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Publications

2013

Electric vehicle integration into modern power networks

Authors
Garcia Valle, R; Lopes, JAP;

Publication
Electric Vehicle Integration into Modern Power Networks

Abstract
Electric Vehicle Integration into Modern Power Networks provides coverage of the challenges and opportunities posed by the progressive integration of electric drive vehicles. Starting with a thorough overview of the current electric vehicle and battery state-of-the-art, this work describes dynamic software tools to assess the impacts resulting from the electric vehicles deployment on the steady state and dynamic operation of electricity grids, identifies strategies to mitigate them and the possibility to support simultaneously large-scale integration of renewable energy sources. New business models and control management architectures, as well as the communication infrastructure required to integrate electric vehicles as active demand are presented. Finally, regulatory issues of integrating electric vehicles into modern power systems are addressed. Inspired by two courses held under the EES-UETP umbrella in 2010 and 2011, this contributed volume consists of nine chapters written by leading researchers and professionals from the industry as well as academia.

2013

Advanced Control Functionalities for Grid Integration of Large Scale Wind Generation

Authors
Resende, F; Almeida, R; Mendonça, Â; Lopes, JP;

Publication
Handbook of Wind Power Systems - Energy Systems

Abstract

2013

Oxygen uptake slow component at submaximal swimming

Authors
Reis, VM; Santos, EL; Oliveira, DR; Goncalves, LF; Carneiro, AL; Fernandes, RJ;

Publication
Gazzetta Medica Italiana Archivio per le Scienze Mediche

Abstract
Aim. The present study analyzed the oxygen uptake slow component of front crawl swimmers during four different intensities of sub maximal exercise, using a multi-exponential function. Methods. Slow component was also assessed with two different fixed interval methods and the three methods were compared. Sixteen male swimmers performed a test comprising four sub maximal 400-m bouts at different intensities where all expired gases were collected breath by breath. Results. Multi-exponential modeling showed that the slow component was below 200 mL·min-1 in the four swimming intensities. Differences were observed in mean values of slow component obtained by the mathematical modeling and the two fixed interval methods in every bout of exercise with higher mean values when the mathematical modeling was used (F=7,337; P=0.007; ?2=0,512). There was also a significant effect of the exercise intensity on the slow component (F=10,768; P=0.001; ?2=0,713), although no effect of the interaction method x intensity was present (F=1,107; P=0.422; ?2=0,399). Conclusion. It was concluded that in trained crawl swimmers it is possible to have small slow component even at exercise intensities above that corresponding to the 4 mM-1 threshold. Moreover, the mathematical modeling of the oxygen uptake on-kinetics tends to show higher slow component as compared to fixed interval methods.

2013

Proposal of an automatic method to measure the cell free layer in microchannels with bifurcations

Authors
Bento, David; Lima, José; Dias, Ricardo P.; Lima, Rui A.;

Publication
Congress on Numerical Methods in Engineering 2013

Abstract
Blood is an opaque, heterogeneous, non-Newtonian fluid composed by a yellowish homogeneous fluid – the plasma – and a series of cellular elements. Red blood cells (RBCs) in microvessels and microchannels has tendency to undergo axial migration due to the parabolic velocity profile which results in a high shear stress around wall that forces the RBCs to move towards the center induced by the tank treading motion of the RBC membrane [1]. As a result there is a formation of a cell free layer (CFL) with extremely low concentration of cells around the walls of the microchannel [1-3]. This phenomenon is commonly observed in both in vitro [2, 3] and in vivo [4] experiments and has been extensively studied in small straight glass tubes [2, 5]. However, to the best of our knowledge, there are very few quantitative studies on the effect of complex geometries (such as bifurcations and confluences) on the CFL flow behaviour. The main objective of this study is to develop a MatLab script able to measure automatically the RBCs trajectories, at the CFL interface, and CFL thickness in microchannels containing series of bifurcations.

2013

A projected gradient dynamical system modelling the dynamics of bargaining

Authors
Pinheiro, D; Pinto, AA; Xanthopoulos, SZ; Yannacopoulos, AN;

Publication
JOURNAL OF DIFFERENCE EQUATIONS AND APPLICATIONS

Abstract
We propose a projected gradient dynamical system as a model for a bargaining scheme for an asset for which the two interested agents have personal valuations that do not initially coincide. The personal valuations are formed using subjective beliefs concerning the future states of the world, and the reservation prices are calculated using expected utility theory. The agents are not rigid concerning their subjective probabilities and are willing to update them under the pressure to reach finally an agreement concerning the asset. The proposed projected dynamical system, on the space of probability measures, provides a model for the evolution of the agents, beliefs during the bargaining period and is constructed so that an agreement is reached under the minimum possible deviation of both agents from their initial beliefs. The convergence results are shown using techniques from convex dynamics and Lyapunov function theory.

2013

Efficient Dynamic Modeling of the Reflective Semiconductor Optical Amplifier

Authors
Vujicic, Z; Dionisio, RP; Shahpari, A; Pavlovic, NB; Teixeira, A;

Publication
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS

Abstract
Reflective semiconductor optical amplifier (RSOA) is considered a strong candidate to play an important role in realizing the next generation wavelength division multiplexing passive optical network, based on the wavelength reuse concept. Therefore, an accurate and efficient modeling of RSOA is of significant importance. We present a time-domain wideband model for simulation of spatial and temporal distribution of photons and carriers in a bulk RSOA. We provide a novel approach for efficient amplified spontaneous emission modeling, considering a tradeoff between the accuracy and the computational efficiency. The multiobjective genetic algorithm is utilized for parameter extraction. Experimental validation has been performed for continuous wave input, non-return to zero (NRZ) on-off keying, and quadrature phase-shift keying (QPSK) signaling pulses up to 40 Gb/s of bit rate, in both amplification and remodulation regimes. We further present systematic performance evaluation under remodulation scenario. Saturation, noise, chirp, and signal broadening are successfully predicted, while reducing the computational time compared to other wideband models.

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