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Publicações

2024

Automatic Fall Detection with Thermal Camera

Autores
Kalbermatter, RB; Franco, T; Pereira, AI; Valente, A; Soares, SP; Lima, J;

Publicação
OPTIMIZATION, LEARNING ALGORITHMS AND APPLICATIONS, PT I, OL2A 2023

Abstract
People are living longer, promoting new challenges in healthcare. Many older adults prefer to age in their own homes rather than in healthcare institutions. Portugal has seen a similar trend, and public and private home care solutions have been developed. However, age-related pathologies can affect an elderly person's ability to perform daily tasks independently. Ambient Assisted Living (AAL) is a domain that uses information and communication technologies to improve the quality of life of older adults. AI-based fall detection systems have been integrated into AAL studies, and posture estimation tools are important for monitoring patients. In this study, the OpenCV and the YOLOv7 machine learning framework are used to develop a fall detection system based on posture analysis. To protect patient privacy, the use of a thermal camera is proposed to prevent facial recognition. The developed system was applied and validated in the real scenario.

2024

STERN: Attention-driven Spatial Transformer Network for abnormality detection in chest X-ray images

Autores
Rocha, J; Pereira, SC; Pedrosa, J; Campilho, A; Mendonça, AM;

Publicação
ARTIFICIAL INTELLIGENCE IN MEDICINE

Abstract
Chest X-ray scans are frequently requested to detect the presence of abnormalities, due to their low-cost and non-invasive nature. The interpretation of these images can be automated to prioritize more urgent exams through deep learning models, but the presence of image artifacts, e.g. lettering, often generates a harmful bias in the classifiers and an increase of false positive results. Consequently, healthcare would benefit from a system that selects the thoracic region of interest prior to deciding whether an image is possibly pathologic. The current work tackles this binary classification exercise, in which an image is either normal or abnormal, using an attention-driven and spatially unsupervised Spatial Transformer Network (STERN), that takes advantage of a novel domain-specific loss to better frame the region of interest. Unlike the state of the art, in which this type of networks is usually employed for image alignment, this work proposes a spatial transformer module that is used specifically for attention, as an alternative to the standard object detection models that typically precede the classifier to crop out the region of interest. In sum, the proposed end-to-end architecture dynamically scales and aligns the input images to maximize the classifier's performance, by selecting the thorax with translation and non-isotropic scaling transformations, and thus eliminating artifacts. Additionally, this paper provides an extensive and objective analysis of the selected regions of interest, by proposing a set of mathematical evaluation metrics. The results indicate that the STERN achieves similar results to using YOLO-cropped images, with reduced computational cost and without the need for localization labels. More specifically, the system is able to distinguish abnormal frontal images from the CheXpert dataset, with a mean AUC of 85.67% -a 2.55% improvement vs. the 0.98% improvement achieved by the YOLO-based counterpart in comparison to a standard baseline classifier. At the same time, the STERN approach requires less than 2/3 of the training parameters, while increasing the inference time per batch in less than 2 ms. Code available via GitHub.

2024

Developing a Comparative Model of Predicted Associations for Invariable Question Tag Types in British English and European Portuguese

Autores
Silvano, C; González, MG;

Publicação
Constructional and Cognitive Explorations of Contrastive Linguistics

Abstract
The present chapter scrutinises invariable question tags in British English and European Portuguese from a contrastive point of view. Most previous research focuses on variable question tags and, if contrastive, compares other languages. This study shows that invariable question tags are more frequent and varied in European Portuguese than in British English. Furthermore, the results reveal that, while some invariable question tags appear across the two languages, others are registered only in one of them, despite the existence of equivalent expressions in the other. Additional asymmetries emerge concerning linguistic features of invariable question tags across the two languages. Based on the significant correlations between invariable question tags and their features, a model of predicted associations is put forward. © The Editor(s) (ifapplicable) and The Author (s),under exclusive license to Springer Nature Switzerland AG 2024.

