Browsing by Author "Martínez, Cristina"
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Item Comprehensive analysis of smart grids functionalities virtualization(2024-12) Lázaro-Elorriaga, Laura; Guerra, David; García-Pastor, Imanol; Martínez, Cristina; Sanchez, Eutimio; Perea, Eugenio; POWER ELECTRONICS AND SYSTEM EQUIPMENT; DIGITAL ENERGYThe implementation of advanced digital technologies in the conventional electric grid has triggered a transformation towards an intelligent network, known as Smart Grid. The associated benefits are diverse, ranging from more efficient energy management and demand response to the distributed integration of renewable energy sources. Ultimately, this transition promotes a more reliable, sustainable, and cost-effective energy supply. In this context, there is increasing recognition of the advantages of employing intelligent at edge to provide redundancy, virtualize functions that were previously in different proprietary hardware in the same device, or introduce new functionalities into the electric grid. This study focuses on conducting a comprehensive analysis on the key aspects to consider when implementing virtualized solutions in substations. Strategies have been sought to ensure the optimal deployment of virtualized nodes within the electrical sector, taking into account factors such as functional requirements, facility types, virtualization methodologies, and node specifications, among others. Furthermore, throughout the study, several virtualization tools have been analysed to determine their feasibility and the advantages they offer when integrated into the Smart Grid.Item Noise Sources, Effects and Countermeasures in Narrowband Power-Line Communications Networks: A Practical Approach: A practical approach(2017-08) López, Gregorio; Moreno, José Ignacio; Sánchez, Eutimio; Martínez, Cristina; Martín, Fernando; POWER ELECTRONICS AND SYSTEM EQUIPMENTThe integration of Distributed Generation, Electric Vehicles, and storage without compromising the quality of the power delivery requires the deployment of a communications overlay that allows monitoring and controlling low voltage networks in almost real time. Power Line Communications are gaining momentum for this purpose since they present a great trade-off between economic and technical features. However, the power lines also represent a harsh communications medium which presents different problems such as noise, which is indeed affected by Distributed Generation, Electric Vehicles, and storage. This paper provides a comprehensive overview of the types of noise that affects Narrowband Power Line Communications, including normative noises, noises coming from common electronic devices measured in actual operational power distribution networks, and noises coming from photovoltaic inverters and electric vehicle charging spots measured in a controlled environment. The paper also reviews several techniques to mitigate the effects of noise, paying special attention to passive filtering, as for being one of the most widely used solution to avoid this kind of problems in the field. In addition, the paper presents a set of tests carried out to evaluate the impact of some representative noises on Narrowband Power Line Communications network performance, as well as the effectiveness of different passive filter configurations to mitigate such an impact. In addition, the considered sources of noise can also bring value to further improve PLC communications in the new scenarios of the Smart Grid as an input to theoretical models or simulations.Item VITALAS at TRECVID-2009(2009) Diou, Christos; Stephanopoulos, George; Dimitriou, Nikos; Panagiotopoulos, Panagiotis; Papachristou, Christos; Delopoulos, Anastasios; Rode, Henning; Tsikrika, Theodora; de Vries, Arjen P.; Schneider, Daniel; Schwenninger, Jochen; Viaud, Marie Luce; Saulnier, Agnès; Altendorf, Peter; Schröter, Birgit; Elser, Matthias; Rego, Angel; Rodriguez, Alex; Martínez, Cristina; Etxaniz, Iñaki; Dupont, Gérard; Grilhères, Bruno; Martin, Nicolas; Boujemaa, Nozha; Joly, Alexis; Enficiaud, Raffi; Verroust, Anne; Selmi, Souheil; Khadhraoui, Mondher; CIBERSEC&DLT; HPAThis paper describes the participation of VITALAS in the TRECVID-2009 evaluation where we submitted runs for the High-Level Feature Extraction (HLFE) and Interactive Search tasks. For the HLFE task, we focus on the evaluation of low-level feature sets and fusion methods. The runs employ multiple low-level features based on all available modalities (visual, audio and text) and the results show that use of such features improves the retrieval effectiveness significantly. We also use a concept score fusion approach that achieves good results with reduced low-level feature vector dimensionality. Furthermore, a weighting scheme is introduced for cluster assignment in the "bag-of-words" approach. Our runs achieved good performance compared to a baseline run and the submissions of other TRECVID-2009 participants. For the Interactive Search task, we focus on the evaluation of the integrated VITALAS system in order to gain insights into the use and effectiveness of the system's search function-alities on (the combination of) multiple modalities and study the behavior of two user groups: professional archivists and non-professional users. Our analysis indicates that both user groups submit about the same total number of queries and use the search functionalities in a similar way, but professional users save twice as many shots and examine shots deeper in the ranked retrieved list.The agreement between the TRECVID assessors and our users was quite low. In terms of the effectiveness of the different search modalities, similarity searches retrieve on average twice as many relevant shots as keyword searches, fused searches three times as many, while concept searches retrieve even up to five times as many relevant shots, indicating the benefits of the use of robust concept detectors in multimodal video retrieval.