2018
Autores
Fernandes, G; Amaral, A; Varajão, J;
Publicação
Procedia Computer Science
Abstract
This paper describes a quantitative study for the validation of the Wagnild and Young's Resilience Scale ® to Information Systems Students. Individual resilience can be described as the person's ability to deal with problems, overcome obstacles, or resist the pressure caused by adverse situations, without entering into rupture. Therefore, resilience can have a significant role in students' education. However, little is known about the determinants that might undermine the resilience level of students, as well as which could affect their mental status and wellbeing, thus requiring new research efforts. This paper shows that Wagnild and Young's Resilience Scale ® is suitable for Information Systems Students: Perseverance, Self-Reliance, Equanimity, Meaningfulness and Existential Aloneness, emerged as main themes from the principal components analysis, as in the original study by Wagnild and Young suggested. Additionally, it is demonstrated that health have influence in the individual resilience. © 2018 The Authors. Published by Elsevier Ltd..
2018
Autores
Gomes, AD; Silveira, B; Warren Smith, SC; Becker, M; Rothhardt, M; Frazao, O;
Publicação
OPTICS AND LASER TECHNOLOGY
Abstract
A fiber Bragg grating was inscribed in an abrupt fiber taper using a femtosecond laser and phase-mask interferometer. The abrupt taper transition allows to excite a broad range of guided modes with different effective refractive indices that are reflected at different wavelengths according to Bragg's law. The multimode-Bragg reflection expands over 30 nm in the telecom-C-band. This corresponds to a mode field overlap of up to 30% outside of the fiber, making the device suitable for evanescent field sensing. Refractive index and temperature measurements are performed for different reflection peaks. Temperature independent refractive index measurements are achieved by considering the difference between the wavelength shifts of two measured reflection peaks. A minimum refractive index sensitivity of 16 +/- 1 nm/RlU was obtained in a low refractive index regime (1.3475-1.3720) with low influence of temperature (-0.32 0.06 pm/degrees C). The cross sensitivity for this structure is 2.0 x 10(-5) RlU/degrees C.. The potential for simultaneous measurement of refractive index and temperature is also studied.
2018
Autores
Ribeiro, C; Pinto, T; Vale, Z; Baptista, J;
Publicação
DISTRIBUTED COMPUTING AND ARTIFICIAL INTELLIGENCE
Abstract
Several challenges arrive with electrical power restructuring, liberalized electricity markets emerge, aiming to improve the system's efficiency while offering new economic solutions. Privatization and liberalization of previously nationally owned systems are examples of the transformations that have been applied. Microgrids and smart grids emerge and new business models able to cope with new opportunities start being developed. New types of players appear, allowing aggregating a diversity of entities, e. g. generation, storage, electric vehicles, and consumers, Virtual Power Players (VPPs) are a new type of player that allows aggregating a diversity of players to facilitate their participation in the electricity markets. A major task of VPPs is the remuneration of generation and services (maintenance, market operation costs and energy reserves), as well as charging energy consumption. The paper proposes a normalization method that supports a clustering methodology for the remuneration and tariffs definition. This model uses a clustering algorithm, applied on normalized load values, the value of the micro production, generated in the bus associated to the same load, was subtracted from the value of the consumption of that load. This calculation is performed in a real smart grid on buses with associated micro production. This allows the creation of sub-groups of data according to their correlations. The clustering process is evaluated so that the number of data sub-groups that brings the most added value for the decision making process is found, according to players characteristics.
2018
Autores
Guimarães, N; Figueira, A; Torgo, L;
Publicação
Proceedings of the 10th International Joint Conference on Knowledge Discovery, Knowledge Engineering and Knowledge Management, IC3K 2018, Volume 1: KDIR, Seville, Spain, September 18-20, 2018.
