96,286 research outputs found
Time Quantified Monte Carlo Algorithm for Interacting Spin Array Micromagnetic Dynamics
In this paper, we reexamine the validity of using time quantified Monte Carlo
(TQMC) method [Phys. Rev. Lett. 84, 163 (2000); Phys. Rev. Lett. 96, 067208
(2006)] in simulating the stochastic dynamics of interacting magnetic
nanoparticles. The Fokker-Planck coefficients corresponding to both TQMC and
Langevin dynamical equation (Landau-Lifshitz-Gilbert, LLG) are derived and
compared in the presence of interparticle interactions. The time quantification
factor is obtained and justified. Numerical verification is shown by using TQMC
and Langevin methods in analyzing spin-wave dispersion in a linear array of
magnetic nanoparticles.Comment: Accepted for publication in Phys. Rev.
Density functional approach to finite temperature nuclear properties and the role of a momentum dependent isovector interaction
Using a density functional approach based on a Skyrme interaction,
thermodynamic properties of finite nuclei are investigated at non-zero
temperture. The role of a momentum dependent isovector term is now studied
besides volume, symmetry, surface and Coulomb effects. Various features
associated with both mechanical and chemical instability and the liquid-gas
coexistence curve are sensitive to the Skyrme interaction. The separated
effects of the isoscalar term and the isovector term of momentum dependent
interaction are studied for a modified SKM() interaction. The frequently
used Skyrme interaction SLy4 is one of the cases considered and is shown to
have better features for neutron star studies due to a larger symmetry energy.Comment: 14 pages, 6 figures, added more discussio
Analytical Solution to Transport in Brownian Ratchets via Gambler's Ruin Model
We present an analogy between the classic Gambler's Ruin problem and the
thermally-activated dynamics in periodic Brownian ratchets. By considering each
periodic unit of the ratchet as a site chain, we calculated the transition
probabilities and mean first passage time for transitions between energy minima
of adjacent units. We consider the specific case of Brownian ratchets driven by
Markov dichotomous noise. The explicit solution for the current is derived for
any arbitrary temperature, and is verified numerically by Langevin simulations.
The conditions for vanishing current and current reversal in the ratchet are
obtained and discussed.Comment: 4 pages, 3 figure
Extraction of the beam elastic shape from uncertain FBG strain measurement points
Aim of the present paper is the analysis of the strain along the beam that is equipped with Glass Fibers Reinforced Polymers (GFRP) with an embedded set of optical Fiber Bragg Grating sensors (FBG), in the context of a project to equip with these new structural elements an Italian train bridge. Different problems are attacked, and namely: (i)during the production process [1] it is difficult to locate precisely the FBG along the reinforcement bar, therefore the following question appears: How can we associate the strain measurements to the points along the bar? Is it possible to create a signal analysis procedure such that this correspondence is found?(ii)the beam can be inflected and besides the strain at some points, we would like to recover the elastic shape of the deformed beam that is equipped with the reinforcement bars. Which signal processing do we use to determine the shape of the deformed beam in its inflection plane?(iii)if the beam is spatially inflected, in two orthogonal planes, is it possible to recover the beam spatial elastic shape? Object of the paper is to answer to these questions
Integrable model of interacting XX and Fateev-Zamolodchikov chains
We consider the exact solution of a model of correlated particles, which is
presented as a system of interacting XX and Fateev-Zamolodchikov chains. This
model can also be considered as a generalization of the multiband anisotropic
model in the case we restrict the site occupations to at most two
electrons. The exact solution is obtained for the eigenvalues and eigenvectors
using the Bethe-ansatz method.Comment: 10 pages, no figure
Generalized Pseudopotentials for the Anisotropic Fractional Quantum Hall Effect
We generalize the notion of Haldane pseudopotentials to anisotropic fractional quantum Hall (FQH) systems that are physically realized, e.g., in tilted magnetic field experiments or anisotropic band structures. This formalism allows us to expand any translation-invariant interaction over a complete basis, and directly reveals the intrinsic metric of incompressible FQH fluids. We show that purely anisotropic pseudopotentials give rise to new types of bound states for small particle clusters in the infinite plane, and can be used as a diagnostic of FQH nematic order. We also demonstrate that generalized pseudopotentials quantify the anisotropic contribution to the effective interaction potential, which can be particularly large in models of fractional Chern insulators
