Papers by Keyword: Monte-Carlo Method (MC-Method)

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Authors: Yoshiki Komiya, Shoichi Hirosawa, Tatsuo Sato
Abstract: The formation of nanoclusters in the early aging stage is not fully clarified due to their extremely small sizes. To clarify the atomic-scale clustering of solute atoms, a three-dimensional atom probe (3DAP) analysis and a Monte Carlo computer simulation have been conducted together for Al-Zn alloys. The nanoclusters in the alloy aged at room temperature were successfully detected in the obtained 3DAP maps. From these maps the growth behavior of nanoclusters during aging was experimentally examined. In the Monte Carlo simulation, on the other hand, many-body nearest neighbor interactions between atoms and between atoms and a vacancy were taken into account. The Zn concentration of the clusters calculated in the 4-body interaction model best agreed with that obtained experimentally, suggesting the importance of many-body interactions. Therefore, it was confirmed that the combined analysis of 3DAP and the well-constructed Monte Carlo simulation is useful to make clear the nanocluster formation in alloys.
Authors: Liz Añez, Juan Primera, Anwar Hasmy, Pedro Franceschini, Néstor Sánchez, Thierry Woignier
Abstract: This study introduces a method for a computational calculus of the Elasticity Modulus (E) of simulated porous media using the Monte Carlo technique. The porous media of known geometry is simulated as an elastic network of central forces, to which a known deformation is applied. The minimum strain energy is calculated applying the Monte Carlo technique. The Elasticity Modulus is obtained from the theoretical relations between the elastic energy of a system and its deformation. The computational method is validated by applying it in systems of known analytic solution and over porous media generated through aggregation algorithm in two dimensions i.e. Random Sequential Aggregation and Diffusion Limited Cluster-Cluster Aggregation (RSA and DLCA respectively). The latter used to simulate the structure of silica aerogels. As for the range of concentrations studied for the DLCA and RSA systems, it was found that the elasticity modulus E decreases as the porosity of the system increases, being the E value higher for the DLCA system with respect to RSA. The method used is able to differentiate the elastic properties for two different aggregation models. Being E values different for equal porosities, the coordination number (Z) was the geometric parameter that best explains the behavior of the Elasticity Modulus.
Authors: Gi Ok Kim, Sugie Shim
Abstract: The Penna model for biological aging was modified. The reproducibility of each individual was determined according to the number of mutations relevant at that time. The results of Monte-Carlo calculations using the modified model show that the ranges of the reproducible age are broadened as time goes by, thus showing self-organization in biological aging to the direction of maximum self-conservation. In addition, the population, survival rate, and average life span were calculated and analyzed by changing the number of new mutations at birth. It is observed that the more the number of new mutations at birth is considered, the shorter the average life span that is obtained.
Authors: Jin Hui Xue, Tao Yong Li, Hai Rong, Zhi Yang, Xiao Dan Yang
Abstract: On the base of fundamental principle of multiple-average harmonic Algorithm, a novel Harmonic calculating method is proposed, by which the amplitude and phase of every harmonics can be calculated accurately and conveniently. Computer simulation and physical experiment prove that the Algorithm has very high accuracy. Further, the influence of noise at samples to the result has been discussed by Monte Carlo method and given a qualitative result for practical engineering application.
Authors: Dong Seok Kim, Han Seung Lee, Seong Min Lee, Xiao Yong Wang
Abstract: Chloride attacks concrete structures becoming a primary factor that deteriorates the durability of concrete structures. For this reason, research has been conducted on chloride ion penetration and diffusion. This research produced an accurate durability life prediction through reliability assessments and proposes a prediction method for the chloride ion diffusion coefficient of a concrete applied assessment program for reliability. As a result, test materials were fabricated using different admixtures and chloride ion diffusion coefficient was calculated by applying an RCPT test at each equivalent age. Based on these results, reliability prediction formulas were indicated through the reliability analysis for a durability life design using a Montecarlo method. In addition, propriety was verified through comparisons and analysis using the proposed formula with the investigated data for chloride ion diffusion.
Authors: Tu Hong, Jun Yong Kang
Abstract: A venation-like groove structure (VGS) is proposed to improve light extraction efficiency (LEE) of vertical GaN-based light-emitting-diode by reshaping the undoped GaN (U-GaN) layer. The light extraction characteristics of the venation-like groove structure are simulated and compared to the same electrode structure without grooves by the Monte Carlo photon-tracing method. It is found that VGS has a 20.3% enhancement on LEE at the chip size of 300 μm × 300 μm. The simulated LEE distribution pattern shows that VGS has advantages in brightness and uniformity compared to interdigitated-multi-fingered and square groove structures. These advantages are contributed to the partition and deformation in VGS.
Authors: Xing Lei Hu, Ya Zhou Sun, Ying Chun Liang, Jia Xuan Chen
Abstract: Monte Carlo (MC) method and molecular dynamics (MD) are combined to analyze the influence of ageing on mechanical properties of machined nanostructures. Single crystal copper workpiece is first cut in MD simulation, and then the machined workpiece is used in MC simulation of ageing process, finally the tensile mechanical properties of machined nanostructures before and after ageing are investigated by MD simulation. The results show that machining process and ageing have obvious influence of tensile mechanical properties. After machining, the yield strength, yield strain, fracture strain and elastic modulus reduce by 36.02%, 28.86%, 20.79% and 7.16% respectively. However, the yield strength, yield strain and elastic modulus increase by 4.84%, 1.41% and 1.02% respectively, fracture strain reduce by 24.53% after ageing process. To research the ageing processes of machined nanostructures by MC simulation is both practical and meaningful.
Authors: S.V. Alekseyev, Pavel V. Prudnikov, Vladimir V. Prudnikov
Abstract: The ageing phenomena in two-dimensional XY model at the low temperatures are investigated by Monte-Carlo method. The two-time correlation function and dynamic susceptibility are measured. Violations of the fluctuation-dissipation theorem are investigated.
Authors: Chang Hong Liu, Xin Tian Liu, Dong Zhou, Li Hui Zhao, Hu Huang, Fu Zhen Xuan
Abstract: Firstly, according to the theory of dual variable, a procedure of the calculating fracture probability of the pressure vessel is presented. Secondly, according to the results of calculating the random numbers of the parameters in the fracture probability model, the dual variable method for the fracture probability of pressure vessel is proved to be a good technical to reduce variance. Finally, the results between the simple sampling and the dual variable method showed that dual variable method is very simple and can be widely used in engineering.
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