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Stochastic resonance is a phenomenon where a noise of appropriate intensity enhances the input signal strength. In this work, by employing the recently developed convex optimization methods in the context of dynamical systems and stochastic…

Dynamical Systems · Mathematics 2023-09-22 Minjae Cho

Magnetic reconnection is a ubiquitous plasma phenomenon that plays a critical role in particle heating and energization. During reconnection, the topology of magnetic field rearranges, depositing energy into the surrounding plasma through…

The growing complexity of the power grid, driven by increasing share of distributed energy resources and by massive deployment of intelligent internet-connected devices, requires new modelling tools for planning and operation. Physics-based…

Machine Learning · Statistics 2018-11-26 Francesco Fusco

An analysis of instability dynamics in a stochastic magnetic field is presented for the tractable case of the resistive interchange. Externally prescribed static magnetic perturbations convert the eigenmode problem to a stochastic…

Plasma Physics · Physics 2023-06-14 Mingyun Cao , P. H. Diamond

We propose a generalization of the random matrix theory following the basic prescription of the recently suggested concept of superstatistics. Spectral characteristics of systems with mixed regular-chaotic dynamics are expressed as weighted…

Statistical Mechanics · Physics 2007-05-23 A. Y. Abul-Magd

The spectral density of random graphs with topological constraints is analysed using the replica method. We consider graph ensembles featuring generalised degree-degree correlations, as well as those with a community structure. In each case…

Disordered Systems and Neural Networks · Physics 2011-04-08 Tim Rogers , Conrad Pérez Vicente , Koujin Takeda , Isaac Pérez Castillo

A quantum theory of magnetization dynamics of a nanomagnet as a sequence of scatterings of each electron spin with the macrospin state of the magnetization results in each encounter a probability distribution of the magnetization recoil…

Mesoscale and Nanoscale Physics · Physics 2012-03-30 Yong Wang , L. J. Sham

In magnetized capacitively coupled radio-frequency discharges operated at low pressure the influence of the magnetic flux density on discharge properties has been studied recently both by experimental investigations and in simulations. It…

The dynamics of a relativistic blast wave propagating through magnetized medium is considered taking into account possible inhomogeneities of density and magnetic field and additional energy supply. Under the simplifying assumption of a…

Astrophysics · Physics 2009-11-07 Maxim Lyutikov

Collective excitations in magnetic materials can be investigated by means of inelastic neutron scattering. We show that this experimental method gives access to the complete spectrum of magnetic fluctuations through the energy- and…

Strongly Correlated Electrons · Physics 2007-05-23 B. Roessli , P. Böni

A method to extract primary $\gamma$-ray spectra from particle-$\gamma$ coincidences at excitation energies up to the neutron binding energy is described. From these spectra, the level density and $\gamma$-ray strength function can be…

Nuclear Experiment · Physics 2007-05-23 M. Guttormsen , M. Hjorth-Jensen , J. Rekstad , S. Siem , A. Schiller , A. Voinov

In our work we examine the influence of background stochastic excitations on the power output generated by the energy harvester. The harvesting device we considered is composed of two small magnets, attached to piezoelastic oscillators,…

Adaptation and Self-Organizing Systems · Physics 2014-07-01 K. Kucab , G. Górski , J. Mizia

Multiscale phenomena which include several processes occuring simultaneously at different length scales and exchanging energy with each other, are widespread in magnetism. These phenomena often govern the magnetization reversal dynamics,…

Materials Science · Physics 2009-10-31 V. V. Dobrovitski , M. I. Katsnelson , B. N. Harmon

The dynamics of a domain wall in magnetostrictive materials is investigated. The domain wall is modeled by a d-dimensional interface moving in a d+1-dimensional environment. Long-range demagnetization effects and quenched disorder are…

Condensed Matter · Physics 2007-05-23 Alexei Vazquez , Oscar Sotolongo-Costa

A system's internal dynamics and its interaction with the environment can be determined by tracking how external perturbations affect its transition rates between states. Quantitative measurements of these rates are crucial for optimizing…

We introduce the stochastic multiplicative point process modelling trading activity of financial markets. Such a model system exhibits power-law spectral density S(f) ~ 1/f**beta, scaled as power of frequency for various values of beta…

Statistical Mechanics · Physics 2008-12-02 Vygintas Gontis , Bronislovas Kaulakys

We compute spectra of large stochastic matrices $W$, defined on sparse random graphs, where edges $(i,j)$ of the graph are given positive random weights $W_{ij}>0$ in such a fashion that column sums are normalized to one. We compute spectra…

Disordered Systems and Neural Networks · Physics 2015-06-23 Reimer Kuehn

During training, weight matrices in machine learning architectures are updated using stochastic gradient descent or variations thereof. In this contribution we employ concepts of random matrix theory to analyse the resulting stochastic…

Disordered Systems and Neural Networks · Physics 2024-11-22 Gert Aarts , Ouraman Hajizadeh , Biagio Lucini , Chanju Park

A stochastic differential equation that describes the dynamics of single-domain magnetic particles at any temperature is derived using a classical formalism. The deterministic terms recover existing theory and the stochastic process takes…

Mesoscale and Nanoscale Physics · Physics 2015-10-28 Michail Tzoufras , Gregory J. Parker , Michael K. Grobis

A power allocation to active and reactive power in stochastic resonance is discussed for energy harvesting from mechanical noise. It is confirmed that active power can be increased at stochastic resonance, in the same way of the…

Physics and Society · Physics 2016-01-20 Madoka Kubota , Ryo Takahashi , Takashi Hikihara