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It is well-known in the modified gravity scene that the calculation of junction conditions in certain complicated theories leads to ambiguities and conflicts between the various formulations. This paper introduces a general framework to…

General Relativity and Quantum Cosmology · Physics 2024-06-26 Bence Racskó

Diffusion models are getting popular in generative image and video synthesis. However, due to the diffusion process, they require a large number of steps to converge. To tackle this issue, in this paper, we propose to perform the diffusion…

Computer Vision and Pattern Recognition · Computer Science 2023-09-06 Yuanhao Gong

Diffusion models have emerged as powerful tools for solving inverse problems, yet prior work has primarily focused on observations with Gaussian measurement noise, restricting their use in real-world scenarios. This limitation persists due…

Machine Learning · Statistics 2025-02-11 Alessandro Micheli , Mélodie Monod , Samir Bhatt

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

We present an extension to the Poisson-Boltzmann model where the dipolar features of solvent molecules are taken explicitly into account. The formulation is derived at mean-field level and can be extended to any order in a systematic…

Soft Condensed Matter · Physics 2012-01-31 Ariel Abrashkin , David Andelman , Henri Orland

Using the Newman and Penrose spin coefficient (NP) formalism, we examine the full Bianchi identities of general relativity in the context of gravitational lensing, where the matter and space-time curvature are projected into a lens plane…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Thomas P. Kling , Bryan Campbell

The special relativistic hydrodynamics with weak gravity is hitherto unknown in the literature. Whether such an asymmetric combination is possible was unclear. Here, the hydrodynamic equations with Poisson-type gravity considering fully…

General Relativity and Quantum Cosmology · Physics 2016-12-21 Jai-chan Hwang , Hyerim Noh

Linear systems occur throughout engineering and the sciences, most notably as differential equations. In many cases the forcing function for the system is unknown, and interest lies in using noisy observations of the system to infer the…

The method of characteristics is a classical method for gaining understanding in the solution of a partial differential equation. It has recently been applied to the adjoint equations of the 2D Euler equations and the first goal of this…

Fluid Dynamics · Physics 2023-05-08 Kevin Ancourt , Jacques Peter , Olivier Atinault

This work presents an illustrative application of the second-order adjoint sensitivity analysis procedure (SO-ASAP) to a paradigm neutron diffusion problem, which is sufficiently simple to admit an exact solution, thereby making transparent…

Mathematical Physics · Physics 2015-05-20 Dan G. Cacuci

The conjugate gradient method is a widely used algorithm for the numerical solution of a system of linear equations. It is particularly attractive because it allows one to take advantage of sparse matrices and produces (in case of infinite…

Numerical Analysis · Mathematics 2017-11-27 Sergey Voronin , Christophe Zaroli , Naresh P. Cuntoor

In high-temperature plasma physics, a strong magnetic field is usually used to confine charged particles. Therefore, for studying the classical mathematical models of the physical problems it is needed to consider the effect of external…

Numerical Analysis · Mathematics 2023-10-11 Anjiao Gu , Yajuan Sun

The problem of phase retrieval has many applications in the field of optical imaging. Motivated by imaging experiments with biological specimens, we primarily consider the setting of low-dose illumination where Poisson noise plays the…

Numerical Analysis · Mathematics 2024-03-28 Benedikt Diederichs , Frank Filbir , Patricia Römer

In the optimization of turbomachinery components, shape sensitivities for fluid dynamical objective functions have been used for a long time. As peak stress is not a differential func- tional of the shape, such highly efficient procedures…

Numerical Analysis · Mathematics 2018-02-15 Hanno Gottschalk , Mohamed Saadi , Onur Tanil Doganay , Kathrin Klamroth , Sebastian Schmitz

We develop and analyse finite volume methods for the Poisson problem with boundary conditions involving oblique derivatives. We design a generic framework, for finite volume discretisations of such models, in which internal fluxes are not…

Numerical Analysis · Mathematics 2019-08-12 Jerome Droniou , Matej Medla , Karol Mikula

We consider the non-relativistic limit of general relativity coupled to a $(p+1)$-form gauge field and a scalar field in arbitrary dimensions and investigate under which conditions this gives rise to a Poisson equation for a Newton…

High Energy Physics - Theory · Physics 2024-10-02 Eric A. Bergshoeff , Giacomo Giorgi , Luca Romano

Mean-Field is an efficient way to approximate a posterior distribution in complex graphical models and constitutes the most popular class of Bayesian variational approximation methods. In most applications, the mean field distribution…

Machine Learning · Computer Science 2015-02-23 Pierre Baqué , Jean-Hubert Hours , François Fleuret , Pascal Fua

In this paper we show how to augment classical methods for inverse problems with artificial neural networks. The neural network acts as a prior for the coefficient to be estimated from noisy data. Neural networks are global, smooth function…

Machine Learning · Statistics 2018-09-17 Jens Berg , Kaj Nyström

We review the methods of constructing confidence intervals that account for a priori information about one-sided constraints on the parameter being estimated. We show that the so-called method of sensitivity limit yields a correct solution…

Data Analysis, Statistics and Probability · Physics 2015-05-20 A. V. Lokhov , F. V. Tkachov

In this paper we outline equipotential and equidensity methods of constructing axisymmetric models for galaxies. The former method defines equipotentials, from which the corresponding densities of the galaxy models can be obtained using…

Astrophysics · Physics 2008-06-10 Zhenglu Jiang , Daoyuan Fang , David Moss
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