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Publications

2023

Simulating a real time Walrasian local electricity market design: assessing auctioneer algorithm and price behavior

Authors
Mello, J; Retorta, F; Silva, R; Villar, J; Saraiva, JT;

Publication
2023 19TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET, EEM

Abstract
In Walrasian markets, an auctioneer proposes a price to the market participants, who react by revealing the quantities they are willing to buy or sell at this price. The auctioneer then proposes new prices to improve the demand and supply match until the equilibrium is reached. This market, common for stock exchanges, has also been proposed for electricity markets like power electricity exchanges, where iterations among auctioneer and market participants take place before the interval settlement period (ISP) until supply and demand match and a stable price is reached. We propose a Walrasian design for local electricity markets where the iterations between auctioneer and market participants happen in real time, so previous imbalances are used to correct the proposed price for the next ISP. The designs are simulated to test convergence and their capability of achieving efficient dynamic prices.

2023

Quartic solitons of a mode-locked laser distributed model

Authors
Malheiro, D; Facao, M; Carvalho, MI;

Publication
OPTICS LETTERS

Abstract
Dissipative quartic solitons have gained interest in the field of mode-locked lasers for their energy-width scaling which allows the generation of ultrashort pulses with high energies. Pursuing the characterization of such pulses, here we found soliton solutions of a distributed model for mode locked lasers in the presence of either positive or negative fourth-order dispersion (4OD). We studied the impact the laser parameters may have on the profiles, range of existence, and energy-width relation of the output pulses. The most energetic and narrowest solutions occur for negative 4OD, with the energy having an inverse cubic dependence with the width in most cases. Our simulations showed that the spectral filtering has the biggest contribution in the generation of short (widths as low as 39 fs) and very energetic (391 nJ) optical pulses.(c) 2023 Optica Publishing Group

2023

Using the motion of S2 to constrain scalar clouds around Sgr A

Authors
Foschi A.; Abuter R.; Aimar N.; Amaro Seoane P.; Amorim A.; Bauböck M.; Berger J.P.; Bonnet H.; Bourdarot G.; Brandner W.; Cardoso V.; Clénet Y.; Dallilar Y.; Davies R.; De Zeeuw P.T.; Defrère D.; Dexter J.; Drescher A.; Eckart A.; Eisenhauer F.; Ferreira M.C.; Förster Schreiber N.M.; Garcia P.J.V.; Gao F.; Gendron E.; Genzel R.; Gillessen S.; Gomes T.; Habibi M.; Haubois X.; Heißel G.; Henning T.; Hippler S.; Hönig S.F.; Horrobin M.; Jochum L.; Jocou L.; Kaufer A.; Kervella P.; Kreidberg L.; Lacour S.; Lapeyrère V.; Le Bouquin J.B.; Léna P.; Lutz D.; Millour F.; Ott T.; Paumard T.; Perraut K.; Perrin G.; Pfuhl O.; Rabien S.; Ribeiro D.C.; Sadun Bordoni M.; Scheithauer S.; Shangguan J.; Shimizu T.; Stadler J.; Straub O.; Straubmeier C.; Sturm E.; Sykes C.; Tacconi L.J.; Vincent F.; Von Fellenberg S.; Widmann F.; Wieprecht E.; Wiezorrek E.; Woillez J.; Yazici S.;

Publication
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

Abstract
The motion of S2, one of the stars closest to the Galactic Centre, has been measured accurately and used to study the compact object at the centre of the Milky Way. It is commonly accepted that this object is a supermassive black hole, but the nature of its environment is open to discussion. Here, we investigate the possibility that dark matter in the form of an ultralight scalar field 'cloud' clusters around Sgr A*. We use the available data for S2 to perform a Markov Chain Monte Carlo analysis and find the best-fit estimates for a scalar cloud structure. Our results show no substantial evidence for such structures. When the cloud size is on the order of the size of the orbit of S2, we are able to constrain its mass to be smaller than 0.1 % of the central mass, setting a strong bound on the presence of new fields in the galactic centre.

