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We investigate the reconstruction of a turbulent flow field in the atmospheric boundary layer from a time series of lidar measurements, using Large-Eddy Simulations (LES) and a 4D-Var data assimilation algorithm. This leads to an…

Fluid Dynamics · Physics 2020-11-17 Pieter Bauweraerts , Johan Meyers

Reconstructing the mass density, velocity, and tidal (MTV) fields of dark matter from galaxy surveys is essential for advancing our understanding of the LSS of the Universe. In this work, we present a machine learning-based framework using…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-27 Feng Shi , Zitong Wang , Xiaohu Yang , Yizhou Gu , Chengliang Wei , Ming Li , Jiaxin Han , Zhejie Ding , Huiyuan Wang , Youcai Zhang , Wensheng Hong , Yirong Wang , Xiao-dong Li

In this paper we survey the various implementations of a new data assimilation (downscaling) algorithm based on spatial coarse mesh measurements. As a paradigm, we demonstrate the application of this algorithm to the 3D Leray-$\alpha$…

Analysis of PDEs · Mathematics 2017-02-07 Aseel Farhat , Evelyn Lunasin , Edriss S. Titi

The principles of measuring the shapes of galaxies by a model-fitting approach are discussed in the context of shape-measurement for surveys of weak gravitational lensing. It is argued that such an approach should be optimal, allowing…

Astrophysics · Physics 2009-11-13 L. Miller , T. D. Kitching , C. Heymans , A. F. Heavens , L. Van Waerbeke

3D reconstruction is a fundamental task in robotics that gained attention due to its major impact in a wide variety of practical settings, including agriculture, underwater, and urban environments. This task can be carried out via view…

Accurate analyses of present and next-generation galaxy surveys require new ways to handle effects of non-linear gravitational structure formation in data. To address these needs we present an extension of our previously developed algorithm…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-15 Jens Jasche , Guilhem Lavaux

Neural implicit surface representation methods have recently shown impressive 3D reconstruction results. However, existing solutions struggle to reconstruct driving scenes due to their large size, highly complex nature and their limited…

Computer Vision and Pattern Recognition · Computer Science 2025-03-19 Hala Djeghim , Nathan Piasco , Moussab Bennehar , Luis Roldão , Dzmitry Tsishkou , Désiré Sidibé

We investigate distortions in the velocity fields of disc galaxies and their use to reveal the dynamical state of interacting galaxies at different redshift. For that purpose, we model disc galaxies in combined N-body/hydrodynamic…

Astrophysics · Physics 2009-11-13 T. Kronberger , W. Kapferer , S. Schindler , B. L. Ziegler

Many algorithms for the computation of correspondences between deformable shapes rely on some variant of nearest neighbor matching in a descriptor space. Such are, for example, various point-wise correspondence recovery algorithms used as a…

Computer Vision and Pattern Recognition · Computer Science 2016-07-13 Matthias Vestner , Roee Litman , Alex Bronstein , Emanuele Rodolà , Daniel Cremers

We compare Tully-Fisher (TF) data for 838 galaxies within cz=3000 km/sec from the Mark III catalog to the peculiar velocity and density fields predicted from the 1.2 Jy IRAS redshift survey. Our goal is to test the relation between the…

Astrophysics · Physics 2009-10-28 Jeffrey A. Willick , Michael A. Strauss , Avishai Dekel , Tsafrir Kolatt

Reconstructing the density fluctuations in the early Universe that evolved into the distribution of galaxies we see today is a challenge of modern cosmology [ref.]. An accurate reconstruction would allow us to test cosmological models by…

Astrophysics · Physics 2015-06-24 Uriel Frisch , Sabino Matarrese , Roya Mohayaee , Andrei Sobolevski

Lagrangian reconstruction of large-scale peculiar velocity fields can be strongly affected by observational biases. We develop a thorough analysis of these systematic effects by relying on specially selected mock catalogues. For the purpose…

Astrophysics · Physics 2009-11-13 G. Lavaux , R. Mohayaee , S. Colombi , R. B. Tully , F. Bernardeau , J. Silk

The dark sirens method combines gravitational waves and catalogs of galaxies to constrain the cosmological expansion history, merger rates and mass distributions of compact objects, and the laws of gravity. However, the incompleteness of…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-09 Konstantin Leyde , Tessa Baker , Wolfgang Enzi

Particle Imaging Velocimetry (PIV) estimates the flow of fluid by analyzing the motion of injected particles. The problem is challenging as the particles lie at different depths but have similar appearance and tracking a large number of…

Computer Vision and Pattern Recognition · Computer Science 2020-03-24 Zhong Li , Jinwei Ye , Yu Ji , Hao Sheng , Jingyi Yu

Integral field spectroscopy of high-redshift galaxies has become a powerful tool for understanding their dynamics and evolutionary states. However, in the case of gravitationally lensed systems, it has proved difficult to model both lensing…

Astrophysics of Galaxies · Physics 2022-04-13 Anthony J. Young , Charles R. Keeton , Andrew J. Baker

Our aim is to present a fast and general Bayesian inference framework based on the synergy between machine learning techniques and standard sampling methods and apply it to infer the physical properties of clumpy dusty torus using infrared…

Instrumentation and Methods for Astrophysics · Physics 2011-02-11 A. Asensio Ramos , C. Ramos Almeida

Fitting parameterized models to images of galaxies has become the standard for measuring galaxy morphology. This forward modelling technique allows one to account for the PSF to effectively study semi-resolved galaxies. However, using a…

Astrophysics of Galaxies · Physics 2021-12-22 Tim B. Miller , Pieter van Dokkum

This is the third in a series of papers in which we assemble and analyze a homogeneous catalog of peculiar velocity data. In Papers I and II, we described the Tully-Fisher (TF) redshift-distance samples that constitute the bulk of the…

We present a new method for extracting the true 3-d velocity and density fields from the nonlinear redshift--space projected density field. The method is based on the nonlinear, nonlocal transformation of the density field. We assume a…

Astrophysics · Physics 2015-06-24 A. N. Taylor , M. Rowan-Robinson

We study methods for reconstructing Bayesian uncertainties on dynamical mass estimates of galaxy clusters using convolutional neural networks (CNNs). We discuss the statistical background of approximate Bayesian neural networks and…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-16 Matthew Ho , Arya Farahi , Markus Michael Rau , Hy Trac