2021
Autores
Fontes, X; Aparício, D; Silva, MI; Malveiro, B; Ascensão, JT; Bizarro, P;
Publicação
Proceedings of the 2nd Workshop on Search, Exploration, and Analysis in Heterogeneous Datastores (SEA-Data 2021) co-located with 47th International Conference on Very Large Data Bases (VLDB 2021), Copenhagen, Denmark, August 20, 2021.
Abstract
2021
Autores
Andrade, C; Teixeira, LF; Vasconcelos, MJM; Rosado, L;
Publicação
JOURNAL OF IMAGING
Abstract
Dermoscopic images allow the detailed examination of subsurface characteristics of the skin, which led to creating several substantial databases of diverse skin lesions. However, the dermoscope is not an easily accessible tool in some regions. A less expensive alternative could be acquiring medium resolution clinical macroscopic images of skin lesions. However, the limited volume of macroscopic images available, especially mobile-acquired, hinders developing a clinical mobile-based deep learning approach. In this work, we present a technique to efficiently utilize the sizable number of dermoscopic images to improve the segmentation capacity of macroscopic skin lesion images. A Cycle-Consistent Adversarial Network is used to translate the image between the two distinct domains created by the different image acquisition devices. A visual inspection was performed on several databases for qualitative evaluation of the results, based on the disappearance and appearance of intrinsic dermoscopic and macroscopic features. Moreover, the Frechet Inception Distance was used as a quantitative metric. The quantitative segmentation results are demonstrated on the available macroscopic segmentation databases, SMARTSKINS and Dermofit Image Library, yielding test set thresholded Jaccard Index of 85.13% and 74.30%. These results establish a new state-of-the-art performance in the SMARTSKINS database.
2021
Autores
Paulos, JP; Fidalgo, JN; Saraiva, JT; Barbosa, N;
Publicação
2021 IEEE MADRID POWERTECH
Abstract
In Europe, clean distributed generation, DG, is perceived as a crucial instrument to build the path towards carbon emission neutrality. DG already reached a large share in the generation mix of several countries and the reduction of technical losses is one of its most mentioned advantages. In this scope, this paper discusses the weaknesses of this postulation using real networks. The adopted methodology involves the power flow simulation of a collection of real networks, using 15 min real measurements of loads and generations for a whole year. The clustering of similar cases allows identifying the situations that cause higher losses. A complementary objective of this research was to define an approach to mitigate this problem in terms of identifying the branches that, if reinforced, most contribute to losses reduction. The results obtained confirm the rationality of the proposed methodology.
2021
Autores
Osorio, GJ; Lotfi, M; Gough, M; Javadi, M; Espassandim, HMD; Shafie khah, M; Catalao, JPS;
Publicação
JOURNAL OF CLEANER PRODUCTION
Abstract
Electric vehicles (EVs) are seen as a crucial tool to reduce the polluting emissions caused by the transport and power systems (PS) sector and the associated shift to a cleaner and more sustainable energy sector. The com-bination of EVs and solar photovoltaics (PV) in PS, specifically through the aggregation of EVs in parking lots (PLs), may improve the reliability and flexibility of the PS, assisting the power network in critical moments. This work proposes a novel aggregator agent in the energy system which is an EV charging station with an installed PV system. In this work, an optimal operation strategy for the solar-powered EV PL (EVSPL) operation is pre-sented. The model optimizes the EVSPL's participation in various energy and ancillary services markets, including the effects of capacity payments. The results show that the EVSPL leads to higher profits. The EVSPL's participation in ancillary services is highly influenced by the prices. The results of this work show that this novel agent can actively participate in the energy system in an economically viable manner while respecting the technical constraints of the network and providing important ancillary services to the system operator.
2021
Autores
Costa, LALDC; Fan, BR; Burgos, R; Boroyevich, D; Chen, WR; Blasko, V;
Publicação
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS
Abstract
Matrix converters feature low switching loss, small electromagnetic interference filter, and the potential for achieving high power density. With the employment of wide-bandgap devices, such as silicon carbide devices, the converter performance can be further improved. For a safe operation of matrix converters, an overvoltage protection circuit is necessary to limit the voltage stress of the devices during fault conditions. Due to the high switching speed of silicon carbide devices, the topology and layout design of the overvoltage protection circuit is critical to ensure fast and robust protection for the devices. In this article, a detachable overvoltage protection circuit is designed for each phase leg of the matrix converter. The topology and hardware layout design are elaborated. A 15-kW full silicon carbide implemented matrix converter is built, and the designed overvoltage protection circuits are employed and tested.
2021
Autores
Maia, P; Morgado, J; Goncalves, T; Albuquerque, T;
Publicação
MACHINE LEARNING AND PRINCIPLES AND PRACTICE OF KNOWLEDGE DISCOVERY IN DATABASES, PT II
Abstract
Pollutant emissions from passenger cars give rise to harmful effects on human health and the environment. Predicting traffic flow is a challenging problem, but essential to understand what factors influence car traffic and what measures should be taken to reduce carbon dioxide emissions. In this work, we developed a predictive model to forecast traffic flow in several locations in the city of Porto for 24 h later, i.e., the next day at the same time. We trained a XGBoost Regressor with multi-modal data from 2018 and 2019 obtained from traffic and weather sensors of the city of Porto and the geographic location of several points of interest. The proposed model achieved a mean absolute error, mean square error, Spearman's rank correlation coefficient, and Pearson correlation coefficient equal to 80.59, 65395, 0.9162, and 0.7816, respectively, when tested on the test set. The developed model makes it possible to analyse which areas of the city of Porto will have more traffic the next day and take measures to optimise this increasing flow of cars. One of the ideas present in the literature is to develop intelligent traffic lights that change their timers according to the expected traffic in the area. This system could help decrease the levels of carbon dioxide emitted and therefore decrease its harmful effects on the health of the population and the environment.
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.