Analysis of a three-dimensional dissimilar material joint with one real singularity using a conservative integral

In the present study, a conservative integral based on the Betti reciprocal principle is formulated to determine the intensity of singularity at a vertex of the interface in three-dimensional dissimilar material joints with one real singularity. Eigenanalysis formulated using a three-dimensional finite element method (FEM) is used to calculate the order of stress singularity, angular functions of displacements and stresses. Models with various element sizes and various integral areas are used to investigate the effect of the integration area on the accuracy of the results. The results are compared with those obtained from the boundary element method (BEM) using a curve-fitting technique to calculate the intensity of singularity. In addition, models of various lengths and various material combinations are used to investigate the stress singularity characteristics in three-dimensional dissimilar material joints. The results of the present study indicate that the conservative integral can be used to determine the intensity of singularity in three-dimensional bi-material joints. The accuracy of the results can be improved by mesh refinement. Finally, the relationships among the intensity of singularity, the order of stress singularity and the model geometry are discussed.     

Different Zhang functions leading to different Zhang-dynamics models illustrated via time-varying reciprocal solving

Along with neural dynamics (based on analog solvers) widely arising in scientific computation and optimization fields in recent decades which attracts extensive interest and investigation of researchers, a novel type of neural dynamics, called Zhang dynamics (ZD), has been formally proposed by Zhang et al. for the online solution of time-varying problems. By following Zhang et al.’s neural-dynamics design method, the ZD model, which is based on an indefinite Zhang function (ZF), can guarantee the exponential convergence performance for the online time-varying problems solving. In this paper, different indefinite Zhang functions, which can lead to different ZD models, are proposed and developed as the error-monitoring functions for the time-varying reciprocal problem solving. Additionally, for the goal of developing the floating-point processors or coprocessors for the future generation of computers, the MATLAB Simulink modeling and simulative verifications of such different ZD models are further presented for online time-varying reciprocal solving. The modeling results substantiate the efficacy of such different ZD models for time-varying reciprocal solving.     

A Padé family of iterations for the matrix sign function and related problems

In this paper we consider the Pad'e family of iterations for computing the matrix sign function and the Padé family of iterations for computing the matrix p‐sector function. We prove that all the iterations of the Padé family for the matrix sign function have a common convergence region. It completes a similar result of Kenney and Laub for half of the Padé family. We show that the iterations of the Padé family for the matrix p‐sector function are well defined in an analogous common region, depending on p. For this purpose we proved that the Padé approximants to the function (1?z)^?σ, 0<σ<1, are a quotient of hypergeometric functions whose poles we have localized. Furthermore we proved that the coefficients of the power expansion of a certain analytic function form a positive sequence and in a special case this sequence has the log‐concavity property. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of In_x Ga_(1-x )N “continuously graded” buffer layer on InGaN epilayer grown by metalorganic chemical vapor deposition

In this paper we report on the effect of an In x Ga1-x N continuously graded buffer layer on an InGaN epilayer grown on a GaN template.In our experiment,three types of buffer layers including constant composition,continuously graded composition,and the combination of constant and continuously graded composition are used.Surface morphologies,crystalline quality,indium incorporations,and relaxation degrees of InGaN epilayers with different buffer layers are investigated.It is found that the In x Ga1-x N continuously graded buffer layer is effective to improve the surface morphology,crystalline quality,and the indium incorporation of the InGaN epilayer.These superior characteristics of the continuously graded buffer layer can be attributed to the sufficient strain release and the reduction of dislocations.     

求解矩形夹层板在集中载荷下的稳定问题

在考虑了横向切应力和横向正应力对夹层板稳定影响的情况下,给出了矩形夹层板结构屈曲失稳的控制方程、基本解以及边界条件。应用功的互等定理求解了在均布载荷作用下的矩形夹层板的屈曲失稳问题。     

BASIC THEOREMS IN LINEAR MICROMORPHIC THERMOELECTROELASTICITY AND THEIR PRIMARY APPLICATION

As a natural extension of the micromorphic continuum theory, the linear theory of micromorphic thermoelectroelasticity is developed to characterize the nano-micro scale behavior of thermoelectroelastic materials with remarkable microstructures. After the basic governing equations are given and the reciprocal theorem is deduced, both the generalized variational principle and the generalized Hamilton principle for mixed boundary-initial value problems of micromorphic thermoelectroelastodynamics in convolution form are established. Finally, as a primary application, steady state responses of an unbounded homogeneous isotropic micromorphic thermoelectroelastic body to external concentrated loads with mechanical, electric, and thermal origins are analyzed.     

The Qiao--Liu Equation with Self-Consistent Sources and Its Solutions

The Qiao--Liu equation with self-consistent sources (QLESCS) and its Lax representation are derived. A reciprocal transformation for the QLESCS is given. By making use of the reciprocal transformation and the solutions of the mKdV equation with self-consistent sources (mKdVSCS), the solutions of the QLESCS are presented.     

Lp[0,1](1《p《∞)空间正系数多项式的倒数逼近的Jackson型估计

本文讨论了Lp[0,1](1相似文献   

应用混合变量余能原理求解不同载荷作用下四边简支矩形板的弯曲

由功的互等定理导出了弯曲矩形板混合变量的总余能,应用混合变量余能原理求解四边简支矩形板弯曲问题,给出了四边简支矩形板的混合变量余能表达式,求解了不同载荷作用下四边简支矩形板的弯曲问题,并将计算的不同载荷作用下的挠度和弯矩值与ANSYS有限元的计算值比较,给出了一种求解四边简支矩形板的新方法。     

Separation and determination of six catechins in tea by pressurized capillary electrochromatography

An efficient pressurized capillary electrochromatography (pCEC) method has been successfully developed for the determination of six catechins in tea. The separation was performed on a reversed-phase EP-100-20/45-3-C18 capillary column (total length of 45?cm, effective length of 20?cm, diameter of 100?μm, ODS packing inside for 3?μm). The mobile phase ratio of organic phase, the concentration of phosphate buffer and sodium heptanesulfonate, separation voltage, and other experimental conditions were investigated and optimized. The mobile phase was 15?mM NaH₂PO₄ and 12?mM sodium heptanesulfonate (pH 3.0)/methanol (64:36) at a flow rate of 0.04?mL/min. Under optimal conditions including applied voltage of ?4?kV and a UV detection wavelength of 230?nm, the six catechins in the tea were well separated. The calibration curves for the analytes had good linearity in the range of 8.02?μg/mL–202.13?μg/mL with a correlation coefficient of 0.9928–0.9997. The limits of detection (LOD) for the six catechins were 4.62?μg/mL–11.63?μg/mL (S/N?=?3). The recoveries of the six catechins were 96.2%–108.4% with a relative standard deviation (RSD) between 0.78% and 4.51%. The method has been used for the determination of six catechins in tea samples with good results.