2023

Home-Based Rehabilitation of the Shoulder Using Auxiliary Systems and Artificial Intelligence: An Overview

Authors
Cunha, B; Ferreira, R; Sousa, ASP;

Publication
SENSORS

Abstract
Advancements in modern medicine have bolstered the usage of home-based rehabilitation services for patients, particularly those recovering from diseases or conditions that necessitate a structured rehabilitation process. Understanding the technological factors that can influence the efficacy of home-based rehabilitation is crucial for optimizing patient outcomes. As technologies continue to evolve rapidly, it is imperative to document the current state of the art and elucidate the key features of the hardware and software employed in these rehabilitation systems. This narrative review aims to provide a summary of the modern technological trends and advancements in home-based shoulder rehabilitation scenarios. It specifically focuses on wearable devices, robots, exoskeletons, machine learning, virtual and augmented reality, and serious games. Through an in-depth analysis of existing literature and research, this review presents the state of the art in home-based rehabilitation systems, highlighting their strengths and limitations. Furthermore, this review proposes hypotheses and potential directions for future upgrades and enhancements in these technologies. By exploring the integration of these technologies into home-based rehabilitation, this review aims to shed light on the current landscape and offer insights into the future possibilities for improving patient outcomes and optimizing the effectiveness of home-based rehabilitation programs.

2023

Automatic characterisation of Dansgaard-Oeschger events in palaeoclimate ice records

Authors
Barbosa, S; Silva, ME; Dias, N; Rousseau, D;

Publication

Abstract
Greenland ice core records display abrupt transitions, designated as Dansgaard-Oeschger (DO) events, characterised by episodes of rapid warming (typically decades) followed by a slower cooling. The identification of abrupt transitions is hindered by the typical low resolution and small size of paleoclimate records, and their significant temporal variability. Furthermore, the amplitude and duration of the DO events varies substantially along the last glacial period, which further hinders the objective identification of abrupt transitions from ice core records Automatic, purely data-driven methods, have the potential to foster the identification of abrupt transitions in palaeoclimate time series in an objective way, complementing the traditional identification of transitions by visual inspection of the time series.In this study we apply an algorithmic time series method, the Matrix Profile approach, to the analysis of the NGRIP Greenland ice core record, focusing on:- the ability of the method to retrieve in an automatic way abrupt transitions, by comparing the anomalies identified by the matrix profile method with the expert-based identification of DO events;- the characterisation of DO events, by classifying DO events in terms of shape and identifying events with similar warming/cooling temporal patternThe results for the NGRIP time series show that the matrix profile approach struggles to retrieve all the abrupt transitions that are identified by experts as DO events, the main limitation arising from the diversity in length of DO events and the method’s dependence on fixed-size sub-sequences within the time series. However, the matrix profile method is able to characterise the similarity of shape patterns between DO events in an objective and consistent way.

2023

A Review on the Video Summarization and Glaucoma Detection

Authors
Correia, T; Cunha, A; Coelho, P;

Publication
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST

Abstract
Glaucoma is a severe disease that arises from low intraocular pressure, it is asymptomatic in the initial stages and can lead to blindness, due to its degenerative characteristic. There isn’t any available cure for it, and it is the second most common cause of blindness in the world. Regular visits to the ophthalmologist are the best way to prevent or contain it, with a precise diagnosis performed with professional equipment. From another perspective, for some individuals or populations, this task can be difficult to accomplish, due to several restrictions, such as low incoming resources, geographical adversities, and traveling restrictions (distance, lack of means of transportation, etc.). Also, logistically, due to its dimensions, relocating the professional equipment can be expensive, thus becoming inviable to bring them to remote areas. As an alternative, some low-cost products are available in the market that copes with this need, namely the D-Eye lens, which can be attached to a smartphone and enables the capture of fundus images, presenting as major drawback lower quality imaging when compared to professional equipment. Some techniques rely on video capture to perform summarization and build a full image with the desired features. In this context, the goal of this paper is to present a review of the methods that can perform video summarization and methods for glaucoma detection, combining both to indicate if individuals present glaucoma symptoms, as a pre-screening approach. © 2023, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.

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