The electron swarm parameters of SF6/N2 are calculated in the present study using an improved Monte Carlo collision simulation method （MCS）. And some improved sampling techniques are also adopted. The simulation res...The electron swarm parameters of SF6/N2 are calculated in the present study using an improved Monte Carlo collision simulation method （MCS）. And some improved sampling techniques are also adopted. The simulation results show that the improved simulation method can provide more accurate results.展开更多
Considering the tunneling effect and the Schottky effect,the metal semiconductor contact is simulated by using self consistent ensemble Monte Carlo method.Under different biases or at different barrier heights,the i...Considering the tunneling effect and the Schottky effect,the metal semiconductor contact is simulated by using self consistent ensemble Monte Carlo method.Under different biases or at different barrier heights,the investigation into the tunneling current indicates that the tunneling effect is of great importance under reverse biases.The Schottky barrier diode current due to Schottky effect is in agreement with the theoretical one.The barrier lowering is found a profound effect on the current transport at the metal semiconductor interface.展开更多
By three-dimensional kinetic Monte Carlo simulations, the effects of the temperature, the flux rate, the total coverage and the interruption time on the distribution and the number of self-assembled InAs/GaAs （001） ...By three-dimensional kinetic Monte Carlo simulations, the effects of the temperature, the flux rate, the total coverage and the interruption time on the distribution and the number of self-assembled InAs/GaAs （001） quantum dot （QD） islands are studied, which shows that a higher temperature, a lower flux rate and a longer growth time correspond to a better island distribution. The relations between the number of islands and the temperature and the flux rate are also successfully simulated. It is observed that for the total coverage lower than 0.5 ML, the number of islands decreases with the temperature increasing and other growth parameters fixed and the number of islands increases with the flux rate increasing when the deposition is lower than 0.6 ML and the other parameters are fixed.展开更多
A Monte Carlo method was used to take thorough account of the influences of different reactivity ratios and initial feed compositions on copolymer microstructure.The model proves the lack of azeotropic behavior in sys...A Monte Carlo method was used to take thorough account of the influences of different reactivity ratios and initial feed compositions on copolymer microstructure.The model proves the lack of azeotropic behavior in systems in which r_A>1 and r_B<1 or vice versa;it is also able to calculate the drift in the copolymer properties:copolymer composition,and randomness parameter.Moreover,for each reactivity ratio pair given,there is a unique reaction conversion,at which macromolecules produced inherit their ...展开更多
Electron inelastic mean free path （IMFP） is an important parameter for surface chemical quantification by surface electron spectroscopy techniques. It can be obtained from analysis of elastic peak electron spectrosc...Electron inelastic mean free path （IMFP） is an important parameter for surface chemical quantification by surface electron spectroscopy techniques. It can be obtained from analysis of elastic peak electron spectroscopy （EPES） spectra measured on samples and a Monte Carlo simulation method. To obtain IMFP parameters with high accuracy, the surface excitation effect on the measured EPES spectra has to be quantified as a surface excitation parameter （SEP）, which can be calculated via a dielectric response theory. However, such calculated SEP does not include influence of elastic scattering of electrons inside samples during their incidence and emission processes, which should not be neglected simply in determining IMFP by an EPES method. In this work a Monte Carlo simulation method is employed to determine surface excitation parameter by taking account of the elastic scattering effect. The simulated SEPs for different primary energies are found to be in good agreement with the experiments particularly for larger incident or emission angles above 60° where the elastic scattering effect plays a more important role than those in smaller incident or emission angles. Based on these new SEPs, the IMFP measurement by EPES technique can provide more accurate data.展开更多
In the present work, the possibility of existence of spin glass phase using classical Heisenberg model with Edwards-Anderson type of interactions has been explored employing Monte Carlo simulation of Binder parameter ...In the present work, the possibility of existence of spin glass phase using classical Heisenberg model with Edwards-Anderson type of interactions has been explored employing Monte Carlo simulation of Binder parameter （g （L, T））. Previous experimental studies show that there is finite temperature phase transition but this study indicates that there is no finite temperature phase transition in 3D Heisenberg vector spin glass model.展开更多