Material and doping dependence of the nodal and anti-nodal dispersion renormalizations in single- and multi-layer cuprates
In this paper we present a review of bosonic renormalization effects on
electronic carriers observed from angle-resolved photoemission spectra in the
cuprates. We specifically discuss the viewpoint that these renormalizations
represent coupling of the electrons to the lattice, and review how the wide
range of materials dependence, such as the number of CuO layers, and the
doping dependence can be straightforwardly understood as arising due to novel
electron-phonon coupling.Comment: 9 pages and 6 figures. Submitted as a review article for Advances in
Condensed Matter Physic
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The elicitation of key performance indicators of e-government providers: A bottom-up approach
Copyright @ 2013 EMCIS.Delivering an adequate e-Government service (e-service) is becoming more of a necessity in today's digital world. In order to improve e-services and increase the engagement of both users' and providers' side, studies on the performance evaluation of such provided e-services are taking places. However a clear identification of the key performance indicators from the e-Government providers’ side is not well explored. This shortcoming hampers the conduct of a holistic evaluation of an e-service provision from the perspective of its stakeholders in order to improve e-services as well as to increase e-services take-ups. In this paper, a systematic process to identify indicators is implemented based on a bottom-up approach. The process used three focus-group meetings with providers, users, and academics in Qatar, Lebanon and UK to collect, identify and validate key indicators from the perspective of e-services’ providers. The approach resulted in the identification of five factors levels (service, technology, employees, policy and management and social responsibilities) with fifteen sub-categories of SMART variables. Hence, leading to the development of a new model, STEPS, that can fully explain and predict e-government success from the providers’ point of view. It will work as a strategic management tool to align various stakeholders on common goal and values based on evidence based evaluation of e-services using smart measurable indicators for the improvement of an e-service at the engagement level in the field of e-government. In addition, other fields can benefit from the outcome of this work, such as logistics service providers, who make their services available across new and existing relationships between the Internet commerce firms, their customers, and their vendors
A test of the power law relationship between gamma-ray burst pulse width ratio and energy expected in fireballs or uniform jets
Recently, under the assumption that the Doppler effect of the
relativistically expanding fireball surface is important, Qin et al. showed
that in most cases the power law relationship between the pulse width and
energy of gamma-ray bursts (GRBs)would exist in a certain energy range. We
check this prediction with two GRB samples which contain well identified
pulses. A power law anti-correlation between the full pulse width and energy
and a power law correlation between the pulse width ratio and energy are seen
in the light curves of the majority (around 65%) of bursts of the two samples
within the energy range of BATSE, suggesting that these bursts are likely to
arise from the emission associated with the shocks occurred on a
relativistically expanding fireball surface. For the rest of the bursts, the
relationships between these quantities were not predicted previously. We
propose to consider other spectral evolutionary patterns or other radiation
mechanisms such as a varying synchrotron or Comptonized spectrum to check if
the observed relationships for these rest bursts can also be accounted for by
the Doppler model. In addition, we find that the upper limits of the width
ratio for the two samples do not exceed 0.9, in agrement with what predicted
previously by the Doppler model. The plateau/power law/plateau and the peaked
features predicted and detected previously by Qin et al. are generally
observed, with the exceptions being noticed only in a few cases. According to
the distinct values of two power law indices of FWHM and ratio and energy, we
divide the bursts into three subsets which are located in different areas of
the two indices plane. We suspect that different locations of the two indices
might correspond to different mechanisms.Comment: 16 pages, 7 figures, MNRAS accepte
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