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Estimating directional data from network topology for improving tracking performance
Publication . Tomic, Slavisa; Beko, Marko; Dinis, Rui; Montezuma, Paulo; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DEE2010-A1 Telecomunicações; DEE - Departamento de Engenharia Electrotécnica e de Computadores; MDPI - Multidisciplinary Digital Publishing Institute
This work proposes a novel approach for tracking a moving target in non-line-of-sight (NLOS) environments based on range estimates extracted from received signal strength (RSS) and time of arrival (TOA) measurements. By exploiting the known architecture of reference points to act as an improper antenna array and the range estimates, angle of arrival (AOA) of the signal emitted by the target is first estimated at each reference point. We then show how to take advantage of these angle estimates to convert the problem into a more convenient, polar space, where a linearization of the measurement models is easily achieved. The derived linear model serves as the main building block on top of which prior knowledge acquired during the movement of the target is incorporated by adapting a Kalman filter (KF). The performance of the proposed approach was assessed through computer simulations, which confirmed its effectiveness in combating the negative effect of NLOS bias and superiority in comparison with its naive counterpart, which does not take prior knowledge into consideration.
A critical analysis of the Caputo–Fabrizio operator
Publication . Ortigueira, Manuel D.; Machado, J. Tenreiro; DEE2010-B2 Sistemas; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DEE - Departamento de Engenharia Electrotécnica e de Computadores; Elsevier Science B.V., Amsterdam.
This short note analyses the Caputo–Fabrizio operator. It is verified that it does not fit the usual concepts neither for fractional nor for integer derivative/integral.
Power transistor fault diagnosis in SRM drives based on indexes of symmetry
Publication . Amaral, Tito G.; Pires, V. Fernão; Pires, A. J.; Martins, J. F.; Chen, Hao; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DEE2010-B1 Energia; DEE - Departamento de Engenharia Electrotécnica e de Computadores
To reduce the negative impacts of power converters on a machine such as switched reluctance motor (SRM) a fast and accurate fault detection method is required. Several fault types could occur in SRM drives, such as, open and short-circuit transistor faults. Thus, this paper presents a new fault detection and diagnosis method for transistor faults in a SRM drive. The method is based on symmetry indexes that are created from the analysis of the currents patterns. The proposed approach results in a fast and robust method, presenting immunity to different mechanical conditions. The characteristics of the proposed method will be verified through several simulation tests.
Roots of Collaboration: Nature-inspired solutions for collaborative networks
Publication . Camarinha-Matos, Luis M.; Afsarmanesh, Hamideh; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Institute of Electrical and Electronics Engineers (IEEE)
Last decades have witnessed considerable growth in formation of collaborative networks in industry and services, as well as in the rest of society. This trend is boosted by progress in information and communication technologies, and more specifically by ubiquitous access to computing and fast move toward the hyper-connected world. But, this growth has also raised fundamental questions regarding its effectiveness and sustainability of networks. On the other hand, nature is full of examples of successful collaborative processes, both intra- and inter-species. Hence, we consider learning from nature to provide a promising strategy toward both better understanding of collaboration and more effective designing of networks with sustained collaboration. As such, a systematic literature survey is conducted on recent works originated in nature-related disciplines with a focus on collaboration. As a result, a set of important organizational models, collaborative behavior patterns, and collaboration facilitation mechanisms are identified and categorized. Furthermore, our analysis results on potential contribution of such aspects to more intelligent and optimized collaborative networks area are briefly outlined.
Control Charts to Support Trust Monitoring in Dynamic Logistics Networks
Publication . Abreu, António; Requeijo, José; Calado, João M. F.; Dias, Ana; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial
Nowadays, companies to be competitive must develop capabilities that enable them to respond quickly to market needs. According to some managers, the strategy is the development of dynamic logistics networks based on a collaborative environment. However, the absence of mechanisms to detect and even anticipate potential opportunistic behaviour is an obstacle to the proliferation of this way of working. The article aims to understand the role of trust to sustainability of collaborative processes. The paper begins by discussing the trust properties. It is then discussed how statistical control charts can be used to support the trust monitoring of each member within a collaborative ecosystem. The control charts’ tools suggested in this paper are the Z control charts for trust level monitoring and the Zi capacity index. Finally, it is discussed how this approach can be applied to dynamic logistics networks within the context of a collaborative ecosystem.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/EEA/00066/2013