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Publications

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

2016

A bridgeless controlled rectifier for single split-phase systems

Authors
Marinus, NSML; Jacobina, CB; dos Santos, EC; Rocha, N; de Freitas, NB;

Publication
2016 IEEE Energy Conversion Congress and Exposition (ECCE)

Abstract

2016

The role of fire-suppression force in limiting the spread of extremely large forest fires in Portugal

Authors
Fernandes, PM; Pacheco, AP; Almeida, R; Claro, J;

Publication
EUROPEAN JOURNAL OF FOREST RESEARCH

Abstract
Large forest fires are notorious for their environmental and socio-economic impacts and are assigned a disproportionately high percentage of the fire management budget. This study addresses extremely large fires (ELF, C2500 ha) in Portugal (2003-2013). We analysed the effect of fire-suppression force variation on ELF duration, size and growth rate, versus the effect of the concomitant fire environment (namely fuel and weather) conditions. ELF occurred in highly flammable landscapes and typically were impelled by extreme fire weather conditions. Allocation of suppression resources (normalized per unit of burned area or perimeter length) was disparate among fires, suggesting inadequate incident management. Fire-suppression effort did not affect time to containment modelled by survival analysis. Regression tree analysis indicated ELF spread to be negatively affected by higher fire-suppression resourcing, less severe fire weather, lower time to containment and higher presence of <9-year-old fuels, by decreasing order of importance; regional variability was relevant. Fire environment-to-fire suppression ratios of influence were 3: 1 for fire size and 1: 1 for fire growth rate, respectively, explaining 76 and 60 % of the existing variability. Results highlight the opportunistic nature of large-fire containment. To minimize the area burned by ELF, management and operational improvements leading to faster containment are recommended, rather than higher fire-suppression resourcing; more effective identification and exploration of containment opportunities are preferable to the accumulation of suppression resources.

2016

A Lock-Free Hash Trie Design for Concurrent Tabled Logic Programs

Authors
Areias, M; Rocha, R;

Publication
INTERNATIONAL JOURNAL OF PARALLEL PROGRAMMING

Abstract
Tabling is an implementation technique that improves the declarativeness and expressiveness of Prolog systems in dealing with recursion and redundant sub-computations. A critical component in the design of a concurrent tabling system is the implementation of the table space. One of the most successful proposals for representing tables is based on a two-level trie data structure, where one trie level stores the tabled subgoal calls and the other stores the computed answers. In previous work, we have presented a sophisticated lock-free design where both levels of the tries where shared among threads in a concurrent environment. To implement lock-freedom we used the CAS atomic instruction that nowadays is widely found on many common architectures. CAS reduces the granularity of the synchronization when threads access concurrent areas, but still suffers from problems such as false sharing or cache memory effects. In this work, we present a simpler and efficient lock-free design based on hash tries that minimizes these problems by dispersing the concurrent areas as much as possible. Experimental results in the Yap Prolog system show that our new lock-free design can effectively reduce the execution time and scales better than previous designs.

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