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Computations of incompressible flows with velocity boundary conditions require solution of a Poisson equation for pressure with all Neumann boundary conditions. Discretization of such a Poisson equation results in a rank-deficient matrix of…

Numerical Analysis · Mathematics 2022-02-08 Shantanu Shahane , Surya Pratap Vanka

The speed of sound in two-phase pipe flow systems is often several orders of magnitude greater than the travelling speed of hydraulic information (volume fractions.) Dynamically simulating such flows requires resolution of acoustic and…

Computational Physics · Physics 2018-11-30 Andreas Holm Akselsen

Observing and studying the evolution of rare non-repetitive natural phenomena such as optical rogue waves or dynamic chemical processes in living cells is a crucial necessity for developing science and technologies relating to them. One…

Optics · Physics 2020-04-22 Farshid Shateri , Shiva Behzadfar , Zahra Kavehvash

We study the nonparametric estimation of the jump density of a compound Poisson process from the discrete observation of one trajectory over $[0,T]$. We consider the microscopic regime when the sampling rate $\Delta=\Delta_T\rightarrow0$ as…

Statistics Theory · Mathematics 2012-03-15 Céline Duval

With the rising of modern data science, data--driven turbulence modeling with the aid of machine learning algorithms is becoming a new promising field. Many approaches are able to achieve better Reynolds stress prediction, with much lower…

Fluid Dynamics · Physics 2020-06-19 Xianwen Guo , Zhenhua Xia , Heng Xiao , Jinlong Wu , Shiyi Chen

The purpose of this paper is to estimate the intensity of a Poisson process $N$ by using thresholding rules. In this paper, the intensity, defined as the derivative of the mean measure of $N$ with respect to $ndx$ where $n$ is a fixed…

Statistics Theory · Mathematics 2008-01-22 Patricia Reynaud-Bouret , Vincent Rivoirard

We consider the problem of estimating parameters in large-scale weakly nonlinear inverse problems for which the underlying governing equations is a linear, time-dependent, parabolic partial differential equation. A major challenge in…

Numerical Analysis · Mathematics 2016-05-04 Tania Bakhos , Arvind K. Saibaba , Peter K. Kitanidis

Physics-informed neural networks (PINNs) have been widely used to solve partial differential equations in a forward and inverse manner using deep neural networks. However, training these networks can be challenging for multiscale problems.…

Fluid Dynamics · Physics 2023-02-01 Sukirt Thakur , Maziar Raissi , Harsa Mitra , Arezoo Ardekani

Reconstruction error bounds in compressed sensing under Gaussian or uniform bounded noise do not translate easily to the case of Poisson noise. Reasons for this include the signal dependent nature of Poisson noise, and also the fact that…

Information Theory · Computer Science 2017-09-26 Sukanya Patil , Karthik Gurumoorthy , Ajit Rajwade

This paper considers the noisy sparse phase retrieval problem: recovering a sparse signal $x \in \mathbb{R}^p$ from noisy quadratic measurements $y_j = (a_j' x )^2 + \epsilon_j$, $j=1, \ldots, m$, with independent sub-exponential noise…

Statistics Theory · Mathematics 2015-06-11 T. Tony Cai , Xiaodong Li , Zongming Ma

A compound Poisson process whose jump measure and intensity are unknown is observed at finitely many equispaced times. We construct a purely data-driven estimator of the L\'evy density $\nu$ through the spectral approach using general…

Statistics Theory · Mathematics 2019-02-12 Alberto J. Coca

We study the quickest detection problem of a sudden change in the arrival rate of a Poisson process from a known value to an unknown and unobservable value at an unknown and unobservable disorder time. Our objective is to design an alarm…

Probability · Mathematics 2007-08-03 Erhan Bayraktar , Savas Dayanik , Ioannis Karatzas

We consider error estimates for the fully discretized instationary Navier-Stokes problem. For the spatial approximation we use conforming inf-sup stable finite element methods in conjunction with grad-div and local projection stabilization…

Numerical Analysis · Mathematics 2016-09-06 Daniel Arndt , Helene Dallmann , Gert Lube

Data assimilation (DA) plays a crucial role in extracting valuable information from flow measurements in fluid dynamics problems. Often only time-averaged data is available, which poses challenges for DA in the context of unsteady flow…

Fluid Dynamics · Physics 2024-05-30 Justin Plogmann , Oliver Brenner , Patrick Jenny

Non-convex constraints have recently proven a valuable tool in many optimisation problems. In particular sparsity constraints have had a significant impact on sampling theory, where they are used in Compressed Sensing and allow structured…

Information Theory · Computer Science 2012-05-09 Thomas Blumensath

This paper presents a new resolution strategy for multi-scale streamer discharge simulations based on a second order time adaptive integration and space adaptive multiresolution. A classical fluid model is used to describe plasma…

Numerical Analysis · Mathematics 2012-04-10 Max Duarte , Zdenek Bonaventura , Marc Massot , Anne Bourdon , Stéphane Descombes , Thierry Dumont

In this paper, the pressure correctionfinite element method is proposed for the 2D/3D time-dependent thermomicropolarfluid equations. Thefirst-order and second-order backward difference formulas (BDF) are adopted to approximate the time…

Numerical Analysis · Mathematics 2022-03-30 Yuhang Ren , Demin Liu

Recent research has shown that performance in signal processing tasks can often be significantly improved by using signal models based on sparse representations, where a signal is approximated using a small number of elements from a fixed…

Optimization and Control · Mathematics 2011-11-18 Adam S. Charles , Pierre Garrigues , Christopher J. Rozell

This paper investigates the asymptotic behavior of solutions to the steady pressure-free Prandtl system. By employing a modified von Mises transformation, we rigorously prove the far-field convergence of Prandtl solutions to Blasius flow. A…

Analysis of PDEs · Mathematics 2025-05-13 Chen Gao , Chuankai Zhao

We provide a detailed comparison of the two-dimensional, temporal and the spatiotemporal linearized analyses of the viscoelastic free shear flows in the limit of low to moderate Reynolds number and Elasticity number obeying four different…

Fluid Dynamics · Physics 2021-06-02 Diksha Bansal , Dipa Ghosh , Sarthok Sircar