Effect of the dispersibility of ZrO2 nanoparticles in Ni-ZrO2 electroplated nanocomposite coatings on the mechanical properties of nanocomposite coatings

ZrO₂ nanoparticles was uniformly co-deposited into a nickel matrix by electroplating of nickel from a Watts bath containing particles in suspension which were monodispersed with dispersant under DC electrodeposition condition. It was found that morphology, orientation and hardness of the nanocomposite coatings with monodispersed ZrO₂ nanoparticles had lots of difference from the nanocomposite coatings with agglomerated ZrO₂ nanoparticles and pure nickel coatings. Especially, the result of hardness showed that only a very low volume percent (less than 1 wt.%) of monodispered ZrO₂ nanoparticles in Ni-ZrO₂ nanocomposite coatings would result in higher hardness of the coatings. The hardness of Ni-ZrO₂ nanocomposite coatings with monodispersed and agglomerated ZrO₂ nanoparticles were 529 and 393 HV, respectively. The hardness value of the former composite coatings was over 1.3 times higher than that of the later. All these composite coatings were two-three times higher than that of pure nickel plating (207 HV) prepared under the same condition. The strengthening mechanisms of the Ni-ZrO₂ nanocomposite coatings based on a combination of grain refinement strengthening from nickel matrix grain refining and dispersion strengthening from dispersion state of ZrO₂ nanoparticles in the coatings.     

介质的非均匀性对高次谐波影响的研究

讨论了气体介质的非均匀性对飞秒激光高次谐波产生过程的可能影响.计算结果表明,采用喷阀技术所提供的气体介质的密度梯度和气体原子运动速度的影响很小,不会产生实验上可观测的效果.这一结果支持了喷气靶在高次谐波产生中的广泛应用 关键词： 高次谐波 气体介质 各向异性 飞秒激光     

The Level-split of the Two-level Entangled Atom in an Optical Field

The behavior of a two-level entangled atom in an optical field with circular polarization is studied in this paper. The interaction of an optical field and one of the entangled atoms is analyzed in detail. A general solution of the SchrAo¨Gdinger equation about the motion of the entangled atom is obtained. The properties of the action are dependent on the initial state of the atom. By detecting the entangled atom out of the field, we can obtain the state of the other atom moving in the field. It is shown that the state of the atom out of the field will influence the energies of the split-levels of the atom in the field.     

NO-2-I-体系双波长紫外分光光度法测定痕量亚硝酸根

在稀盐酸介质中,亚硝酸根氧化碘化钾的反应产物I-3在288nm和352nm处有两个强吸收峰.基于此建立了双波长紫外分光光度法测定痕量NO-2的新方法.该法简便、快速、选择性好,线性范围为0-0.4μg/mL,检出限为3.4×10-9g/mL.用于河水、井水、矿泉水中亚硝酸根的测定,结果令人满意.     

推广的Kantorovich算子在Ba空间中的逼近

利用Ditzian-Totik光滑模,研究了推广的Kantorovich算子在Ba空间中的逼近,得到逼近的正定理与等价定理.所得结果改进、推广和统一了一些作者的结果.     

On the third largest Laplacian eigenvalue of a graph

In this article, a sharp lower bound for the third largest Laplacian eigenvalue of a graph is given in terms of the third largest degree of the graph.     

椭圆强非局域空间光孤子

对傍轴椭圆高斯光束在具有椭圆对称响应特性的强非局域非线性介质中的演化规律进行研究，得到了光束各参量演化的精确解析解，分析了单向空间光孤子和强非局域椭圆空间光孤子的形成条件，发现了椭圆光孤子的相移与介质响应函数的椭圆率有关. 关键词： 椭圆对称强非局域响应介质 椭圆强非局域空间光孤子 相移     

On Polynomial Functions over Finite Commutative Rings

Let R be an arbitrary finite commutative local ring. In this paper, we obtain a necessary and sufficient condition for a function over R to be a polynomial function. Before this paper, necessary and sufficient conditions for a function to be a polynomial function over some special finite commutative local rings were obtained.     

Computations of critical groups and applications to asymptotically linear wave equation and beam equation

In this paper, by using the Morse index theory for strongly indefinite functionals developed in [Nonlinear Anal. TMA, in press], we compute precisely the critical groups at the origin and at infinity, respectively. The abstract theorems are used to study the existence (multiplicity) of nontrivial periodical solutions for asymptotically wave equation and beam equation with resonance both at infinity and at zero.