In electron probe microanalysis or scanning electron microscopy, the Monte Carlo method is widely used for modeling electron transport within specimens and calculating X-ray spectra. For an accurate simulation, the calculation of secondary fluorescence (SF) is necessary, especially for samples with complex geometries. In this study, we developed a program, using a hybrid model that combines the Monte Carlo simulation with an analytical model, to perform SF correction for three-dimensional (3D) heterogeneous materials. The Monte Carlo simulation is performed using MC X-ray, a Monte Carlo program, to obtain the 3D primary X-ray distribution, which becomes the input of the analytical model. The voxel-based calculation of MC X-ray enables the model to be applicable to arbitrary samples. We demonstrate the derivation of the analytical model in detail and present the 3D X-ray distributions for both primary and secondary fluorescence to illustrate the capability of our program. Examples for non-diffusion couples and spherical inclusions inside matrices are shown. The results of our program are compared with experimental data from references and with results from other Monte Carlo codes. They are found to be in good agreement.
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http://dx.doi.org/10.1017/S1431927620001531 | DOI Listing |
Geotech Geol Eng (Dordr)
January 2025
School of Mechanical, Aerospace and Civil Engineering, The University of Sheffield, Sheffield, UK.
Earthquake induced soil liquefaction poses a significant threat to buildings and infrastructure, as evidenced by numerous catastrophic seismic events. Existing approaches of regional liquefaction hazard assessment predominantly rely on deterministic analysis methods. This paper presents a novel Probabilistic Liquefaction Hazard Analysis (PLHA) framework based on Monte-Carlo (MC) simulations to mitigate future seismic risks associated with liquefaction.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
UK Catalysis Hub, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, OX11 0FA, UK.
Methanol adsorption isotherms of fresh f-ZSM-5 and steamed s-ZSM-5 (Si/Al ≈ 40) are investigated experimentally at room temperature under equilibrium and by grand canonical Monte Carlo (GCMC) simulations with the aim of understanding the adsorption capacity, geometry and sites as a function of steam treatment (at 573 K for 24 h). Methanol adsorption energies calculated by GCMC are complemented by density functional theory (DFT) employing both periodic and quantum mechanics/molecular mechanics (QM/MM) techniques. Physical and textural properties of f-ZSM-5 and s-ZSM-5 are characterised by diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS) and N-physisorption, which form a basis to construct models for f-ZSM-5 and s-ZSM-5 to simulate methanol adsorption isotherms by GCMC.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Physics and Astronomy, University of Manitoba, Winnipeg R3T 2N2, Canada.
Theory and simulations are used to demonstrate implementation of a variational Bayes algorithm called "active inference" in interacting arrays of nanomagnetic elements. The algorithm requires stochastic elements, and a simplified model based on a magnetic artificial spin ice geometry is used to illustrate how nanomagnets can generate the required random dynamics. Examples of tracking and PID control are demonstrated and shown to be consistent with the original stochastic differential equation formulation of active inference.
View Article and Find Full Text PDFJ Exp Psychol Hum Percept Perform
January 2025
School of Psychology, University of Leeds.
Multi-item retro-cueing effects refer to better working memory performance for multiple items when they are cued after their offset compared to a neutral condition in which all items are cued. However, several studies have reported boundary conditions, and findings have also sometimes failed to replicate. We hypothesized that a strategy to focus on only one of the cued items could possibly yield these inconsistent patterns.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
The microenvironment is recognized to be as crucial as active sites in heterogeneous catalysis. It was found that the catalytic activity of a set of chemical reactions can be significantly influenced by the confined space of carbon nanotubes (CNTs), with some reactions showing superior activity, while others experience a negative impact. The rational design of confined catalysis must rely on the accurate insights of confined microenvironment.
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