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Publications

2017

Improving Renewable Energy Forecasting With a Grid of Numerical Weather Predictions

Authors
Andrade, JR; Bessa, RJ;

Publication
IEEE TRANSACTIONS ON SUSTAINABLE ENERGY

Abstract
In the last two decades, renewable energy forecasting progressed toward the development of advanced physical and statistical algorithms aiming at improving point and probabilistic forecast skill. This paper describes a forecasting framework to explore information from a grid of numerical weather predictions (NWP) applied to both wind and solar energy. The methodology combines the gradient boosting trees algorithm with feature engineering techniques that extract the maximum information from the NWP grid. Compared to a model that only considers one NWP point for a specific location, the results show an average point forecast improvement (in terms of mean absolute error) of 16.09% and 12.85% for solar and wind power, respectively. The probabilistic forecast improvement, in terms of continuous ranked probabilistic score, was 13.11% and 12.06%, respectively.

2017

Future Trends for Big Data Application in Power Systems

Authors
Bessa, RJ;

Publication
Big Data Application in Power Systems

Abstract
The technological revolution in the electric power system sector is producing large volumes of data with pertinent impact in the business and functional processes of system operators, generation companies, and grid users. Big data techniques can be applied to state estimation, forecasting, and control problems, as well as to support the participation of market agents in the electricity market. This chapter presents a revision of the application of data mining techniques to these problems. Trends like feature extraction/reduction and distributed learning are identified and discussed. The knowledge extracted from power system and market data has a significant impact in key performance indicators, like operational efficiency (e.g., operating expenses), investment deferral, and quality of supply. Furthermore, business models related to big data processing and mining are emerging and boosting new energy services.

2017

Refractive Index Sensor using a Fabry-Perot cavity in Polymer Fiber

Authors
Ferreira, MFS; Statkiewicz Barabach, G; Kowal, D; Mergo, P; Urbanczyk, W; Frazao, O;

Publication
2017 25TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS (OFS)

Abstract
The possibility of using polymer fiber as a refractive index sensor is presented. The sensor is based on a Fabry-Perot interferometer formed at the tip of the polymer fiber. The interference is granted due to reflections between a fiber Bragg grating and the fiber end-face. The sensor was characterized to refractive index changes at constant temperature using a fast Fourier transform analysis of the interference signal. A sensitivity of -1.94 RIU-1 was achieved with a resolution of 1 x 10(-3) RIU and a cross sensitivity to temperature of 1 x 10(-4) RIU/degrees C

2017

Deposition parameters and annealing key role in setting structural and polar properties of Bi0.9La0.1Fe0.9Mn0.1O3 thin films

Authors
Carvalho, TT; Figueiras, FG; Pereira, SMS; Fernandes, JRA; Perez de la Cruz, JP; Tavares, PB; Almeida, A; Agostinho Moreira, JA;

Publication
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS

Abstract
The present work explores the processing conditions of Bi0.9La0.1Fe0.9Mn0.1O3 (BLFM) thin films, grown by RF sputtering on platinum metalized silicon substrates, and its impact on the structural and ferroelectric properties. The optimized processing conditions were found to be a combination of deposition of an amorphous film at low substrate temperature (ae550 A degrees C), followed by a thermal treatment at 550 A degrees C during 30 min, in order to prevent bismuth volatilization. This procedure leads to the formation of high-quality monophasic crystalline films with well-defined piezoelectric response exhibiting micron size domains.

2017

INSTITUTIONAL PRACTICES FOR ADOPTION OF DISTANCE LEARNING/B-LEARNING IN HIGHER EDUCATION INSTITUTIONS: PROMOTING TEACHERS MOTIVATION

Authors
Maia, A; Borges, J; Vaz, C; Martins, P; Reis, A; Barroso, J; Mourao, JL;

Publication
9TH INTERNATIONAL CONFERENCE ON EDUCATION AND NEW LEARNING TECHNOLOGIES (EDULEARN17)

Abstract

2017

Optimization of Cascaded Hydro Units Modeled as Price Makers Using the linprog Function of MATLAB (R) and Considering the Tailwater Effect

Authors
Silva e Castro, MSE; Saraiva, JT;

Publication
2017 14TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM 17)

Abstract
This paper describes an enhanced model for the Short Term Hydro Scheduling Problem, HSP, that includes the impact of operation decisions on the market prices and the possibility of adjusting the tailwater level. Additionally, the efficiency of hydraulic turbines is treated as a variable dependent on the discharged flows. The developed solution algorithm uses an iterative approach that solves in each iteration a linearized HSP problem using the linprog function of the MATLAB (R) Optimization Toolbox. In each iteration, the value of the head to use in the next iteration is updated. The paper reports results from a realistic Case Study based on the cascade of 9 hydro stations (4 of them with pumping) installed in the Portuguese section of the Douro River.

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