Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

2020

Flexibility-Oriented Scheduling of Microgrids Considering the Risk of Uncertainties

Authors
MansourLakouraj, M; Javadi, MS; Catalao, JPS;

Publication
2020 INTERNATIONAL CONFERENCE ON SMART ENERGY SYSTEMS AND TECHNOLOGIES (SEST)

Abstract
Increasing the penetration of renewable resources has aggravated the operational flexibility at distribution level. In this study, a flexibility-oriented scheduling of microgrids (MGs) is suggested to reduce the power fluctuations in distribution feeders caused by the high penetration of wind turbines (WTs) in MGs. A flexibility constraint as viable and practical solution is used in MG scheduling to address this challenge. The presented scheduling model, implemented using mixed integer linear programming (MILP) and a stochastic framework, exercises risk constraints to capture the uncertainties associated with wind turbines, loads and market prices. The effectiveness of the model is investigated on a MG with high penetration of WTs in the presence of demand response (DR) and energy storage systems (ESSs). Numerical studies show the influence of risk parameters' changing on operation costs. In addition, the flexibility constraint mitigates the sharp variation of the net load at distribution level, which improves the flexibility of the distribution system.

2020

Implementing Hybrid Semantics: From Functional to Imperative

Authors
Goncharov, S; Neves, R; Proença, J;

Publication
THEORETICAL ASPECTS OF COMPUTING, ICTAC 2020

Abstract
Hybrid programs combine digital control with differential equations, and naturally appear in a wide range of application domains, from biology and control theory to real-time software engineering. The entanglement of discrete and continuous behaviour inherent to such programs goes beyond the established computer science foundations, producing challenges related to e.g. infinite iteration and combination of hybrid behaviour with other effects. A systematic treatment of hybridness as a dedicated computational effect has emerged recently. In particular, a generic idealized functional language HYBCORE with a sound and adequate operational semantics has been proposed. The latter semantics however did not provide hints to implementing HYBCORE as a runnable language, suitable for hybrid system simulation (e.g. the semantics features rules with uncountably many premises). We introduce an imperative counterpart of HYBCORE, whose semantics is simpler and runnable, and yet intimately related with the semantics of HYBCORE at the level of hybrid monads. We then establish a corresponding soundness and adequacy theorem. To attest that the resulting semantics can serve as a firm basis for the implementation of typical tools of programming oriented to the hybrid domain, we present a web-based prototype implementation to evaluate and inspect hybrid programs, in the spirit of GHCI for HASKELL and UTOP for OCAML. The major asset of our implementation is that it formally follows the operational semantic rules.

2020

Educação OnLIFE: a dimensão ecológica das arquiteturas digitais de aprendizagem

Authors
Schlemmer, E; Felice, MD; Serra, IMRdS;

Publication
Educar em Revista

Abstract
RESUMO As últimas gerações de redes de comunicação e de interação começaram a estender a conectividade aos objetos (internet of things), às superfícies e ao meio-ambiente (sensores), criando ecologias interativas (the internet of everything) nas quais todas as diversas entidades (dados, algoritmos, software, coisas, territórios, pessoas) desenvolvem suas ações e possibilidades em diálogos e por meio das demais. Tal transformação determina a passagem da forma de arquiteturas de aprendizagem frontais e analógicas, para dimensões reticulares e digitais. A digitalização do mundo e a conexão generalizada possibilitam a construção de redes e de arquiteturas conectivas interagentes, nas quais a aprendizagem passa a ser compreendida, a partir de uma lógica ecossistêmica em que atores humanos e entidades diversas (às quais a digitalização deu voz) dialogam e, num processo de interdependência, constroem uma ecologia inteligente. Desse contexto emerge uma nova cultura relacional, ecológica, ligada a indicadores e critérios de sustentabilidade, o que nos permite falar de uma Educação OnLIFE, numa realidade hiperconectada, na qual o “real” e “virtual” se (con)fundem, instigando instituições, professores e estudantes a repensar o sistema educativo, enquanto ecossistema. O artigo, a partir da reflexão sobre a nova conexão planetária e o habitar em rede, questiona que problematizações e desafios essa nova realidade coloca para a Educação. Apresenta três abordagens interpretativas da relação humano-tecnologia digital em contexto educacional e, finaliza com elaborações sobre a Educação OnLIFE.

