Papers by Keyword: Monte-Carlo Simulation

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Authors: Giorgio Lulli, Roberta Nipoti
Abstract: In this work under-mask penetration of Al+ ions implanted in 4H-SiC is investigated by computer simulation based on the Monte-Carlo binary collision approximation (MC–BCA). Results indicate that a small fraction of ions, implanted normal to a (0001) 4H-SiC wafer (8° off-axis towards the {11-20}), is scattered and become channeled in the <1120> directions perpendicular to the <0001> axis. Due to this phenomenon, doped regions with concentration ≤ 10− 4 of the peak value, may extend laterally for a few µm below the edge of a SiO2 mask.
Authors: A.S. Shirinyan, Yu. S. Bilogorodskyy
Abstract: The process of phase formation at the initial stage of the reaction diffusion and growth of a new phase particles - at the atomic level by applying the Monte-Carlo simulation of the crystalline nanoalloy is presented. The influence of initial composition on the kinetics of phase separation in a binary alloy with the fcc crystal lattice has been analyzed in detail. The dependences of various parameters of tire process - the average size of new-phase particles, volume of new-phase clusters, size distribution function, dispersion and supersaturation - on time have been calculated. The obtained results demonstrate the opportunity of a three-stage separation process at low initial supersaturation values and a two-stage separation at large initial supersaturation values.
Authors: T.V. Zaporozhets, I.V. Sobchenko, Andriy Gusak
Abstract: The 3D Monte Carlo scheme is proposed for simulation of simultaneous self-consistent current redistribution, surface diffusion, drift and void migration and coalescence at the interface metal/dielectric. Results of simulation as well as simple phenomenological model demonstrate a possibility of trapping at and migration along the grainboundaries (GBs). Critical size of “detrapping” after coalescence has been estimated.
Authors: Mo Wen Xie, Zeng Fu Wang, Xiang Yu Liu, Ning Jia
Abstract: The Various methods of optimization or random search have been developed for locating the critical slip surface of a slope and the related minimum safety factor in the limit equilibrium stability analysis of slope. But all these methods are based on a two-dimensional (2D) method and no one had been adapted for a search of the three-dimensional (3D) critical slip surface. In this paper, a new Monte Carlo random simulating method has been proposed to identify the 3D critical slip surface, in which assuming the initial slip to be the lower part of an ellipsoid, the 3D critical slip surface in the 3D slope stability analysis is located by minimizing the 3D safety factor of limit equilibrium approach. Based on the column-based three-dimensional limit equilibrium slope stability analysis models, new Geographic Information Systems (GIS) grid-based 3D deterministic limit equilibrium models are developed to calculate the 3D safety factors. Several practical examples, of obtained minimum safety factor and its critical slip surface by a 2D optimization or random technique, are extended to 3D slope problems to locate the 3D critical slip surface and to compare with the 2D results. The results shows that, comparing with the 2D results, the resulting 3D critical slip surface has no apparent difference only from a cross section, but the associated 3D safety factor is definitely higher.
Authors: Xun Luo, Wei Zhao, Bao Shun Liu, Yan Ming Zhang
Abstract: It is proposed a parallel Monte Carlo algorithm to simulate templated grain growth in sintering ceramics materials. The algorithm applies the general Potts model to treat the matrix as the discrete lattices for simulating the grain growth and there will be a number of lattices to be computed synchronously. The scheme is performed by CUDA GPU parallelization programming framework which is of much more feasibility and low cost comparing with the former conventional program. The most key point is that the parallel algorithm is of great temporal performance which means it takes less time to complete a simulation. The results of comparative experiments show that the algorithm is unquestionable effective while the other statistic numerical features of simulations are almost the same.
Authors: H.-E. Nilsson, E. Bellotti, K.F. Brennan, M. Hjelm
Authors: Muhammad A. Arafin, Jerzy A. Szpunar
Abstract: A model for intergranular damage propagation in polycrystalline materials is proposed, based on Markov Chain theory, Monte Carlo simulation and percolation concept. The model takes into account crack branching and coalescence, multiple crack nucleation sites, crack-turning etc., as well as the effect of grain boundary plane orientations with respect to the external stress direction. Both honeycomb and voronoi microstructures were utilized as the input microstructures. The effect of multiple crack nucleation sites has been found to have great influence on the crack propagation length. It has been observed that percolation threshold reported in the literature based on hexagonal microstructure is not applicable when the effect of external stress direction on the susceptibilities of grain boundaries is considered. The successful integration of voronoi algorithm with the Markov Chain and Monte Carlo simulations has opened up the possibilities of evaluating the intergranular crack propagation behaviour in a realistic manner.
Authors: Hao Xu, Fu Ting Bao, Chen Cheng, Bin Hang Wang
Abstract: In the assessment of internal ballistic performance reliability of Solid Rocket Motor (SRM), eigenvalue discriminance method has long been used. In order to avoid the limitations of the traditional methods, a curve similarity discriminance modification combined with Hausdorff Distance was introduced. A Monte-Carlo simulation model of internal ballistic performance was established, and several uncertain parameters were chosen. A sample analysis of performance reliability of a designed SRM was presented. The result was credible, which proved the modification is feasible and it can meet the needs of the assessment of the internal ballistic performance reliability.
Authors: Hiroshi Okuda, Shojiro Ochiai
Abstract: A Monte Carlo simulation using semi grand canonical ensemble method was applied to examine the condition that precipitation free zone (PFZ) appears in an Al-based composite materials under two step aging. The present simulation uses a fcc lattice with a periodic boundary condition for y and z directions, and a grain boundary existing at the end for x direction. A simple grain boundary segregation case gave a nealy parabolic growth law in PFZ width and the volume fraction of precipitates. Different origin of PFZ, namely, mobility or chemical potential, lead to the opposite effect upon secondary heat treatment.
Authors: Muhammad A. Arafin, Jian Lu, Jerzy Szpunar
Abstract: In this paper, a multiscale modeling approach has been developed to simulate the intergranular crack propagation in textured polycrystalline materials. Embedded Atom Method (EAM) and Molecular Dynamics (MD) simulations were carried out to determine the energy and fracture strength of different types of grain boundaries in Ni3Al. Subsequently, the atomistic model has been integrated with the microstructure based model of crack propagation using the Voronoi-Markov Chain-Monte Carlo approach. The model has been utilized to evaluate the crack length for various scenarios and reasonable results are obtained.
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