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In Computer Vision, edge detection is one of the favored approaches for feature and object detection in images since it provides information about their objects boundaries. Other region-based approaches use probabilistic analysis such as…

Computer Vision and Pattern Recognition · Computer Science 2019-08-20 Dominique Beaini , Sofiane Achiche , Fabrice Nonez , Maxime Raison

We present a framework for the hierarchical identification and characterization of voids based on the Watershed Void Finder. The Hierarchical Void Finder is based on a generalization of the scale space of a density field invoked in order to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 M. A. Aragon-Calvo , R. van de Weygaert , P. Araya-Melo , E. Platen , A. S. Szalay

Edges, boundaries and contours are important subjects of study in both computer graphics and computer vision. On one hand, they are the 2D elements that convey 3D shapes, on the other hand, they are indicative of occlusion events and thus…

Computer Vision and Pattern Recognition · Computer Science 2019-01-04 Mengtian Li , Zhe Lin , Radomir Mech , Ersin Yumer , Deva Ramanan

A second derivative-based moment method is proposed for describing the thickness and shape of the region where viscous forces are dominant in turbulent boundary layer flows. Rather than the fixed location sublayer model presently employed,…

Fluid Dynamics · Physics 2020-09-21 David Weyburne

The massive exploitation of cosmic voids for precision cosmology in the upcoming dark energy experiments, requires a robust understanding of their internal structure, particularly of their density profile. We show that the void density…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 E. Ricciardelli , V. Quilis , J. Varela

Upcoming surveys such as \LSST{} and \Euclid{} will significantly improve the power of weak lensing as a cosmological probe. To maximise the information that can be extracted from these surveys, it is important to explore novel statistics…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-18 Christopher T. Davies , Marius Cautun , Benjamin Giblin , Baojiu Li , Joachim Harnois-Déraps , Yan-Chuan Cai

The shapes of cosmic voids are prone to distortions by the external tidal forces since their low-densities imply a lower internal resistance. This susceptibility of the void shapes to the tidal distortions makes them useful as an indicator…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Jounghun Lee , Fiona Hoyle

This paper introduces a novel approach to compute the numerical fluxes at the cell boundaries in the finite volume approach. Explicit gradients used in deriving the reconstruction polynomials are replaced by high-order gradients computed by…

Numerical Analysis · Mathematics 2021-06-04 Amareshwara Sainadh Chamarthi , Steven H. Frankel , Abhishek Chintagunta

We present a local detection method for dissipative particle dynamics (DPD) involving arbitrarily shaped geometric three-dimensional domains. By introducing an indicator variable of boundary volume fraction (BVF) for each fluid particle,…

Computational Physics · Physics 2020-05-12 Zhen Li , Xin Bian , Yu-Hang Tang , George Em Karniadakis

Cosmic voids are the largest and most underdense structures in the Universe. Their properties have been shown to encode precious information about the laws and constituents of the Universe. We show that machine learning techniques can…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-10 Bonny Y. Wang , Alice Pisani , Francisco Villaescusa-Navarro , Benjamin D. Wandelt

This paper reports turbulent boundary layer measurements made over open-cell reticulated foams with varying pore size and thickness, but constant porosity ($\epsilon \approx 0.97$). The foams were flush-mounted into a cutout on a flat…

Fluid Dynamics · Physics 2018-03-14 Christoph Efstathiou , Mitul Luhar

Periodic travelling waves at the free surface of an incompressible inviscid fluid in two dimensions under gravity are numerically computed for an arbitrary vorticity distribution. The fluid domain over one period is conformally mapped from…

Fluid Dynamics · Physics 2025-02-26 Alex Doak , Vera Mikyoung Hur , Jean-Marc Vanden-Broeck

The large-scale distribution of matter in the universe forms a network of clusters, filaments and walls enclosing large empty voids. Voids in turn can be described as a cellular system in which voids/cells define dynamically distinct…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-03 M. A. Aragon-Calvo

The progress of image processing during recent years allows the measurement of pedestrian characteristics on a "microscopic" scale with low costs. However, density and flow are concepts of fluid mechanics defined for the limit of infinitely…

Physics and Society · Physics 2015-05-14 Bernhard Steffen , Armin Seyfried

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in a dispersed two-phase flow has up to now been restricted to relatively sparse particle densities and to identifying only…

Fluid Dynamics · Physics 2024-04-01 Rixin Xua , Zuojie Huanga , Wenchao Gonga , Wu Zhoua , Cameron Tropea

We show how a fixed point based boundary-layer analysis technique can be used to obtain the steady-state particle density profiles of driven exclusion processes on two-lane systems with open boundaries. We have considered two distinct…

Statistical Mechanics · Physics 2015-06-11 Vandana Yadav , Rajesh Singh , Sutapa Mukherji

This article describes two independent developments aimed at improving the Particle Tracking Method for measurements of flow or particle velocities. First, a stereoscopic multicamera calibration method that does not require any optical…

Cosmic voids are low-mass-density regions on intergalactic scales. They are where cosmic expansion and acceleration are most dominant, important places to understand and analyze for cosmology. This entry summarises theoretical underpinnings…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-01 Yan-Chuan Cai , Mark Neyrinck

We present a simple stochastic quadrant model for calculating the transport and de- position of heavy particles in a fully developed turbulent boundary layer based on the statistics of wall-normal fluid velocity fluctuations obtained from a…

Fluid Dynamics · Physics 2016-08-02 C. Jin , I. Potts , M. W. Reeks

Density estimation is a crucial component of many machine learning methods, and manifold learning in particular, where geometry is to be constructed from data alone. A significant practical limitation of the current density estimation…

Classical Analysis and ODEs · Mathematics 2016-01-06 Tyrus Berry , Timothy Sauer