Search results for "Carlo"
showing 10 items of 1845 documents
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.
Applying univariate vs. multivariate statistics to investigate therapeutic efficacy in (pre)clinical trials: A Monte Carlo simulation study on the ex…
2020
BackgroundSmall sample sizes combined with multiple correlated endpoints pose a major challenge in the statistical analysis of preclinical neurotrauma studies. The standard approach of applying univariate tests on individual response variables has the advantage of simplicity of interpretation, but it fails to account for the covariance/correlation in the data. In contrast, multivariate statistical techniques might more adequately capture the multi-dimensional pathophysiological pattern of neurotrauma and therefore provide increased sensitivity to detect treatment effects.ResultsWe systematically evaluated the performance of univariate ANOVA, Welch's ANOVA and linear mixed effects models ver…
On the nuclear response of the helium-cooled lithium lead test blanket module in ITER
2005
Abstract The helium-cooled lithium lead (HCLL) concept has been recently selected as one of the two European reference designs foreseen for the breeding blanket of a demonstration fusion reactor. In particular, within the framework of the research and development activities on this blanket line, an HCLL test blanket module (TBM) has to be designed and manufactured to be implemented in ITER. At the Department of Nuclear Engineering (DIN) of the University of Palermo, a research campaign has been carried out to investigate the nuclear response of HCLL-TBM inside ITER by a numerical approach based on the Monte Carlo method. A realistic 3D heterogeneous model of HCLL-TBM has been set-up and ins…
Study of the helium-cooled lithium lead test blanket module nuclear behaviour under irradiation in ITER
2009
Abstract The present paper deals with the detailed investigation of the helium-cooled lithium lead test blanket module (HCLL-TBM) nuclear behaviour under irradiation in ITER, carried out at the Department of Nuclear Engineering of the University of Palermo adopting a numerical approach based on the Monte Carlo method. A realistic 3D heterogeneous model of the HCLL-TBM was set-up and inserted into an ITER 3D semi-heterogeneous model that realistically simulates the reactor lay-out up to the cryostat. A Gaussian-shaped neutron source was adopted for the calculations. The main features of the HCLL-TBM nuclear response were assessed, paying a particular attention to the neutronic and photonic d…
The liquid-solid transition of hard discs: first-order transition or Kosterlitz-Thouless-Halperin-Nelson-Young scenario?
2002
We consider the question of whether a two-dimensional hard-disc fluid has a first-order transition from the liquid state to the solid state as in the three-dimensional melting-crystallization transition or whether one has two subsequent continuous transitions, from the liquid to the hexatic phase and then to the solid phase, as proposed by Kosterlitz, Thouless, Halperin, Nelson and Young (KTHNY). Monte Carlo (MC) simulations of the fluid that study the growth of the bond orientational correlation length, and of the crystal are discussed. The emphasis is on a recent consistency test of the KTHNY renormalization group (RG) scenario, where MC simulations are used to estimate the bare elastic c…