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We have developed a Monte Carlo technique for self-consistently calculating the hydrodynamic structure of oblique, steady-state shocks, together with the first-order Fermi acceleration process and associated non-thermal particle…

Astrophysics · Physics 2009-10-28 Donald C. Ellison , Matthew G. Baring , Frank C. Jones

This paper introduces a class of Monte Carlo algorithms which are based upon the simulation of a Markov process whose quasi-stationary distribution coincides with a distribution of interest. This differs fundamentally from, say, current…

Methodology · Statistics 2020-04-14 Murray Pollock , Paul Fearnhead , Adam M. Johansen , Gareth O. Roberts

We have developed an analytic model to describe coupling of plasma and neutral fluids in the partially ionized heliosphere plasma medium. The sources employed in our analytic model are based on a $\kappa$-distribution as opposed to the…

Space Physics · Physics 2015-05-19 Dastgeer Shaikh , B Dasgupta

There is no accepted mechanism that explains the equilibrium structures that form in collisionless cosmological N-body simulations. Recent work has identified nonextensive thermodynamics as an innovative approach to the problem. The…

Astrophysics · Physics 2008-11-26 Eric I. Barnes , Liliya L. R. Williams , Arif Babul , Julianne J. Dalcanton

The bulk flow is a volume average of the peculiar velocities and a useful probe of the mass distribution on large scales. The gravitational instability model views the bulk flow as a potential flow that obeys a Maxwellian Distribution. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-31 Abhinav Kumar , Yuyu Wang , Hume A. Feldman , Richard Watkins

Numerical solutions of the Enskog-Vlasov (EV) equation are used to determine the velocity distribution function of atoms spontaneously evaporating into near-vacuum conditions. It is found that an accurate approximation is provided by a…

Fluid Dynamics · Physics 2021-03-15 Sergiu Busuioc , Livio Gibelli , Duncan A. Lockerby , James E. Sprittles

We demonstrate a scaling method for non-Markovian Monte Carlo wave-function simulations used to study open quantum systems weakly coupled to their environments. We derive a scaling equation, from which the result for the expectation values…

Quantum Physics · Physics 2009-11-10 J. Piilo , S. Maniscalco , A. Messina , F. Petruccione

Context. Recent studies on Kappa distribution functions invoked in space plasma applications have emphasized two alternative approaches which may assume the temperature parameter either dependent or independent of the power-index $\kappa$.…

Plasma Physics · Physics 2017-06-07 M. Lazar , V. Pierrard , S. M. Shaaban , H. Fichtner , S. Poedts

The mutual derivation between arbitrary distribution forms of momenta and momentum components of particles produced in an isotropic emission source are systematically studied in terms of probability theory and mathematical statistics. The…

Nuclear Theory · Physics 2019-07-23 Pei-Pin Yang , Qi Wang , Fu-Hu Liu

Several Lagrangian methodologies have been proposed in recent years to simulate advection-dispersion of solutes in fluids as a mass exchange between numerical particles carrying the fluid. In this paper, we unify these methodologies,…

Computational Physics · Physics 2019-02-26 Guillem Sole-Mari , Michael J. Schmidt , Stephen D. Pankavich , David A. Benson

Large scale simulations and analytical theory have been combined to obtain the non-equilibrium velocity distribution, $f(v)$, of randomly accelerated particles in suspension. The simulations are based on an event-driven algorithm,…

Statistical Mechanics · Physics 2013-09-09 Andrea Fiege , Benjamin Vollmayr-Lee , Annette Zippelius

In recent years efficient algorithms have been developed for the numerical computation of relativistic single-particle path integrals in quantum field theory. Here, we adapt this "worldline Monte Carlo" approach to the standard problem of…

The present work addresses the question how sampling algorithms for commonly applied copula models can be adapted to account for quasi-random numbers. Besides sampling methods such as the conditional distribution method (based on a…

Computation · Statistics 2016-03-15 Mathieu Cambou , Marius Hofert , Christiane Lemieux

The distribution of pairwise, relative peculiar velocities, $f(u;r)$, on small nonlinear scales, $r$, is derived from the Press--Schechter approach. This derivation assumes that Press--Schechter clumps are virialized and isothermal. The…

Astrophysics · Physics 2015-06-24 Ravi K. Sheth , U. C. Berkeley

In 1988, Constantino Tsallis proposed an extension of the Boltzmann statistical mechanics by postulating a new entropy formula, $S_q = k_B\ln_q W$, where $W$ is the number of microstates accessible to the system, and $\ln_q$ defines a…

Statistical Mechanics · Physics 2025-03-03 J. A. S. Lima , M. H. Benetti

In computational and applied statistics, it is of great interest to get fast and accurate calculation for the distributions of the quadratic forms of Gaussian random variables. This paper presents a novel approximation strategy that…

Methodology · Statistics 2023-12-29 Hong Zhang , Judong Shen , Zheyang Wu

Models of the continuum radiation from accreting hot plasmas typically assume that the plasma heating mechanism produces energetic particles distributed in energy either as a Maxwellian (the ``thermal'' models) or as an extended power law…

Astrophysics · Physics 2007-05-23 Paolo S. Coppi

Monte Carlo simulation is one of the most important tools in the study of diffusion processes. For constant diffusion coefficients, an appropriate Gaussian distribution of particle's steplengths can generate exact results, when compared…

Computational Physics · Physics 2015-06-12 V. Ruiz Barlett , M. Hoyuelos , H. O. Mártin

The KAPPA package is designed for calculations of optically thin spectra for the non-Maxwellian \k{appa}-distributions. This paper presents extension of the database to allow calculations of the spectra for extreme values of \k{appa} < 2,…

Solar and Stellar Astrophysics · Physics 2023-10-10 Elena Dzifcakova , Jaroslav Dudik , Martina Pavelkova , Bozena Solarova , Alena Zemanova

In a microcanonical ensemble (constant $NVE$, hard reflecting walls) and in a molecular dynamics ensemble (constant $NVE\mathbf{PG}$, periodic boundary conditions) with a number $N$ of smooth elastic hard spheres in a $d$-dimensional volume…

Statistical Mechanics · Physics 2015-09-01 Enrico Scalas , Adrian T. Gabriel , Edgar Martin , Guido Germano
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