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Publicações

2021

Task scheduling in the fog computing paradigm: Proposal of a context-aware model and evaluation of its performance [Escalonamento de pedidos no paradigma fog computing: Proposta de um modelo sensível ao contexto e avaliação do seu desempenho]

Autores
Barros, C; Rocio, V; Sousa, A; Paredes, H;

Publicação
RISTI - Revista Iberica de Sistemas e Tecnologias de Informacao

Abstract
Application execution requests in cloud architecture and fog paradigm are generally heterogeneous and scheduling in these architectures is an optimization problem with multiple constraints. In this paper, we conducted a survey on the related works on scheduling in cloud architecture and fog paradigm, we identify their limitations, we explore some prospects for improvements and we propose a context-aware scheduling model for fog paradigm. The proposed solution uses Min-Max normalization, to solve heterogeneity and normalize the different context parameters. The priority of requests is set by applying the Multiple Linear Regression analysis technique and the scheduling is done using the Multiobjective Nonlinear Programming Optimization technique. The results obtained from simulations on iFogSim toolkit, show that our proposal performs better compared to the non-context-aware proposals.

2021

Block Coordinate Decent Robust Bidding Strategy of a Solar Photovoltaic coupled Energy Storage System operating in a Day-ahead Market

Autores
Aghamohamadi, M; Mahmoudi, A; Ward, JK; Haque, MH; Catalao, JPS;

Publicação
2021 IEEE PES INNOVATIVE SMART GRID TECHNOLOGIES - ASIA (ISGT ASIA)

Abstract
This paper presents a two-stage adaptive robust optimization approach to develop an optimal bidding strategy for a grid-connected solar photovoltaic (PV) plant with a coupled energy storage system (ESS). This study models the power flow through system elements as well as the exact interactions between the system and upstream network. The uncertainties of solar radiation, affecting the PV generation and market prices are characterized by bounded intervals in polyhedral uncertainty sets. A robust optimization is formed as a min-max-min problem characterizing both here-and-now and wait-and-see variables. This tri-level robust optimization is solved through a decomposition approach, where it is recast into a min master problem and a max-min subproblem. Unlike previous conventional robust optimization models, that utilise duality for solving the inner subproblem, a block coordinate decent (BCD) methodology is used in this study. Accordingly, instead of conducting duality theory, the subproblem is solved over a first-order Taylor series approximation of uncertainties. This results in a moderate computation/mathematical burden. Moreover, there is no need to linearize the dualized problem anymore, as no duality is conducted. Using BCD methodology in solving the robust optimization model also allows modelling binary variables as recourse actions, which differentiates this approach to conventional dual-based robust optimization models. An illustrative example is provided to demonstrate the performance of the proposed bidding strategy model.

2021

Optimal Modeling of Load Variations in Distribution System Reconfiguration

Autores
Mahdavi, M; Javadi, MS; Wang, F; Catalao, JPS;

Publicação
2021 21ST IEEE INTERNATIONAL CONFERENCE ON ENVIRONMENT AND ELECTRICAL ENGINEERING AND 2021 5TH IEEE INDUSTRIAL AND COMMERCIAL POWER SYSTEMS EUROPE (EEEIC/I&CPS EUROPE)

Abstract
Distribution networks have a prominent role in electricity delivery to individual consumers. Nevertheless, their energy losses are higher than transmission systems, which this issue affects the distribution operational costs. Hence, the minimization of power losses in distribution networks has particular importance for the system operators. Distribution network reconfiguration (DNR) is an effective way to reduce energy losses. However, some research works regarding DNR have not considered load variations in power loss calculations. Load level has an essential role in network losses determination and significantly influences the energy losses amount. On the other hand, considering load variations in DNR increases the computational burden and processing time of the relevant algorithms. Therefore, this paper presents an effective reconfiguration framework for minimization of distribution losses, while the energy demand is changing. The simulation results show the effectiveness of the proposed strategy for optimal reconfiguration of distribution systems in presence of load variations.

2021

Nano-Displacement Measurement Using an Optical Drop-Shaped Structure

Autores
Robalinho, P; Frazao, O;

Publicação
IEEE PHOTONICS TECHNOLOGY LETTERS

Abstract
This letter presents a new optical fiber structure with the capability of measuring nano-displacement. This device is composed by a cleaved fiber and a drop-shaped microstructure that is connected to the fiber cladding. This optical structure is responsible for the light beam division and the formation of new optical paths. The operation mode consists of the Vernier effect that allows achieving higher sensitivity than the currently sensors. During the experimental execution, displacement sensitivities of 1.05 +/- 0.01 nm , 15.1 +/- 0.1 nm, 24.7 +/- 0.3 nm and 28.3 +/- 0.3 nm , were achieved for the carrier, the fundamental of the envelope, the first harmonic and the second harmonic, respectively. The M-factor of 27 was attained, allowing a minimum resolution of 0.7 nm. In addition to displacement sensing, the proposed optical sensor can be used as a cantilever enabling non-evasive measurements.

2021

Towards an Immersive Learning Knowledge Tree - a Conceptual Framework for Mapping Knowledge and Tools in the Field

Autores
Beck, D; Morgado, L; Lee, M; Gütl, C; Dengel, A; Wang, MJ; Warren, S; Richter, J;

Publicação
2021 7TH INTERNATIONAL CONFERENCE OF THE IMMERSIVE LEARNING RESEARCH NETWORK (ILRN)

Abstract
The interdisciplinary field of immersive learning research is scattered. Combining efforts for better exploration of this field from the different disciplines requires researchers to communicate and coordinate effectively. We call upon the community of immersive learning researchers for planting the Knowledge Tree of Immersive Learning Research, a proposal for a systematization effort for this field, combining both scholarly and practical knowledge, cultivating a robust and ever-growing knowledge base and methodological toolbox for immersive learning. This endeavor aims at promoting evidence-informed practice and guiding future research in the field. This paper contributes with the rationale for three objectives: 1) Developing common scientific terminology amidst the community of researchers; 2) Cultivating a common understanding of methodology, and 3) Advancing common use of theoretical approaches, frameworks, and models.

2021

Handling Privacy Preservation in a Software Ecosystem for the Querying and Processing of Deep Sequencing Data

Autores
Rocha, A; Costa, A; Oliveira, MA; Aguiar, A;

Publicação
ERCIM NEWS

Abstract
iReceptor Plus will enable researchers around the world to share and analyse huge immunological distributed datasets, from multiple countries, containing sequencing data pertaining to both healthy and sick individuals. Most of the Adaptive Immune Receptor Repertoire sequencing (AIRR-seq) data is currently stored and curated by individual labs, using a variety of tools and technologies.

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