共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
应用作者提出的逐级取样方法于NPT正则系综,提出了有效求取流体混合物超额Gibbs自由能的模拟方法。应用该方法模拟了Ar-Kr二元流体混合物、求得了T=115.8K,P=0时整个组成范围的超额Gibbs自由能,这些结果与McDonald采用常规NPTMonteCarlo模拟方法得到的近似结果在误差范围内相符。在交叉势能混合参数ζ=0.989时,模拟结果与实验结果一致。 相似文献
3.
用巨正则系综MonteCarlo方法模拟了甲烷在活性炭孔中的吸附行为 .在此模拟中 ,甲烷分子采用单点LJ球型分子模型 ,狭缝活性炭孔墙采用 1 0 4 3模型 .在低温时 (T =74 0 5K) ,模拟并观察到了甲烷分子在狭缝活性炭孔中的吸附、脱附以及毛细凝聚现象 ,得到了吸附等温线和孔中流体的局部密度轮廓图 .同时 ,把所得的数据与Jiang、Rhykerd和Gubbins的模拟结果进行了比较 ,结果表明 ,模拟方法是正确的 .在此基础上 ,进一步模拟了常温下 (T =30 0K)甲烷分子在狭缝活性炭孔中的吸附存储行为 ,得到了常温下甲烷在不同孔宽活性炭孔中的吸附等温线、有效存储量随压力变化的图像以及有效存储量随孔宽变化的图像 ,并求出了狭缝孔吸附存储甲烷的最佳孔宽和合理的吸附压力 . 相似文献
4.
5.
6.
引 言近年来 ,随着计算机硬件能力的不断提高和新的模拟方法的不断涌现 ,对于高分子溶液的相平衡问题的计算机模拟研究取得了很大的进展 ,但大多将注意力放在如何改进模拟方法以获得更长的均聚高分子溶液的相平衡数据 ,以检验Flory -Huggins理论、修正Freed理论等的有效性 .如Madden等[1]曾利用蛇行法 (reptation)和伪动态模拟算法( pseudokineticsimulationalgorithm)、Mackie等[2 ]在邻位数Zn=2 6的格子模型上用Gibbs系综法、Wilding等[3]用键长涨… 相似文献
7.
基于凝胶的三维网络模型 ,利用MonteCarlo模拟研究了凝胶网络中溶质分子的扩散特性 ,考察溶质分子与网络纤维之间引力和斥力对溶质分子扩散特性的影响 .发现凝胶网络中溶质分子的运动不是Markoff过程 ,具有明显的相关性 .溶质分子越大 ,其运动的异常扩散指数越大 ,相关性越强 .当溶质分子和凝胶网络纤维之间存在引力和斥力等相互作用时 ,溶质分子的运动受到明显阻滞 ,扩散系数显著降低 .增强相互作用和减小溶质分子尺寸均可增强相互作用对溶质分子扩散的阻滞作用 相似文献
8.
9.
引言一氧化碳加氢合成甲醇虽已实现工业化生产,但反应过程中存在的热力学平衡及传热限制的问题并未彻底解决.超临界流体由于具有许多独特的性质,已引起广泛的关注.钟炳等将超临界流体正己烷引入甲醇合成反应,在解决上述两大难题方面取得了进展.目前,文献中针对该体系的有关实验数据还很缺乏,因此,计算机模拟技术不失为获得该体系溶液结构性质的一种较好的方法.Jorgensen以及Debenedetti在溶液的计算机模拟方面做了大量的工作,对有关溶液中分子之间的相互作用进行了详细的分析,但针对正己烷-甲醇体系,特别是超临界条件下该体系… 相似文献
10.
用NVT系综Monte Carlo方法模拟苯在超临界水中的亲水性 总被引:1,自引:0,他引:1
用NVT系综MonteCarlo方法模拟了苯分子在常温及超临界条件下水溶液中的径向分布函数及微观结构图像 .模拟中 ,水采用SPC势能模型 ,苯分子采用单点LJ球型分子模型 .模拟时应用Metropolis抽样及周期边界条件 .应用Ewald方法考虑了水分子间的电荷长程作用 .考虑了 1 0个不同的模拟条件 ,得到了苯与水分子间的径向分布函数图 ,分析了苯在超临界水中的亲水性质随温度、密度及组成的变化 .通过分析得出了苯在超临界水中亲水的结论 ,并推荐了较为适宜的亲水超临界条件 . 相似文献
11.
