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1.
Recently, in our laboratory a closed form expression for the correlation function of the hard-sphere dimer fluid obtained
from Wertheims multidensity Ornstein-Zernike integral equation theory with Percus-Yevick approximation was presented by Kim
et al. [2001]. However, it is difficult to apply its expression to perturbation theory and vapor-liquid equilibria calculations,
since it is of very complex form. In this work, we present a simplified expression for the first shell of the radial distribution
function (RDF) of the hard-sphere dimer fluid using a series expansion of the analytical expression. The expansion is carried
out in terms of both the packing fraction and the radial distance. Expressions are also obtained for the coordination number
and its first and second derivatives as functions of radial distance and packing fraction. These expressions, which are useful
in perturbation theory, are simpler to use than those obtained from the starting equation, while giving good agreement with
the original expression results. Then we present an simplified equation of state for the square-well dimer fluid of variable
well width (λ) based on Barker-Henderson perturbation theory using its expression for the radial distribution function of
the hard-sphere dimer fluid, and test its expression with NVT and Gibbs ensemble Monte Carlo simulation data [Kim et al.,
2001]. 相似文献
2.
An efficient algorithm for the random packing of spheres can significantly save the cost of the preparation of an initial configuration often required in discrete element simulations. It is not trivial to generate such random packing at a large scale, particularly when spheres of various sizes and geometric domains of different shapes are present. Motivated by the idea of compression complemented by an efficient physical process to increase packing density, shaking, a new approach, termed compression algorithm, is proposed in this work to randomly fill any arbitrary polyhedral or cylindrical domains with spheres of various sizes. The algorithm features both simplicity and high efficiency. Tests show that it takes 181 s on a 1.4-GHz PC to complete the filling of a cylindrical domain with a total number of 26,787 spheres, achieving a packing density of 52.89%. 相似文献
3.
4.
We present an efficient algorithm for collision detection between static rigid objects using a dual bounding volume hierarchy which consists of an oriented bounding box (OBB) tree enhanced with bounding spheres. This approach combines the compactness of OBBs and the simplicity of spheres. The majority of distant objects are separated using the simpler sphere tests. The remaining objects are in close proximity, where some separation axes are significantly more effective than others. We select 5 from among the 15 potential separating axes for OBBs. Experimental results show that our algorithm achieves considerable speedup in most cases with respect to the existing OBB algorithms. 相似文献
5.
Wei Zhang Kazuki Tainaka Seongyool Ahn Hiroaki Watanabe Toshiaki Kitagawa 《Advanced Powder Technology》2018,29(10):2322-2330
In this study, an experimental and a numerical investigations are performed to investigate the effect of particle’s shape and size distribution on its dispersion behavior. Firstly, particle dispersion of pulverized coal and spherical polymer particles is observed by Particle Image Velocimetry (PIV) technique in the experiment. Secondly, a simulation is performed to analyze the particle dispersion in detail. Spherical and spheroidal motion models are applied to particle’s movement to investigate the shape effect. Furthermore, monodisperse and polydisperse for particles are applied to investigate the size distribution effect on the dispersion. Experimental results show that in the jet turbulence flow, pulverized coal particles, which have complex shapes and various sizes, have quite different dispersion behavior compared to spherical particles. In terms of the results of the simulation, this difference is mainly caused by the size distribution effect. Although particle’s shape affects the dispersity, it is weakened by the size distribution effect. 相似文献
6.
A NEW COMPLEX SPHERE DETECTOR WITH SE ENUMERATION 总被引:1,自引:0,他引:1
7.
在极度不平衡分类问题中,球形分类器将分类正确样本的损失计为零,仅使用误分样本构造决策函数.文中提出光滑有下界的奖惩结合损失函数,将分类正确样本的损失计为负,实现对目标函数的奖励,避免边界附近噪声的干扰.基于最大间隔双球面支持向量机,利用损失函数,建立奖惩结合的最大间隔双球模型.通过牛顿法构造两个同心球.小球体在覆盖多数类样本的同时抛弃多余的空隙.大球通过增加两个同心球之间的间隔,排除少数类.实验表明,文中模型分类效果较优. 相似文献
8.
详细介绍了封闭体内球形样件轮廓度工业CT精确测量方法,在获得球体样件CT断层图像的基础上,利用CT插值方式提取球体样件的轮廓线边界系列CT值,再根据二次曲线逐次逼近拟合法获得其圆心坐标及平均半径,建立了封闭体内球形样件轮廓度及壁厚的工业CT精确测量方法,并编制了专用测量软件用于实际球形样件轮廓度的测量,比较该方法及三坐标法对不同直径、不同壁厚系列球体模拟件测量结果,在95%置信度下,测量精度达到0.05mm. 相似文献
9.
介绍了本单位新建400 m3丁二烯球罐焊后内燃法整体热处理的过程及方法,经过检测,热处理的工艺和实施方案是可行的,并对效果进行评价. 相似文献
10.
Hong Rok Kim Jayeeta Chattopadhyay Jae Ik Son Daewon Pak 《Korean Journal of Chemical Engineering》2008,25(4):775-779
Pure TiO2 hollow spheres were prepared by using poly(styrene-methacrylic acid) latex particles as template; thereafter, titania hollow
spheres were coated by platinum with an appropriate amount of choloroplatinic acid solution to obtain Pt/TiO2 catalysts. The morphology and structure of nonstructural Pt/TiO2 hollow spheres were characterized by BET, XRD, TGA, SEM and TEM analysis. In the samples, a remarkably uniform layer of Pt
consisting of particles from 5 to 70 nm in size was formed over TiO2 hollow spheres. We found the electrocatalytic nature of the samples by cyclic voltammetric experiment in acidic solution.
The anodic peak current density of 20 wt% Pt-loaded TiO2 hollow particles was observed 2.5 times higher than that of 5 wt% Pt/TiO2 in the same experimental condition. Also, the anodic current density of 20 wt% Pt/TiO2 hollow spheres calcined at various temperatures followed the order: 400 °C≈500 °C>600 °C. The electrocatalytic activity of
the Pt-loaded TiO2 hollow spheres depends on the amount of atomic platinum present in the sample; a higher concentration of platinum results
in a larger current density value in anodic sweep, resulting in more oxygen production during electrolysis. Pt/TiO2 hollow sphere catalysts have also shown long term electrocatalytic stability in acidic media. 相似文献