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Publicações

2024

How have the European Union countries approached the Europe 2020 targets?

Autores
Figueiredo, A; Figueiredo, F;

Publicação
Research in Statistics

Abstract

2024

Screening Chromium Contamination in Wood Samples using Laser-Induced Breakdown Spectroscopy Imaging

Autores
Guimaraes, D; Capela, D; Lones, T; Magalhaes, P; Pessanha, S; Jorge, PAS; Silva, NA;

Publicação
2024 IEEE SENSORS APPLICATIONS SYMPOSIUM, SAS 2024

Abstract
Recycling of post-consumer wood waste into wood-based panels may be hindered by the presence of physical and chemical impurities in the waste stream. Therefore greater attention should be given to assessing the quality of wood waste and in particular to heavy metals contamination. One of the elements that poses concern is Chromium (Cr). Cr compounds can be toxic, particularly hexavalent chromium (Cr(VI)), which is a known human carcinogen. Hence, screening for Cr in wood waste plays a pivotal role in enhancing recycling facility operations and mitigating contamination before final product incorporation. In this study, a Laser-Induced Breakdown Spectroscopy (LIBS) methodology was optimized for screening wood waste for Cr and validated by X-ray Fluorescence (XRF) measurements. LIBS spectral complexity and sample matrix effects challenges were addressed through careful selection of Cr lines and tailored data analysis algorithms. The results showed that LIBS imaging successfully provided a straightforward timely output revealing the contaminated wood samples, crucial for quick decision-making in production lines.

2024

Novel Digital Signal Processing Method for Data Acquired From Low Coherence Interferometry

Autores
Robalinho, P; Rodrigues, AV; Novais, S; Ribeiro, AL; Silva, S; Frazao, O;

Publicação
IEEE SENSORS JOURNAL

Abstract
The aim of this work is to introduce a novel digital signal processing method for data acquired using low coherence interferometry (LCI) with a 1-kHz actuator oscillation frequency. Convolution and correlation operations are employed as efficient filters, reducing computational complexity for multilayer filtering. An envelope filtering technique is developed to address discrepancies in peak signal determination caused by nonlinear actuator motion. Additionally, a phase linearization method is presented to normalize the peak position relative to the actuator signal. Experimental results demonstrate a significant signal-to-noise ratio (SNR) improvement of 50 dB. Long-term measurements reveal an 11-dB noise reduction for frequencies below 1 mHz. This research enables LCI implementation at sampling rates of at least 1 kHz and expands its applicability to extreme measurement conditions.

2024

LPC: A Local Path-Based Centrality Method for Identifying Influential Nodes in Temporal Networks

Autores
Sadhu, S; Mallick, D; Namtirtha, A; Curado Malta, M; Dutta, A;

Publicação
Proceedings of the 8th International Conference on Data Science and Management of Data (12th ACM IKDD CODS and 30th COMAD)

Abstract

2024

On the summary measures for the resource-constrained project scheduling problem

Autores
Van Eynde, R; Vanhoucke, M; Coelho, J;

Publicação
ANNALS OF OPERATIONS RESEARCH

Abstract
The resource-constrained project scheduling problem is a widely studied problem in the literature. The goal is to construct a schedule for a set of activities, such that precedence and resource constraints are respected and that an objective function is optimized. In project scheduling literature, summary measures are often used as a tool to evaluate the performance of algorithms and to analyze instances and datasets. They can be classified in two groups, network measures describe the precedence constraints of a project, while resource measures focus on the resource constraints of the instance. In this manuscript we make an exhaustive evaluation of the summary measures for project scheduling. We provide an overview of the most prevalent measures and also introduce some new ones. For our tests we combine different datasets from the literature and generate a new set with diverse characteristics. We evaluate the performance of the summary measures on three dimensions: consistency, instance complexity and algorithm selection. We conclude by providing an overview of which measures are best suited for each of the three investigated dimensions.

2024

A Practical Methodology for Real-Time Adjustment of Kalman Filter Process Noise for Lithium Battery State-of-Charge Estimation

Autores
da Silva, CT; Dias, BMD; Araújo, RE; Pellini, EL; Laganá, AAM;

Publicação
BATTERIES-BASEL

Abstract
The methodology presented in this work allows for the creation of a real-time adjustment of Kalman Filter process noise for lithium battery state-of-charge estimation. This work innovates by creating a methodology for adjusting the process (Q) and measurement (R) Kalman Filter noise matrices in real-time. The filter algorithm with this adaptative mechanism achieved an average accuracy of 99.56% in real tests by comparing the estimated battery voltage and measured battery voltage. A cell-balancing strategy was also implemented, capable of guaranteeing the safety and efficiency of the battery pack in all conducted tests. This work presents all the methods, equations, and simulations necessary for the development of a battery management system and applies the system in a practical, real environment. The battery management system hardware and firmware were developed, evaluated, and validated on a battery pack with eight LiFePO4 cells, achieving excellent performance on all conducted tests.

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