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In a variety of problems originating in supervised, unsupervised, and reinforcement learning, the loss function is defined by an expectation over a collection of random variables, which might be part of a probabilistic model or the external…

Machine Learning · Computer Science 2016-01-06 John Schulman , Nicolas Heess , Theophane Weber , Pieter Abbeel

In this paper, we exploit the gradient flow structure of continuous-time formulations of Bayesian inference in terms of their numerical time-stepping. We focus on two particular examples, namely, the continuous-time ensemble Kalman-Bucy…

Numerical Analysis · Mathematics 2019-06-24 Sahani Pathiraja , Sebastian Reich

Inverse energy cascade regime of two dimensional turbulence is investigated by means of high resolution numerical simulations. Numerical computations of conditional averages of transverse pressure gradient increments are found to be…

Chaotic Dynamics · Physics 2009-11-07 G. Boffetta , M. Cencini , J. Davoudi

In this paper, we discuss selected adjoint approaches for the turbulent flow control. In particular, we focus on the application of adjoint solvers for the scope of noise reduction, in which flow solutions are obtained by large eddy and…

Optimization and Control · Mathematics 2018-05-01 Emre Özkaya , Nicolas R. Gauger , Daniel Marinc , Holger Foysi

Uncertainty propagation and filtering can be interpreted as gradient flows with respect to suitable metrics in the infinite dimensional manifold of probability density functions. Such a viewpoint has been put forth in recent literature, and…

Optimization and Control · Mathematics 2017-10-31 Abhishek Halder , Tryphon T. Georgiou

The present work investigates the evolution of linear perturbations of time-dependent ideal fluid flows with advected quantities, expressed in terms of the second order variations of the action corresponding to a Lagrangian defined on a…

Fluid Dynamics · Physics 2024-04-02 Darryl D. Holm , Ruiao Hu , Oliver D. Street

The gradient-flow formalism is applied to a non-Abelian gauge theory with scalar and fermionic particles, dubbed "scalar QCD". It is shown that the flowed scalar quark requires a field renormalization, albeit only beyond the one-loop level.…

High Energy Physics - Phenomenology · Physics 2025-03-26 J. Borgulat , N. Felten , R. V. Harlander , J. T. Kohnen

We derive a system of coupled flow equations for the proper-vertices of the background effective average action and we give an explicit representation of these by means of diagrammatic and momentum space techniques. This explicit…

High Energy Physics - Theory · Physics 2015-04-01 Alessandro Codello

We study the radial flow of retarded Green's function of energy-momentum tensor and $R$-current of dual gauge theory in presence of generic higher derivative terms in bulk Lagrangian. These are first order non-linear Riccati equations. We…

High Energy Physics - Theory · Physics 2014-11-21 Nabamita Banerjee , Suvankar Dutta

We consider a class of optimization problems on the space of probability measures motivated by the mean-field approach to studying neural networks. Such problems can be solved by constructing continuous-time gradient flows that converge to…

Optimization and Control · Mathematics 2026-02-18 Petra Lazić , Linshan Liu , Mateusz B. Majka

We use the distances introduced in a previous joint paper to exhibit the gradient flow structure of some drift-diffusion equations for a wide class of entropy functionals. Functional inequalities obtained by the comparison of the entropy…

Analysis of PDEs · Mathematics 2012-12-06 Jean Dolbeault , Bruno Nazaret , Giuseppe Savaré

Chaotic flow is studied in a series of numerical magnetohydrodynamical simulations that use the shearing box formalism. This mimics important features of local accretion disk dynamics. The magnetorotational instability gives rise to flow…

Astrophysics · Physics 2009-11-07 W. F. Winters , S. A. Balbus , J. F. Hawley

In this note, we propose a new idea by analyzing the basic disturbance equations, and give starting equations for understanding the instability phenomena of laminar flows and transition to turbulence. It is considered that there is an…

Fluid Dynamics · Physics 2007-05-23 Hua-Shu Dou

The effects of three-dimensional perturbations in two-dimensional turbulence are investigated, through a conformal field theory approach. We compute scaling exponents for the energy spectra of enstrophy and energy cascades, in a strong…

High Energy Physics - Theory · Physics 2009-10-28 L. Moriconi

In ordinary turbulence research it has been a long standing tradition to solve the equations in spectral space giving the best possible accuracy. This is indeed a natural choice for incompressible problems with periodic boundaries, but it…

Astrophysics · Physics 2009-11-07 A. Brandenburg , W. Dobler

In this paper, we investigate the partition functions of conformal field theories (CFTs) with the $T\bar{T}$ deformation on a torus in terms of the perturbative QFT approach. In Lagrangian path integral formalism, the first- and…

High Energy Physics - Theory · Physics 2021-09-29 Song He , Yuan Sun , Yu-Xuan Zhang

Results of direct numerical simulations and laboratory experiments have been used in order to show that the buoyancy driven bubbly flows at high gas volume fraction are mixed by deterministic chaos with typical exponential spectrum of the…

Fluid Dynamics · Physics 2022-04-29 A. Bershadskii

Hydrodynamics is nowadays understood as an effective field theory that describes the dynamics of the long-wavelength and slow-time fluctuations of an underlying microscopic theory. In this work we extend the relativistic hydrodynamics to…

High Energy Physics - Theory · Physics 2020-05-27 Saulo M. Diles , Luis A. H. Mamani , Alex S. Miranda , Vilson T. Zanchin

Some features of the calculation of fluid dynamo systems in magnetohydrodynamics are studied. In the coupled set of the ordinary linear differential equations for the spherically symmetric $\alpha^2-$dynamos, the problem represented by the…

Mathematical Physics · Physics 2007-06-13 Miloslav Znojil , Uwe Guenther

A layer of granular material on a vertically vibrating sawtooth-shaped base exhibits horizontal flow whose speed and direction depend on the parameters specifying the system in a complex manner. Discrete-particle simulations reveal that the…

Soft Condensed Matter · Physics 2009-11-07 M. Levanon , D. C. Rapaport