Search results for " Monte Carlo"
showing 10 items of 400 documents
An experience of elicited inquiry elucidating the electron transport in semiconductor crystals
2016
In this study we report the results of an inquiry-driven learning path experienced by a sample of 10 electronic engineering students, engaged to investigate the electron transport in semiconductors. The undergraduates were first instructed by following a lecture-based class on condensed matter physics and then involved into an inquiry based path of simulative explorations. The students were invited by two instructors to explore the electron dynamics in a semiconductor bulk by means of Monte Carlo simulations. The students, working in group, had to design their own procedure of exploration, as expected in a traditional guided inquiry. But they experienced several difficulties on planning and…
Pattern Formation Kinetics for Charged Molecules on Surfaces: Microscopic Correlation Function Analysis
2011
The kinetics of pattern formation and phase separation in a system of two types of oppositely charged molecules with competing short- and long-range interactions on surfaces/interfaces is studied combining three methods: a microscopic formalism of the joint correlation functions, reverse Monte Carlo, and nonequilibrium charge-screening factors. The molecular ordering occurs on the background of the Ostwald ripening and thus is strongly nonequilibrium. We have demonstrated how initial random distribution of molecules is changed for loose similar-molecule aggregates, with further reorganization into dense macroscopic domains of oppositely charged molecules. Pattern formation process is charac…
Microscopic calculations of the hipernucleus λ5He
1993
Ground state results for the hypernucleus λ5He are reported. They have been calculated with a variatonal Jastrow-like trial wave function and also within the Diffusion Monte Carlo method. Simple central potential have been used to describe NN and λN interactions. The validity of the rigid core approximation is discussed. Guardiola Barcena, Rafael, Rafael.Guardiola@ific.uv.es Navarro Salas, Jose, Jose.Navarro@ific.uv.es
EXAFS study of hydrogen intercalation into ReO 3 using the evolutionary algorithm.
2014
In this study we have investigated the influence of hydrogen intercalation on the local atomic structure of rhenium trioxide using a new approach to EXAFS data analysis, based on the evolutionary algorithm (EA). The proposed EA-EXAFS method is an extension of the conventional reverse Monte Carlo approach but is computationally more efficient. It allows one to perform accurate analysis of EXAFS data from distant coordination shells, taking into account both multiple-scattering and disorder (thermal and static) effects. The power of the EA-EXAFS method is first demonstrated on an example of the model system, pure ReO3, and then it is applied to an in situ study of hydrogen bronze HxReO3 upon …
Temperature-dependent EXAFS study of the local structure and lattice dynamics in cubic Y2O3
2016
The local structure and lattice dynamics in cubic Y2O3were studied at the YK-edge by X-ray absorption spectroscopy in the temperature range from 300 to 1273 K. The temperature dependence of the extended X-ray absorption fine structure was successfully interpreted using classical molecular dynamics and a novel reverse Monte Carlo method, coupled with the evolutionary algorithm. The obtained results allowed the temperature dependence of the yttria atomic structure to be followed up to ∼6 Å and to validate two force-field models.
Monte Carlo simulation in phylogenies: an application to test the constancy of evolutionary rates.
1994
Monte Carlo simulation has commonly been used in phylogenetic studies to test different tree-reconstruction methods, and consequently, its application for testing evolutionary models can be considered as a natural extension of this usage. Repetitive simulation of a given evolutionary process, under the restrictions imposed by the model to be tested, along a determinate tree topology allow the estimate of probability distributions for the desired parameters. Next, the phylogenetic tree can be reconstructed again without the constraints of the model, and the parameter of interest, derived from this tree, can be compared to the corresponding probability distribution derived from the restricted…
Uncertainty analysis of life cycle assessment of asphalt surfacings
2023
The Life Cycle Assessment (LCA) of asphalt pavements are associated with significant uncertainty resulting from variability in the quantity and impact of individual components, the quality of data for each component, and variability of asphalt durability. This study presents a framework to quantify and incorporate the uncertainty of LCA and asphalt durability data into LCA of asphalt surfacings. The suggested framework includes: estimating the uncertainty of asphalt production processes by the pedigree matrix method, conducting a deterministic LCA, applying Monte Carlo Simulation (MCS) to estimate the probability density functions (PDFs) of the considered impacts using the uncertainty data,…
A new OLS-based procedure for clusterwise linear regression
2009
Data heterogeneity, within a (linear) regression framework, often suggests the use of a Clusterwise Linear Regression (CLR) procedure, which implies, among other things, the estimate of the appropriate number of clusters as well as the cluster membership of each unit. The approaches to the estimation of a CLR model are essentially based on the Ordinary Least Square (OLS) criterion or the likelihood criterion. In this paper, in a context of OLS approach, we propose an estimation of the model making use of an algorithm based on a threshold criterion for the determination coefficient of each cluster, to identify the appropriate number of clusters, and of a modified Spath's algorithm, to estima…
Early Treatment in HCV: Is it a Cost-Utility Option from the Italian Perspective?
2016
In Italy, the Italian Pharmaceutical Agency (AIFA) criteria used F3–F4 fibrosis stages as the threshold to prioritise the treatment with interferon (IFN)-free regimens, while in genotype 1 chronic hepatitis C (G1 CHC) patients with fibrosis of liver stage 2, an approach with pegylated interferon (PEG-IFN)-based triple therapy with simeprevir was suggested. The key clinical question is whether, in an era of financial constraints, the application of a universal IFN-free strategy in naive G1 CHC patients is feasible within a short time horizon. The aim of this study is to perform an economic analysis to estimate the cost-utility of the early innovative therapy in Italy for managing hepatitis C…
Guide to Practical Work with the Monte Carlo Method
2002
The guide is structured such that we proceed from the “easy” simulation methods and algorithms to the more sophisticated. For each method the algorithms are presented by the technique of stepwise refinement. We first present the idea and the basic outline. From then on we proceed by breaking up the larger logical and algorithmic structures into smaller ones, until we have reached the level of single basic statements. Sometimes we may elect not to go to such a depth and the reader is asked to fill in the gaps.