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Publicações

2019

A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty

Autores
Abuter, R; Amorim, A; Bauboeeck, M; Berger, JP; Bonnet, H; Brandner, W; Clenet, Y; du Foresto, VC; de Zeeuw, PT; Dexter, J; Duvert, G; Eckart, A; Eisenhauer, F; Schreiber, NMF; Garcia, P; Gao, F; Gendron, E; Genzel, R; Gerhard, O; Gillessen, S; Habibi, M; Haubois, X; Henning, T; Hippler, S; Horrobin, M; Jimenez Rosales, A; Jocou, L; Kervella, P; Lacour, S; Lapeyrere, V; Le Bouquin, JB; Lena, P; Ott, T; Paumard, T; Perraut, K; Perrin, G; Pfuhl, O; Rabien, S; Coira, GR; Rousset, G; Scheithauer, S; Sternberg, A; Straub, O; Straubmeier, C; Sturm, E; Tacconi, LJ; Vincent, F; von Fellenberg, S; Waisberg, I; Widmann, F; Wieprecht, E; Wiezorrek, E; Woillez, J; Yazici, S;

Publicação
ASTRONOMY & ASTROPHYSICS

Abstract
We present a 0.16% precise and 0.27% accurate determination of R-0, the distance to the Galactic center. Our measurement uses the star S2 on its 16-year orbit around the massive black hole Sgr A* that we followed astrometrically and spectroscopically for 27 years. Since 2017, we added near-infrared interferometry with the VLTI beam combiner GRAVITY, yielding a direct measurement of the separation vector between S2 and Sgr A* with an accuracy as good as 20 mu as in the best cases. S2 passed the pericenter of its highly eccentric orbit in May 2018, and we followed the passage with dense sampling throughout the year. Together with our spectroscopy, in the best cases with an error of 7 km s(-1), this yields a geometric distance estimate of R-0 = 8178 +/- 13(stat.) +/- 22(sys.) pc. This work updates our previous publication, in which we reported the first detection of the gravitational redshift in the S2 data. The redshift term is now detected with a significance level of 20 sigma with f(redshift) = 1.04 +/- 0.05.

2019

Using HandSpy to Study Writing in Real Time: a Comparison between Low- and High-Quality Texts in Grade 2

Autores
Alves R.A.; Leal J.P.; Limpo T.;

Publicação
Studies in Writing

Abstract

2019

Proceedings of the 24th European Conference on Pattern Languages of Programs, EuroPLoP 2019, Irsee, Germany, July 3-7, 2019

Autores
Sousa, TB;

Publicação
EuroPLop

Abstract

2019

Impact of strategic behaviors of the electricity consumers on power system reliability

Autores
Gazafroudi, AS; Shafie Khah, M; Fitiwi, DZ; Santos, SF; Corchado, JM; Catalão, JPS;

Publicação
Studies in Systems, Decision and Control

Abstract

2019

Full-body motion assessment: Concurrent validation of two body tracking depth sensors versus a gold standard system during gait

Autores
Vilas Boas, MD; Pereira Choupina, HMP; Rocha, AP; Fernandes, JM; Silva Cunha, JPS;

Publicação
JOURNAL OF BIOMECHANICS

Abstract
RGB-D cameras provide 3-D body joint data in a low-cost, portable and non-intrusive way, when compared with reference motion capture systems used in laboratory settings. In this contribution, we evaluate the validity of both Microsoft Kinect versions (v1 and v2) for motion analysis against a Qualisys system in a simultaneous protocol. Two different walking directions in relation to the Kinect (towards - WT, and away - WA) were explored. For each gait trial, measures related with all body parts were computed: velocity of all joints, distance between symmetrical joints, and angle at some joints. For each measure, we compared each Kinect version and Qualisys by obtaining the mean true error and mean absolute error, Pearson's correlation coefficient, and optical-to-depth ratio. Although both Kinect v1 and v2 and/or WT and WA data present similar accuracy for some measures, better results were achieved, overall, when using WT data provided by the Kinect v2, especially for velocity measures. Moreover, the velocity and distance presented better results than angle measures. Our results show that both Kinect versions can be an alternative to more expensive systems such as Qualisys, for obtaining distance and velocity measures as well as some angles metrics (namely the knee angles). This conclusion is important towards the off-lab non-intrusive assessment of motor function in different areas, including sports and healthcare.

2019

Environmental Factors Influencing the Adoption of Digitalization Technologies in Automotive Supply Chains

Autores
Simoes, A; Oliveira, L; Rodrigues, JC; Simas, O; Dalmarco, G; Barros, AC;

Publicação
2019 IEEE INTERNATIONAL CONFERENCE ON ENGINEERING, TECHNOLOGY AND INNOVATION (ICE/ITMC)

Abstract
Previous literature shows that there are different environmental factors with different impacts on the adoption of technologies in a supply chain context. Thus, the adoption of technologies in supply chains may vary according to different environmental factors. Despite the existence of several studies about adoption of technologies in supply chain contexts that include environmental factors, there is a gap in identifying which environmental factors influence the adoption of digitalization technologies in supply chains. The purpose of this study is therefore to identify and analyze the environmental factors that influence the adoption of digitalization technologies in the supply chain. An exploratory qualitative research was conducted using semi-structured interviews with Portuguese managers of companies at several tiers of the automotive supply chain. Environmental factors were pointed as particularly critical drivers to promote the adoption of digitalization technologies in the automotive supply chain. Such adoption is mainly driven by the Original Equipment Manufacturer ( OEM), through coercive and normative pressures over the other tiers of the supply chain. Relevant factors identified are: compliance with standards and legislation, market and industry pressures, and benchmark the evolution of supply chain partners. This study contributes to the literature with new knowledge concerning new specificities of the environmental factors that showed an important influence on the adoption decision.

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