The investigation was carried out on the technical problems of finishing the inner surface of elbow parts and the action mechanism of particles in elbow precision machining by abrasive flow.This work was analyzed and ...The investigation was carried out on the technical problems of finishing the inner surface of elbow parts and the action mechanism of particles in elbow precision machining by abrasive flow.This work was analyzed and researched by combining theory,numerical and experimental methods.The direct simulation Monte Carlo(DSMC)method and the finite element analysis method were combined to reveal the random collision of particles during the precision machining of abrasive flow.Under different inlet velocity,volume fraction and abrasive particle size,the dynamic pressure and turbulence flow energy of abrasive flow in elbow were analyzed,and the machining mechanism of particles on the wall and the influence of different machining parameters on the precision machining quality of abrasive flow were obtained.The test results show the order of the influence of different parameters on the quality of abrasive flow precision machining and establish the optimal process parameters.The results of the surface morphology before and after the precision machining of the inner surface of the elbow are discussed,and the surface roughness Ra value is reduced from 1.125μm to 0.295μm after the precision machining of the abrasive flow.The application of DSMC method provides special insights for the development of abrasive flow technology.展开更多
提出并采用基于 Monte Carlo模拟与动力学实验相结合的化学反应动力学参数估算方法 ,由基元反应确定 Monte Carlo模拟具体做法 ,将 Monte Carlo模拟结果与动力学实验结果相比较 ,根据比较结果自动调整和优化动力学参数 ,从而无需事先确...提出并采用基于 Monte Carlo模拟与动力学实验相结合的化学反应动力学参数估算方法 ,由基元反应确定 Monte Carlo模拟具体做法 ,将 Monte Carlo模拟结果与动力学实验结果相比较 ,根据比较结果自动调整和优化动力学参数 ,从而无需事先确定动力学方程即可有效估算各种化学反应的动力学参数值 .采用该方法估算了丙烯氨氧化反应动力学参数 ,并对估算结果进行了分析与讨论 .展开更多
Direct Monte Carlo(MC) simulation is a powerful probabilistic safety assessment method for accounting dynamics of the system.But it is not efficient at simulating rare events.A biasing transition rate method based on ...Direct Monte Carlo(MC) simulation is a powerful probabilistic safety assessment method for accounting dynamics of the system.But it is not efficient at simulating rare events.A biasing transition rate method based on direct MC simulation is proposed to solve the problem in this paper.This method biases transition rates of the components by adding virtual components to them in series to increase the occurrence probability of the rare event,hence the decrease in the variance of MC estimator.Several cases are used to benchmark this method.The results show that the method is effective at modeling system failure and is more efficient at collecting evidence of rare events than the direct MC simulation.The performance is greatly improved by the biasing transition rate method.展开更多
The new improved directional vector simulation method foranalyzing the reliability of struc- tural systems failure probabilityis researched. This paper also points out the defects of generaldirectional vector simulati...The new improved directional vector simulation method foranalyzing the reliability of struc- tural systems failure probabilityis researched. This paper also points out the defects of generaldirectional vector simulation, and gives rise to a new higheraccuracy approximate integral formula of structural systems failureprobability. A new geometric meaning of characteristic function isobtained. A new simple method of generating uniformly distributedrandom vector sample sin n-dimensional unit hyper-spherical surfaceis put forward and strictly proved. This method is easy to put intopractice. Numerical examples are given to show the applicability andeffectiveness of the suggested approach to structural systemsreliability problems.展开更多
基金National Natural Science Foundation of China(Nos.50607004,90715029)the Science Foundation of Hunan University,China
文摘The electron swarm parameters of SF6/N2 are calculated in the present study using an improved Monte Carlo collision simulation method （MCS）. And some improved sampling techniques are also adopted. The simulation results show that the improved simulation method can provide more accurate results.
文摘Considering the tunneling effect and the Schottky effect,the metal semiconductor contact is simulated by using self consistent ensemble Monte Carlo method.Under different biases or at different barrier heights,the investigation into the tunneling current indicates that the tunneling effect is of great importance under reverse biases.The Schottky barrier diode current due to Schottky effect is in agreement with the theoretical one.The barrier lowering is found a profound effect on the current transport at the metal semiconductor interface.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60908028,60971068,and 10979065)the Fundamental Research Funds for the Central Universities,China(Grant No.2011RC0402)the Program for New Century Excellent Talents in University,China(Grant No.NCET-10-0261)
文摘By three-dimensional kinetic Monte Carlo simulations, the effects of the temperature, the flux rate, the total coverage and the interruption time on the distribution and the number of self-assembled InAs/GaAs （001） quantum dot （QD） islands are studied, which shows that a higher temperature, a lower flux rate and a longer growth time correspond to a better island distribution. The relations between the number of islands and the temperature and the flux rate are also successfully simulated. It is observed that for the total coverage lower than 0.5 ML, the number of islands decreases with the temperature increasing and other growth parameters fixed and the number of islands increases with the flux rate increasing when the deposition is lower than 0.6 ML and the other parameters are fixed.
文摘A Monte Carlo method was used to take thorough account of the influences of different reactivity ratios and initial feed compositions on copolymer microstructure.The model proves the lack of azeotropic behavior in systems in which r_A>1 and r_B<1 or vice versa;it is also able to calculate the drift in the copolymer properties:copolymer composition,and randomness parameter.Moreover,for each reactivity ratio pair given,there is a unique reaction conversion,at which macromolecules produced inherit their ...
