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Publicações

2024

Shapley-Scarf Housing Markets: Respecting Improvement, Integer Programming, and Kidney Exchange

Autores
Biró, P; Klijn, F; Klimentova, X; Viana, A;

Publicação
MATHEMATICS OF OPERATIONS RESEARCH

Abstract
In a housing market of Shapley and Scarf, each agent is endowed with one indivisible object and has preferences over all objects. An allocation of the objects is in the (strong) core if there exists no (weakly) blocking coalition. We show that, for strict preferences, the unique strong core allocation respects improvement-if an agent's object becomes more desirable for some other agents, then the agent's allotment in the unique strong core allocation weakly improves. We extend this result to weak preferences for both the strong core (conditional on nonemptiness) and the set of competitive allocations (using probabilistic allocations and stochastic dominance). There are no counterparts of the latter two results in the two-sided matching literature. We provide examples to show how our results break down when there is a bound on the length of exchange cycles. Respecting improvements is an important property for applications of the housing markets model, such as kidney exchange: it incentivizes each patient to bring the best possible set of donors to the market. We conduct computer simulations using markets that resemble the pools of kidney exchange programs. We compare the game-theoretical solutions with current techniques (maximum size and maximum weight allocations) in terms of violations of the respecting improvement property. We find that game-theoretical solutions fare much better at respecting improvements even when exchange cycles are bounded, and they do so at a low efficiency cost. As a stepping stone for our simulations, we provide novel integer programming formulations for computing core, competitive, and strong core allocations.

2024

Improving coffee capsules recyclability- A combined assessment of circularity and environmental performance of a novel design

Autores
Pinto, SM; Gouveia, JR; Sousa, M; Rodrigues, B; Oliveira, J; Pinto, C; Baptista, AJ;

Publicação
SUSTAINABLE PRODUCTION AND CONSUMPTION

Abstract
Coffee capsules have gained high levels of popularity in the last decades due to their convenience of use, flavour choices, and consistent extraction quality. As governmental bodies are promoting more circular solutions for packaging products, concerns have been raised regarding the environmental impacts of single-use coffee capsules, namely their end-of-life treatment and effective recyclability. This paper presents a novel design based on thin steel sheet material application for new packaging solutions that can support a more circular economy. To validate this new design, a framework was presented for a cross-assessment of Life Cycle Assessment with Circularity Analysis to compare the new tinplate capsule with conventional polypropylene and aluminium capsules. The novel design is more circular (0.97 in the material circularity indicator), in comparison with the polypropylene (0.1) and aluminium (0.80) conventional capsules, due to the ferromagnetic properties that allow for better effectiveness during sorting in urban packaging recycling facilities. As for the environmental assessment, the tinplate has higher environmental impacts than the aluminium and the polypropylene capsules (more 63 % and more 92 %, respectively) due to the high energy intensity processes required to produce this material. These results demonstrate that the novel tinplate capsule should complement the strong results in circularity with further improvements in its environmental performance, namely by the transition of the steel industry to the upcoming generation of decarbonized steel production.

2024

Interferência dos periódicos da área de gestão na determinação das publicações historicamente mais influentes da Ciência da Informação e Biblioteconomia

Autores
Gerson Pech; Catarina Delgado;

Publicação
Informação & Informação

Abstract
Objetivo: descobrir a razão pela qual resultados inesperados foram gerados na determinação das publicações historicamente mais influentes (landmarks) de Ciência da Informação e Biblioteconomia (CI&B) da Web of Science (WoS). Metodologia: Recuperamos dados de todos os artigos e revisões do CI&B, do período 1980-2017 (N=93.330), identificamos e analisamos as áreas de periódicos dos artigos que citaram os landmarks. Resultados: Mostramos que os periódicos que mais citam os dois primeiros landmarks da CI&B são da área de Gestão, Negócios e Sistemas de Informação. Mostramos também que cinco dos dez primeiros landmarks possuem conteúdos fortemente voltados para Gestão, Sociologia, Marketing, Comunicação e Sistemas de Informação e que só aparecem como landmarks da CI&B porque são citados por periódicos da área de Gestão, categorizados no WoS, também, como CI&B. No caso da área “Métricas da Informação”, o resultado revela publicações reconhecidas na literatura como cruciais. Conclusões: Quando se desenvolve um estudo de uma área de pesquisa utilizando a categorização da WoS como base para a amostra, outra área pode interferir neste estudo, produzindo resultados inconsistentes. A análise da categorização dos periódicos, conforme realizada por este estudo, é fundamental para avaliar corretamente o impacto de um artigo, pois as métricas de produção utilizadas na avaliação acadêmica precisam ser normalizadas por área.

2024

Black Start of an Off-grid Offshore Wind Farm with Grid Forming Converter

Autores
Prakash, H; Lopes, P; Silva, B;

Publicação
IET Conference Proceedings

Abstract
This paper presents a comprehensive procedure for conducting a black start service from an offshore wind farm (OWF) by integrating grid-forming (GFM) control. The proposed strategy utilizes a grid-forming battery energy storage system (BESS) to provide black start service within an OWF that is equipped with grid-following wind turbines. The paper elaborates on the modeling of controllers and the operational methodology taking wind variability during the black start procedure. To showcase the effectiveness of the proposed control and operation principles, the study utilizes an OWF as a case study. Simulation analyses are performed using Matlab/Simulink software to validate the feasibility of the proposed strategy. © Energynautics GmbH.

2024

Cost-Oriented Prototyping of a Soil Moisture Sensor for Precision Agriculture

Autores
Gomes, LM; Gonçalves, J; Coelho, JP;

Publicação
Lecture Notes in Educational Technology

Abstract
The fourth industrial revolution is based on the production process’s digitisation to promote traceability, reduction of waste and decision support. This transition from the physical to the information domain requires, besides the process’s digital representation, sensors and transducers capable of capturing the system states. In the case of agricultural processes, due to the heterogeneity of production conditions, as well as the large area in which it takes place, physical characterisation often requires a large number of sensors spread over several hectares. This fact makes the economic costs associated with the digitisation of agriculture a very relevant aspect. In particular, if robust and precise sensors are to be deployed. Within this reference frame, this paper describes the approach taken to develop low-cost sensors capable of measuring soil moisture at three different depths. Robustness is achieved through the use of materials with high mechanical strength and corrosion resistance and both accuracy and repeatability are accomplished by using a signal conditioning strategy based on a programmable analogue front-end. Details about the methodology used are presented throughout the article. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

2024

Proceedings of the 19th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications, VISIGRAPP 2024, Volume 2: VISAPP, Rome, Italy, February 27-29, 2024

Autores
Radeva, P; Furnari, A; Bouatouch, K; de Sousa, AA;

Publicação
VISIGRAPP (2): VISAPP

Abstract

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