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Visualizing the features captured by Convolutional Neural Networks (CNNs) is one of the conventional approaches to interpret the predictions made by these models in numerous image recognition applications. Grad-CAM is a popular solution…

Computer Vision and Pattern Recognition · Computer Science 2021-02-17 Sam Sattarzadeh , Mahesh Sudhakar , Konstantinos N. Plataniotis , Jongseong Jang , Yeonjeong Jeong , Hyunwoo Kim

A desireable property of accelerometric gait-based identification systems is robustness to new device orientations presented by users during testing but unseen during the training phase. However, traditional Convolutional neural networks…

Computer Vision and Pattern Recognition · Computer Science 2020-08-18 Bowen Jing , Vinay Prabhu , Angela Gu , John Whaley

A model is proposed, according to which the metric tensor field in the standard gravitational Lagrangian is decomposed into a projection (generally - with a non-zero covariant derivative) tensor field, orthogonal to an arbitrary 4-vector…

General Relativity and Quantum Cosmology · Physics 2007-05-23 B. G. Dimitrov

Convex optimization methods have been extensively used in the fields of communications and signal processing. However, the theory of quaternion optimization is currently not as fully developed and systematic as that of complex and real…

Optimization and Control · Mathematics 2023-12-27 Shuning Sun , Qiankun Diao , Dongpo Xu , Pauline Bourigault , Danilo P. Mandic

Computational Fluid Dynamics (CFD) simulations are a very important tool for many industrial applications, such as aerodynamic optimization of engineering designs like cars shapes, airplanes parts etc. The output of such simulations, in…

Computer Vision and Pattern Recognition · Computer Science 2021-03-12 Theodoros Georgiou , Sebastian Schmitt , Thomas Bäck , Nan Pu , Wei Chen , Michael Lew

Quaternion wavelets are redundant wavelet transforms generalizing complex-valued non-decimated wavelet transforms. In this paper we propose a matrix-formulation for non-decimated quaternion wavelet transforms and define spectral tools for…

Applications · Statistics 2019-03-05 Taewoon Kong , Brani Vidakovic

We address the challenging problem of deep representation learning--the efficient adaption of a pre-trained deep network to different tasks. Specifically, we propose to explore gradient-based features. These features are gradients of the…

Machine Learning · Computer Science 2020-04-14 Fangzhou Mu , Yingyu Liang , Yin Li

The Fractional Fourier Transform is a ubiquitous signal processing tool in basic and applied sciences. The Fractional Fourier Transform generalizes every property and application of the Fourier Transform. Despite the practical importance of…

Signal Processing · Electrical Eng. & Systems 2020-10-21 Amir R. Nafchi , Eric Hamke , Cristina Pereyra , Ramiro Jordan

Supervised operator learning centers on the use of training data, in the form of input-output pairs, to estimate maps between infinite-dimensional spaces. It is emerging as a powerful tool to complement traditional scientific computing,…

Machine Learning · Computer Science 2024-08-14 Nicholas H. Nelsen , Andrew M. Stuart

Recent progress in AI has established neural operators as powerful tools that can predict the evolution of partial differential equations, such as the Navier-Stokes equations. Some complex problems rely on sophisticated algorithms to deal…

Machine Learning · Computer Science 2025-05-21 Paolo Guida , William L. Roberts

Accurate prediction of three-dimensional (3D) wind fields over complex mountainous terrain is essential for renewable energy deployment and regional weather modeling. Traditional computational fluid dynamics (CFD) simulations face two…

Fluid Dynamics · Physics 2026-05-26 Yujia Zhang , Jiaxi Qi , Ruiyan Chen , Yong Liu , Yuzhou Zhang , Lyulin Kuang , Rita Zhang , Shengze Cai

This Ph.D. thesis provides a comprehensive review of the state-of-the-art in the field of Variational Quantum Algorithms and Quantum Machine Learning, including numerous original contributions. The first chapters are devoted to a brief…

Quantum Physics · Physics 2023-06-19 Stefano Mangini

Computational Fluid Dynamics (CFD) plays a pivotal role in fluid mechanics, enabling precise simulations of fluid behavior through partial differential equations (PDEs). However, traditional CFD methods are resource-intensive, particularly…

Computational Engineering, Finance, and Science · Computer Science 2025-02-06 Tiffany Fan , Murray Cutforth , Marta D'Elia , Alexandre Cortiella , Alireza Doostan , Eric Darve

This paper derives a new directional uncertainty principle for quaternion valued functions subject to the quaternion Fourier transformation. This can be generalized to establish directional uncertainty principles in Clifford geometric…

Rings and Algebras · Mathematics 2013-06-07 Eckhard Hitzer

This paper introduces feature gradient flow, a new technique for interpreting deep learning models in terms of features that are understandable to humans. The gradient flow of a model locally defines nonlinear coordinates in the input data…

Image and Video Processing · Electrical Eng. & Systems 2023-07-26 Yinzhu Jin , Jonathan C. Garneau , P. Thomas Fletcher

Data-driven prediction of fluid flow and temperature distribution in marine and aerospace engineering has received extensive research and demonstrated its potential in real-time prediction recently. However, usually large amounts of…

Fluid Dynamics · Physics 2023-08-02 Yanfang Lyu , Xiaoyu Zhao , Zhiqiang Gong , Xiao Kang , Wen Yao

We describe in detail the implementation of a systematic perturbative approach to observables in the QCD gradient-flow formalism. This includes a collection of all relevant Feynman rules of the five-dimensional field theory and the…

High Energy Physics - Lattice · Physics 2022-10-12 Johannes Artz , Robert V. Harlander , Fabian Lange , Tobias Neumann , Mario Prausa

Data assimilation (DA) is crucial for enhancing solutions to partial differential equations (PDEs), such as those in numerical weather prediction, by optimizing initial conditions using observational data. Variational DA methods are widely…

Machine Learning · Computer Science 2025-09-30 Hamidreza Moazzami , Asma Jamali , Nicholas Kevlahan , Rodrigo A. Vargas-Hernández

Learning from data in the quaternion domain enables us to exploit internal dependencies of 4D signals and treating them as a single entity. One of the models that perfectly suits with quaternion-valued data processing is represented by 3D…

Audio and Speech Processing · Electrical Eng. & Systems 2022-12-16 Danilo Comminiello , Marco Lella , Simone Scardapane , Aurelio Uncini

The gradient-flow formalism proves to be a useful tool in lattice calculations of quantum chromodynamics. For example, it can be used as a scheme to renormalize composite operators by inverting the short-flow-time expansion of the…

High Energy Physics - Lattice · Physics 2024-11-05 Janosch Borgulat , Robert V. Harlander , Jonas T. Kohnen , Fabian Lange