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Publicações

2022

Optimal location of Power Quality Monitors in distribution grids based on MRA methodology

Autores
Ferreira, V; Cerveira, A; Baptista, J;

Publicação
Renewable Energy and Power Quality Journal

Abstract
Distribution grids currently face news paradigms where Power Quality (PQ) has become one of the most important aspects for distribution system operators (DSO) and consumers. To ensure a PQ within the limits defined by international standards, there is a permanent need to monitor all parameters associated with the distributed voltage by the grid. This task is carried out using the installation of Power Quality Monitors (PQM) at strategic points of the grid. The main aim of this paper is to define a methodology to optimize the best location for the PQM installation. To achieve this target the Monitor Reach Area (MRA) matrix is calculated and an Integer Linear Programming (ILP) optimization model was used to find the best solution. Two case studies were carried out, in which residual voltage values were observed when three-phase short circuits are applied to all nodes. The results obtained show the good effectiveness of the developed method, presenting solutions that allow the total monitoring of the studied networks, using the smallest possible number of PQMs. In this way, it is possible for the DSO to keep the network monitored in real-time with huge efficiency gains. © 2022, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved.

2022

Hybridization of CEVESA MIBEL market model based on market outcomes

Autores
Oliveira A.R.D.; Navega V.; Collado J.V.; Saraiva J.T.; Campos F.A.;

Publicação
International Conference on the European Energy Market, EEM

Abstract
Fundamental electricity market models tend to underestimate the real market prices because they do not properly represent the real variable production cost of the generation units, nor the strategic markup that generation companies add to their costs to price the offered energy. This markup can increase bid prices above the marginal cost of the generation units, which may leave bids out of the market, decreasing the total cleared production, but increasing the final market price. This paper proposes a simple procedure, based on the real market outcomes, to estimate these markups and improve CEVESA MIBEL market model by reducing the gap between the simulated and the real market prices.

2022

From a millennium to a sustainable water and sanitation development: were we there already?

Autores
Pereira, MA; Marques, RC;

Publicação
AQUA-WATER INFRASTRUCTURE ECOSYSTEMS AND SOCIETY

Abstract
The Sustainable Development Goals (SDGs) of the United Nations (UN) brought many countries closer to the best practices in several sectors. However, regarding water and sanitation services (WSS), the evolution from the original Millennium Development Goals (MDGs) is not yet understood. Therefore, analysing whether low- and middle-income nations were able to converge in terms of WSS is fundamental for policy-making. Here, we propose a benchmarking exercise aimed at assessing the performance of 123 low- and middle-income UN Member States regarding WSS development targets over the 2001-2015 period of MDG pursuance. In the end, we show that, on average, the assessed Member States were already fully convergent before the implementation of the SDGs, despite further improvements with the latter. Additionally, we show that all UN regional groupings were able to decrease not only the performance spread of their Member States, but also the gap between the best practice frontier and the worst practice frontier. Besides, the Proportion of population using an improved drinking water source was the indicator with the highest performance growth in the considered period.

2022

The METIS Warm Support Structure Final Design

Autores
Costa, R; Amorim, A; Bone, A; Filho, M; Lopo, F; Ngando, M; Garcia, PJV;

Publicação
GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY IX

Abstract
This article presents the final design of the METIS/ELT warm support structure subsystem. It provides the mechanical interface between the cryostat and the Nasmyth platform, and it consists of three substructures: the elevation platform, the cryostat alignment structure, and the instrument access platform. The elevation platform is connected to the Nasmyth platform and holds the cryostat alignment platform, consisting of seven legs connected to three nodes. The cryostat alignment platform is a hexapod holding the cryostat, allowing maintenance, alignment, and positioning. The instrument access platform allows human access to the cryostat, it bears the cable support system and is prepared to support the future Single Laser Adaptive Optics system. The subsystem requirements, design trade-offs, interface considerations, and the substructures' final design and simulation results will be detailed as presented to the METIS Final Design Review in 2022.

2022

Organisation, Classification and Analysis of Online Reviews Directed to Retail in the Municipality of Porto

Autores
Braga, P; Brito, PQ; Roxo, MT;

Publicação
MARKETING AND SMART TECHNOLOGIES, VOL 1

Abstract
Web 2.0 has allowed collaboration, interaction and sharing of information online, such as online review platforms. Consequently, these short and straightforward opinions have increasingly proved to be essential sources of information not only for consumers but also for companies, as they represent the consumer's sincere evaluation, free from any kind of bias. In this sense, there should be an interest in the analysis and monitoring of online reviews by companies, as the result of these actions may provide guidelines to readjust their strategy, support decision-making and ensure the satisfaction of their consumers. To generate useful information to assist decision-making and strategies' implementation by retailers in the Municipality of Porto, online reviews from the GoogleMyBusiness platform were organised, classified, and analysed. 9945 online reviews were extracted, directed to 246 retail adaptations of the Municipality of Porto, from 2017 to 2020, which were later classified by the polarity of sentiment (positive, negative, neutral, or mixed). Sentiment analysis was conducted, combined with statistical tests and frequency distribution tables to discover relevant information for retailers. With sentiment analysis, retailers can understand their consumers and their behaviour to adapt their strategies and make the right decisions to ensure their customers' satisfaction. With the results obtained, this study proves that it is possible to extract useful information from online reviews and reveals that it is still an area of little interest for retailers in the Municipality of Porto.

2022

ATOM: A general calibration framework for multi-modal, multi-sensor systems

Autores
Oliveira, M; Pedrosa, E; de Aguiar, AP; Rato, DFPD; dos Santos, FN; Dias, P; Santos, V;

Publicação
EXPERT SYSTEMS WITH APPLICATIONS

Abstract
The fusion of data from different sensors often requires that an accurate geometric transformation between the sensors is known. The procedure by which these transformations are estimated is known as sensor calibration. The vast majority of calibration approaches focus on specific pairwise combinations of sensor modalities, unsuitable to calibrate robotic systems containing multiple sensors of varied modalities. This paper presents a novel calibration methodology which is applicable to multi-sensor, multi-modal robotic systems. The approach formulates the calibration as an extended optimization problem, in which the poses of the calibration patterns are also estimated. It makes use of a topological representation of the coordinate frames in the system, in order to recalculate the poses of the sensors throughout the optimization. Sensor poses are retrieved from the combination of geometric transformations which are atomic, in the sense that they are indivisible. As such, we refer to this approach as ATOM - Atomic Transformations Optimization Method. This makes the approach applicable to different calibration problems, such as sensor to sensor, sensor in motion, or sensor to coordinate frame. Additionally, the proposed approach provides advanced functionalities, integrated into ROS, designed to support the several stages of a complete calibration procedure. Results covering several robotic platforms and a large spectrum of calibration problems show that the methodology is in fact general, and achieves calibrations which are as accurate as the ones provided by state of the art methods designed to operate only for specific combinations of pairwise modalities.

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