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Publications

Publications by António Cunha

2024

Deep Learning for Automatic Grapevine Varieties Identification: A Brief Review

Authors
Carneiro, GA; Cunha, A; Sousa, J;

Publication

Abstract
The Eurasian grapevine (\textit{Vitis vinifera L.}) is the most widely grown horticultural crop in the world and is important for the economy of many countries. In the wine production chain, grape varieties play an important role, as they directly influence the authenticity and classification of the product. Identifying the different grape varieties is therefore fundamental for quality control and control activities, as well as for regulating production. Currently, ampelography and molecular analysis are the main approaches to identifying grape varieties. However, both methods have limitations. Ampelography is subjective and prone to errors and is experiencing enormous difficulties as ampelographers are increasingly scarce. On the other hand, molecular analyses are very demanding in terms of cost and time. In this scenario, Deep Learning (DL) methods have emerged as a classification alternative to deal with the scarcity of ampelographers and avoid molecular analyses. In this study, the most recent and current methods for identifying grapevine varieties using DL classification-based approaches are presented through a systematic literature review. The steps of the standard DL-based classification pipeline were described for the 18 most relevant studies found in the literature, highlighting their pros and cons. Potential directions for improving this field of research were also presented.

2024

Web Diagnosis for COVID-19 and Pneumonia Based on Computed Tomography Scans and X-rays

Authors
Antunes, C; Rodrigues, JMF; Cunha, A;

Publication
UNIVERSAL ACCESS IN HUMAN-COMPUTER INTERACTION, PT III, UAHCI 2024

Abstract
Pneumonia and COVID-19 are respiratory illnesses, the last caused by the severe acute respiratory syndrome virus, coronavirus 2 (SARS-CoV-2). Traditional detection processes can be slow, prone to errors, and laborious, leading to potential human mistakes and a limited ability to keep up with the speed of pathogen development. A web diagnosis application to aid the physician in the diagnosis process is presented, based on a modified deep neural network (AlexNet) to detect COVID-19 on X-rays and computed tomography (CT) scans as well as to detect pneumonia on X-rays. The system reached accuracy results well above 90% in seven well-known and documented datasets regarding the detection of COVID-19 and Pneumonia on X-rays and COVID-19 in CT scans.

2020

Bioactive hybrid nanowires: a new in trend for site-specific drug delivery and targeting

Authors
Fernandes A.R.; Dias-Ferreira J.; Teixeira M.C.; Shimojo A.A.M.; Severino P.; Silva A.M.; Shegokar R.; Souto E.B.;

Publication
Drug Delivery Trends: Volume 3: Expectations and Realities of Multifunctional Drug Delivery Systems

Abstract
The current progress of modern medicine is based on the resistance of malignant tumors in advanced medical treatments, as well as on the need to develop new therapeutic approaches. In the last few years, numerous studies have focused their attention on the promising use of nanomaterials, such as nanowires, zinc oxide, or mesoporous silica nanoparticles, among others. All these particles are studied in the treatment of cancer and metastasis prevention with the advantage of operating directly at the biomolecular scale. These are innovative designs of magnetic nanomaterials based on a core/shell approach that started to gain prominence due to their versatility to tailor properties of both core and shell and to offer multifunctionality, such as core protection, biofunctionalization platform, toxicity reduction, and enhanced biocompatibility. These nanowire structural improvements allow the development of new bioanalytical chemistry and medical diagnostics advanced tools that will bring about a new age of nanotechnology with widespread use of nanowires for biomedical applications.

