Browsing by Author "Urbańska MA"

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    Extracting Group Velocity Dispersion values using quantum-mimic Optical Coherence Tomography and Machine Learning
    (Springer Nature Limited, 2023-04-22) Maliszewski KA; Urbańska MA; Kolenderski P; Vetrova V; Kolenderska SM
    Quantum-mimic Optical Coherence Tomography (Qm-OCT) images are cluttered with artefacts - parasitic peaks which emerge as a by-product of the algorithm used in this method. However, the shape and behaviour of an artefact are uniquely related to Group Velocity Dispersion (GVD) of the layer this artefact corresponds to and consequently, the GVD values can be inferred by carefully analysing them. Since for multi-layered objects the number of artefacts is too high to enable layer-specific analysis, we employ a solution based on Machine Learning. We train a neural network with Qm-OCT data as an input and dispersion profiles, i.e. depth distribution of GVD within an A-scan, as an output. By accounting for noise during training, we process experimental data and estimate the GVD values of BK7 and sapphire as well as provide a qualitative GVD value distribution in a grape and cucumber. Compared to other GVD-retrieving methods, our solution does not require user input, automatically provides dispersion values for all the visualised layers and is scalable. We analyse the factors affecting the accuracy of determining GVD: noise in the experimental data as well as general physical limitations of the detection of GVD-induced changes, and suggest possible solutions.
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    Mechanical properties of kiwifruit as influenced by water loss, location, and compression velocity with respect to compression damage
    (Elsevier B V, 2025-11-01) Urbańska MA; Li M; East A
    International distribution of kiwifruit to overseas markets often results in high loads being applied to the fruit for a prolonged time. These high loads may cause compression damage. Compression damage refers to the permanent deformation of near-surface tissue. Kiwifruit affected by compression damage are less attractive to consumers and might result in further deterioration of the fruit. Previous research has been done to model the behaviour of kiwifruit under compression loads and predict compression damage susceptibility. Nevertheless, there is limited understanding of the influence of fruit water loss, compression location and velocity on kiwifruit mechanical properties. In this article, we demonstrate that Young modulus decreases 10-fold during kiwifruit storage (from about 3 MPa to 0.3 MPa). Additionally, kiwifruit of the same flesh firmness and different water loss can present a 2-fold difference in Young's modulus value, with lower values towards the higher water loss. Furthermore, small increase in compression velocity (0.01–0.08 mms−1) led to 2-fold decrease in Young's modulus values. Also, the stem end was found to have a slightly but significantly higher Young's modulus value than the middle of the fruit and the blossom end for soft fruit. These dependencies prove the complexity of the kiwifruit compression damage behaviour and the importance of improvement of the currently existing models.
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    OCT-based dynamic mechanical analysis of vitreous humour
    (Elsevier Ltd, 2024-01) Urbańska MA; Thakur SS; Kolenderska SM
    The vitreous humour plays an important role in shock absorption, i.e. the damping of the mechanical movement, to protect the delicate tissues within the eye. However, this damping is different for movements with different frequencies/velocities. While the collective low-frequency (below 100 Hz) damping behaviour of the vitreous humour associated with the saccadic and lens movements is well-studied, to the best of our knowledge, the high-frequency damping behaviour of the vitreous humour, which represents the response of the microstructural components, is not exhaustively documented. Here, we utilise a non-destructive testing method called Optical Coherence Tomography (OCT) to measure the high-frequency (100–350 Hz, waves able to probe approximately 500 µm distances) biomechanical behaviour of the vitreous humour. We parametrise this behaviour by calculating the shear storage modulus, shear loss modulus and phase angle. We compare these parameters to their low-frequency counterparts obtained with a rheometer, providing a comprehensive mechanical spectrum of the vitreous humour behaviour. The processing method developed in this study and the data collected help better understand the vitreous humour shock absorption properties. Consequently, they could allow a development of better vitreous humour substitutes. The local probing of the high-frequency regime and the non-invasive character of the OCT method provide new qualities in mapping the damping behaviour.