Search results for "MONTE CARLO"
showing 10 items of 1587 documents
Efficient simulation of the random-cluster model
2013
The simulation of spin models close to critical points of continuous phase transitions is heavily impeded by the occurrence of critical slowing down. A number of cluster algorithms, usually based on the Fortuin-Kasteleyn representation of the Potts model, and suitable generalizations for continuous-spin models have been used to increase simulation efficiency. The first algorithm making use of this representation, suggested by Sweeny in 1983, has not found widespread adoption due to problems in its implementation. However, it has been recently shown that it is indeed more efficient in reducing critical slowing down than the more well-known algorithm due to Swendsen and Wang. Here, we present…
Can hydrophobic interactions be correctly reproduced by the continuum models?
1996
The ability of the continuum models to describe hydrophobic interactions is investigated. In this work we have studied the interactions between two methane molecules in aqueous solution by means of a continuum model. The resulting potential of mean force is in good agreement with those obtained using Monte Carlo and molecular dynamics techniques. The three energy contributions appearing in the continuum energy partition (electrostatic, dispersion−repulsion, and cavitation) have been analyzed. The cavitation free energy plays the most important role of the three, determining the existence of an energy barrier between the contact minimum and the separated methane monomers. This barrier, which…
Measuring the Spatial Homogeneity in Corneal Endotheliums by Means of a Randomization Test
1999
Quantification of regularity of cell sizes and the spatial arrangement of cells in corneal endotheliums becomes of a great importance associated to stress situations such as cataract surgery, corneal transplantation or implantation of intra-ocular lenses. A new index of regularity of the spatial distribution of cell sizes in corneal endotheliums is proposed. The corneal endothelium is described by means of a spatial marked point pattern (the cell centroids marked with the cell areas). The hypothesis of no dependency between mark and locations is tested by a Monte Carlo test. The new index is the p-value of the test validating the hypothesis. Pairs of endotheliums from different eyes of the …
Local structure of A-atom in ABO3 perovskites studies by RMC-EXAFS
2020
The measurements of Sr K-edge XAFS were performed under the approval of Proposal No. 97G042 of Photon Factory (KEK) and partially supported by the Research Grants of Hirosaki University. This work was supported by Bruce Ravel providing data for BTO. Boby Joseph acknowledges IISc Bangalore and ICTP Trieste for financial support through the award of the IISc-ICTP fellowship.
Reconstruction of random media using Monte Carlo methods.
1998
A simulated annealing algorithm is applied to the reconstruction of two-dimensional porous media with prescribed correlation functions. The experimental correlation function of an isotropic sample of Fontainebleau sandstone and a synthetic correlation function with damped oscillations are used in the reconstructions. To reduce the numerical effort we follow a proposal suggesting the evaluation of the correlation functions only along certain directions. The results show that this simplification yields significantly different microstructures as compared to a full evaluation of the correlation function. In particular, we find that the simplified reconstruction method introduces an artificial a…
Monte Carlo estimation of transverse and longitudinal correlation functions in the model
2010
Abstract Monte Carlo simulations of the three-dimensional O ( 4 ) model in the ordered phase are performed to study the Goldstone mode effects. Our data show a distinct scaling region, where the Fourier-transformed transverse correlation function behaves as ∝ k − λ ⊥ with λ ⊥ 2 ( λ ≃ 1.95 ), in disagreement with the standard theoretical prediction λ ⊥ = 2 .
Economic comparison between offshore and inshore aquaculture production systems of European sea bass in Italy
2014
Abstract Offshore production system is predicted to increase in the near future driven by the lack of coastal space and lower environmental impacts. The aim of this paper has been to evaluate the economic performance of offshore production system respect to inshore one, by comparing net present value (NPV), discounted payback time (DPBT) and internal rate of return (IRR) of two Italian mariculture farms that produce European sea bass. Results showed a better economic profitability of offshore farm, even if sensitivity analysis revealed that financial indicators of both aquaculture production systems have been very sensitive to market condition changes. So, offshore production system could r…
The Tax Returns of Public Spending on Universities: An Estimate with Monte Carlo Simulations
2015
Pastor J. M. and Peraita C. The tax returns of public spending on universities: an estimate with Monte Carlo simulations, Regional Studies. This paper proposes a methodology based on counterfactual scenarios and the existence of uncertainty to estimate the tax returns of public spending of regional governments on their public universities. The introduction of differences in the time spent by the students at university and the proportion of the total public expenditure implies making assumptions about uncertainty. The paper applies Monte Carlo simulations incorporating stochastic elements to estimate the tax returns of public spending in the University of the Basque Country (Spain). The resu…
Monte Carlo study of surface critical behavior in the XY model.
1989
We have used Monte Carlo simulations to study the behavior of $L\ifmmode\times\else\texttimes\fi{}L\ifmmode\times\else\texttimes\fi{}D$ slabs containing classical spins which interact via nearest-neighbor $\mathrm{XY}$ coupling. The coupling constant ${J}_{S}$ for spins in the surface layer is fixed at $0.5J$. Finite-size scaling is used to analyze data for $D=59$ and to extract estimates for the surface critical exponents. We find that ${\ensuremath{\beta}}_{1}$ is in good agreement with theoretical predictions.
HIGH-PRECISION MONTE CARLO DETERMINATION OF α/ν IN THE 3D CLASSICAL HEISENBERG MODEL
1994
To study the role of topological defects in the three-dimensional classical Heisenberg model we have simulated this model on simple cubic lattices of size up to 803, using the single-cluster Monte Carlo update. Analysing the specific-heat data of these simulations, we obtain a very accurate estimate for the ratio of the specific-heat exponent with the correlation-length exponent, α/ν, from a usual finite-size scaling analysis at the critical coupling Kc. Moreover, by fitting the energy at Kc, we reduce the error estimates by another factor of two, and get a value of α/ν, which is comparable in accuracy to best field theoretic estimates.