and a standard statistical data analysis technique used in many fields, including machine learning, pattern recognition, image analysis, information retrieval, and bioinformatics. This project analyzes data to extract possible failure patterns in Solar Photovoltaic (PV) Panels. When managing PV Panels, preventive maintenance procedures focus on identifying and monitoring potential equipment problems. Failure patterns such as soiling, shadowing, and equipment damage can disturb the PV system from operating efficiently. We propose a multiobjective evolutionary algorithm that uses different distance functions to explore the conflicts between different perspectives of the problem. By the end, we obtain a non-dominated set, where each solution carries out information about a possible clustering structure. After that, we pursue a-posteriori analysis to exploit the knowledge of non-dominated solutions and enhance the fault detection process of PV panels.

2021

Resource definition and allocation for a multi-asset portfolio with heterogeneous degradation

Authors
Dias, L; Leitao, A; Guimaraes, L;

Publication
RELIABILITY ENGINEERING & SYSTEM SAFETY

Abstract
When making long-term plans for their asset portfolios, decision-makers have to define a priori a maintenance budget that is to be shared among the several assets and managed throughout the planning period. During the planning period, the a priori budget is then allocated by managers to different operation and maintenance interventions ensuring the overall performance of the system. Because asset degradation is stochastic, a considerable amount of uncertainty is associated with this problem. Hence, to define a robust budget, it is essential to account for several degradation scenarios pertaining to the individual condition of each asset. This paper presents a novel mathematical formulation to tackle this problem in a heterogeneous multiasset portfolio. The proposed mathematical model was formulated as a mixed-integer programming two-stage stochastic optimization model with mean-variance constraints to minimize the number of scenarios with an insufficient budget. A Gamma process was used to model the condition of each individual asset while taking into consideration different technological features and operating conditions. We compared the solutions obtained with our model to alternative practices in a set of generated instances covering different types of multi-asset portfolios. This comparison allowed us to explore the value of modeling uncertainty and how it affects the generated solutions. The proposed approach led to gains in performance of up to 50% depending on the level of uncertainty. Furthermore, the model was validated using real-world data from a utility company working with portfolios of power transformers. The results obtained showed that the company could reduce costs by as much as 40%. Further conclusions showed that the cost-saving potential was higher in asset portfolios in worse condition and that defining a priori operation and maintenance interventions led to worse results. Finally, the results showcased how different decision-maker risk-levels affect the value of taking uncertainty into account.

2021

An unsupervised approach for fault diagnosis of power transformers

Authors
Dias, L; Ribeiro, M; Leitao, A; Guimaraes, L; Carvalho, L; Matos, MA; Bessa, RJ;

Publication
QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL

Abstract
Electrical utilities apply condition monitoring on power transformers (PTs) to prevent unplanned outages and detect incipient faults. This monitoring is often done using dissolved gas analysis (DGA) coupled with engineering methods to interpret the data, however the obtained results lack accuracy and reproducibility. In order to improve accuracy, various advanced analytical methods have been proposed in the literature. Nonetheless, these methods are often hard to interpret by the decision-maker and require a substantial amount of failure records to be trained. In the context of the PTs, failure data quality is recurrently questionable, and failure records are scarce when compared to nonfailure records. This work tackles these challenges by proposing a novel unsupervised methodology for diagnosing PT condition. Differently from the supervised approaches in the literature, our method does not require the labeling of DGA records and incorporates a visual representation of the results in a 2D scatter plot to assist in interpretation. A modified clustering technique is used to classify the condition of different PTs using historical DGA data. Finally, well-known engineering methods are applied to interpret each of the obtained clusters. The approach was validated using data from two different real-world data sets provided by a generation company and a distribution system operator. The results highlight the advantages of the proposed approach and outperformed engineering methods (from IEC and IEEE standards) and companies legacy method. The approach was also validated on the public IEC TC10 database, showing the capability to achieve comparable accuracy with supervised learning methods from the literature. As a result of the methodology performance, both companies are currently using it in their daily DGA diagnosis.

2013

A flexible decision support tool for maintenance float systems - A simulation approach

Authors
Peito, F; Pereira, G; Leitao, A; Dias, L; Oliveira, JA;

Publication
12th International Conference on Modeling and Applied Simulation, MAS 2013, Held at the International Multidisciplinary Modeling and Simulation Multiconference, I3M 2013

Abstract
This paper is concerned with the use of simulation as a decision support tool in maintenance systems, specifically in MFS (Maintenance Float Systems). For this purpose and due to its high complexity, in this paper the authors explore and present a way to develop a flexible MFS model, for any number of machines in the workstation, spare machines and maintenance crews, using Arena simulation language. Also in this paper, some of the most common performance measures are identified, calculated and analysed. Nevertheless this paper would concentrate on the two most important performance measures in maintenance systems: system availability and maintenance total cost. As far as these two indicators are concerned, it was then quite clear that they assumed different behaviour patterns, especially when using extreme values for periodic overhauls rates. In this respect, system availability proved to be a more sensitive parameter.

Supervised
thesis

2023

Conceção de sistemas de fluxo de matérias-primas e semiacabados numa empresa da indústria automóvel.

Author
Carina Vieira Marques

Institution
UP-FEUP

2023

Definição de indicadores de performance para painel de gestão e melhoria dos fluxos de processos de negócio

Author
João Pedro Lopes Falcão

Institution
UP-FEUP

2023

O Balanced Scorecard como ferramenta de gestão estratégica numa empresa metalomecânica

Author
João Pedro Oliveira Lago

Institution
UP-FEUP

2023

Implementation of the Reliability Centered Maintenance methodology to the door systems of a train carriage

Author
António Pedro Teixeira Pereira

Institution
UP-FEUP

2022

Implementation of a Preventive Maintenance System in a Recycling Plant

Author
Renata Nogueira Silva Moreira

Institution
UP-FEUP