基金This work was supported by the National Natural Science Foundation of China （No.11274288 and No.11574289）. We thank the Supercomputing Center of USTC for support in performing parallel computations.
文摘Electron inelastic mean free path （IMFP） is an important parameter for surface chemical quantification by surface electron spectroscopy techniques. It can be obtained from analysis of elastic peak electron spectroscopy （EPES） spectra measured on samples and a Monte Carlo simulation method. To obtain IMFP parameters with high accuracy, the surface excitation effect on the measured EPES spectra has to be quantified as a surface excitation parameter （SEP）, which can be calculated via a dielectric response theory. However, such calculated SEP does not include influence of elastic scattering of electrons inside samples during their incidence and emission processes, which should not be neglected simply in determining IMFP by an EPES method. In this work a Monte Carlo simulation method is employed to determine surface excitation parameter by taking account of the elastic scattering effect. The simulated SEPs for different primary energies are found to be in good agreement with the experiments particularly for larger incident or emission angles above 60° where the elastic scattering effect plays a more important role than those in smaller incident or emission angles. Based on these new SEPs, the IMFP measurement by EPES technique can provide more accurate data.
文摘In the present work, the possibility of existence of spin glass phase using classical Heisenberg model with Edwards-Anderson type of interactions has been explored employing Monte Carlo simulation of Binder parameter （g （L, T））. Previous experimental studies show that there is finite temperature phase transition but this study indicates that there is no finite temperature phase transition in 3D Heisenberg vector spin glass model.
基金Projects(51206011,U1937201)supported by the National Natural Science Foundation of ChinaProject(20200301040RQ)supported by the Science and Technology Development Program of Jilin Province,China+1 种基金Project(JJKH20190541KJ)supported by the Education Department of Jilin Province,ChinaProject(18DY017)supported by Changchun Science and Technology Program of Changchun City,China。
文摘The investigation was carried out on the technical problems of finishing the inner surface of elbow parts and the action mechanism of particles in elbow precision machining by abrasive flow.This work was analyzed and researched by combining theory,numerical and experimental methods.The direct simulation Monte Carlo(DSMC)method and the finite element analysis method were combined to reveal the random collision of particles during the precision machining of abrasive flow.Under different inlet velocity,volume fraction and abrasive particle size,the dynamic pressure and turbulence flow energy of abrasive flow in elbow were analyzed,and the machining mechanism of particles on the wall and the influence of different machining parameters on the precision machining quality of abrasive flow were obtained.The test results show the order of the influence of different parameters on the quality of abrasive flow precision machining and establish the optimal process parameters.The results of the surface morphology before and after the precision machining of the inner surface of the elbow are discussed,and the surface roughness Ra value is reduced from 1.125μm to 0.295μm after the precision machining of the abrasive flow.The application of DSMC method provides special insights for the development of abrasive flow technology.
文摘提出并采用基于 Monte Carlo模拟与动力学实验相结合的化学反应动力学参数估算方法 ,由基元反应确定 Monte Carlo模拟具体做法 ,将 Monte Carlo模拟结果与动力学实验结果相比较 ,根据比较结果自动调整和优化动力学参数 ,从而无需事先确定动力学方程即可有效估算各种化学反应的动力学参数值 .采用该方法估算了丙烯氨氧化反应动力学参数 ,并对估算结果进行了分析与讨论 .
基金supported by the Special Projects of International Thermonuclear Experimental Reactor(2015GB116000)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA03040000)+1 种基金the Informatizational Special Projects of Chinese Academy of Sciences(No.XXH12504-1-09)the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2014FXCX004)
文摘Direct Monte Carlo(MC) simulation is a powerful probabilistic safety assessment method for accounting dynamics of the system.But it is not efficient at simulating rare events.A biasing transition rate method based on direct MC simulation is proposed to solve the problem in this paper.This method biases transition rates of the components by adding virtual components to them in series to increase the occurrence probability of the rare event,hence the decrease in the variance of MC estimator.Several cases are used to benchmark this method.The results show that the method is effective at modeling system failure and is more efficient at collecting evidence of rare events than the direct MC simulation.The performance is greatly improved by the biasing transition rate method.
文摘The new improved directional vector simulation method foranalyzing the reliability of struc- tural systems failure probabilityis researched. This paper also points out the defects of generaldirectional vector simulation, and gives rise to a new higheraccuracy approximate integral formula of structural systems failureprobability. A new geometric meaning of characteristic function isobtained. A new simple method of generating uniformly distributedrandom vector sample sin n-dimensional unit hyper-spherical surfaceis put forward and strictly proved. This method is easy to put intopractice. Numerical examples are given to show the applicability andeffectiveness of the suggested approach to structural systemsreliability problems.
