نتایج جستجو برای: particle evolution

تعداد نتایج: 508088  

2010
Sylvain Franke Wolfgang Ackermann Thomas Weiland

The Vlasov equation can describe the evolution of a particle density under the effects of electromagnetic fields and thus it is possible to describe the evolution of a charged particle beam within an accelerator beam line. The Vlasov equation forms a partial differential equation in a 6D phase space witch renders it very expensive if it is solved via classical methods. A more efficient approach...

2003
N. Barat

Theorems (most notably by Hegerfeldt) prove that an initially localized particle whose time evolution is determined by a positive Hamiltonian will violate causality. We argue that this apparent paradox is resolved for a positive energy free particle described by either the Dirac equation or the Klein-Gordon equation because such a particle cannot be localized in the sense required by the theorems.

2001
N. Barat J. C. Kimball

Theorems (most notably by Hegerfeldt) prove that an initially localized particle whose time evolution is determined by a positive Hamiltonian will violate causality. We argue that this apparent paradox is resolved for a free particle described by either the Dirac equation or the Klein-Gordon equation because such a particle cannot be localized in the sense required by the theorems.

2009
S. Park J. Hwang K. Rou E. Kim

In this paper, we consider a new particle filter inspired by biological evolution. In the standard particle filter, a resampling scheme is used to decrease the degeneracy phenomenon and improve estimation performance. Unfortunately, however, it could cause the undesired the particle deprivation problem, as well. In order to overcome this problem of the particle filter, we propose a novel filter...

Journal: :Foundations and Trends in Machine Learning 2012
Pierre Del Moral Peng Hu Liming Wu

This monograph presents some new concentration inequalities for Feynman-Kac particle processes. We analyze different types of stochastic particle models, including particle profile occupation measures, genealogical tree based evolution models, particle free energies, as well as backward Markov chain particle models. We illustrate these results with a series of topics related to computational ph...

Journal: :Applied Mathematics and Computation 2007
Xueming Yang Jinsha Yuan Jiangye Yuan Huina Mao

This paper proposes a modified particle swarm optimization algorithm with dynamic adaptation. In this algorithm, a modified velocity updating formula of the particle is used, where the randomness in the course of updating particle velocity is relatively decreased and the inertia weight of each particle is different. Moreover, this algorithm introduces two parameter describing the evolving state...

M. Ghalambaz, M. Shahmiri,

Abstract: Cooling slope-casting processing is a relatively new technique to produce semisolid cast feedstock for the thixoforming process. Simple equipment, ease of operation, and low processing costs are the main advantages of this process in comparison with existing processes such as mechanical stirring, electromagnetic stirring, etc. The processing parameters of cooling slope casting are...

2011
Chaohua Dai Weirong Chen Lili Ran Yi Zhang Yu Du

Human Group Optimization (HGO) algorithm, derived from the previously proposed seeker optimization algorithm (SOA), is a novel swarm intelligence algorithm by simulating human behaviors, especially human searching/foraging behaviors. In this paper, a canonical HGO with local search (L-HGO) is proposed. Based on the benchmark functions provided by CEC2005, the proposed algorithm is compared with...

2011
W. A. Cooper G. A. Cooper J. P. Graves Yu. Isaev

A Hamiltonian/Lagrangian theory to describe guiding center orbit drift motion that is canonical in Boozer magnetic coordinates is developed to include full electrostatic and electromagnetic perturbed fields in axisymmetric tokamak geometry. Furthermore, the radial component of the equilibrium magnetic field in the covariant representation is retained and the background equilibrium state extends...

2007
C. D. Westbrook R. J. Hogan A. J. Illingworth E. J. O’Connor

[1] Vertically pointing Doppler radar has been used to study the evolution of ice particles as they sediment through a cirrus cloud. The measured Doppler fall speeds, together with radar-derived estimates for the altitude of cloud top, are used to estimate a characteristic fall time tc for the ‘average’ ice particle. The change in radar reflectivity Z is studied as a function of tc, and is foun...

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