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In this work we focus on the problem of minimizing the sum of convex cost functions in a distributed fashion over a peer-to-peer network. In particular, we are interested in the case in which communications between nodes are prone to…

Optimization and Control · Mathematics 2020-07-24 Nicola Bastianello , Ruggero Carli , Luca Schenato , Marco Todescato

Jet-plasmas emanating from the vicinity of relativistic objects and in gamma-ray bursts have been observed to propagate with Lorentz factors laying in the range between one and several hundreds. On the other hand, the numerical studies of…

High Energy Astrophysical Phenomena · Physics 2012-01-31 A. A. Hujeirat , S. Fehlmann

We are concerned with the large-time behavior of the solution to one-dimensional (1D) cubic non-convex scalar viscous conservation laws. Due to the inflection point of the cubic non-convex flux, the solution to the corresponding inviscid…

Analysis of PDEs · Mathematics 2024-09-04 Feimin Huang , Yi Wang , Jian Zhang

Complexity is often exhibited in dynamical systems, where certain parameters evolve with time in a strange and chaotic nature. These systems lack predictability and are common in the physical world. Dissipative systems are one of such…

Fluid instabilities arise in a variety of contexts and are often unwanted results of engineering imperfections. In one particular model for a magnetized target fusion reactor, a pressure wave is propagated in a cylindrical annulus comprised…

Fluid Dynamics · Physics 2017-04-26 Michael Lindstrom

We solve the Riemann problem for the deceleration of an arbitrarily magnetized relativistic flow injected into a static unmagnetized medium in one dimension. We find that for the same initial Lorentz factor, the reverse shock becomes…

Recent dispersive techniques developed by us are applied to discuss three problems: 1. A long standing discrepan-cy between the measurements of $R(s)$ for $\sqrt{s} = (5\div 7.5)GeV$ by Crystal Ball and MARK I has been analyzed and its…

High Energy Physics - Phenomenology · Physics 2007-05-23 Y. Srivastava , S. Pacetti , G. Pancheri , A. Widom

We present the results obtained with an end-to-end simulator of an Extreme Adaptive Optics (XAO) system control loop. It is used to predict its on-sky performances and to optimise the AO loop algorithms. It was first used to validate a…

Instrumentation and Methods for Astrophysics · Physics 2023-01-10 Anthony Berdeu , Michel Tallon , Éric Thiébaut , Mary Angelie Alagao , Sitthichat Sukpholtham , Maud Langlois , Adithep Kawinkij , Puttiwat Kongkaew

We study the resolution of discontinuous singularities in gas dynamics via rarefaction waves. The mechanism is well-understood in the one dimensional case. We will prove the non-nonlinear stability of the Riemann problem for…

Analysis of PDEs · Mathematics 2024-09-20 Tian-Wen Luo , Pin Yu

Nonlinear acoustic evolution is often discussed in the context of wave-steepening that leads to shock formation, and is of special interest in applications where the shock continues to strengthen due to a narrowing of its channel or the…

Fluid Dynamics · Physics 2023-12-27 Tamar Faran , Christopher D. Matzner , Eliot Quataert

We review some of the properties of Advection-Dominated Accretion Flow (ADAF) models and show that they successfully describe many astrophysical systems. Despite these successful applications some fundamental problems still remain to be…

Astrophysics · Physics 2009-10-30 Jean-Pierre Lasota

This paper is presented to give numerical solutions of some cases of nonlinear wave-like equations with variable coefficients by using Reduced Differential Transform Method (RDTM). RDTM can be applied most of the physical, engineering,…

Numerical Analysis · Mathematics 2014-07-21 Murat Gubes , Yildiray Keskin , Galip Oturanc

In the previous works harmonic, phase-mixed, Alfven wave dynamics was considered both in the kinetic and magnetohydrodynamic regimes. Up today only magnetohydrodynamic, phase-mixed, Gaussian Alfven pulses were investigated. In the present…

Solar and Stellar Astrophysics · Physics 2017-01-03 D. Tsiklauri

We consider linear instability of solitary waves of several classes of dispersive long wave models. They include generalizations of KDV, BBM, regularized Boussinesq equations, with general dispersive operators and nonlinear terms. We obtain…

Analysis of PDEs · Mathematics 2008-02-04 Zhiwu Lin

Reaction-diffusion equations (RDEs) are often derived as continuum limits of lattice-based discrete models. Recently, a discrete model which allows the rates of movement, proliferation and death to depend upon whether the agents are…

Dynamical Systems · Mathematics 2021-05-19 Yifei Li , Peter van Heijster , Matthew J. Simpson , Martin Wechselberger

We derive a reformulation of the linearized Arnowitt-Deser-Misner (ADM) equations as a Hodge-Dirac wave system with the divdiv complex, addressing challenges in numerical relativity such as gauge fixing, constraint propagation, and tensor…

General Relativity and Quantum Cosmology · Physics 2025-11-26 Marien-Lorenzo Hanot , Kaibo Hu

Numerical simulations of dispersive turbulence in magnetized plasmas based on the Hall-MHD description are presented, assuming spatial variations along a unique direction making a prescribed angle with the ambient magnetic field. Main…

Earth and Planetary Astrophysics · Physics 2015-05-18 D. Laveder , L. Marradi , T. Passot , P. L. Sulem

This paper develops the basic sets of equations which lead to the conservation laws describing collisionless plasma shock waves. We discuss the evolution of shock waves by wave steepening, derive the Rankine-Hugoniot conditions for…

Astrophysics · Physics 2008-05-16 R. A. Treumann , C. H. Jaroschek

The evolution of a linearly-polarized, long-wavelength Alfv\'en wave --propagating in a collisionless magnetized plasma with a sheared parallel-directed velocity flow-- is here studied by means of two-dimensional hybrid Vlasov-Maxwell (HVM)…

The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV) equation for small but finite amplitude electrostatic ion-acoustic waves in unmagnitized collisionless weakly relativistic warm plasma. The Lagrangian…

Plasma Physics · Physics 2010-06-29 El-Said A. El-Wakil , Essam M. Abulwafa , Emad K. El-shewy , Abeer A. Mahmoud
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