J. Sun
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24 records found
1
Spatial Reasoning from Synthetic Scenes
A Synthetic Data Pipeline for Spatial Reasoning in Remote Sensing Visual Question Answering
Bayesian Inverse Generative Neural Operator
Latent-Space Posterior Formulation for PDE-Constrained Inverse Problems
Comparison of surrogate model classes on out-of-distribution data
Comparing data-driven, physics informed and hybrid models on out-of-distribution data
Can Physics-Informed Training Improve Neural-Operator Data Efficiency?
A Controlled FNO and PINO Comparison for PDE Surrogate Modelling
Accuracy, Performance, and Robustness of Physics-Informed Surrogate Models
Physics-Informed Learning for CFD Surrogate Modelling and Neural Operator Methods
Can GRQO based fine-tuning speed up the inference stage of the denoising pipeline by reducing the reliance on the TTA?
Reinforcement Learning Based Learning for Seismic Denoising
Where Does Adaptation Matter?
Layer-wise Importance of Parameter-Efficient Adaptation of Vision Foundation Models to Seismic Denoising
Reconstructing missing seismic traces on BP 2007 and Viking Line 12
Comparing U-Net, SwinV2, and SFM on synthetic and field data
Seeing Through Seismic Noise with Soft Spatial Blending
Parameter-Efficient Soft Spatial Blending of Vision Foundation Models for Seismic Denoising
Learning from Neighbouring Seismic Slices
Parameter-Efficient 2.5D Multi-Channel Adaptation of Visual Foundation Models for Seismic Denoising
The empirical study uses a common mixed-domain FNO baseline across Poisson, advection–diffusion, and Helmholtz operators. This baseline provides the shared backbone, input representation, and transfer protocol against which the constraint modules are compared. The experiments therefore focus on whether adding physical structure improves downstream adaptation under matched training and evaluation conditions.
The experiments evaluate minimally invasive zero-mode constraints and residual constraints for partial differential equations. The results show that the soft partial differential equation residual penalty is the most promising tested add-on, improving transfer performance for Poisson and advection–diffusion across a broad range of downstream data budgets. In contrast, a hard zero-mode projection is generally unattractive, suggesting that exact universal projections can be too rigid in a mixed transfer setting. Helmholtz remains less conclusive, with noisier and less separable constraint effects.
Finally, experiments on PDE coefficient ranges outside the pretraining regime show that pretraining lowers error relative to scratch for Poisson and advection–diffusion, but does not remove the challenge of extrapolation. For Helmholtz, higher-frequency settings expose instability in scratch training that is less severe for the mixed pretrained model. Overall, the results support a restrained view: modular constraints can help foundation-model neural operators, but their usefulness depends strongly on enforcement type, partial differential equation family, and shift severity. ...
The empirical study uses a common mixed-domain FNO baseline across Poisson, advection–diffusion, and Helmholtz operators. This baseline provides the shared backbone, input representation, and transfer protocol against which the constraint modules are compared. The experiments therefore focus on whether adding physical structure improves downstream adaptation under matched training and evaluation conditions.
The experiments evaluate minimally invasive zero-mode constraints and residual constraints for partial differential equations. The results show that the soft partial differential equation residual penalty is the most promising tested add-on, improving transfer performance for Poisson and advection–diffusion across a broad range of downstream data budgets. In contrast, a hard zero-mode projection is generally unattractive, suggesting that exact universal projections can be too rigid in a mixed transfer setting. Helmholtz remains less conclusive, with noisier and less separable constraint effects.
Finally, experiments on PDE coefficient ranges outside the pretraining regime show that pretraining lowers error relative to scratch for Poisson and advection–diffusion, but does not remove the challenge of extrapolation. For Helmholtz, higher-frequency settings expose instability in scratch training that is less severe for the mixed pretrained model. Overall, the results support a restrained view: modular constraints can help foundation-model neural operators, but their usefulness depends strongly on enforcement type, partial differential equation family, and shift severity.
To address this problem, the influence of varying amounts of additional data on generalisation to novel cloud regimes is evaluated. The study compares representation learning strategies, including self-supervised and supervised approaches, to assess their effectiveness in structuring the latent space for distinguishing cloud types. In parallel, two learning paradigms, transfer learning and episodic meta-learning, are analysed to determine how effectively they incorporate additional data when adapting to novel classes.
The results show that self-supervised learning is most effective in the strict few-shot regime, while supervised transfer learning makes the most effective use of additional data. In particular, Barlow Twins achieves the strongest performance under minimal data by avoiding reliance on noisy labels. When additional out-of-domain data, such as ImageNet and auxiliary cloud datasets, is introduced, supervised pre-training combined with transfer learning attains performance comparable to standard supervised learning, while requiring only a small number of labelled examples. ...