采用改进的键长涨落空穴扩散算法对平板狭缝中的对称两嵌段共聚高分子熔体的微相分离形态、密度分布以及结构因子进行了MonteCarlo(MC)模拟 .模拟结果表明 :在不同性质壁面的平板狭缝中对称两嵌段共聚高分子熔体的微相结构都是层状的 ,但其取向由壁面性质决定 ,对称中性壁面形成垂直于壁面的层状结构 ,对称选择性吸引壁面以及非对称的选择性吸引和选择性排斥壁面组合导致平行于壁面的层状结构 ,而非对称的选择性吸引和中性壁面的组合形成的层状结构 ,在吸引壁一侧平行于壁面、在中性壁一侧则垂直于壁面 .对结构因子的计算表明对称体系微相结构主要取决于外场的对称性 相似文献
12.
13.
The usefulness of Monte Carlo simulation of aggregation phenomena is discussed and applied in analysis of the structure of particle deposits. The structural properties of depositional aggregates in single and multiparticle regimes are obtained and expressed in terms of fractal geometrical concepts. These properties are related to the Peclet number and to the concentration in the non-aggregate (vapour) phase. The topological properties of the aggregates are obtained from random walk simulation, thus confirming the anomalous properties of these structures, even in the case of multiparticle simulations, i.e. for high values of the concentration in the vapour phase. 相似文献
14.
为提高Monte Carlo分子模拟的取样效率,加速模拟过程的收敛,本文提出了根据粒子能量进行取样的方法。通过对凝固点附近的L-J流体的模拟,将能量选择取样法与Metropolis取样法以及力偏倚取样法的收敛性和模拟结果作了比较,表明能量选择取样法的收敛速度显著高于Metropolis取样法,与力偏倚取样法相当,而计算量比力偏倚取样法小。 相似文献
15.
TESTS FOR FRACTIONAL INTEGRATION:A MONTE CARLO INVESTIGATION 总被引:1,自引:0,他引:1
Abstract. The performance of the Geweke-Porter-Hudak (GPH) test, the modified rescaled range (MRR) test and two Lagrange multiplier (LM) type tests for fractional integration in small samples is examined using Monte Carlo methods. Both the GPH and MRR tests are found to be robust to moderate autoregressive moving-average components, autoregressive conditional heteroskedasticity effects and shifts in the variance. However, these two tests are sensitive to large autoregressive moving-average components and shifts in the mean. It is also found that the LM tests are sensitive to deviations from the null hypothesis. As an illustration, the GPH test is applied to two economic data series. 相似文献
16.
Atichat Wongkoblap 《Chemical Engineering Communications》2013,200(11):1382-1395
A grand canonical Monte Carlo simulation (GCMC) method is used to study adsorption in a carbon slit pore of finite length. Methane is used as a model for the nonpolar molecule, while the polar molecule is modeled as water. The behavior of a nonpolar molecule in the finite-length pore is investigated and compared with that obtained for a commonly used infinite slit pore. The adsorption of methane in the finite pore is significantly different from that in the infinite pore, both the capacity and the hysteresis loop. In addition to nonpolar molecules, the adsorption of water in finite pores has also been studied. The adsorption of water on activated carbon is very complex, and it strongly depends on the concentration as well as the position of the functional groups in the pore. For both cases of nonpolar and polar fluids, effects of pore size on the behavior of adsorption isotherms are also investigated. 相似文献
17.
18.
This article presents a methodology for checking the existence of the azeotrope and computing its composition, density, and pressure at a given temperature by integrating chemical engineering insights with molecular simulation principles. Liquid-vapor equilibrium points are computed by molecular simulations using the Gibbs ensemble Monte Carlo (GEMC) method at constant volume. The appearance of the azeotropic point is marked by a shift of the equilibrium constant from one side of the unity to the other. After each GEMC simulation, an identity change move is derived in the grand canonical ensemble to progress towards the azeotrope along the equilibrium curve. The effectiveness of the proposed methodology is successfully tested for several binary Lennard-Jones mixtures reported in the literature. 相似文献
19.
THE PREDICTIVE PERFORMANCE OF THREE AUTOREGRESSIVE MOVING-AVERAGE MODELS:A MONTE CARLO INVESTIGATION
Abstract. The relative accuracy of point and interval forecasts from three related autoregressive moving-average (ARMA) models—multivariate, univariate, and transfer function—is evaluated in this study. It is found that the multivariate models produce the most accurate one- and three-step-ahead point forecasts of nonindependent series. However, the most accurate point forecasts of independent series are generated by the univariate models. Compared with the multivariate models, the transfer function predictions are relatively unreliable, but with the appropriate restrictions they are superior to the univariate forecasts in certain cases. Interval forecasts from the correctly specified models are reliable indicators of forecast dispersion. 相似文献