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Solving the Euler equations of ideal hydrodynamics as accurately and efficiently as possible is a key requirement in many astrophysical simulations. It is therefore important to continuously advance the numerical methods implemented in…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-02 Kevin Schaal , Andreas Bauer , Praveen Chandrashekar , Rüdiger Pakmor , Christian Klingenberg , Volker Springel

We present a class of high order finite volume schemes for the solution of non-conservative hyperbolic systems that combines the one-step ADER-WENO finite volume approach with space-time adaptive mesh refinement (AMR). The resulting…

Numerical Analysis · Mathematics 2015-06-15 Michael Dumbser , Arturo Hidalgo , Olindo Zanotti

We present first results obtained with a 3+1 dimensional adaptive mesh code in numerical general relativity. The adaptive mesh is used in conjunction with a standard ADM code for the evolution of a dynamically sliced Schwarzschild spacetime…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Bernd Bruegmann

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 a corrective function to compensate errors in contact area computations coming from mesh discretization. The correction is based on geometrical arguments and requires only one additional quantity to be computed: the length of…

Soft Condensed Matter · Physics 2017-04-24 Vladislav A. Yastrebov , Guillaume Anciaux , Jean-Francois Molinari

We study the numerical solution of a Cahn-Hilliard/Allen-Cahn system with strong coupling through state and gradient dependent non-diagonal mobility matrices. A fully discrete approximation scheme in space and time is proposed which…

Numerical Analysis · Mathematics 2024-08-02 Aaron Brunk , Herbert Egger , Oliver Habrich

Convergence failure and slow convergence rate are among the biggest challenges with solving the system of non-linear equations numerically. While using strictly small time steps sizes and unconditionally stable fully implicit scheme…

Numerical Analysis · Mathematics 2024-12-20 Hanyu Li , Mary F. Wheeler

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

We present a modification to the Berger and Oliger adaptive mesh refinement algorithm designed to solve systems of coupled, non-linear, hyperbolic and elliptic partial differential equations. Such systems typically arise during constrained…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Frans Pretorius , Matthew W. Choptuik

The high repair cost of (n,k) Maximum Distance Separable (MDS) erasure codes has recently motivated a new class of codes, called Regenerating Codes, that optimally trade off storage cost for repair bandwidth. On one end of this spectrum of…

Information Theory · Computer Science 2010-04-19 Changho Suh , Kannan Ramchandran

The study of regenerating codes has advanced tremendously in recent years. However, most known constructions require large field size, and hence may be hard to implement in practice. By using notions from the theory of extension fields, we…

Information Theory · Computer Science 2016-09-22 Netanel Raviv

Samples from a high-dimensional AR[1] process are observed by a sender which can communicate only finitely many bits per unit time to a receiver. The receiver seeks to form an estimate of the process value at every time instant in…

Information Theory · Computer Science 2022-02-01 Rooji Jinan , Parimal Parag , Himanshu Tyagi

The rigorous convergence analysis of adaptive finite element methods for regularized variational models of quasi-static brittle fracture in strain-limiting elastic solids is presented. This work introduces two novel adaptive mesh refinement…

Numerical Analysis · Mathematics 2025-11-19 Ram Manohar , S. M. Mallikarjunaiah

The convergence analysis for least-squares finite element methods led to various adaptive mesh-refinement strategies: Collective marking algorithms driven by the built-in a posteriori error estimator or an alternative explicit…

Numerical Analysis · Mathematics 2023-09-18 Philipp Bringmann

With the forthcoming VLBI images of Sgr A* and M87, simulations of accretion flows onto black holes acquire a special importance to aid with the interpretation of the observations and to test the predictions of different accretion…

General Relativity and Quantum Cosmology · Physics 2019-10-09 Hector Olivares , Oliver Porth , Yosuke Mizuno

We present an adaptive space-time mesh refinement approach based a domain decomposition approach (Singh and Wheeler, 2018) that allows different time-step sizes and mesh refinements in different subdomains. Our numerical experiments…

Numerical Analysis · Mathematics 2018-09-10 Gurpreet Singh , Mary F. Wheeler

Adaptive interface-Mesh un-Refinement (AiMuR) based Sharp-Interface Level-Set-Method (SI-LSM) is proposed for both uniform and non-uniform Cartesian-Grid. The AiMuR involves interface location based dynamic un-refinement (with merging of…

Fluid Dynamics · Physics 2021-11-09 Kuntal Patel , Javed Shaikh , Absar Lakdawala , Atul Sharma

\emph{Multiresolution mode decomposition} (MMD) is an adaptive tool to analyze a time series $f(t)=\sum_{k=1}^K f_k(t)$, where $f_k(t)$ is a \emph{multiresolution intrinsic mode function} (MIMF) of the form \begin{eqnarray*}…

Numerical Analysis · Mathematics 2018-10-10 Gao Tang , Haizhao Yang

Klein-Gordon equations describe the dynamics of waves/particles in sub-atomic scales. For a system of nonlinear Klein-Gordon equations, a systematic analysis of the time evolution for their spatially uniform solutions has been performed…

Mathematical Physics · Physics 2023-10-03 Yasuhiro Takei , Yoritaka Iwata

We propose a new self-adaptive, double-loop smoothing algorithm to solve composite, nonsmooth, and constrained convex optimization problems. Our algorithm is based on Nesterov's smoothing technique via general Bregman distance functions. It…

Optimization and Control · Mathematics 2018-08-15 Quoc Tran-Dinh , Ahmet Alacaoglu , Olivier Fercoq , Volkan Cevher