2024

Image Stitching of Low-Resolution Retinography Using Fundus Blur Filter and Homography Convolutional Neural Network

Authors
Santos, L; Almeida, M; Almeida, J; Braz, G; Camara, J; Cunha, A;

Publication
INFORMATION

Abstract
Great advances in stitching high-quality retinal images have been made in recent years. On the other hand, very few studies have been carried out on low-resolution retinal imaging. This work investigates the challenges of low-resolution retinal images obtained by the D-EYE smartphone-based fundus camera. The proposed method uses homography estimation to register and stitch low-quality retinal images into a cohesive mosaic. First, a Siamese neural network extracts features from a pair of images, after which the correlation of their feature maps is computed. This correlation map is fed through four independent CNNs to estimate the homography parameters, each specializing in different corner coordinates. Our model was trained on a synthetic dataset generated from the Microsoft Common Objects in Context (MSCOCO) dataset; this work added an important data augmentation phase to improve the quality of the model. Then, the same is evaluated on the FIRE retina and D-EYE datasets for performance measurement using the Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index (SSIM). The obtained results are promising: the average PSNR was 26.14 dB, with an SSIM of 0.96 on the D-EYE dataset. Compared to the method that uses a single neural network for homography calculations, our approach improves the PSNR by 7.96 dB and achieves a 7.86% higher SSIM score.

2024

Chestnut Burr Segmentation for Yield Estimation Using UAV-Based Imagery and Deep Learning

Authors
Carneiro, GA; Santos, J; Sousa, JJ; Cunha, A; Pádua, L;

Publication
DRONES

Abstract
Precision agriculture (PA) has advanced agricultural practices, offering new opportunities for crop management and yield optimization. The use of unmanned aerial vehicles (UAVs) in PA enables high-resolution data acquisition, which has been adopted across different agricultural sectors. However, its application for decision support in chestnut plantations remains under-represented. This study presents the initial development of a methodology for segmenting chestnut burrs from UAV-based imagery to estimate its productivity in point cloud data. Deep learning (DL) architectures, including U-Net, LinkNet, and PSPNet, were employed for chestnut burr segmentation in UAV images captured at a 30 m flight height, with YOLOv8m trained for comparison. Two datasets were used for training and to evaluate the models: one newly introduced in this study and an existing dataset. U-Net demonstrated the best performance, achieving an F1-score of 0.56 and a counting accuracy of 0.71 on the proposed dataset, using a combination of both datasets during training. The primary challenge encountered was that burrs often tend to grow in clusters, leading to unified regions in segmentation, making object detection potentially more suitable for counting. Nevertheless, the results show that DL architectures can generate masks for point cloud segmentation, supporting precise chestnut tree production estimation in future studies.

2024

A Multi-Stage Automatic Method Based on a Combination of Fully Convolutional Networks for Cardiac Segmentation in Short-Axis MRI

Authors
da Silva, IFS; Silva, AC; de Paiva, AC; Gattass, M; Cunha, AM;

Publication
APPLIED SCIENCES-BASEL

Abstract
Magnetic resonance imaging (MRI) is a non-invasive technique used in cardiac diagnosis. Using it, specialists can measure the masses and volumes of the right ventricle (RV), left ventricular cavity (LVC), and myocardium (MYO). Segmenting these structures is an important step before this measurement. However, this process can be laborious and error-prone when done manually. This paper proposes a multi-stage method for cardiac segmentation in short-axis MRI based on fully convolutional networks (FCNs). This automatic method comprises three main stages: (1) the extraction of a region of interest (ROI); (2) MYO and LVC segmentation using a proposed FCN called EAIS-Net; and (3) the RV segmentation using another proposed FCN called IRAX-Net. The proposed method was tested with the ACDC and M&Ms datasets. The main evaluation metrics are end-diastolic (ED) and end-systolic (ES) Dice. For the ACDC dataset, the Dice results (ED and ES, respectively) are 0.960 and 0.904 for the LVC, 0.880 and 0.892 for the MYO, and 0.910 and 0.860 for the RV. For the M&Ms dataset, the ED and ES Dices are 0.861 and 0.805 for the LVC, 0.733 and 0.759 for the MYO, and 0.721 and 0.694 for the RV. These results confirm the feasibility of the proposed method.

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