Asymptotic analysis of a thin linearly elastic plate equipped with a periodic distribution of stiffeners

We derive several models of thin plates equipped with a periodic distribution of stiffeners. Depending on the orders of magnitude of the different parameters involved, diverse situations arise, from classical Kirchhoff–Love behaviour with additional energy term to full rigidification.     

Nano-deformation of a Ni-P coating surface after nanoparticle impacts

Chemical mechanical polishing (CMP) has become a primary planarization technique required for the manufacture of a computer hard disk substrate. In CMP, erosive wear, which is regarded as one of the wear mechanisms underlying the interaction between the abrasive particles and polished surfaces, can occur when materials are removed by the surface collision of particles which are carried by a fluid medium. A fundamental understanding of the process in which nanoparticles impact on the surface of the nickel-phosphorous (Ni-P) coating plated on the computer hard disk substrate is important to the control and preventing of surface defects during CMP. In this study, a cylindrical liquid jet containing de-ionized water and SiO₂ nanoparticles impacts obliquely on the surface of Ni-P coating at a speed of 10 m/s. Microscopic examinations of the impacted surface are performed using a high resolution transmission electron microscope, an atomic force microscope, etc. Experimental results indicate that craters and scratches in the surface have taken place after nanoparticle impacts, and crystal grains in nano-scale and an element phosphorus concentration can be found in the sub-surface layer of the impacted surface.     

Evanescent light–atom interaction detected by optogalvanic effect

An evanescent light penetrating an atomic vapour near a dielectric surface could be a probe for many atom-boundary phenomena. We show the possibility of very sensitive detection of the resonant atom–light interaction near the surface by using the optogalvanic effect for an evanescent wave. We observe a narrowing of the profile of the detected atomic line, and we point out some properties of the optogalvanic effect in the evanescent wave.     

Slow mixing of Glauber dynamics for the hard‐core model on regular bipartite graphs

Let ∑ = (V,E) be a finite, d‐regular bipartite graph. For any λ > 0 let π_λ be the probability measure on the independent sets of ∑ in which the set I is chosen with probability proportional to λ^|I| (π_λ is the hard‐core measure with activity λ on ∑). We study the Glauber dynamics, or single‐site update Markov chain, whose stationary distribution is π_λ. We show that when λ is large enough (as a function of d and the expansion of subsets of single‐parity of V) then the convergence to stationarity is exponentially slow in |V(∑)|. In particular, if ∑ is the d‐dimensional hypercube {0,1}^d we show that for values of λ tending to 0 as d grows, the convergence to stationarity is exponentially slow in the volume of the cube. The proof combines a conductance argument with combinatorial enumeration methods. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006     

基于遗传进化的聚类分析新方法

提出了一种基于遗传进化策略的聚类分析新方法，将聚类问题转换为实数空间的优化问题．用遗传策略在连续的实数空间寻找最优类中心，既可避免求解组合优化问题，减少计算量，又可避免在优化过程中陷入局部最优．此遗传聚类方法用于对4组实际数据进行硬分类和模糊分类，结果令人满意．     

Shear viscosity of hydrogen and helium fluids at extended regions of temperatures and pressures

Shear viscosities of hydrogen (H₂) and helium (He) fluids are investigated at extended regions of temperature and pressure using an improved equation of state, in which the the long-range attractive forces are incorporated into the formalism via the double Yukawa (DY) potential fitted to the empirical H₂ and He potentials. Quantum effects, which become paramount at low temperatures, are taken into account through a first-order quantum correction based on the Wigner–kirkwood expansion. The dimerization of H₂ is treated as a hard convex body for which an equation of state can be derived based on the scaled particle theory.     

6种不同取代基的双吖啶类探针的化学发光性质及其构效关系的研究

研究了10，10’-二甲基-9，9’-双吖啶二硝酸盐(DMBAI)N)；10，10’-二甲基-3，3’-二磺酸基-9，9’-双吖啶(I)MDSBA)；3，3’-二磺酸基-9，9’-双吖啶二硝酸盐(DSBADN)；10，10’-二乙羧基-9，9’-双吖啶硝酸盐(DEBADN)；10，10’一二甲基-3，3’-二氨基-9，9’-双吖啶(DMDABA)和10，10’-二(4-氨基丁基)-9，9’-双吖啶硝酸盐(DABADN)等6种9，9’-双吖啶类探针的化学发光性质，获得了9，9’-双吖啶类探针的结构与化学发光性质之间的某些关系，为设计合成新型用于化学发光免疫分析的高发光效率的9，9’-双吖啶类探针提供了一定的理论和实验依据。     

MDI与TDI封端聚酯预聚物和扩链剂间反应速率的研究

用ＦＴＩＲ法系统地研究了不同硬段结构对聚酯型聚氨酯扩链反应动力学的影响，结果显示：不同类二异氰酸酯ＭＤＩ和ＴＤＩ形成的ＮＣＯ封端的聚酯预聚体与二元胺（ＭＯＣＡ）和三元醇（ＴＭＰ）的扩链反应均为二级反应，由ＭＤＩ形成ＮＣＯ封端的聚酯预聚体与胺或醇的扩链反应速度比ＴＤＩ类的要快，ＭＯＣＡ扩链比ＴＭＰ扩链反应活化能低，从基团反应活性不同体系扩链反速度的差别进行了讨论。     

Study of the selectivity of inorganic anions in hydro-organic solvents using indirect capillary electrophoresis

In capillary electrophoresis (CE) analysis of small inorganic anions, the ability to control the electroosmotic flow (EOF) and the ability to alter the electrophoretic mobility of the ions are essential to improve resolution and separation speed. In this work, a CE method for separation of small inorganic anions using indirect detection in mixed methanol/water buffers is presented. The suitability of different UV absorbing probes commonly used for indirect detection including chromate, iodide, phthalate, benzoate, trimellitate, and pyromellitate, in mixed methanol/water buffers is examined. The effect of the electrolyte buffer system, including the pH, buffer concentration and the organic solvent on the electrophoretic mobility of the probes and analytes are also investigated. The EOF was reversed using cationic surfactant, cetyltrimethylammonium bromide (CTAB) so ions were separated under co-EOF mode. The organic solvent alters the electrophoretic mobility of the probes and the analytes differently and hence choice of the appropriate probe is essential to achieve high degree of detection sensitivity. Separations of six anions in less than 2.5 min were accomplished in buffers containing up to 30% MeOH. Adjustment of the methanol content helps to improve the selectivity and resolution of inorganic anions. Limit of detection, reproducibility and application of the method for quantification of anions in water samples will also be discussed.     

The chemical potential for dilute hard-sphere mixtures

Accurate Monte Carlo evaluation of the probability of inserting an additional particle of arbitrary size into a hard-sphere fluid at various densities allows a quantitative check on the scaled particle interpolation formula for this probability, which is rigorously known when the added particle is either very small or very large. The simple scaled particle formula is remarkably accurate due to a favorable choice of the functional dependence of the surface tension on curvature. The biggest deviation occurs at liquid-like densities where the insertion probability is about 20% larger for larger particles, indicating a larger probability of occurrence of larger density fluctuations, and resulting in a smaller (3%) excess chemical potential than the simple theory predicts. On the other hand, at lower densities the insertion probability for large particles is slightly smaller than the theory predicts.