Study of the stress intensity factor of preformed V shape fracture tip

This paper gives the complex stress function of preformed V shape fracture under the blasting load. With Westergaard's method, the stress field and displacement field of preformed V shape fracture tip are derived, and hence its stress intensity factor is obtained. The blasting test result shows that the formulas derived are correct and effective.     

Loewner chain and quasiconformal extension of some classes of univalent functions

ABSTRACT

In this article, we obtain quasiconformal extensions of some classes of conformal maps defined either on the unit disc or on the exterior of it onto the extended complex plane. Some of these extensions have been obtained by constructing suitable Loewner chains and others have been found by applying a well-known result.     

Effects of SO2 Treatment of Commercial Catalysts on Selective Catalytic Reduction of NOx by NH3

Nitrogen oxide(NO_x) emitted from stationary and mobile sources is a major air pollutant. Selective catalytic reduction(SCR) of NO_x over a catalyst is a main technology for NO_x elimination. Catalysts used for practical applications would be deactivated in flue containing SO₂. In this work, three typical commercial catalysts were investigated before and after SO₂ treatment. The catalysts were characterized by X-ray diffraction(XRD), X-ray fluorescene(XRF), temperature programme reduction(TPR), temperature programme desorption(TPD) and diffuse reflectance Fourier transform infrared(DRIFT) techniques. Results showed that SO₂ treatment significantly influenced the performance of V₂O₅/TiO₂ catalyst. The amount of V₂O₅ in the catalyst primarily affected the accumulation of sulfur species in the SO₂atmosphere. The performance of catalysts with small amounts of V₂O₅ could be improved under the same experimental conditions for acidity enhancement.     

多金属氧酸盐TBA3[VW5O19]及TBA4[PVW11O40]的固体核磁共振研究

多金属氧酸盐（简称多酸,Polyoxometalates,POMs)是由处于d⁰电子构型的前过渡金属元素通过共边或共角缩聚而成的金属-氧簇类化合物．由于其具有丰富的分子结构和独特的物理化学性质,已经被广泛应用于功能材料、催化化学和药物化学等领域．其中钒取代的多酸阴离子具有很好的催化活性,特别是对烃类的氧化,它的活性主要受钒取代的数目和钒中心的阴离子环境这两个因素影响．该文利用固体核磁技术分析了一取代钒的两类典型结构中⁵¹V的局域结构和化学环境,以及有机阳离子对多酸阴离子结构的影响,特别是对⁵¹V的化学环境的影响,为研究多酸的催化活性和催化机理提供基本的结构信息．     

光电自准直仪中分划丝的分析与比较

根据CCD增维测量原理,分析了制约测量范围的因素,提出了改进分划板的刻线形式的几种方法,并做了比较。     

D301大孔树脂吸附钒(V)的性能研究

研究了D301大孔树脂对钒的吸附性能.结果表明,pH值对D301树脂吸附钒的影响很大,与钒在溶液中的赋存状态有关,且在pH=2时吸附效果最好:测得吸附热力学参数分别为:△H=8.97kJ/mol,△G_(313)=-5.69kJ/mol,△G_(303)=-5.2kJ/mol,△G_(293)=-4.9kJ/mol,△S=46.84J/mol·K.等温吸附服从Freundlich经验式;考察了溶液浓度、搅拌速率对交换过程的影响,并对实验数据运用相关理论模型进行拟合,结果显示钒(V)在D301树脂上吸附交换过程控制步骤为颗粒扩散控制,反应级数n为0.2391.     

Numerical solution of the 3D time dependent Schrödinger equation in spherical coordinates: Spectral basis and effects of split-operator technique

We study a numerical solution of the multi-dimensional time dependent Schrödinger equation using a split-operator technique for time stepping and a spectral approximation in the spatial coordinates. We are particularly interested in systems with near spherical symmetries. One expects these problems to be most efficiently computed in spherical coordinates as a coarse grain discretization should be sufficient in the angular directions. However, in this coordinate system the standard Fourier basis does not provide a good basis set in the radial direction. Here, we suggest an alternative basis set based on Chebyshev polynomials and a variable transformation.     

Trajectory analysis of nonlinear kinetic models of population dynamics of several species

The existence and uniqueness of global solutions are proved for kinetic models of coupled population dynamics. Moreover, under consideration, the uniqueness and the stability analysis of this steady-state solution are discussed. This analysis uses, essentially, the dissipativity, a subtangential condition and the positivity of the related C₀-semigroup.