Abstract
Misinformation propagation on social media has been significantly growing, reaching a major exposition in the 2016 United States Presidential Election. Since then, the scientific community and major tech companies have been working on the problem to avoid the propagation of misinformation. For this matter, research has been focused on three major sub-fields: the identification of fake news through the analysis of unreliable posts, the propagation patterns of posts in social media, and the detection of bots and spammers. However, few works have tried to identify the characteristics of a post that shares unreliable content and the associated behaviour of its account. This work presents four main contributions for this problem. First, we provide a methodology to build a large knowledge database with tweets who disseminate misinformation links. Then, we answer research questions on the data with the goal of bridging these problems to similar problem explored in the literature. Next, we focus on accounts which are constantly propagating misinformation links. Finally, based on the analysis conducted, we develop a model to detect social media accounts that spread unreliable content. Using Decision Trees, we achieved 96% in the F1-score metric, which provides reliability on our approach. Copyright 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
2018
Autores
Karl, M; Pfuhl, O; Eisenhauer, F; Genzel, R; Grellmann, R; Habibi, M; Abuter, R; Accardo, M; Amorim, A; Anugu, N; Avila, G; Benisty, M; Berger, JP; Blind, N; Bonnet, H; Bourget, P; Brandner, W; Brast, R; Buron, A; Garatti, ACO; Chapron, F; Clenet, Y; Collin, C; du Foresto, VC; de Wit, WJ; de Zeeuw, T; Deen, C; Delplancke Stroebele, F; Dembet, R; Derie, F; Dexter, J; Duvert, G; Ebert, M; Eckart, A; Esselborn, M; Fedou, P; Finger, G; Garcia, P; Dabo, CEG; Lopez, RG; Gao, F; Gendron, E; Gillessen, S; Gonte, F; Gordo, P; Groezinger, U; Guajardo, P; Guieu, S; Haguenauer, P; Hans, O; Haubois, X; Haug, M; Haussmann, F; Henning, T; Hippler, S; Horrobin, M; Huber, A; Hubert, Z; Hubin, N; Jakob, G; Jochum, L; Jocou, L; Kaufer, A; Kellner, S; Kendrew, S; Kern, L; Kervella, P; Kiekebusch, M; Klein, R; Koehler, R; Kolb, J; Kulas, M; Lacour, S; Lapeyrere, V; Lazareff, B; Le Bouquin, JB; Lena, P; Lenzen, R; Leveque, S; Lin, CC; Lippa, M; Magnard, Y; Mehrgan, L; Merand, A; Moulin, T; Mueller, E; Mueller, F; Neumann, U; Oberti, S; Ott, T; Pallanca, L; Panduro, J; Pasquini, L; Paumard, T; Percheron, I; Perraut, K; Perrin, G; Pflueger, A; Duc, TP; Plewa, PM; Popovic, D; Rabien, S; Ramirez, A; Ramos, J; Rau, C; Riquelme, M; Rodriguez Coira, G; Rohloff, RR; Rosales, A; Rousset, G; Sanchez Bermudez, J; Scheithauer, S; Schoeller, M; Schuhler, N; Spyromilio, J; Straub, O; Straubmeier, C; Sturm, E; Suarez, M; Tristram, KRW; Ventura, N; Vincent, F; Waisberg, I; Wank, I; Widmann, F; Wieprecht, E; Wiest, M; Wiezorrek, E; Wittkowski, M; Woillez, J; Wolff, B; Yazici, S; Ziegler, D; Zins, G;
Publicação
ASTRONOMY & ASTROPHYSICS
Abstract
This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for theta(1) Ori B, theta(2) Ori B, and theta(2) Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for theta(1) Ori A, theta(1) Ori C, theta(1) Ori D, and theta(2) Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary theta(1) Ori C and we are able to derive a new orbit for theta(1) Ori D. We find a system mass of 21.7 M-circle dot and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.
2018
Autores
Dogansahin, K; Kekezoglu, B; Yumurtaci, R; Erdinc, O; Catalao, JPS;
Publicação
ENERGIES
Abstract
Increasing demand for electricity, as well as rising environmental and economic concerns have resulted in renewable energy sources being a center of attraction. Integration of these renewable energy resources into power systems is usually achieved through distributed generation (DG) techniques, and the number of such applications increases daily. As conventional power systems do not have an infrastructure that is compatible with these energy sources and generation systems, such integration applications may cause various problems in power systems. Therefore, planning is an essential part of DG integration, especially for power systems with intermittent renewable energy sources with the objective of minimizing problems and maximizing benefits. In this study, a mathematical model is proposed to calculate the maximum permissible DG integration capacity without causing overvoltage problems in the power systems. In the proposed mathematical model, both the minimum loading condition and maximum generation condition are taken into consideration. In order to prove the effectiveness and the consistency of the proposed mathematical model, it is applied to a test system with different case studies, and the results are compared with the results obtained from other models in the literature.
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