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Publications

2016

Three-phase four-wire AC-DC-AC multilevel topologies obtained from an interconnection of three-leg converters

Authors
Maia, ACN; Jacobina, CB; Freitas, NB; Queiroz, APD; Silva, ERC;

Publication
2016 IEEE Energy Conversion Congress and Exposition (ECCE)

Abstract

2016

Evaluating Selection, Manipulation and Navigation Tasks by People with Intellectual Disabilities Learning level comparison of user interaction performance with digital content

Authors
Rocha, T; Bessa, M; Melo, M; Barroso, J; Cabral, L;

Publication
2016 23RD PORTUGUESE MEETING ON COMPUTER GRAPHICS AND INTERACTION (EPCGI)

Abstract
This paper presents a study on the evolution of digital skills of a group of people with intellectual disabilities, when performing tasks such as painting, making puzzles, playing games, or word search. For the effect, we compare results in two assessment moments: in the first one, the group with intellectual disabilities had little or no experience as regards as performing universal tasks (selection, manipulation and navigation) and with the Web; in the second one, the group had some experience obtained within the 6 months after the first assessment moment. We aimed at evaluating the evolution of their digital skills by comparing the two assessment moments through the following usability variables: successful conclusion of activities, type of difficulties found, errors, satisfaction, motivation and autonomy indicators. The results revealed that participants showed learning skills when performing all the three universal tasks (namely: selection, manipulation and navigation) which is indicated by the number of participants that was able to conclude the activities, also confirmed by the prominent results of the second assessment moment. When it comes to errors, they made more errors in the first assessment moment, in general. When handling the input devices the participants had a better performance with the mouse than the keyboard. On the other hand, they improved their keyboard handling. However, it was observed that it is not a device that they can be autonomous with due to their reading/writing difficulties, which itself represents a didactic challenge when it comes to the very presentation of appropriate methodologies and techniques that may help them overcome such problem.

2016

A control strategy for the stable operation of shunt active power filters in power grids

Authors
Mehrasa, M; Pouresmaeil, E; Zabihi, S; Rodrigues, EMG; Catalao, JPS;

Publication
ENERGY

Abstract
This paper introduces a control strategy for the assessment of SAPF (shunt active power filters) role in the electrical power networks. The proposed control scheme is based on the Lyapunov control theory and defines a stable operating region for the interfaced converter during the integration time with the utility grid. The compensation of instantaneous variations of reference current components in the control loop of SAPF in ac-side, and dc-link voltage oscillations in dc-side of the proposed model, is thoroughly considered in the stable operation of interfaced converter, which is the main contribution of this proposal in comparison with other potential control approaches. The proposed control scheme can guarantee the injection of all harmonic components of current and reactive power of grid-connected loads, with a fast dynamic response that results in a unity power factor between the grid currents and voltages during the integration of SAPF into the power grid. An extensive simulation study is performed, assessing the effectiveness of the proposed control strategy in the utilization of SAPF in power networks.

2016

Experimental Assessment of Using Network Coding and Cooperative Diversity Techniques in IEEE 802.15.4 Wireless Sensor Networks

Authors
Valle, OT; Budke, G; Montez, C; Pinto, AR; Hernandez, F; Vasques, F; Vargas, F; Gatti, E;

Publication
2016 IEEE WORLD CONFERENCE ON FACTORY COMMUNICATION SYSTEMS (WFCS)

Abstract
The use of wireless sensor networks (WSN) to support critical monitoring applications is becoming a relevant topic of interest. These networks allow a highly flexible approach to data monitoring and, consequently, a major breakthrough for several application domains, from industrial control applications to large building domotics and health care applications. One of the major impairments of using wireless networks to support critical monitoring applications is the electromagnetic noise, which may increase the packet loss ratio to unacceptable values. In this paper, we assess different techniques of cooperative communication and network coding that can be useful to mitigate the aforementioned problem. These techniques may be implemented in WSN nodes in conformance with the IEEE 802.15.4 standard, to reduce the impact of electromagnetic interferences upon the packet loss ratio. In this paper, we report an experimental assessment of the network coding and cooperative diversity techniques, where the network is subjected to a controlled electromagnetic interference inside of an anechoic chamber. The experimental results show that, by using these techniques, it is possible to increase the success rate of communication in typical electromagnetic noisy environments.

2016

Fibrinogen scaffolds with immunomodulatory properties promote in vivo bone regeneration

Authors
Vasconcelos, DM; Goncalves, RM; Almeida, CR; Pereira, IO; Oliveira, MI; Neves, N; Silva, AM; Ribeiro, AC; Cunha, C; Almeida, AR; Ribeiro, CC; Gil, AM; Seebach, E; Kynast, KL; Richter, W; Lamghari, M; Santos, SG; Barbosa, MA;

Publication
BIOMATERIALS

Abstract
The hypothesis behind this work is that fibrinogen (Fg), classically considered a pro-inflammatory protein, can promote bone repair/regeneration. Injury and biomaterial implantation naturally lead to an inflammatory response, which should be under control, but not necessarily minimized. Herein, porous scaffolds entirely constituted of Fg (Fg-3D) were implanted in a femoral rat bone defect and investigated at two important time points, addressing the bone regenerative process and the local and systemic immune responses, both crucial to elucidate the mechanisms of tissue remodelling. Fg-3D led to early infiltration of granulation tissue (6 days post-implantation), followed by bone defect closure, including periosteum repair (8 weeks post-injury). In the acute inflammatory phase (6 days) local gene expression analysis revealed significant increases of pro-inflammatory cytokines IL-6 and IL-8, when compared with non-operated animals. This correlated with modified proportions of systemic immune cell populations, namely increased T cells and decreased B, NK and NIT lymphocytes and myeloid cell, including the Mac 1+ (CD18+/CD11b+) subpopulation. At 8 weeks, Fg-3D led to decreased plasma levels of IL-1 beta and increased TGF-beta 1. Thus, our data supports the hypothesis, establishing a link between bone repair induced by Fg-3D and the immune response. In this sense, Fg-3D scaffolds may be considered immunomodulatory biomaterials.

2016

Energy consumption forecasting based on Hybrid Neural Fuzzy Inference System

Authors
Jozi, A; Pinto, T; Praça, I; Silva, F; Teixeira, B; Vale, ZA;

Publication
2016 IEEE Symposium Series on Computational Intelligence, SSCI 2016, Athens, Greece, December 6-9, 2016

Abstract

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