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Publications

2020

A Distributed Multi-Tier Emergency Alerting System Exploiting Sensors-Based Event Detection to Support Smart City Applications

Authors
Costa, DG; Vasques, F; Portugal, P; Aguiar, A;

Publication
Sensors

Abstract
The development of efficient sensing technologies and the maturation of the Internet of Things (IoT) paradigm and related protocols have considerably fostered the expansion of sensor-based monitoring applications. A great number of those applications has been developed to monitor a set of information for better perception of the environment, with some of them being dedicated to identifying emergency situations. Current IoT-based emergency systems have limitations when considering the broader scope of smart cities, exploiting one or just a few monitoring variables or even allocating high computational burden to regular sensor nodes. In this context, we propose a distributed multi-tier emergency alerting system built around a number of sensor-based event detection units, providing real-time georeferenced information about the occurrence of critical events, while taking as input a configurable number of different scalar sensors and GPS data. The proposed system could then be used to detect and to deliver emergency alarms, which are computed based on the detected events, the previously known risk level of the affected areas and temporal information. Doing so, modularized and flexible perceptions of critical events are provided, according to the particularities of each considered smart city scenario. Besides implementing the proposed system in open-source electronic platforms, we also created a real-time visualization application to dynamically display emergency alarms on a map, demonstrating a feasible and useful application of the system as a supporting service. Therefore, this innovative approach and its corresponding physical implementation can bring valuable results for smart cities, potentially supporting the development of adaptive IoT-based emergency-aware applications.

2020

Modelling Coverage Failures Caused by Mobile Obstacles for the Selection of Faultless Visual Nodes in Wireless Sensor Networks

Authors
Jesus, TC; Costa, DG; Portugal, P; Vasques, F; Aguiar, A;

Publication
IEEE Access

Abstract
Wireless sensor networks comprising nodes equipped with cameras have become common in many scenarios, providing valuable visual data for some relevant services such as localization, tracking, patterns identification and emergencies detection. In this context, algorithms and optimization approaches have been designed to perform different types of quality assessment or performance enhancement tasks, addressing challenging issues such as networking, compression, availability, reliability, security, energy efficiency and virtually any subject related to the operational challenges of those networks. However, the dynamics of coverage failures have not been properly modelled in visual sensor networks, resulting in unrealistic perceptions when optimizing or assessing quality in most visual sensing scenarios. Particularly, the Field of View of visual sensors will be affected by occlusion caused by obstacles in the monitored field, which may turn such sensors inadequate for the expected monitoring services of the considered network. Therefore, this article proposes a mathematical model to assess occlusion caused by mobile obstacles such as vehicles on a road or forklifts in an industrial plant, aiming at the selection of the visual sensor nodes that will not have their coverage significantly restricted by those obstacles. Doing so, the proposed model can be exploited by any optimization or quality assessment approach in wireless visual sensor networks, providing a preprocessing method when selecting visual nodes. © 2013 IEEE.

2020

FoV-Based Quality Assessment and Optimization for Area Coverage in Wireless Visual Sensor Networks

Authors
Jesus, TC; Costa, DG; Portugal, P; Vasques, F;

Publication
IEEE Access

Abstract

2019

Handling Real-Time Communication in Infrastructured IEEE 802.11 Wireless Networks: The RT-WiFi Approach

Authors
Costa, R; Lau, J; Portugal, P; Vasques, F; Moraes, R;

Publication
JOURNAL OF COMMUNICATIONS AND NETWORKS

Abstract
In this paper, the RT-WiFi architecture is proposed to handle real-time (RT) communication in infrastructured IEEE 802.11 networks operating in high density industrial environments. This architecture is composed of a time division multiple access (TDMA)-based coordination layer that schedules the medium access of RT traffic flows, and an underlying traffic separation mechanism that is able do handle the coexistence of RT and non-RT traffic sources in the same communication environment. The simulation assessment considers an overlapping basic service set (OBSS), where a set of RT and non-RT stations share the same frequency band. The performance assessment compares the behaviour of the RT-WiFi architecture vs. the behaviour of standard distributed coordination function (DCF), point coordination function (PCF), enhanced distributed channel access (EDCA), and hybrid coordination function (HCF) controlled channel access (HCCA) medium access control mechanisms. A realistic error-prone model has been used to measure the impact of message losses in the RT-WiFi architecture. It is shown that the proposed RT-WiFi architecture offers a significantly enhanced behaviour when compared with the use of IEEE 802.11 standard mechanisms, in what concerns average deadline misses and average access delays. Moreover, it also offers an almost constant access delay, which is a relevant characteristic when supporting RT applications.

2019

Wireless visual sensor networks redeployment based on dependability optimization

Authors
Jesus, TC; Costa, DG; Portugal, P;

Publication
IEEE International Conference on Industrial Informatics (INDIN)

Abstract
Wireless visual sensor networks (WVSN) bring a more comprehensive perception of monitored environments, leading to an increase adoption of such networks as a promising solution for a wide range of applications. Among many examples, highlight industrial applications related to the industry 4.0 paradigm, which increasingly require more data from manufacturing systems. Those sensor-based applications are in many cases safety-critical, requiring dependability guarantees mainly related with reliability and availability, that should be maintained during the whole network operation. Although several approaches have provided network deployment with dependability guarantees, sometimes the monitored environment or the application configurations can change during the network operation, which can violate the dependability requirements and demand network redeployment in order to keep those guarantees. In this paper we propose a novel algorithm to redeploy WVSN guided by the optimization of the application dependability, considering changes on cameras' orientations. A methodology is defined to support dependability analysis. We compare the results of the proposed algorithm with previous algorithms found in literature. The achieved results show that the proposed algorithm is useful and efficient to provide network redeployment, keeping or improving the application dependability. © 2019 IEEE.

Supervised
thesis

2019

Development of a Flexible Communication Framework to support Testing and Production of Automotive Products

Author
Manuel Pedro Gomes dos Santos Ferreira Rebelo

Institution
UP-FEUP

2019

Dependability Evaluation on Wireless Visual Sensor Networks

Author
Thiago Cerqueira de Jesus

Institution
UP-FEUP

2019

DySMCAr: Dynamic Star-Mesh Communication Architecture for Manufacturing Wireless Sensor Networks with IEEE 802.15.4e LLDN mode

Author
Benedito Rodrigues Bitencourt Júnior

Institution
UP-FEUP

2018

Alimentação Automática de Blocos de Polímeros a Linha de Misturação de Borracha Big Tandem

Author
Carlos Jorge Bessa Damas da Silva

Institution
UP-FEUP

2018

Estação deteção de incêndios florestais

Author
Daniel José Damas da Silva Leal

Institution
UP-FEUP