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MOTION OF TRACER PARTICLES IN A CENTRIFUGAL PUMP AND ITS TRACKING CHARACTERISTICS

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Journal of Hydrodynamics 2012年第5期24卷 785-793页

作者： LI Ya-lin yuan Shou-qi TANG Yue yuan Jian-ping Research Center of Fluid Machinery Engineering and Technology Jiangsu University Zhenjiang 212013 China

The Basset-Boussinesq-Oseen （BBO） equation can be used for most flows to trace the motion of a particle, but in a centrifugal pump, among the forces that act on the particles, one should also include those due to the impeller rotation, as additional effects. This paper firstly reviews various approximations of the BBO equation for the motion of dispersion particles in a viscous fluid. Then based on the motion equation for particles in low Reynolds number centrifugal pumps, a formula for calculating the tracking characteristics of tracer particles is deduced through the Fourier integral transformation. After that the deviations of the particle motion from the fluid motion, as predicted by the various approximations, are discussed and compared. At last, with an emphasis on the Particle Image Velocimetry （PIV） results, the tracking characteristics of particles are estimated. Also, advantages and disadvantages of different tracer particles are discussed and suitable tracer particles for application in PIV studies for flow fields in centrifugal pumps are suggested.

关键词： tracer particles equations of motion tracking characteristics centrifugal pump Particle Image Velocimetry (PIV)

A solution to parabolic system with the fractional Laplacian

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Applied Mathematics(A Journal of Chinese Universities) 2009年第2期24卷 184-190页

作者： FANG lin FANG Dao-yuan Dept. of Math. Zhejiang Univ. Hangzhou 310027 China

The existence of a solution to the parabolic system with the fractional Laplacian （-△） α/2, α 〉 0 is proven, this solution decays at different rates along different time sequences going to infinity. As an application, the existence of a solution to the generalized Navier-Stokes equations is proven, which decays at different rates along different time sequences going to infinity. The generalized Navier-Stokes equations are the equations resulting from replacing -△ in the Navier-Stokes equations by （-△）^m, m〉 0. At last, a similar result for 3-D incompressible anisotropic Navier-Stokes system is obtained.

关键词： parabolic system fractional Laplacian decay rate

Effect of Microstructure on Thermal Expansion Coeffcient of 7A09 Aluminum Alloy

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Journal of Materials Science & Technology 2011年第9期27卷 797-801页

作者： Hongzhi Ji lin yuan Debin Shan School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The relationship between microstructure evolution and coefficient of thermal expansion （CTE） of 7A09 aluminum alloy was investigated in this paper. Differential scanning calorimetry （DSC） was combined with transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM） to investigate microstructure evolution taking place in 7A09 aluminum alloy during heating and cooling process. The corresponding CTE curves of the 7A0g alloy were recorded by thermal dilatometer. Results indicated that GPII zones and Ur phase were main precipitates in the highest strength tempered （T6） 7A09 alloy. The r/phase was the main participate in 7A09 alloy during the cooling process. The nonlinear dependency existed between CTE and temperature in both changing temperature processes. During the heating process, obvious additional contraction of alloy volume was directly caused by phase transition, such as dissolution of η＇ phase, transition from η＇ to η phase and dissolution of η phase. The additional contraction could slow down the increase of CTE greatly and be expressed in the nonlinearity of CTE curve. Volume and energy changes of alloy system influenced the variation trend of CTE directly, which was caused by the precipitation of U phase during the cooling process. These effects were revealed by the corresponding nonlinear change of CTE.

关键词： Aluminum Coefficient alloy Changing temperature process Microstructure evolution of thermal expansion

Effect of TiO_2 nanotubes lateral spacing on photovoltaic properties of dye-sensitized solar cells

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Chinese Science Bulletin 2014年第34期59卷 4735-4740页

作者： Qingwen Sun yuan lin CAS Key Laboratory of Photochemistry Institute of ChemistryChinese Academy of Sciences University of Chinese Academy of Sciences

Vertically aligned Ti O2 nanotube arrays(*8 lm long, *110 nm wide) have been fabricated through anodic oxidation of Ti-metal sheet in fluoridecontaining electrolyte. By changing the volume ratio of ethylene glycol and diethylene glycol in the electrolyte,Ti O2 nanotube arrays with different tube-to-tube lateral spacing, i.e., closely packed, just separated, and fully separated, have been synthesized and applied as photoanodes for dye-sensitized solar cells(DSSCs). Photovoltaic efficiency of 2.99 %, 3.34 %, and 3.44 % has been obtained for DSSCs based on the closely packed, just separated, and fully separated Ti O2 nanotube arrays,respectively, illustrating the effect of tube-to-tube lateral spacing of Ti O2 nanotube arrays on the performances of DSSCs. It is suggested that fully separated Ti O2 nanotube arrays are beneficial to the conversion efficiency of DSSCs due to higher dye loading and faster electron transfer.

