VISCOUS FORCES BETWEEN TWO SPHERES COLLIDING THROUGH INTERSTITIAL POWER-LAW FLUID

Interaction between two spheres with an interstitial fluid is essential in Discrete Element modeling for simulating the behaviors of ‘wet‘ particulate materials. In this paper the interaction between two spheres with an interstitial Power-law fluid was approximately resolved as normal and tangential interactive models respectively, for which the governing equations were simplified on the basis of Reynolds approximation. These equations were then solved an alytically together with the boundary conditions to obtain the pressure distributions for each individual model, and event ually solutions of the viscous squeeze force and the tangential viscous resistance were obtained, which provide a set of solutions for implementing into DEM code or other purposes.     

准分子激光增强高分子材料粘着力的机理研究

 由热方程计算激光与液体薄膜材料相互作用时的温度场,分析高分子材料表面熔化及材料表面液体膜汽化产生的材料的表面粗化;近一步分析高分子的断裂、F原子 替代等光化学反应;从而提出激光增强高分子材料的粘着力的表面粗化和光化学反应的机理。     

MEASUREMENT OF ADHESION FORCES IN AIR WITH THE VIBRATION METHOD

The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally alternating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. For the calculation of the adhesion forces, an approach by Rabinovich was combined with approximations of plastic micro asperity flattening. The Rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces, rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas.     

"中国电子企业质量百强排行榜"评选标准简介

1.领导 "领导"项用于评审组织的高层领导如何确立价值观、方向、绩效期望和以顾客及其他相关方为中心的经营观念,以及如何授权、创新、学习.包括:组织的领导、公共责任.     

原子力显微镜针尖同接触面的纳米压痕粘着力

建立了原子力显微镜(AFM)针尖同接触面的纳米压痕物理模型;根据Hamaker三个假设和Lennard-Jones 势理论,利用连续方法推导出针尖同接触面的纳米压痕粘着力表达式.针对Hamaker常数实验值受环境影响较大,给Hamaker常数的具体应用产生困难的问题,从Lifshitz理论,得出Hamaker常数的近似表达式,并计算了Au、Cu、Al、Ag、Hg的Hamaker常数.计算结果同有关文献的实验结果符合,从而为微机械中广泛存在的纳米接触、"微碰"现象研究提供理论基础.     

微间隙受限液体行为与昆虫爪垫在光滑壁面的粘着机理

自然界中许多昆虫通过分泌一层油性液体薄膜实现其爪垫表皮和光滑壁面之间粘附和解粘附,从而实现在光滑壁布的快速爬行.为了提示昆虫爪垫与光滑壁面间微量液体薄膜对生物粘着的意义,基于自行研制的粘着接触实验仪,采用微量的[emim[Tf2N]离子液体和聚α烯烃油,观测其受限在纳米级光滑钢球表面与玻璃表面之间的接触行为以及法向粘着力.实验发现,临界体积(10^-12—10^-9L)范围内的受限液滴达到临界厚度（小于2μm）后会出现自动铺展和瞬时收缩行为，并同时提供幅值稳定且数值 关键词： 受限液体 粘着力 昆虫爪垫 类固化     

群策群力,打造精品——一节优质课的磨课纪实

2011年湖北省高中青年数学教师优质课评比暨观摩活动于2011年11月8日至11月9日在古城荆州举行.我校高二青年数学教师夏云晶参加了这次在荆州举行的说课比赛活动,从众多的选手中脱颖而出,获得了湖北省高中青年数学教师说课一等奖的第一名.这个优异成绩的取得,实属不易.既