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Publications

2018

Power systems simulation using ontologies to enable the interoperability of multi-agent systems

Authors
Santos, G; Silva, F; Teixeira, B; Vale, Z; Pinto, T;

Publication
20th Power Systems Computation Conference, PSCC 2018

Abstract
A key challenge in the power and energy field is the development of decision-support systems that enable studying big problems as a whole. The interoperability between systems that address specific parts of the global problem is essential. Ontologies ease the interoperability between heterogeneous systems providing semantic meaning to the information exchanged between the various parties. The use of ontologies within Smart Grids has been proposed based on the Common Information Model, which defines a common vocabulary describing the basic components used in electricity transportation and distribution. However, these ontologies are focused on utilities needs. The development of ontologies that allow the representation of diverse knowledge sources is essential, aiming at supporting the interaction between entities of different natures, facilitating the interoperability between these systems. This paper proposes a set of ontologies to enable the interoperability between different types of simulators, namely regarding electricity markets, the smart grid, and residential energy management. A case study based on real data shows the advantages of the proposed approach in enabling comprehensive power system simulation studies. © 2018 Power Systems Computation Conference.

2018

Load Forecasting in WiFi Access Points over the LTE Network

Authors
Marques, H; Torres, PMB; Marques, P; Dionísio, R; Rodriguez, J;

Publication
Lecture Notes in Networks and Systems

Abstract
The concept of smart cities grew with the need to rethink the use of urban spaces based on the constant technological advances and respecting sustainability. Today the urbanism and the methodologies to think about the city are changing, as citizens want more access to digital information on almost everything. Therefore, cities need to be planned and equipped with infrastructures that enable connectivity between the citizens’ devices and the digital information. This challenge raises technological problems, such as traffic management, in an attempt to guarantee fair network access to all users. Solutions based on wireless resource management and self-organizing networks are key when design the connectivity for these smart cities. This paper presents a study on forecasting the daily load of Wi-Fi city hotspots, taking also in consideration the weather conditions. This is particularly interesting to predict the network load and resource requirements needed to ensure proper quality of service is provided to the hotspot users. The study was performed in a Wi-Fi hotspot located in the city of Castelo Branco, Portugal. The results show the ARIMA model is capable of identifying and forecasting seasonality events for one week in advance including its capability to correlate the number of hotspot users with weather conditions. © 2018, Springer International Publishing AG.

2018

A study of the publications of educational robotics: A systematic review of literature

Authors
Bezerra J.; De Lima R.; Queiroz P.;

Publication
IEEE Latin America Transactions

Abstract
Educational Robotics has been presented as a great pedagogical tool because it demonstrates an attractive way of working the theoretical knowledge put into practice. Thus, several educational technologies have emerged with different approaches, with the purpose of applying robotics in the educational area in a more attractive and playful way. This article presents the conduction of a Systematic Review of Literature (SRL), whose objective is to identify the teaching approaches used with educational robotics. With this, we present experiences reports, and at the same time show the skills and competencies that are explored through robotics and education. This review uses scientific papers published in the period from 2011 to 2016.

2018

Metalearning and Recommender Systems: A literature review and empirical study on the algorithm selection problem for Collaborative Filtering

Authors
Cunha, T; Soares, C; de Carvalho, ACPLF;

Publication
INFORMATION SCIENCES

Abstract
The problem of information overload motivated the appearance of Recommender Systems. From the several open problems in this area, the decision of which is the best recommendation algorithm for a specific problem is one of the most important and less studied. The current trend to solve this problem is the experimental evaluation of several recommendation algorithms in a handful of datasets. However, these studies require an extensive amount of computational resources, particularly processing time. To avoid these drawbacks, researchers have investigated the use of Metalearning to select the best recommendation algorithms in different scopes. Such studies allow to understand the relationships between data characteristics and the relative performance of recommendation algorithms, which can be used to select the best algorithm(s) for a new problem. The contributions of this study are two-fold: 1) to identify and discuss the key concepts of algorithm selection for recommendation algorithms via a systematic literature review and 2) to perform an experimental study on the Metalearning approaches reviewed in order to identify the most promising concepts for automatic selection of recommendation algorithms.

2018

Statistical analysis and lessons learned of SPHERE adaptive optics performance

Authors
Mouillet, D; Milli, J; Sauvage, JF; Fusco, T; Beuzit, JL; Vigan, A; Albert, D; Boccaletti, A; Cantalloube, F; Chauvin, G; Correia, C; Delorme, P; Dohlen, K; Kasper, M; Lagrange, AM; Meunier, N; Pannetier, C;

Publication
ADAPTIVE OPTICS SYSTEMS VI

Abstract
The SPHERE instrument, dedicated to high contrast imaging on VLT, has been routinely operated for more than 3 years, over a large range of conditions and producing observations from visible to NIR. A central part of the instrument is the high order adaptive optics system, named SAXO, designed to deliver high Strehl image quality with a balanced performance budget for bright stars up to magnitude R=9. We take benefit now from the very large set of observations to revisit the assumptions and analysis made at the time of the design phase: We compare the actual AO behavior as a function of expectations. The data set consists of the science detector data, for both coronagraphic images and non-coronagraphic PSF calibrations, but also of AO internal data from the high frequency sensors and statistics computations from the real-time computer which are systematically archived, and finally of environmental data, monitored at VLT level. This work is supported and made possible by the SPHERE Data Center infrastructure hosted at Grenoble which provides an efficient access and the capability for the homogeneous analysis of this large and statistically-relevant data set. We review in a statistical manner the actual AO performance as a function of external conditions for different regimes and we discuss the possible performance metrics, either derived from AO internal data or directly from the high contrast images. We quantify the dependency of the actual performance on the most relevant environmental parameters. By comparison to earlier expectations, we conclude on the reliability of the usual AO modeling. We propose some practical criteria to optimize the queue scheduling and the expression of observer requirements; finally, we revisit what could be the most important AO specifications for future high contrast imagers as a function of the primary science goals, the targets and the turbulence properties.

2018

The influence of document characteristics on the quality of health web documents

Authors
Oroszlanyova, M; Lopes, CT; Nunes, S; Ribeiro, C;

Publication
2018 13TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
The quality of consumer-oriented health information on the Web is usually assessed through the medical certification of websites. These tools are built upon quality indicators but, so far, no standard set of indicators has been defined. The objective of the present study is to explore the popularity of specific document features and their influence on the quality of health web documents, using HON code as ground truth. A set of top-ranked health documents retrieved from a major search engine was characterized in a univariate analysis, and then used in a bivariate analysis to seek features that affect documents' quality. The univariate analysis provides insights into the characteristics of the overall population of the health web documents. The bivariate analysis reveals strong relations between documents' quality and a set of features (namely split content, videos, images, advertisements, English language) that are potential quality indicators. We characterized health web documents and identified specific document features that can be used to assess whether the information in such documents is trustworthy. The main contribution of this work is to provide other features as candidate indicators of quality. Non-health professionals can use these indicators in automatic and manual assessments of health content.

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