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Publicações

2021

Fuzzy Automata as Coalgebras

Autores
Liu, A; Wang, S; Barbosa, LS; Sun, M;

Publicação
MATHEMATICS

Abstract
The coalgebraic method is of great significance to research in process algebra, modal logic, object-oriented design and component-based software engineering. In recent years, fuzzy control has been widely used in many fields, such as handwriting recognition and the control of robots or air conditioners. It is then an interesting topic to analyze the behavior of fuzzy automata from a coalgebraic point of view. This paper models different types of fuzzy automata as coalgebras with a monad structure capturing fuzzy behavior. Based on the coalgebraic models, we can define a notion of fuzzy language and consider several versions of bisimulation for fuzzy automata. A group of combinators is defined to compose fuzzy automata of two branches: state transition and output function. A case study illustrates the coalgebraic models proposed and their composition.

2021

Pressureless static solutions in a Newton-Yukawa gravity model

Autores
Ferreira, TD; Novo, J; Silva, NA; Guerreiro, A; Bertolami, O;

Publicação
PHYSICAL REVIEW D

Abstract
Nonminimally coupled curvature-matter gravity models are an interesting alternative to the theory of general relativity to address the dark energy and dark matter cosmological problems. These models have complex field equations that prevent a full analytical study. Nonetheless, in a particular limit, the behavior of a matter distribution can, in these models, be described by a Schrodinger-Newton system. In nonlinear optics, the Schrodinger-Newton system can be used to tackle a wide variety of relevant situations, and several numerical tools have been developed for this purpose. Interestingly, these methods can be adapted to study general relativity problems as well as its extensions. In this work, we report the use of these numerical tools to study a particular nonminimal coupling model that introduces two new potentials, an attractive Yukawa potential, and a repulsive potential proportional to the energy density. Using the imaginary-time propagation method, we have shown that static solutions arise even at low energy density regimes.

2021

Overview of Robotic Based System for Rehabilitation and Healthcare

Autores
Chellal A.A.; Lima J.; Fernandes F.P.; Gonçalves J.; Pacheco M.F.; Monteiro F.C.;

Publicação
Communications in Computer and Information Science

Abstract
As in many other fields, robots are increasingly being used in the healthcare sector, particularly for hospital logistics support, surgery and rehabilitation. Rehabilitation is a concern for millions of people around the world, and because of this, there has been a constant progress over the last decade in the rehabilitation robotics field, with the use of new technologies aimed at overcoming the different challenges faced in this field. In this sense, this paper reviews the main applications developed in the last ten years of rehabilitation robotics, as well as the different challenges that still need to be addressed in order to achieve the design of a prototype that is easy to use, small, safe, less costly and brings real added value to this field. Much of the efforts of the researchers in this topics is focused on providing as many DOF and ROM as possible, and also on the designing of new robots control algorithms.

2021

Point Cloud Interaction and Manipulation in Virtual Reality

Autores
Garrido, D; Rodrigues, R; de Sousa, AA; Jacob, J; Silva, DC;

Publicação
AIVR

Abstract
The use of virtual reality technologies for data visualization and analysis has been an emerging topic of research in the past years. However, one type of data has been left neglected, the point cloud. While some strides have been made in the visualization and analysis of point clouds in immersive environments, these have yet to be used for direct manipulation interactions. It is hypothesized that as with other types of data, bringing direct interactions and 3D visualization to point clouds may increase the ease of performing basic handling tasks. An immersive application for virtual reality HMDs was developed in Unity to help research this hypothesis. It is capable of parsing classified point cloud files with extracted objects and representing them in a virtual environment. Several editing tools were also developed, designed with the HMD controllers in mind. The end result allows the user to perform basic transformative tasks to the point cloud with an ease of use and intuitive feeling unmatched by the traditional desktop-based tools.

2021

Impact of Electric Vehicles in Three-Phase Distribution Grids

Autores
Prakash, P; Tavares, BC; Prata, R; Fidalgo, N; Moreira, C; Soares, F;

Publicação
IET Conference Proceedings

Abstract
Recent advances in electric vehicle (EV) charging capability have seen a wide growth in the consumer market, which will continue to increase in future years with favourable policy incentives. However, the uncontrolled connection and charging of EV may have an adverse effect on three-phase distribution grids operation. This paper presents the impact of EV integration in a real LV Portuguese urban network. It analyses the network loading, energy losses, and voltage imbalances, under different scenarios of EV charging location and phase connection. The DIgSILENT Power Factory software is used in the voltage imbalance studies. Preliminary results show that the voltage drop in the analysed network is significantly affected by the location of the EV. Furthermore, as expected, the unbalanced EV loading leads to an increase of voltage unbalance between phases which is more pronounced when higher levels of EV are considered. © 2021 The Institution of Engineering and Technology.

2021

Análise Econômica para Inclusão de Baterias de Segunda Vida para Prossumidores no Brasil

Autores
Rafaella M. B. Prado; Célia S. A. Sena; Wanessa O. Guedes; Bruno H. Dias; Tiago A. Soares; Leonardo W. Oliveira;

Publicação
Procedings do XV Simpósio Brasileiro de Automação Inteligente

Abstract

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