2020

Wind-driven halo in high-contrast images: I. Analysis of the focal-plane images of SPHERE

Authors
Cantalloube, F; Farley, OJD; Milli, J; Bharmal, N; Brandner, W; Correia, C; Dohlen, K; Henning, T; Osborn, J; Por, E; Valles, MS; Vigan, A;

Publication
ASTRONOMY & ASTROPHYSICS

Abstract
Context. The wind-driven halo is a feature that is observed in images that were delivered by the latest generation of ground-based instruments that are equipped with an extreme adaptive optics system and a coronagraphic device, such as SPHERE at the Very Large Telescope (VLT). This signature appears when the atmospheric turbulence conditions vary faster than the adaptive optics loop can correct for. The wind-driven halo is observed as a radial extension of the point spread function along a distinct direction (this is sometimes referred to as the butterfly pattern). When this is present, it significantly limits the contrast capabilities of the instrument and prevents the extraction of signals at close separation or extended signals such as circumstellar disks. This limitation is consequential because it contaminates the data for a substantial fraction of the time: about 30% of the data produced by the VLT/SPHERE instrument are affected by the wind-driven halo. Aims. This paper reviews the causes of the wind-driven halo and presents a method for analyzing its contribution directly from the scientific images. Its effect on the raw contrast and on the final contrast after post-processing is demonstrated. Methods. We used simulations and on-sky SPHERE data to verify that the parameters extracted with our method can describe the wind-driven halo in the images. We studied the temporal, spatial, and spectral variation of these parameters to point out its deleterious effect on the final contrast. Results. The data-driven analysis we propose provides information to accurately describe the wind-driven halo contribution in the images. This analysis confirms that this is a fundamental limitation of the finally reached contrast performance. Conclusions. With the established procedure, we will analyze a large sample of data delivered by SPHERE in order to propose post-processing techniques that are tailored to removing the wind-driven halo.

2020

Symphony

Authors
Kurunathan, H; Severino, R; Koubaa, A; Tovar, E;

Publication
ACM SIGBED Review

Abstract
Deterministic Synchronous Multichannel Extension (DSME) is a prominent MAC behavior first introduced in IEEE 802.15.4e. It can avail deterministic and best effort Service using its multisuperframe structure. RPL is a routing protocol for wireless networks with low power consumption and generally susceptible to packet loss. These two standards were designed independently but with the common objective to satisfy the requirements of IoT devices in terms of limited energy, reliability and determinism. A combination of these two protocols can integrate real-time QoS demanding and large-scale IoT networks. In this paper, we propose a new multi-channel, multi-timeslot scheduling algorithm called Symphony that provides QoS efficient schedules in DSME networks. In this paper we provide analytical and simulation based delay analysis for our approach against some state of the art algorithms. In this work, we show that integrating routing with DSME can improve reliability by 40% and by using Symphony, we can reduce the network delay by 10--20% against the state of the art algorithms.

2020

Layout optimization of an airborne wind energy farm for maximum power generation

Authors
Roque, LAC; Paiva, LT; Fernandes, MCRM; Fontes, DBMM; Fontes, FACC;

Publication
ENERGY REPORTS

Abstract
We consider a farm of Kite Power Systems (KPS) in the field of Airborne Wind Energy (AWE), in which each kite is connected to an electric ground generator by a tether. In particular, we address the problem of selecting the best layout of such farm in a given land area such that the total electrical power generated is maximized. The kites, typically, fly at high altitudes, sweep a greater area than that of traditional wind turbines, and move within a conic shaped volume with vertex on the ground station. Therefore, constraints concerning kite collision avoidance and terrain boundaries must be considered. The efficient use of a given land area by a set of KPS depends on the location of each unit, on its tether length and on the elevation angle. In this work, we formulate the KPS farm layout optimization problem. Considering a specific KPS and wind characteristics of the given location, we study the power curve as a function of the tether length and elevation angle. Combining these results with an area with specified length and width, we develop and implement a heuristic optimization procedure to devise the layout of a KPS farm that maximizes wind power generation. (C) 2019 Published by Elsevier Ltd.

  • 1602
  • 4537