Improvement of polyacrylate coating by filling modified nano-TiO2

Nano-TiO₂ is modified by a method, by which nano-TiO₂ first reacts with silane coupling agent WD-70 with double bond group which subsequently copolymerizes with methyl methacrylate and butyl acrylate to produce a thin polymer shell on the nanoparticles. The modified nanoparticles have stable organophilicity. They are applied to polyacrylate coating and performances of the coating are measured by different methods. The modification of nano-TiO₂ particles can improve their dispersibility in coating, enhance hardness of coating and reduce water absorption and permeability of polyacrylate coating. The mechanism has been analyzed in this paper.     

On scattering of electromagnetic radiation by inhomogeneities of the velocity of motion of the medium

Analysis of the scattering of a plane monochromatic electromagnetic wave by an inhomogeneity of the velocity of motion of the medium is carried out. The inhomogeneity corresponds to the rotation of a finite portion of the medium with a constant angular velocity under the conditions of spatial homogeneity of the permittivity and the permeability. The case of oblique incidence of the wave is studied. The scattering cross sections for an inhomogeneity having the shape of a cylinder or a sphere of different dimensions are found for different angles of incidence of radiation.     

The Khler-Einstein metric for some Hartogs domains over symmetric domains

We study the complete Kahler-Einstein metric of a Hartogs domainΩbuilt on an irreducible bounded symmetric domainΩ, using a power Nμof the generic norm ofΩ.The generating function of the Kahler-Einstein metric satisfies a complex Monge-Ampere equation with a boundary condition. The domainΩis in general not homogeneous, but it has a subgroup of automorphisms, the orbits of which are parameterized by X∈[0,1[. This allows us to reduce the Monge-Ampere equation to an ordinary differential equation with a limit condition. This equation can be explicitly solved for a special valueμ0 ofμ.. We work out the details for the two exceptional symmetric domains. The special valueμ0 seems also to be significant for the properties of other invariant metrics like the Bergman metric; a conjecture is stated, which is proved for the exceptional domains.     

The Closed Orbits of a Class of Cubic Vector Fields in R3

In this paper, we investigate the isolated closed orbits of two types of cubic vector fields in R₃ by using the idea of central projection transformation, which sets up a bridge connecting the vector field X(x) in R₃ with the planar vector fields. We have proved that the cubic vector field in R₃ can have two isolated closed orbits or one closed orbit on the invariant cone. As an application of this result, we have shown that a class of 3-dimensional cubic system has at least 10 isolated closed orbits located on 5 invariant cones, and another type of 3-dimensional cubic system has at least 26 isolated closed orbits located on 13 invariant cones or 26 invariant cones.     

Electron impact fragmentation of some cyclohexyl thiophosphororganic amides

This paper presents the mass spectra, fragmentation pathways and structures of ions obtained by electron impact from methyl cyclohexyl phosphinomorpholinylamidothioate (1), cyclohexyl phosphonomorpholinylamidochloridothioate (2), cyclohexyl morpholinylamidophosphonothioic acid (3) and O-methyl cyclohexyl phosphonomorpholinylamidothioate (4). The fragmentation pathways and ion structures were established by exact mass determinations on compound 1 and by metastable transitions of all the compounds.     

带有多次速率改变行为的单机排序问题

研究机器带有多次速率改变行为的单机排序问题.机器可以通过不超过t个时段的中断来调整加工速度, 即每个工件在每次中断时段前后加工的加工时间可能不同.因此问题就需要决定是否中断,以及何时中断,使得最大完工时间、完工时间总和、加权完工时间总和等尽可能小.对任意固定的t,关于最大完工时间和完工时间总和目标分别给出了多项式时间最优算法,对满足正则假设的加权完工时间总和目标也给出了一个多项式时间最优算法.     

光子晶体中缺陷的色散导致的群速度降低

利用传输矩阵方法计算了包含色散媒质缺陷的一维光子晶体的复透射系数，其中色散媒质用洛仑兹振子模型描述。计算了由复透射系数定义的等效复折射率并由此研究了频谱位于缺陷模频率附近的光脉冲的群速度。结果发现，由于缺陷模附近的透射谱敏感地依赖于缺陷层的光学厚度，而缺陷层的色散使缺陷层光学厚度随频率变化而改变，从而使包含缺陷的光子晶体的等效色散性质明显地依赖于缺陷的色散行为。由于光脉冲是由多种频率成分的单色场迭加构成的，透射脉冲由各单色场透射后重新迭加构成，因此波包的传播由介质的等效色散性质决定。与包含无色散缺陷的光子晶体相比，缺陷的色散可导致极慢的群速度。通过改变振子强度，群速度可从极慢光速转变为超光速(superluminal)。