关键词：染料敏化太阳能电池二氧化钛纳米管光电转换特性间距纳米管阵列阳极氧化紧密堆积 TiO2

Representations of a Noncommutative Associative Algebra Related to Quantum Torus of Rank Three

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Acta Mathematica Sinica,English Series 2005年第6期21卷 1521-1524页

作者： Shang yuan lin Bin XIN Department of Mathematics Longyan College Fujian 364000 P. R. China Department of Mathematics Shanghai Jiaotong University Shanghai 200240 P. R China

In this paper, we present some modules over the rank-three quantized Weyl algebra, which are closely related to modules over some vertex algebras. The isomorphism classes among these modules are also determined.

关键词： Quantum torus Quantized Weyl algebra Module Isomorphism

Variable Selection for Generalized Varying Coefficient Partially linear Models with Diverging Number of Parameters

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Acta Mathematicae Applicatae Sinica 2012年第2期28卷 237-246页

作者： Zheng-yan lin Yu-ze yuan Department of Mathematics Zhejiang University Hangzhou 310027 China

Semiparametric models with diverging number of predictors arise in many contemporary scientific areas. Variable selection for these models consists of two components： model selection for non-parametric components and selection of significant variables for the parametric portion. In this paper, we consider a variable selection procedure by combining basis function approximation with SCAD penalty. The proposed procedure simultaneously selects significant variables in the parametric components and the nonparametric components. With appropriate selection of tuning parameters, we establish the consistency and sparseness of this procedure.

关键词： generalized linear model varying coefficient high dimensionality SCAD basis function.

Coleman Automorphisms of Generalized Dihedral Groups

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Acta Mathematica Sinica,English Series 2016年第2期32卷 251-257页

作者： Zheng Xing LI yuan lin LI Colledge of Automation EngineeringQingdao University Department of Mathematics Brock University

Let D be a generalized dihedral group and Autcol（D） its Coleman automorphism group. Denote by Outcol（D） the quotient group of Autcol（D） by Inn（D）, where Inn（D） is the inner automorphism group of D. It is proved that either Outcol（D） = i or Outcol（D） is an elementary abelian 2-group whose order is completely determined by the cardinality of π（D）. Furthermore, a necessary and sufficient condition for Outcol（D） = 1 is obtained. In addition, whenever Outcol（D） ≠ 1, it is proved that Autcol（D） is a split extension of Inn（D） by an elementary abelian 2-group for which an explicit description is given.

关键词： Coleman automorphism generalized dihedral group

The Superlinear Convergence Analysis of a Nonmonotone BFGS Algorithm on Convex Objective Functions

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Acta Mathematica Sinica,English Series 2008年第1期24卷 35-42页

作者： Gong lin yuan Zeng Xin WEI School of Science East China University of Science and Technology Shanghai 200237 P. R. China College of Mathematics and Information Science Guangxi University Nanning 530004 P. R. China

We prove the superlinear convergence of a nonmonotone BFGS algorithm on convex objective functions under suitable conditions.

关键词： BFGS method superlinear convergence nonmonotone linesearch

Four Forbidden Subgraph Pairs for Hamiltonicity of 3-connected Graphs

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Acta Mathematicae Applicatae Sinica 2016年第2期32卷 469-476页

作者： Hou-yuan lin Zhi-quan HU School of Mathematics and Quantitative Economics Shandong University of Finance and Economics Faculty of Mathematics and Statistics Central China Normal University

For non-negative integers i,j and k, we denote the generalized net as Ni,j,k, which is a triangle with disjoint paths of length i, j and k, attached to distinct vertices of the triangle. In this paper, we prove that e... 详细信息

关键词： hamiltonian cycle forbidden subgraphs claw-free graphs closure