Browsing by Author "Sousa, Paulo Gandra de"
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- Elements of scalable data processingPublication . Andersson, Björn; Sousa, Paulo Gandra de; Pacheco, Filipe; Andreou, Panayiotis; Marrón, Pedro; Iqbal, UmerCooperating objects (COs) is a recently coined term used to signify the convergence of classical embedded computer systems, wireless sensor networks and robotics and control. We present essential elements of a reference architecture for scalable data processing for the CO paradigm.
- Operational modal monitoring of ancient structures using wireless technologyPublication . Aguilar, Rafael; Ramos, Luis; Lourenço, Paulo; Severino, Ricardo; Gomes, Ricardo; Sousa, Paulo Gandra de; Alves, Mário; Tovar, EduardoOperational Modal Analysis is currently applied in structural dynamic monitoring studies using conventional wired based sensors and data acquisition platforms. This approach, however, becomes inadequate in cases where the tests are performed in ancient structures with esthetic concerns or in others, where the use of wires greatly impacts the monitoring system cost and creates difficulties in the maintenance and deployment of data acquisition platforms. In these cases, the use of sensor platforms based on wireless and MEMS would clearly benefit these applications. This work presents a first attempt to apply this wireless technology to the structural monitoring of historical masonry constructions in the context of operational modal analysis. Commercial WSN platforms were used to study one laboratory specimen and one of the structural elements of a XV century building in Portugal. Results showed that in comparison to the conventional wired sensors, wireless platforms have poor performance in respect to the acceleration time series recorded and the detection of modal shapes. However, for frequency detection issues, reliable results were obtained, especially when random excitation was used as noise source.
- Quality-of-service in wireless sensor networks: state-of-the-art and future directionsPublication . Alves, Mário; Baccour, Nouha; Koubâa, Anis; Severino, Ricardo; Dini, Gianluca; Pereira, Nuno; Sá, Rui; Savino, Ida; Sousa, Paulo Gandra deWireless sensor networks (WSNs) are one of today’s most prominent instantiations of the ubiquituous computing paradigm. In order to achieve high levels of integration, WSNs need to be conceived considering requirements beyond the mere system’s functionality. While Quality-of-Service (QoS) is traditionally associated with bit/data rate, network throughput, message delay and bit/packet error rate, we believe that this concept is too strict, in the sense that these properties alone do not reflect the overall quality-ofservice provided to the user/application. Other non-functional properties such as scalability, security or energy sustainability must also be considered in the system design. This paper identifies the most important non-functional properties that affect the overall quality of the service provided to the users, outlining their relevance, state-of-the-art and future research directions.