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Publications

2016

Regulatory support of wind power producers against strategic and collusive behavior of conventional thermal units

Authors
Shafie Khah, M; Siano, P; Fitiwi, DZ; Santos, SF; Catalao, JPS; Heydarian Forushani, E;

Publication
International Conference on the European Energy Market, EEM

Abstract
Although wind power generation has extended a maturity in technology, there are still many concerns regarding the optimal support of regulatory bodies for renewable resources. In this context, the regulatory body should form a market structure or consider market rules and regulations to not only attract investors to renewable power plants, but also provide an efficient market that reflects a safe and clear competition environment. In this paper, an agent-based game-theoretic model is developed to investigate the electricity market behavior under oligopoly circumstances. The proposed model reveals the potential of collusive and strategic behavior of market participants. By employing the proposed model, impacts of different supportive schemes on the behavior of the wind power producer and conventional thermal units are investigated. According to the results obtained, if the regulatory bodies do not consider strategic collusion of market participants, adverse consequences for wind power producers might happen in the long-term horizon. © 2016 IEEE.

2016

Consideration of the Impacts of a Smart Neighborhood Load on Transformer Aging

Authors
Paterakis, NG; Pappi, IN; Erdinc, O; Godina, R; Rodrigues, EMG; Catalao, JPS;

Publication
IEEE TRANSACTIONS ON SMART GRID

Abstract
Smart grid solutions with enabling technologies such as energy management systems (EMSs) and smart meters promote the vision of smart households, which also allows for active demand side in the residential sector. These technologies enable the control of residential consumption, local small-scale generation, and energy storage systems to respond to time-varying prices. However, shifting loads simultaneously to lower price periods is likely to put extra stress on distribution system assets such as distribution transformers. Especially, additional new types of loads/appliances such as electric vehicles (EVs) can introduce even more burden on the operation of these assets, which is an issue that needs special attention. Such extra stress can cause accelerated aging of distribution system assets and significantly affect the reliability of the system. In this paper, the impact of a smart neighborhood load on distribution transformer aging is investigated. The EMS of each household is designed to respond to prices and other signals emitted by the responsive load serving entity within the relevant demand response strategy. An optimization framework based on mixed-integer linear programming is presented in order to define the EMS structure. Then, the equivalent aging of the distribution transformer is examined with a thermal model under different scenarios. The case studies that are presented indicate that the integration of EVs in residential premises may indeed cause accelerated aging of the distribution transformers, while the need to investigate the efficiency of dynamic pricing mechanisms is rendered evident.

2016

Heuristics for two-dimensional bin-packing problems

Authors
Chan, TM; Alvelos, F; Silva, E; Valério de Carvalho, JM;

Publication
Intelligent Systems

Abstract

2016

Large Scale Graph Representations for Subgraph Census

Authors
Paredes, P; Pinto Ribeiro, PM;

Publication
NetSci-X

Abstract
A Subgraph Census (determining the frequency of smaller subgraphs in a network) is an important computational task at the heart of several graph mining algorithms. Here we focus on the g-tries, an efficient state-of-the art data structure. Its algorithm makes extensive use of the graph primitive that checks if a certain edge exists. The original implementation used adjacency matrices in order to make this operation as fast as possible, as is the case with most past approaches. This representation is very expensive in memory usage, limiting the applicability. In this paper we study a number of possible approaches that scale linearly with the number of edges. We make an extensive empirical study of these alternatives in order to find an efficient hybrid approach that combines the best representations. We achieve a performance that is less than 50% slower than the adjacency matrix on average (almost 3 times more efficient than a naive binary search implementation), while being memory efficient and tunable for different memory restrictions.

2016

Tourism Recommendation System based in user's profile and functionality levels

Authors
Santos, F; Almeida, Ad; Martins, C; Oliveira, P; Gonçalves, R;

Publication
C3S2E

Abstract
This paper describes a proposal to develop a Tourism Recommendation System based in users enhanced profiles (composed by basic user information, relations between user and a set of stereotypes and user functionality levels). The main focus of this work is to evaluate if user's physical and psychological functionality levels considered in user's profiles creation, will produce significant changes in the recommendation results. This work aims also to contribute with a different way to classify points-of-interest (POI) considering their capacity to receive tourists with certain levels of physical and psychological issues that will be described in this paper sections.

2016

The E-ELT first light spectrograph HARMONI: capabilities and modes

Authors
Thatte, NAA; Clarke, F; Bryson, I; Schnetler, H; Tecza, M; Fusco, T; Bacon, RM; Richard, J; Mediavilla, E; Neichel, B; Arribas, S; García Lorenzo, B; Evans, CJ; Remillieux, A; El Madi, K; Herreros, JM; Melotte, D; O'Brien, K; Tosh, IA; Vernet, J; Hammersley, P; Ives, DJ; Finger, G; Houghton, R; Rigopoulou, D; Lynn, JD; Allen, JR; Zieleniewski, SD; Kendrew, S; Ferraro Wood, V; Pécontal Rousset, A; Kosmalski, J; Laurent, F; Loupias, M; Piqueras, L; Renault, E; Blaizot, J; Daguisé, E; Migniau, JE; Jarno, A; Bornh, A; Gallie, AM; Montgomery, DM; Henry, D; Schwartz, N; Taylor, W; Zins, G; Rodríguez Ramos, LF; Cagigas, M; Battaglia, G; López, RR; Revuelta, JSC; Rasilla, JL; Hernández Suárez, E; Gigante Ripoll, JV; López, JP; Martin, MV; Correia, C; Pascal, S; Blanco, L; Vola, P; Epinat, B; Peroux, C; Vigan, A; Dohlen, K; Sauvage, JF; Lee, M; Carlotti, A; Verinaud, C; Morris, T; Myers, R; Reeves, A; Swinbank, M; Calcines, A; Larrieu, M;

Publication
GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY VI

Abstract
HARMONI is the E-ELT's first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 × 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the E-ELT at near-infrared wavelengths. Each spaxel scale may be combined with eleven spectral settings, that provide a range of spectral resolving powers (R ~3500, 7500 and 20000) and instantaneous wavelength coverage spanning the 0.5 - 2.4 µm wavelength range of the instrument. In autumn 2015, the HARMONI project started the Preliminary Design Phase, following signature of the contract to design, build, test and commission the instrument, signed between the European Southern Observatory and the UK Science and Technology Facilities Council. Crucially, the contract also includes the preliminary design of the HARMONI Laser Tomographic Adaptive Optics system. The instrument's technical specifications were finalized in the period leading up to contract signature. In this paper, we report on the first activity carried out during preliminary design, defining the baseline architecture for the system, and the trade-off studies leading up to the choice of baseline.

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