Three-phase upward flow in a vertical pipe

In this paper we develop an approach to design a three-phase, gas–solid–liquid flow system that transports pneumatically scarified solid particles, including sticky ones, through a vertical pipe. The proposed system permits the introduction and maintenance of a liquid film that coats the pipe’s inner wall and acts as a lubricant that ensures sticky particles continue to move upward without permanently adhering to the pipe wall. The system’s operating conditions fall within the boundaries of the annular dispersed region on a typical flow pattern map of vertical flow of a gas–liquid mixture. High gas superficial velocities combined with low liquid superficial velocities characterize such a region. A combination of a modified one-dimensional, two-fluid annular dispersed flow model and a one-dimensional pneumatic conveying model is shown to describe this transport process satisfactorily. Solution of the combined models produces all the necessary design parameters including power requirements and superficial velocities of the two-fluid media needed to transport a given amount of solid particles. Results of model calculations are compared with rare three-phase flow data obtained prior to the development of the present model, by an independent experimental team that used the physical conditions of the present approach. Reasonable agreement justifies the use of the combined model for engineering design purposes.     

Extended and unscented filtering algorithms using one-step randomly delayed observations

In this paper, the least squares filtering problem is investigated for a class of nonlinear discrete-time stochastic systems using observations with stochastic delays contaminated by additive white noise. The delay is considered to be random and modelled by a binary white noise with values of zero or one; these values indicate that the measurement arrives on time or that it is delayed by one sampling time. Using two different approximations of the first and second-order statistics of a nonlinear transformation of a random vector, we propose two filtering algorithms; the first is based on linear approximations of the system equations and the second on approximations using the scaled unscented transformation. These algorithms generalize the extended and unscented Kalman filters to the case in which the arrival of measurements can be one-step delayed and, hence, the measurement available to estimate the state may not be up-to-date. The accuracy of the different approximations is also analyzed and the performance of the proposed algorithms is compared in a numerical simulation example.     

Effect of the alkyl chloride-to-aluminum molar ratio in the catalysts of dec-1-ene oligomerization on the product distribution and the chlorine content in the products

Dec-1-ene oligomerization in the presence of an aluminum—1-dodecyl chloride system was studied. A mixture of low-molecular-weight oligodecenes containing 25–40 wt.% dimers and 30–52 wt.% dec-1-ene trimers is formed at the molar ratios RCl/A1 = 0.5–1.5. The oligomerization was assumed to occur under the action of cationic active sites, which are formed during the reaction of 1-chlorodedecane with aluminum. At temperatures of 120–130°C and molar ratios RCl/A1 = 0.5–1.5 metallic aluminum completely dechlorinates 1-chlorododecane in a dec-1-ene medium. The character of the effect of highly dispersed Al and the RCl/A1 molar rato on the fractional composition and chlorine content in oligodecenes was revealed. The latter are formed by an aluminum—tert-butyl chloride system used in the industrial oligomerization of dec-1-ene. A mechanism of Al dissolution by alkyl chlorides with the simultaneous dechlorination of alkyl chloride and formation of cationic active sites in A1-RCl systems was proposed to explain the results obtained. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 661–665, March, 2008.     

基于丙烯酸酯的全息聚合物分散液晶光栅的动力学理论研究

采用一维无限长模型分析法对全息聚合物分散液晶(HPDLC)做了动力学方面的研究，给出了相关的扩散动力学方程和聚合动力学方程,并与折射率调制度Δn相结合获得了光栅衍射效率的表达式，对HPDLC光栅性能的改善提供了理论上的指导.     

Influence of Moisture on the Structure and Properties of the Interphase Layer of a Composite Based on an Epoxy Binder with a Disperse Filler

Properties of a model composite based on an ED-22 epoxy binder, cured with polyprophylene polyamine, and disperse LiF crystals as a filler were investigated by the methods of dilatometry and X-ray diffractometry. It was established that the density of cross-links of the epoxy binder in the interphase layer was lower than in a block specimen. Therefore, the thermal expansion of the composite on heating to 120°C, in terms of that of the binder, grew significantly with the degree of filling ϕ, and the water uptake also increased at the initial stage. The presence of absorbed water led to considerable changes in the structure and properties of the composite interphase: the binder became more cross-linked, its structural ordering decreased, the thermal expansion at heating diminished by a factor of 3. 7 (at ϕ = 50%), and the glass-transition temperature increased. As a result of long-term action of moisture, changes in the internal stresses had an extreme character.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 4, pp. 535–544, July–August, 2005.     

Soluble metal–polymer catalysts in the hydrogenation of organic compounds

Literature describing the use of soluble metal–polymer catalysts in the molecular hydrogenation of alkenes, alkynes, aromatic and heterocyclic compounds has been reviewed. Special attention has been paid to coordinated metallic and organometallic catalytic systems and highly dispersed colloidal metals stabilized with polymers. The influence of metals, polymers and solvents on the structures of active sites is discussed. The prospects for the application of soluble metal–polymer catalysts in organic synthesis are also considered.     

Bootstrap Approximation to the Distribution of M-estimates in a Linear Model

The authors establish the approximations to the distribution of M-estimates in a linear model by the bootstrap and the linear representation of bootstrap M-estimation,and prove that the approximation is valid in probability 1.A simulation is made to show the effects of bootstrap approximation,randomly weighted approximation and normal approximation.     

Atomically Dispersed Main Group Magnesium on Cadmium Sul-fide as the Active Site for Promoting Photocatalytic Hydrogen Evolution Catalysis

Photoabsorption charge separation/transfer and surface reaction are the three main factors influencing the efficiency of photocatalysis.Band structure engineering has been extensively applied to improve the light absorption of photocatalysts,however,most of the developed photocatalysts still suffer from low photocatalytic performance due to the limited active site(s)and fast recombination of photogenerated charge carriers.In this work,atomically dispersed main group magnesium(Mg)is introduced onto CdS monodispersed nanospheres,which greatly enhances the photocatalytic hydrogen evolution reaction.The photocatalytic hydrogen evolution reaction rate reaches 30.6 mmol·gcatalyst^-1·h^-1,which is about 11.8 and 2.5 times that of pure CdS and Pt(2 wt.%)-CdS.The atomically dispersed Mg on CdS acts as an electron sink to trap photogenerated electrons,and at the same time,greatly reduces the Gibbs free energy of hydrogen evolution reaction(HER)and accelerates HER.     

Scattering of Millimeter Waves from Acid Rain

A theoretical investigation of scattering characteristics of millimeter waves from acid rain is conducted using the method of vector spherical function expansion. The particles of acid rain are considered as the double-layered spheroid. The method is used to derive an analytical solution to the problem of scattering of millimeter waves by a coated dielectric spheroid. The normalized bistatic cross section versus scattering angle for the acid raindrop is calculated at frequencies of 35 GHz and 94 GHz. This is the first part of our study scattering characteristics of millimeter waves from acid rain.     

三维斯托克斯流动在扁球坐标系中的基本解及其应用

通过把Lamb基本解中的调和函数转换为扁球坐标系下的表达式,这项研究成功地得到了一个新的Stokes流动三维基本解.此基本解可用于解决任意多个扁椭球处于任意位置和方向时的流动问题.应用最小二乘法,三维流动问题中常遇到的收敛性差的困难在此得以完全克服.结果表明该方法具有准确度高,收敛性好和计算量小的特点.由于扁球可用于模拟从圆盘到圆球的多种物体形状,此基本解被用于系统地分析了各种几何因素对两个扁球所受力和力矩的影响.为了显示此方法的通用性,该基本解还用于研究了两例三个扁球的问题.