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Publicações

2022

Challenges to the assembly and integration of the WSS with METIS

Autores
Filho, M; Amorim, A; Garcia, P; Carvalho, F; da Costa, R; Ngando, M;

Publicação
MODELING, SYSTEMS ENGINEERING, AND PROJECT MANAGEMENT FOR ASTRONOMY X

Abstract
Portugal will build the warm support and access structure (WSS) to the mid-infrared, first generation ELT instrument METIS. The particular characteristics of METIS and the ELT pose several challenges to designing the WSS according to requirements, as well challenges to the assembly and integration of the WSS. We here provide you an overview of those challenges, as well as strategies to overcome and mitigate issues related to the mass and dimensions of the WSS.

2022

A Short Term Wind Speed Forecasting Model Using Artificial Neural Network and Adaptive Neuro-Fuzzy Inference System Models

Autores
Amoura, Y; Pereira, AI; Lima, J;

Publicação
SUSTAINABLE ENERGY FOR SMART CITIES, SESC 2021

Abstract
Future power systems encourage the use of renewable energy resources, among them wind power is of great interest, but its power output is intermittent in nature which can affect the stability of the power system and increase the risk of blackouts. Therefore, a forecasting model of the wind speed is essential for the optimal operation of a power supply with an important share of wind energy conversion systems. In this paper, two wind speed forecasting models based on multiple meteorological measurements of wind speed and temperature are proposed and compared according to their mean squared error (MSE) value. The first model concerns the artificial intelligence based on neural network (ANN) where several network configurations are proposed to achieve the most suitable structure of the problem, while the other model concerned the Adaptive Neuro-Fuzzy Inference System (ANFIS). To enhance the results accuracy, the invalid input samples are filtered. According to the computational results of the two models, the ANFIS has delivered more accurate outputs characterized by a reduced mean squared error value compared to the ANN-based model.

2022

Assessing the Contribution of ECa and NDVI in the Delineation of Management Zones in a Vineyard

Autores
Esteves, C; Fangueiro, D; Braga, RP; Martins, M; Botelho, M; Ribeiro, H;

Publicação
AGRONOMY-BASEL

Abstract
Precision fertilization implies the need to identify the variability of soil fertility, which is costly and time-consuming. Remotely measured data can be a solution. Using this strategy, a study was conducted, in a vineyard, to delineate different management zones using two indicators: apparent soil electrical conductivity (ECa) and normalized difference vegetation index (NDVI). To understand the contribution of each indicator, three scenarios were used for zone definition: (1) using only NDVI, (2) only ECa, or (3) using a combination of the two. Then the differences in soil fertility between these zones were assessed using simple statistical methods. The results indicate that the most beneficial strategy is the combined use of the two indicators, as it allowed the definition of three distinct zones regarding important soil variables and crop nutrients, such as soil total nitrogen, Mg2+ cation, exchange acidity, and effective cation exchange capacity, and some relevant cation ratios. This strategy also allowed the identification of an ionic unbalance in the soil chemistry, due to an excess of Mg2+, that was harming crop health, as reported by NDVI. This also impacted ECa and NDVI relationship, which was negative in this study. Overall, the results demonstrate the advantages of using remotely sensed data, mainly more than one type of sensing data, and suggest a high potential for differential crop fertilization and soil management in the study area.

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.

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