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Sensitivity analysis, especially adjoint based sensitivity analysis, is a powerful tool for engineering design which allows for the efficient computation of sensitivities with respect to many parameters. However, these methods break down…

Dynamical Systems · Mathematics 2015-06-16 Patrick Blonigan , Qiqi Wang

We consider the problem of learning stabilizable systems governed by nonlinear state equation $h_{t+1}=\phi(h_t,u_t;\theta)+w_t$. Here $\theta$ is the unknown system dynamics, $h_t $ is the state, $u_t$ is the input and $w_t$ is the…

Machine Learning · Computer Science 2021-11-22 Yahya Sattar , Samet Oymak

The development of nonlinear optimization algorithms capable of performing reliably in the presence of noise has garnered considerable attention lately. This paper advocates for strategies to create noise-tolerant nonlinear optimization…

Optimization and Control · Mathematics 2024-10-04 Yuchen Lou , Shigeng Sun , Jorge Nocedal

High fidelity simulations, e.g., large eddy simulation are often needed for accurately predicting pressure losses due to wake mixing in turbomachinery applications. An unsteady adjoint of such high fidelity simulations is useful for design…

Fluid Dynamics · Physics 2015-11-24 Chaitanya Talnikar , Qiqi Wang , Gregory M. Laskowski

Existing customization methods require access to multiple reference examples to align pre-trained diffusion probabilistic models (DPMs) with user-provided concepts. This paper aims to address the challenge of DPM customization when the only…

Computer Vision and Pattern Recognition · Computer Science 2024-03-21 Jiachun Pan , Jun Hao Liew , Vincent Y. F. Tan , Jiashi Feng , Hanshu Yan

Many engineering applications can be formulated as optimizations constrained by conservation laws. Such optimizations can be efficiently solved by the adjoint method, which computes the gradient of the objective to the design variables.…

Optimization and Control · Mathematics 2015-12-24 Han Chen , Qiqi Wang

Uncertainty quantification and sensitivity analyses are a vital component for predictive modeling in the sciences and engineering. The adjoint approach to sensitivity analysis requires solving a primary system of equations and a…

Computational Physics · Physics 2016-12-08 Kelli D. Humbird , Ryan G. McClarren

Systems with time-delayed chaotic dynamics are common in nature, from control theory to aeronautical propulsion. The overarching objective of this paper is to compute the stability properties of a chaotic dynamical system, which is…

Adaptation and Self-Organizing Systems · Physics 2023-03-07 Georgios Margazoglou , Luca Magri

The implementation of the discrete adjoint method for exponential time differencing (ETD) schemes is considered. This is important for parameter estimation problems that are constrained by stiff time-dependent PDEs when the discretized PDE…

Optimization and Control · Mathematics 2016-10-11 Kai Rothauge , Eldad Haber , Uri Ascher

Adjoint methods enable the accurate calculation of the sensitivities of a quantity of interest. The sensitivity is obtained by solving the adjoint system, which can be derived by continuous or discrete adjoint strategies. In acoustic wave…

Computational Physics · Physics 2019-03-28 Luca Magri

The paper contributes to strengthening the relation between machine learning and the theory of differential equations. In this context, the inverse problem of fitting the parameters, and the initial condition of a differential equation to…

Machine Learning · Computer Science 2022-06-22 Imre Fekete , András Molnár , Péter L. Simon

It is a widely accepted fact that data representations intervene noticeably in machine learning tools. The more they are well defined the better the performance results are. Feature extraction-based methods such as autoencoders are…

Neural and Evolutionary Computing · Computer Science 2018-06-12 Naima Chouikhi , Boudour Ammar , Adel M. Alimi

The adjoint method is an efficient way to numerically compute gradients in optimization problems with constraints, but is only formulated to differentiable cost and constraint functions on real variables. With the introduction of complex…

Optimization and Control · Mathematics 2026-01-21 Andrew Zheng , Adam R. Stinchcombe

In real-world applications such as emotion recognition from recorded brain activity, data are captured from electrodes over time. These signals constitute a multidimensional time series. In this paper, Echo State Network (ESN), a recurrent…

Computer Vision and Pattern Recognition · Computer Science 2018-11-26 Rahma Fourati , Boudour Ammar , Javier Sanchez-Medina , Adel M. Alimi

This paper presents the linear theory of adjoint equations as applied to thermo-acoustics. The purpose is to describe the mathematical foundations of adjoint equations for linear sensitivity analysis of thermo-acoustic systems, recently…

Fluid Dynamics · Physics 2014-11-06 Luca Magri , Matthew Juniper

Neural networks trained with standard objectives exhibit behaviors characteristic of probabilistic inference: soft clustering, prototype specialization, and Bayesian uncertainty tracking. These phenomena appear across architectures -- in…

Machine Learning · Computer Science 2026-01-01 Alan Oursland

Designing free-form photonic devices is fundamentally challenging due to the vast number of possible geometries and the complex requirements of fabrication constraints. Traditional inverse-design approaches--whether driven by human…

Optics · Physics 2025-04-25 Dongjin Seo , Soobin Um , Sangbin Lee , Jong Chul Ye , Haejun Chung

Training data-driven turbulence models with high fidelity Reynolds stress can be impractical and recently such models have been trained with velocity and pressure measurements. For gradient-based optimization, such as training deep learning…

Fluid Dynamics · Physics 2021-04-19 Carlos A. Michelén Ströfer , Xin-Lei Zhang , Heng Xiao

We introduce Adjoint Sampling, a highly scalable and efficient algorithm for learning diffusion processes that sample from unnormalized densities, or energy functions. It is the first on-policy approach that allows significantly more…

In recent years, it has been convincingly shown that weather forecasting models can be run in single-precision arithmetic. Several models or components thereof have been tested with even lower precision than this. This previous work has…

Atmospheric and Oceanic Physics · Physics 2020-03-23 Andrew T. T. McRae , Tim N. Palmer