To address this problem, the influence of varying amounts of additional data on generalisation to novel cloud regimes is evaluated. The study compares representation learning strategies, including self-supervised and supervised approaches, to assess their effectiveness in structuring the latent space for distinguishing cloud types. In parallel, two learning paradigms, transfer learning and episodic meta-learning, are analysed to determine how effectively they incorporate additional data when adapting to novel classes.
The results show that self-supervised learning is most effective in the strict few-shot regime, while supervised transfer learning makes the most effective use of additional data. In particular, Barlow Twins achieves the strongest performance under minimal data by avoiding reliance on noisy labels. When additional out-of-domain data, such as ImageNet and auxiliary cloud datasets, is introduced, supervised pre-training combined with transfer learning attains performance comparable to standard supervised learning, while requiring only a small number of labelled examples.
Heliostat Surface Prediction via Physics-Aware Deep Learning
A Feasibility Study
This thesis explores the use of diffusion-based generative models for super-resolution in wind field reconstruction. A progressive SR3 (Super-Resolution via Repeated Refinement) frame- work is developed, combining a multi-stage architecture with stochastic denoising processes to gradually reconstruct high-resolution outputs. Extensive experiments demonstrate that the progressive SR3 consistently outperforms CNN-based baselines in terms of reconstruction accur- acy, perceptual quality, and robustness. Furthermore, a joint training strategy improves both performance and computational efficiency by enabling end-to-end optimization across stages.
The findings support the use of probabilistic diffusion models for meteorological super-resolution tasks and emphasize the effectiveness of progressive refinement in handling large upscaling factors. This approach provides a promising pathway for enhancing data-driven post-processing in atmospheric modeling. ...
This thesis explores the use of diffusion-based generative models for super-resolution in wind field reconstruction. A progressive SR3 (Super-Resolution via Repeated Refinement) frame- work is developed, combining a multi-stage architecture with stochastic denoising processes to gradually reconstruct high-resolution outputs. Extensive experiments demonstrate that the progressive SR3 consistently outperforms CNN-based baselines in terms of reconstruction accur- acy, perceptual quality, and robustness. Furthermore, a joint training strategy improves both performance and computational efficiency by enabling end-to-end optimization across stages.
The findings support the use of probabilistic diffusion models for meteorological super-resolution tasks and emphasize the effectiveness of progressive refinement in handling large upscaling factors. This approach provides a promising pathway for enhancing data-driven post-processing in atmospheric modeling.
The temporal component evaluates a set of linear and nonlinear regression models as flexible MCP-style baselines and extends them with additional contextual information. Temporal structure is incorporated through multi-step time windows, and local spatial structure is added by including neighboring LES grid cells. To represent full-field atmospheric patterns, the models are further enriched with latent encodings of the LES wind-speed field obtained through a Convolutional Autoencoder. The results show that MCP generalizes well to the microscale and that adding temporal and spatial context improves time-series accuracy across all observation locations, with combined strategies outperforming industry-standard methods.
The spatial component introduces Wind Speed-enhanced IDW (WS-IDW), which augments traditional IDW by weighting observation locations not only by geographic distance but also by similarity in LES wind speed. WS-IDW produces consistent improvements over the baseline, particularly when more observation locations are available. Analysis of the correction maps reveals that WS-IDW partially smooths misplaced fine-scale streaks in the LES wind field, supporting the hypothesis that LES is prone to slight spatial misalignment of coherent structures. The proposed method generalizes reasonably across sites and across different numbers of source masts.
Together, the temporal and spatial results demonstrate that incorporating LES-derived spatial and temporal information yields systematic improvements in microscale correction performance. The thesis provides a refined understanding of how LES behavior interacts with data-driven correction methods and offers a foundation for developing more robust microscale WRA correction frameworks in future work. ...
The temporal component evaluates a set of linear and nonlinear regression models as flexible MCP-style baselines and extends them with additional contextual information. Temporal structure is incorporated through multi-step time windows, and local spatial structure is added by including neighboring LES grid cells. To represent full-field atmospheric patterns, the models are further enriched with latent encodings of the LES wind-speed field obtained through a Convolutional Autoencoder. The results show that MCP generalizes well to the microscale and that adding temporal and spatial context improves time-series accuracy across all observation locations, with combined strategies outperforming industry-standard methods.
The spatial component introduces Wind Speed-enhanced IDW (WS-IDW), which augments traditional IDW by weighting observation locations not only by geographic distance but also by similarity in LES wind speed. WS-IDW produces consistent improvements over the baseline, particularly when more observation locations are available. Analysis of the correction maps reveals that WS-IDW partially smooths misplaced fine-scale streaks in the LES wind field, supporting the hypothesis that LES is prone to slight spatial misalignment of coherent structures. The proposed method generalizes reasonably across sites and across different numbers of source masts.
Together, the temporal and spatial results demonstrate that incorporating LES-derived spatial and temporal information yields systematic improvements in microscale correction performance. The thesis provides a refined understanding of how LES behavior interacts with data-driven correction methods and offers a foundation for developing more robust microscale WRA correction frameworks in future work.