Wai Tik Chan

Mr. Wai Tik Chan

orcid

Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 November 2024 in Agriengineering
Verified
Journal Article
Open access
PDF file
Nesma MahmoudNesma Mahmoud
Nesma Mahmoud
IVIndrek Virro
Indrek Virro
AZA. G. M. Zaman
A. G. M. Zaman
TLTormi Lillerand
Tormi Lillerand
WCWai Tik Chan
Wai Tik Chan
JOJüri Olt
Jüri Olt
Machine learning algorithms are increasingly used to enhance agricultural productivity cost-effectively. A critical task in precision agriculture is locating a plant’s root collar. This is required for the site-specific fertilization of the plants. Though state-of-the-art machine learning models achieve stellar performance in object detection, they are often sensitive to noisy inputs and variation in environment settings. In this paper, we propose an innovative technique of smooth perturbations to improve the robustness of root collar detection tasks using the YOLOv5 neural network model. We train a YOLOv5 model on blueberry image data for root collar detection. A small amount noise is added as a smooth perturbation to the bounding box of dimensions 50× 50, and this perturbed image is fed for training. Furthermore, we introduce an additional test set that represents the out-of-distribution (O.O.D.) case by applying Gaussian blur on test images to simulate particle situation. We use three different image datasets to train our model, the (i) Estonian blueberry, (ii) Serbian blueberry image, and (iii) public dataset sourced from Roboflow datasets, of sample size 118, 2779, and 2993, respectively. We achieve an overall precision of 0.886 on perturbed blueberry images compared to 0.871 on original (unperturbed) images for the O.O.D. test set. Similarly, our smooth perturbation training has achieved an mAP of 0.828, which significantly increases against the result of normal training, which only reaches 0.794. The result proves that our proposed smooth perturbation is an effective method to increase the robustness and generalizability of the object detection task.

22 September 2026 in SoftwareX
Verified
Journal Article
Open access
WCWai Tik Chan
Wai Tik Chan
FCFrancis Charette-Migneault
Francis Charette-Migneault
EUEvelyn Uuemaa
Evelyn Uuemaa
Alexander KmochAlexander Kmoch
Alexander Kmoch

12 December 2025 in Abstracts of the ICA
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Journal Article
Open access
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JJJérôme Jacovella-St-Louis
Jérôme Jacovella-St-Louis
MPMatthew Purss
Matthew Purss
Alexander KmochAlexander Kmoch
Alexander Kmoch
WCWai Tik Chan
Wai Tik Chan
PSPeter Strobl
Peter Strobl

30 March 2026 in SSRN Electronic Journal
Verified
Preprint
Open access
WCWai Tik Chan
Wai Tik Chan
FMFrancis Charette Migneault
Francis Charette Migneault
EUEvelyn Uuemaa
Evelyn Uuemaa
Alexander KmochAlexander Kmoch
Alexander Kmoch
The invention of Hypertext Markup Language (HTML) and search engines revolutionised global access to data through the Internet. The HTML standardised how to structure data so users could efficiently discover it via search engines. Nowadays, in environmental research, vast datasets are collected from the Earth and space in various formats, posing challenges for data processing. To address this, researchers turn to the Discrete Global Grid System (DGGS) to standardise global data, similar to the role of "HTML", but it has to reach out to researchers. Therefore, we developed pydggsapi, a query web service for DGGS datasets that conform to the Open Geospatial Consortium (OGC) API-DGGS standard. It provides a unified access to discover data in an integrated view offered by DGGS. Furthermore, it abstracts away technical complexity, enabling DGGS to be smoothly adopted in research.

9 June 2025 in Multimedia Tools and Applications
Verified
Journal Article
Open access
PDF file
Nesma MahmoudNesma Mahmoud
Nesma Mahmoud
HAHanna Antson
Hanna Antson
WCWai Tik Chan
Wai Tik Chan
MSModar Sulaiman
Modar Sulaiman
JCJaesik Choi
Jaesik Choi
Kallol RoyKallol Roy
Kallol Roy
Image classification with deep neural networks has reached state-of-the-art with high accuracy. The unreasonable effectiveness of deep neural networks is credited to the manifold hypothesis that states natural data lies on a low-dimensional manifold embedded in the high-dimensional space. The machine learning models learn patterns on these low-rank representations, which gives the learning algorithms robustness. We test the robustness of learning algorithms using the paradigm of “perturb and learn”. This paper proposes a novel technique called Low-Rank Perturbation Adjustment (LoPA), an implicit regularization method used by machine learning models for resisting external perturbations. LoPA exploits the dependencies in model weights that lie in high-dimensional space and projects to low-dimensional while resisting perturbation. We validate LoPA through singular value decomposition (SVD) theory and empirical experiments, showing the statistical distribution of trained model weights of zero mean and small variance. We inject perturbations into our model by hot-swapping the activation functions and interchanging loss functions during the training. An InceptionV3 Neural Network is trained on common FruitFly Drosophila images for binary classification tasks of cancer cells. The Drosophila cancer images are prepared in our lab through immunostaining protocol.