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Publicações

2020

Big Data Compression in Smart Grids via Optimal Singular Value Decomposition

Autores
Hashemipour, SN; Aghaei, J; Kavousi fard, A; Niknam, T; Salimi, L; del Granado, PC; Shafie khah, M; Wang, F; Catalao, JPS;

Publicação
2020 IEEE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETING

Abstract
The smart grid is a fully automatic delivery grid for electricity power with a two-way reliable flow of electricity and information among different equipment on the grid. With the rapid development of smart grids, smart meters and sensors are used to monitor the system and provide a wide reporting which produce a huge amount of data in various part of the grid. To logical manage this trouble, the presented paper proposes a new lossy data compression approach for big data compression. In the proposed method, at the first step, the optimal singular value decomposition (OSVD) is applied to a matrix that achieves the optimal number of singular values to the sending process and the other ones will be neglected. This goal is done due to the quality of retrieved data and the rate of compression ratio. In the presented scheme, to implementation of the optimization framework, various intelligent optimization methods are used to determine the number of optimal values in the elimination stage. The efficiency and capabilities of the proposed method are examined using the experimental dataset of several residential microgrid consumers and market dataset. Simulation results show the high performance and efficiency of the proposed model in smart grids with big data.

2020

Collaborative Tabletops for Blind People: The Effect of Auditory Design on Workspace Awareness

Autores
Mendes, D; Reis, S; Guerreiro, J; Nicolau, H;

Publicação
Proc. ACM Hum. Comput. Interact.

Abstract
Interactive tabletops offer unique collaborative features, particularly their size, geometry, orientation and, more importantly, the ability to support multi-user interaction. Although previous efforts were made to make interactive tabletops accessible to blind people, the potential to use them in collaborative activities remains unexplored. In this paper, we present the design and implementation of a multi-user auditory display for interactive tabletops, supporting three feedback modes that vary on how much information about the partners' actions is conveyed. We conducted a user study with ten blind people to assess the effect of feedback modes on workspace awareness and task performance. Furthermore, we analyze the type of awareness information exchanged and the emergent collaboration strategies. Finally, we provide implications for the design of future tabletop collaborative tools for blind users.

2020

Effects Analysis of Design Parameters on Three-phase 6/4 and Four-phase 8/6 Switched Reluctance Machines Performance

Autores
Mamede, ACF; Camacho, JR; Araujo, RE; Guimaraes, GC;

Publicação
2020 INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES (ICEM), VOL 1

Abstract
The design of the switched reluctance machine involves several variables that impact the performance of the machine in different ways. The topology, polar arcs, internal and external diameter, number of turns and core length are some of the parameters that must be determined at the design stage. The effect of geometric parameters on performance is different for each switched reluctance machine topology, so this study is dedicated to establishing a sensitivity analysis for two popular topologies, a three-phase 6/4 and a four-phase 8/6. The performance results are estimated through finite element simulations and the dimensional effects analysis is performed using statistical software. The results show the dimensions with the greatest effect on the average torque value and total losses on the machine and can be useful to support the choices made during the design and optimization of this type of machine.

2020

Topics in Theoretical Computer Science

Autores
S. Barbosa, L; Ali Abam, M;

Publicação
Lecture Notes in Computer Science

Abstract

2020

Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole

Autores
Abuter, R; Amorim, A; Baubock, M; Berger, JP; Bonnet, H; Brandner, W; Cardoso, V; Clenet, Y; de Zeeuw, PT; Dexter, J; Eckart, A; Eisenhauer, F; Schreiber, NMF; Garcia, P; Gao, F; Gendron, E; Genzel, R; Gillessen, S; Habibi, M; Haubois, X; Henning, T; Hippler, S; Horrobin, M; Jimenez Rosales, A; Jochum, L; Jocou, L; Kaufer, A; Kervella, P; Lacour, S; Lapeyrere, V; Le Bouquin, JB; Lena, P; Nowak, M; Ott, T; Paumard, T; Perraut, K; Perrin, G; Pfuhl, O; Rodriguez Coira, G; Shangguan, J; Scheithauer, S; Stadler, J; 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; Zins, G;

Publicação
ASTRONOMY & ASTROPHYSICS

Abstract
The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star's radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics (AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this Letter we report the first detection of the General Relativity (GR) Schwarzschild Precession (SP) in S2's orbit. Owing to its highly elliptical orbit (e=0.88), S2's SP is mainly a kink between the pre-and post-pericentre directions of motion approximate to +/- 1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017-2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2's position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states ("flares") of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position and motion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter f(SP) for the SP (f(SP)=0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2, delta phi approximate to 12 ' per orbital period. From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find f(SP)=1.10 +/- 0.19. The S2 data are fully consistent with GR. Any extended mass inside S2's orbit cannot exceed approximate to 0.1% of the central mass. Any compact third mass inside the central arcsecond must be less than about 1000 M-circle dot.

2020

Technology balance of payments and countries' international competitiveness. A dynamic panel data analysis of OECD countries, 2000-2017

Autores
Teixeira, AAC; Barros, D;

Publicação
APPLIED ECONOMICS LETTERS

Abstract
This study investigates the impact of Technology Balance of Payments (TBP) on countries' international competitiveness. Using dynamic panel data estimations for 26 OECD countries over the period 2000-2017, the estimations unambiguously show that a TBP surpluses significantly foster countries' international competitiveness, regardless of how this latter is measured.

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