2025 CMS Winter Meeting
Toronto, Dec 5 - 8, 2025
Org: Peter Gibson (York University) and Yue Zhao (Central China Normal University)
[PDF]
- SPYROS ALEXAKIS, University of Toronto
- TRACEY BALEHOWSKY, Calgary
- ALI FEIZMOHAMMADI, University of Toronto
- PETER GIBSON, York University
- ISAAC HARRIS, Purdue University
Qualitative Methods Applied to Biharmonic Scattering [PDF]
- TRACEY BALEHOWSKY, Calgary
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Inverse wave propagation problems arise in various fields, including non-destructive testing and medical imaging. The central challenge is to develop stable and reliable methods for identifying hidden obstacles or defects. This talk presents recent progress in extending qualitative reconstruction methods to biharmonic scattering problems, which describe wave scattering in long, thin elastic plates. This model is relevant to numerous engineering and physical systems.
Qualitative methods recover the shape of an unknown object from measured scattering data with minimal a priori information. However, these methods often break down at certain frequencies tied to an associated transmission eigenvalue problem. These eigenvalues can, in turn, serve as target signatures for estimating material properties, since they can be recovered from the scattering data and depend (often monotonically) on the unknown parameters.
The talk will outline new analytical results in qualitative reconstruction and explore their connection to transmission eigenvalue problems. Numerical methods for recovering the scatterer from the given data will also be discussed.
- RU-YU LAI, University of Minnesota
- MICHAEL LAMOUREUX, University of Calgary
- WENYUAN LIAO, University of Calgary
Adjoint Analysis of Seismic Wave Equation and its Applications in Full Waveform Inversion [PDF]
- MICHAEL LAMOUREUX, University of Calgary
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The adjoint-state method provides a rigorous framework for analyzing sensitivity and gradient information in inverse problems constrained by partial differential equations. In this talk, we present an adjoint analysis of the seismic wave equation from a mathematical perspective. Starting with the continuous formulation of the acoustic (and elastic) wave equation, we derive the corresponding adjoint system and establish key identities linking perturbations in the model parameters to variations in the data misfit functional. This framework clarifies the structure of the gradient and Hessian operators that underpin full waveform inversion (FWI). We also discuss the role of regularization and the theoretical connections between adjoint analysis and PDE-constrained optimization. The presentation aims to highlight how the adjoint framework unifies sensitivity analysis and optimization theory in the context of seismic imaging.
Finally, if time allows, I will present real-world applications of FWI in hydrocarbon exploration, carbon sequestration monitoring, and medical imaging, emphasizing the central role of adjoint-based analysis in advancing both the theory and practice of seismic inversion.
- CRISTIAN RIOS, University of Calgary
Applications of Alpert wavelets to imaging-based medical diagnosis [PDF]
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We utilized an Alpert wavelet basis to encode images acquired as part of routine clinical late gadolinium enhancement
(LGE) cardiac MRI protocols, and applied machine learning algorithms to develop a classification method to distinguish different types of cardio-myopathhies. The results were compared to non-preprocessed images and images processed with standard wavelet bases. In this talk we introduce the basic concepts of Alpert wavelets and some encouraging outcomes of the study.
The research is done in collaboration with Ramneet Hunjan from the University of Calgary, and the Libin Cardiovascular Institute at the University of Calgary.
- MAHISHANKA WITHANACHCHI, University of Calgary