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Regularization method and Bayesian inverse method are two dominating ways for solving inverse problems generated from various fields, e.g., seismic exploration and medical imaging. The two methods are related with each other by the MAP…

Numerical Analysis · Mathematics 2019-06-18 Junxiong Jia , Qihang Sun , Bangyu Wu , Jigen Peng

To backpropagate the gradients through stochastic binary layers, we propose the augment-REINFORCE-merge (ARM) estimator that is unbiased, exhibits low variance, and has low computational complexity. Exploiting variable augmentation,…

Machine Learning · Statistics 2019-09-11 Mingzhang Yin , Mingyuan Zhou

We introduce CRASH-AMR, a new version of the cosmological Radiative Transfer (RT) code CRASH, enabled to use refined grids. This new feature allows us to attain higher resolution in our RT simulations and thus to describe more accurately…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-01 N. Hariharan , L. Graziani , B. Ciardi , F. Miniati , H. -J. Bungartz

We introduce adaptive particle refinement for compressible smoothed particle hydrodynamics (SPH). SPH calculations have the natural advantage that resolution follows mass, but this is not always optimal. Our implementation allows the user…

Instrumentation and Methods for Astrophysics · Physics 2024-09-19 Rebecca Nealon , Daniel Price

Optimizing machine learning algorithms that are used to solve the objective function has been of great interest. Several approaches to optimize common algorithms, such as gradient descent and stochastic gradient descent, were explored. One…

Machine Learning · Computer Science 2022-10-06 Hilal AlQuabeh , Farha AlBreiki , Dilshod Azizov

We implement general relativistic hydrodynamics in the moving-mesh code AREPO. We also couple a solver for the Einstein field equations employing the conformal flatness approximation. The implementation is validated by evolving isolated…

High Energy Astrophysical Phenomena · Physics 2024-01-10 Georgios Lioutas , Andreas Bauswein , Theodoros Soultanis , Rüdiger Pakmor , Volker Springel , Friedrich K. Röpke

We have written and tested a new general relativistic magnetohydrodynamics (GRMHD) code, capable of evolving MHD fluids in dynamical spacetimes with adaptive-mesh refinement (AMR). Our code solves the Einstein-Maxwell-MHD system of coupled…

High Energy Astrophysical Phenomena · Physics 2010-10-27 Zachariah B. Etienne , Yuk Tung Liu , Stuart L. Shapiro

A covariant energy density functional is calibrated using a principled Bayesian statistical framework informed by experimental binding energies and charge radii of several magic and semi-magic nuclei. The Bayesian sampling required for the…

Nuclear Theory · Physics 2022-09-28 Pablo Giuliani , Kyle Godbey , Edgard Bonilla , Frederi Viens , Jorge Piekarewicz

Full interpretation of data from gravitational wave observations will require accurate numerical simulations of source systems, particularly binary black hole mergers. A leading approach to improving accuracy in numerical relativity…

General Relativity and Quantum Cosmology · Physics 2013-05-29 John G. Baker , James R. van Meter

This work is focused on the extension and assessment of the monotonicity-preserving scheme in [3] and the local bounds preserving scheme in [5] to hierarchical octree adaptive mesh refinement (AMR). Whereas the former can readily be used on…

Numerical Analysis · Mathematics 2020-06-24 Jesus Bonilla , Santiago Badia

We present an adaptive regularization scheme for optimizing composite energy functionals arising in image analysis problems. The scheme automatically trades off data fidelity and regularization depending on the current data fit during the…

Computer Vision and Pattern Recognition · Computer Science 2017-05-10 Byung-Woo Hong , Ja-Keoung Koo , Martin Burger , Stefano Soatto

In many areas of science, complex phenomena are modeled by stochastic parametric simulators, often featuring high-dimensional parameter spaces and intractable likelihoods. In this context, performing Bayesian inference can be challenging.…

Machine Learning · Computer Science 2021-11-10 François Rozet , Gilles Louppe

Recent accelerated MRI reconstruction models have used Deep Neural Networks (DNNs) to reconstruct relatively high-quality images from highly undersampled k-space data, enabling much faster MRI scanning. However, these techniques sometimes…

Image and Video Processing · Electrical Eng. & Systems 2021-04-12 Itzik Malkiel , Sangtae Ahn , Valentina Taviani , Anne Menini , Lior Wolf , Christopher J. Hardy

This research presents the development of an innovative algorithm tailored for the adaptive sampling of residual points within the framework of Physics-Informed Neural Networks (PINNs). By addressing the limitations inherent in existing…

Machine Learning · Computer Science 2023-06-16 Shikhar Nilabh , Fidel Grandia

We present the implementation of a three-dimensional, second order accurate Godunov-type algorithm for magneto-hydrodynamic (MHD), in the adaptive-mesh-refinement (AMR) cosmological code {\tt CHARM}. The algorithm is based on the full…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Francesco Miniati , Daniel F. Martin

Multi-resolution methods such as Adaptive Mesh Refinement (AMR) can enhance storage efficiency for HPC applications generating vast volumes of data. However, their applicability is limited and cannot be universally deployed across all…

Distributed, Parallel, and Cluster Computing · Computer Science 2024-10-02 Daoce Wang , Pascal Grosset , Jesus Pulido , Tushar M. Athawale , Jiannan Tian , Kai Zhao , Zarija Lukić , Axel Huebl , Zhe Wang , James Ahrens , Dingwen Tao

This paper describes the generation of initial conditions for numerical simulations in cosmology with multiple levels of resolution, or multiscale simulations. We present the theory of adaptive mesh refinement of Gaussian random fields…

Astrophysics · Physics 2009-07-09 Edmund Bertschinger

We present new results characterizing cosmological shocks within adaptive mesh refinement N-Body/hydrodynamic simulations that are used to predict non-thermal components of large-scale structure. This represents the first study of shocks…

Modeling quantum many-body systems is enormously challenging due to the exponential scaling of Hilbert dimension with system size. Finding efficient compressions of the wavefunction is key to building scalable models. Here, we introduce…

Computational Physics · Physics 2020-03-16 Christopher Roth

This paper presents an advancement to an approach for model-independent surrogate-based optimization with adaptive batch sampling, known as Adaptive Model Refinement (AMR). While the original AMR method provides unique decisions with…

Optimization and Control · Mathematics 2019-06-04 Payam Ghassemi , Sumeet Sanjay Lulekar , Souma Chowdhury
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