2024

Gaussian Mixture Model for Battery Operation Anomaly Detection.

Autores
Lucas, A; Carvalhosa, S; Golmaryami, S;

Publicação
2024 INTERNATIONAL CONFERENCE ON SMART ENERGY SYSTEMS AND TECHNOLOGIES, SEST 2024

Abstract
This research presents an anomaly detection algorithm for a Vanadium Redox Flow Battery (VRFB) using battery dataset as an example. The algorithm determines the anomaly detection threshold by fitting a Gaussian mixed model (GMM) to an anomaly-free dataset and testing it against a dataset containing only anomalies. By forcing the test dataset to classify all observations as anomalies, the threshold can be found. Applying again the model to the training dataset, classifies 11% of normal observations as failures, indicating that, not all observations were captured by the GMM, resulting in false positives. A percentage based on the likelihood values is suggested for replication to other systems, and a ratio of anomaly detection over time is proposed for preventive maintenance alerts.

2024

Multimodal Knowledge Distillation in Spectral Imaging

Autores
Lopes, T; Capela, D; Ferreira, MFS; Teixeira, J; Silva, C; Guimaraes, DF; Jorge, PAS; Silva, NA;

Publicação
OPTICAL SENSING AND DETECTION VIII

Abstract
Spectral imaging is a powerful technology that uses spatially referenced spectral signatures to create informative visual maps of sample surfaces that can reveal more than what conventional RGB-visual images can show. Indeed, different spectroscopy modalities can provide different information about the same sample: for instance, Laser-Induced Breakdown Spectroscopy (LIBS) imaging can detect the presence of specific elements on the surface, while Raman imaging can identify the molecular structures and compositions of the sample, both of which have potential applications in various industrial processes, from quality control to material sorting. In the path from science to technology, the increasing accessibility to such solutions and the strong market pull have opened a window of opportunity for innovative multimodal imaging solutions, where information from distinct sources is set to be combined in order to enhance the capabilities of the single modality system. However, the practical implementation of multimodal spectral imaging is still a challenge, despite its theoretical potential, and as such, it is yet to be achieved. In this work, we will go over multimodal spectral knowledge distillation, a disruptive approach to multimodal spectral imaging techniques that tries to explore the combination of two techniques to capitalize on their individual strengths. In specific, this approach allows us to utilize one technique as an autonomous supervisor for the other, leveraging the higher degree of knowledge and interpretability of one of the techniques to increase the performance and transparency of the other. We present some example scenarios with LIBS and HSI and Raman spectroscopy and LIBS, discussing the impact of this new approach for scientific and technological applications.

2024

Optimized reconstruction of the absorption spectra of kidney tissues from the spectra of tissue components using the least squares method

Autores
Pinheiro, MR; Fernandes, LE; Carneiro, IC; Carvalho, SD; Henrique, RM; Tuchin, VV; Oliveira, HP; Oliveira, LM;

Publicação
JOURNAL OF BIOPHOTONICS

Abstract
With the objective of developing new methods to acquire diagnostic information, the reconstruction of the broadband absorption coefficient spectra (mu a[lambda]) of healthy and chromophobe renal cell carcinoma kidney tissues was performed. By performing a weighted sum of the absorption spectra of proteins, DNA, oxygenated, and deoxygenated hemoglobin, lipids, water, melanin, and lipofuscin, it was possible to obtain a good match of the experimental mu a(lambda) of both kidney conditions. The weights used in those reconstructions were estimated using the least squares method, and assuming a total water content of 77% in both kidney tissues, it was possible to calculate the concentrations of the other tissue components. It has been shown that with the development of cancer, the concentrations of proteins, DNA, oxygenated hemoglobin, lipids, and lipofuscin increase, and the concentration of melanin decreases. Future studies based on minimally invasive spectral measurements will allow cancer diagnosis using the proposed approach.

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