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Publicações

2018

Robust Probabilistic Load Flow in Microgrids considering Wind Generation, Photovoltaics and Plug-in Hybrid Electric Vehicles

Autores
Baghaee, HR; Parizad, A; Siano, P; Shafie khah, M; Osorio, GJ; Catalao, JPS;

Publicação
2018 IEEE 16TH INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS (INDIN)

Abstract
The power demand uncertainties and intrinsic intermittent characteristics of wind and photovoltaic (PV) distributed energy resources (DERs) make the conventional load flow methods inefficient in active distribution networks (ADNs) and microgrids. Some statistical tools such as Monte Carlo simulation (MCS) are always a reliable solution. However, statistical tools are time-consuming and rather useless in large power systems. In this paper, a new method is proposed for robust probabilistic load flow (PLF) in microgrids and ADNs, including renewable energy resources (RERs), based on singular value decomposition (SVD) unscented Kalman filtering. The probability density functions (PDFs) and cumulative distribution functions (CDFs) for some of the ADN variables are compared with the other reported PLF methods for different test systems and the results validate the robustness, efficiency and accuracy of the proposed method.

2018

Optical fiber sensor Mach-Zehnder interferometer based on TiO<inf>2</inf> coated long period fiber grating

Autores
Vasconcelos H.; De Almeida J.M.M.M.; Jorge P.A.S.; Coelho L.;

Publicação
Optics InfoBase Conference Papers

Abstract
The wavelength sensitivity and spectral resolution of Mach-Zehnder fiber interferometers based on uncoated and TiO2 coated LPFGs is presented and compared with TiO2 coated single LPFGs optical fiber sensors.

2018

Evolutionary based tuning approach of PI?Dµ fractional-order speed controller for multirotor UAV

Autores
Giernacki, W; Coelho, JP;

Publicação
13th APCA International Conference on Control and Soft Computing, CONTROLO 2018 - Proceedings

Abstract
The present paper addresses the use of evolutionary based algorithms for off-line fractional-order controller tuning. In particular, a linearized model of a motor-rotor propulsion device was assumed whose representativeness is supported by laboratorial measurements. Initially, the controller was calibrated, using the devised linear model, by a procedure that uses a cost function defined as the linear combination between the sum of the squared error and the sum of the absolute error. In this work, it was shown that this process can be improved by using an evolutionary based algorithm in order to find the best controller parameters. This strategy allows a more automatic tuning procedure isolating it from the user intervention. Moreover, the results achieved by this process, lead to an improved rotational speed regulation. © 2018 IEEE.

2018

Synthetizing representative periods for chronological hourly electricity generation expansion models

Autores
Domenech, S; Campos, FA; Villar, J;

Publicação
2018 15TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM)

Abstract
Capacity generation expansion problems have traditionally been represented with low time resolution models due to their high computational cost, very often using blocks of hours with similar demand. However, the current transformation of the power system with the new generation and consumption technologies, the flexibility and reserve requirements, and the expected new behavioral consumption patterns, requires more complex and detailed models with higher time resolution to provide accurate investment decisions and allow for closer analyses. In particular, these challenges require chronological hourly models with constraints linking all the years of the planning horizon, compromising in most cases the computational feasibility. This paper presents a new approach to synthetize a reduced representative time period for capacity expansion problems, for being used in detailed chronological hourly models, while keeping them computationally feasible. The representative period is synthetized by selecting, with a genetic algorithm, those real days that minimizes the distance between the duration curves of a set of relevant variables (such as demand, renewable generation, ramps, etc.) computed for the original and for the representative periods. Results show that investments decisions with the representative period are very similar to those obtained with the full planning horizon, while computational times are strongly reduced.

2018

Kinetics of optical properties of human colorectal tissues during optical clearing: a comparative study between normal and pathological tissues

Autores
Carneiro, I; Carvelho, S; Silva, V; Henrique, R; Oliveira, L; Tuchin, VV;

Publicação
JOURNAL OF BIOMEDICAL OPTICS

Abstract
To characterize the optical clearing treatments in human colorectal tissues and possibly to differentiate between treatments of normal and pathological tissues, we have used a simple indirect method derived from Mie scattering theory to estimate the kinetics of the reduced scattering coefficient. A complementary method to estimate the kinetics of the scattering coefficient is also used so that the kinetics of the anisotropy factor and of the refractive index are also calculated. Both methods rely only on the thickness and collimated transmittance measurements made during treatment. The results indicate the expected time dependencies for the optical properties of both tissues: an increase in the refractive index and anisotropy factor and a decrease in the scattering coefficients. The similarity in the kinetics obtained for normal and pathological tissues indicates that optical clearing treatments can be applied also in pathological tissues to produce similar effects. The estimated time dependencies using experimental spectral data in the range from 400 to 1000 nm allowed us to compare the kinetics of the optical properties between different wavelengths. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)

2018

Why does the orientation change mess up my Android application? From GUI failures to code faults

Autores
Amalfitano, D; Riccio, V; Paiva, ACR; Fasolino, AR;

Publicação
SOFTWARE TESTING VERIFICATION & RELIABILITY

Abstract
This paper investigates the failures exposed in mobile apps by the mobile-specific event of changing the screen orientation. We focus on GUI failures resulting in unexpected GUI states that should be avoided to improve the apps quality and to ensure better user experience. We propose a classification framework that distinguishes 3 main classes of GUI failures due to orientation changes and exploit it in 2 studies that investigate the impact of such failures in Android apps. The studies involved both open-source and apps from Google Play that were specifically tested exposing them to orientation change events. The results showed that more than 88% of these apps were affected by GUI failures, some classes of GUI failures were more common than others, and some GUI objects were more frequently involved. The app source code analysis allowed us to identify 6 classes of common faults causing specific GUI failures.

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