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The Riemann problem is fundamental in the computational modeling of hyperbolic partial differential equations, enabling the development of stable and accurate upwind schemes. While exact solvers provide robust upwinding fluxes, their high…

Numerical Analysis · Mathematics 2025-11-26 Akshay Thakur , Matthew J. Zahr

We obtain estimates of the multiplicative constants appearing in local convergence results of the Riemannian Gauss-Newton method for least squares problems on manifolds and relate them to the geometric condition number of [P. B\"urgisser…

Numerical Analysis · Mathematics 2022-09-02 Paul Breiding , Nick Vannieuwenhoven

Problems with localized nonhomogeneous material properties present well-known challenges for numerical simulations. In particular, such problems may feature large differences in length scales, causing difficulties with meshing and…

Numerical Analysis · Mathematics 2021-11-23 Alex Viguerie , Silvia Bertoluzza , Alessandro Veneziani , Ferdinando Auricchio

A network-based analysis of a turbulent channel flow numerically solved at $Re_\tau=180$ is proposed as an innovative perspective for the spatial characterization of the flow field. Two spatial networks corresponding to the streamwise and…

Fluid Dynamics · Physics 2018-08-31 Giovanni Iacobello , Stefania Scarsoglio , J. G. M. Kuerten , Luca Ridolfi

We propose Riemannian Flow Matching (RFM), a simple yet powerful framework for training continuous normalizing flows on manifolds. Existing methods for generative modeling on manifolds either require expensive simulation, are inherently…

Machine Learning · Computer Science 2024-02-27 Ricky T. Q. Chen , Yaron Lipman

The shear shallow water model is a higher order model for shallow flows which includes some shear effects that are neglected in the classical shallow models. The model is a non-conservative hyperbolic system which can admit shocks,…

Numerical Analysis · Mathematics 2022-04-08 Boniface Nkonga , Praveen Chandrashekar

With the rapid increase in mobile subscribers, there is a drive towards achieving higher data rates, prompting the use of higher frequencies in future wireless communication technologies. Wave propagation channel modeling for these…

Signal Processing · Electrical Eng. & Systems 2024-06-13 Xueyun Long , Amina Fellan , Mario Pauli , Hans D. Schotten , Thomas Zwick

This work deals with the one-dimensional Stefan problem with a general time-dependent boundary condition at the fixed boundary. Stochastic solutions are obtained using discrete random walks, and the results are compared with analytic…

Analysis of PDEs · Mathematics 2023-02-06 M. Ogren

In physically inviscid fluid dynamics, "shock capturing" methods adopt either an artificial viscosity contribution or an appropriate Riemann solver algorithm. These techniques are necessary to solve the strictly hyperbolic Euler equations…

Fluid Dynamics · Physics 2015-05-18 G. Lanzafame

In this paper, we study a sampling problem where a source takes samples from a Wiener process and transmits them through a wireless channel to a remote estimator. Due to channel fading, interference, and potential collisions, the packet…

Information Theory · Computer Science 2023-10-19 Jiayu Pan , Yin Sun , Ness B. Shroff

In this work, a new Bayesian framework for OFDM channel estimation is proposed. Using Jaynes' maximum entropy principle to derive prior information, we successively tackle the situations when only the channel delay spread is a priori known,…

Information Theory · Computer Science 2008-11-06 Romain Couillet , Merouane Debbah

We present a rigorous approach and related techniques to construct global solutions of the 2-D Riemann problem with four-shock interactions for the Euler equations for potential flow. With the introduction of three critical angles: the…

Analysis of PDEs · Mathematics 2023-05-25 Gui-Qiang G. Chen , Alexander Cliffe , Feimin Huang , Song Liu , Qin Wang

Random networks are a powerful tool in the analytical modeling of complex networks as they allow us to write approximate mathematical models for diverse properties and behaviors of networks. One notable shortcoming of these models is that…

Physics and Society · Physics 2023-07-10 Laurent Hébert-Dufresne , Márton Pósfai , Antoine Allard

By restricting the iterate on a nonlinear manifold, the recently proposed Riemannian optimization methods prove to be both efficient and effective in low rank tensor completion problems. However, existing methods fail to exploit the easily…

Machine Learning · Statistics 2017-02-24 Tengfei Zhou , Hui Qian , Zebang Shen , Congfu Xu

We present a scheme for simulating conditioned semimartingales taking values in Riemannian manifolds. Extending the guided bridge proposal approach used for simulating Euclidean bridges, the scheme replaces the drift of the conditioned…

Numerical Analysis · Mathematics 2023-02-16 Mathias Højgaard Jensen , Stefan Sommer

In this work, we consider the bilevel optimization problem on Riemannian manifolds. We inspect the calculation of the hypergradient of such problems on general manifolds and thus enable the utilization of gradient-based algorithms to solve…

Optimization and Control · Mathematics 2024-02-09 Jiaxiang Li , Shiqian Ma

We consider the problem of density estimation on Riemannian manifolds. Density estimation on manifolds has many applications in fluid-mechanics, optics and plasma physics and it appears often when dealing with angular variables (such as…

Machine Learning · Statistics 2016-11-10 Mevlana C. Gemici , Danilo Rezende , Shakir Mohamed

We investigate the Riemann problem for the shallow water equations with variable and (possibly) discontinuous topography and provide a complete description of the properties of its solutions: existence; uniqueness in the non-resonant…

Analysis of PDEs · Mathematics 2015-05-28 Philippe G. LeFloch , Mai Duc Thanh

Exploring the free-energy landscape along reaction coordinates or system parameters $\lambda$ is central to many studies of high-dimensional model systems in physics, e.g. large molecules or spin glasses. In simulations this usually…

Statistical Mechanics · Physics 2018-09-05 Viveca Lindahl , Jack Lidmar , Berk Hess

Conjugate gradient (CG) methods are widely acknowledged as efficient for minimizing continuously differentiable functions in Euclidean spaces. In recent years, various CG methods have been extended to Riemannian manifold optimization, but…

Optimization and Control · Mathematics 2026-05-26 Chunming Tang , Shaohui Liang , Huangyue Chen
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