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Publications

2024

Unlocking responsive flexibility within local energy communities in the presence of grid-scale batteries

Authors
Javadi, MS;

Publication
SUSTAINABLE CITIES AND SOCIETY

Abstract
The transition towards a decentralized, decarbonized, and distributed energy infrastructure necessitates technoeconomic initiatives to empower local energy communities (LECs) to achieve self-reliance and evolve into selfsustained electricity networks. It is crucial to underscore the significance of network resilience, especially in the context of local power generation, battery storage, and the radial topology of low-voltage (LV) networks. While contemporary LV networks have made significant attempts to integrate distributed energy resources (DERs), the notable deficiency lies in their lack of network redundancy, posing a substantial challenge in the occurrence of high-impact, low-probability (HILP) events. Therefore, to enhance LV network resilience and leverage its capability to withstand unexpected disruptions, the network operator needs to unlock the potential contributions of end-users within the active distribution networks (ADNs). In this paper, a comprehensive model is developed based on multi-temporal optimal power flow (MTOPF) for unbalanced LV networks addressing the technical issues in islanded microgrid operational planning. The contributions of the grid-scale batteries in forming islanded microgrids and the flexibility that can be provided by the end-users in the LEC have been considered in this paper. To demonstrate the performance of the proposed model, the simulation studies have been carried out on a part of medium and low voltage networks, consisting of network reconfiguration and load transferring capability to reduce the service interruptions during HILP events. The energy-not-served (ENS) is chosen as one of the key performance indicators (KPIs) in this study. With the unlocking flexibility potentials and contribution of the DERs, including grid-scale energy storage (GES) units and Photovoltaic (PV) panels, the ENS has been reduced from 700.8 kWh to 447.5 kWh by activating the local resources, proper switching action, and contribution of the flexible loads, for one of the severe HILP events, i.e., the main grid outage. In this case, the full load curtailment index is reduced from 180 to 106 client hours.

2024

Hybrid Energy Storage System sizing model based on load recurring pattern identification

Authors
Lucas, A; Golmaryami, S; Carvalhosa, S;

Publication
JOURNAL OF ENERGY STORAGE

Abstract
Hybrid Energy Storage Systems (HESS) have attracted attention in recent years, promising to outperform single batteries in some applications. This can be in decreasing the total cost of ownership, extending the combined lifetime, having higher versatility in providing multiple services, and reducing the physical hosting location. The sizing of hybrid systems in such a way that proves to optimally replace a single battery is a challenging task. This is particularly true if such a tool is expected to be a practical one, applicable to different inputs and which can provide a range of optimal solutions for decision makers as a support. This article provides exactly that, presenting a technology -independent sizing model for Hybrid Energy Storage Systems. The model introduces a three-step algorithm: the first block employs a clustering of time series using Dynamic Time Warping (DTW), to analyze the most recurring pattern. The second block optimizes the battery dispatch using Linear Programming (LP). Lastly, the third block identifies an optimal hybridization area for battery size configuration (H indicator), and offers practical insights for commercial technology selection. The model is applied to a real dataset from an office building to verify the tool and provides viable and non-viable hybridization sizing examples. For validation, the tool was compared to a full optimization approach and results are consistent both for the single battery sizing, as well as for confirming the hybrid combination dimensioning. The optimal solution potential (H) in the example provided is 0.13 and the algorithm takes a total of 30s to run a full year of data. The model is a Pythonbased tool, which is openly accessible on GitHub, to support and encourage further developments and use.

2024

Inhomogenous Marketing Mix Diffusion

Authors
Pinto, LG; Cavique, L; Gomes, O; Santos, JMA;

Publication
COMPLEX NETWORKS XV, COMPLENET 2024

Abstract
In this article we extend the Marketing Mix Diffusion (MMD) model to inhomogenous networks (i.e. complex networks of arbitrary topology). The (Homogenous) MMD model is an innovation diffusion model, similar to the Bass model, which includes four decision variables (the 4Ps of Marketing: Product, Price, Place, Promotion). We introduce the Inhomogenous MMD (IMMD) model and we conduct two separate experiments: one based on simulation and another one relying on empirical evidence. The simulation study compares the behavior of the IMMD model with the classic Bass diffusion model. Results suggest that the classic Bass model is able to represent the IMMD curves quite well in most cases. The IMMD is more general and capable of representing extreme scenarios. The empirical study focuses on the geographic diffusion of mobile broadband technology in Japan, combining adoption data with a spatial network of municipalities. The in-sample performance of the model is comparable to the existing methods, which suggests a good explanatory power of the IMMD model.

2024

Sistema de Classificação de Sinalética Gestual em competições de karaté

Authors
Violante, Sónia Correia; Filipe, Vítor; Morais, A. Jorge;

Publication

Abstract
Em contexto de Kumite (combate de Karate) propõe-se investigar um modelo de classificação da sinalética gestual do árbitro para atribuição de pontos, com recurso a Visão Computacional e técnicas de Aprendizagem Profunda. Foram realizadas três abordagens, todas tendo como base o recurso a modelos de Redes Neuronais Convolucionais (Convolutional Neural Network – CNN): Classificação de imagens com recurso a uma CNN; Deteção da pose humana com o modelo MoveNet; e a deteção e classificação de gestos com o modelo YOLOv5, via RoboFlow. A última abordagem obteve melhores resultados, com 100% de precisão para todas as classes, pelo que se testou a sua aplicação para a deteção e classificação dos gestos em vídeo.;
In the context of Kumite (Karate combat), it is proposed to investigate a model for classifying the referee’s gestures to award points using Computer Vision and Deep Learning techniques. Three approaches were used, all based on Convolutional Neural Networks (CNN) models: image classification using a CNN; human pose detection using MoveNet; and object detection using YOLOv5, via RoboFlow. The last approach obtained the best results, with 100% precision for all classes, so we tested its application for video gesture detection and classification.

2024

Coil-shaped Optical Fiber Sensor for Compression Measurements

Authors
Romeiro, F; Cardoso, HR; De Souza, FC; Caldas, P; Giraldi, MR; Frazão, O; Santos, L; Costa, CWA;

Publication
EPJ Web of Conferences

Abstract
This study investigated the effectiveness of a coil-shaped optical fiber interferometric sensor, with a diameter of 13 mm, for measuring compression. The sensor's design utilizes the principles of interferometry to create a pattern that changes with applied pressure. This configuration significantly amplifies the sensor's sensitivity to compression due to the extended optical path length within the compact form factor. The experimental results demonstrated that even small compressive forces caused detectable alterations in the interference pattern, allowing for precise quantification of pressure changes. The 13 mm diameter proved to be particularly advantageous, providing a balance between sensitivity and practical integration into various systems, from structural health monitoring to biomedical devices. This study also highlights the sensor's robustness against electromagnetic interference and environmental variations, attributing this to the intrinsic properties of optical fiber. Overall, the findings suggest that coil-shaped optical fiber interferometric sensors are highly effective for accurate and reliable compression sensing, with potential for broad application across multiple industries. © The Authors.

2024

Instance-based meta-learning for conditionally dependent univariate multi-step forecasting

Authors
Cerqueira, V; Torgo, L; Bontempi, G;

Publication
International Journal of Forecasting

Abstract

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