Francisco Vasques

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.

Abstract

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.

Abstract

Abstract
IEC 61850 is a standard for the design and operation of electrical Substation Automation Systems (SAS) that defines how data may be transferred among Intelligent Electronic Devices (IEDs). The defined data models can be mapped into application protocols, such as SV or GOOSE, which may run upon high speed Ethernet LANs bridged by IEEE 802.1Q compliant switches. The communication system must cope with the timing requirements associated to protective relaying strategies. Given the time constrained nature of SAS applications, a thorough analysis of its timing behavior is required. In this paper, we propose an analytical model for the timing assessment of SV and GOOSE message exchanges in an IEC 61850 process bus. The proposed model allows the communication timing assessment, by analyzing the response time of each message stream of the SAS. This feature is an advantage for the expansion of the SAS, as it allows the evaluation at design time of the maximum number of IEDs that can be supported by the underlying communication system. The results from the proposed analytical model were validated for a typical IEC 61850 communication scenario, both through simulation and through an experimental assessment with IEC 61850 compliant equipment. © 2019 by the Authors.