多孔介质中的Brinkman-Forchheimer模型的收敛性

本文研究Brinkman-Forchheimer方程组的结构稳定性.首先我们得到一些有用的先验界,然后在此基础上推出解所满足的微分不等式,最后建立了解对Brinkman系数v的收敛性结果.     

Global Weak Solutions for the Weakly Dissipative Camassa-Holm Equation

In this paper we prove the existence and uniqueness of global weak solutions to the weakly dissipative Camassa-Holm equation.     

Pattern memory analysis of second-order neural networks with time-delay

In this paper, the pattern memory of the second-order neural networks with time-delay are investigated based on the stability theory. Several sufficient conditions are obtained such that the equilibrium point is locally exponential stable when the equilibrium point located in the saturation region. These conditions can be directly derived from the synaptic connection weights and the external input of the second-order neural networks, and be verified easily. In addition, four examples are given to show the effectiveness of the results.     

A novel approach to the determination of the crosslink density in rubber materials with the dipolar correlation effect in low magnetic fields

We present a novel NMR approach to the determination of crosslink densities in rubber materials. The method is based on the dipolar correlation effect (DCE) on the stimulated echo examined in a series of rubber samples and linear polyisoprene. The parameter evaluated from the echo attenuation curves is the mean‐squared dipolar fluctuation associated with anisotropic reorientations of macromolecular backbones. The contributions to the DCE of the constraints due to excluded volume effects and chemical crosslinks are estimated. A strong dependence of the mean‐squared dipolar fluctuation on the crosslink density of rubber combined with the simplicity of performing the measurements with inexpensive low‐field instruments suggests that the DCE is a useful tool for routine applications. The potential and problems of performing DCE measurements in low‐magnetic‐field conditions are discussed in detail. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2207–2216, 2001     

Spontaneous cyclo-trimerization of propionaldehyde in aqueous solution

The equilibrium between propionaldehyde + propane-1,1-diol + 2,4,6-triethyl-1,3,5-trioxane has been characterized, for the first time, in aqueous solution using NMR techniques. The diffusion coefficients and the molar percentages at different temperatures have been also reported.     

目标规划中权系数的几何意义

本用平面仿射坐标的观点，解释了目标规划中权系数的几何意义，借助于坐标变换，可改进图解法的效果。     

Improved sensitivity of headspace gas chromatography for organic aromatic compounds

Summary The effect of adding an electrolyte and increasing the temperature on the preconcentration of volatile compounds in headspace analysis has been investigated. Quantification of the interactive effects of temperature and addition of salt on the vapor concentration is of interest for the determination of trace organic impurities in pharmaceutical base materials. This study was undertaken to investigate the quantitative effects of the addition of salts alcohols, and acetone, and of increasing the temperature on the vapor concentrations and distribution coefficients of volatile aromatic compounds (benzene, toluene, ando-xylene). It was found that the concentration of aromatic compound residues in the headspace could be increased by adding an inert salt to the water, but this effect was not very significant because of the low orginal solubility of the aromatic compounds in water. The reverse effect can be achieved by use of polar organic additives; this can be explained by the high polarizability of aromatic compounds and their greater solubility in the presence of these solvents. Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999.     

Deriving Energy-Gap of Some Hamiltonians with Kinetic Coupling by the Invariant Eigen-Operator Method

We begin with proposing a unitary operator responsible for diagonalizing the Hamiltonian with kinetic couplings in particle physics to get a new form of Hamiltonian which has no coupling terms. By virtue of the invariant eigen-operator (IEO) method we search for the invariant eigen-operators for the new Hamiltonian. In this way the energy-gap of the Hamiltonians can be naturally obtained. This method may be generalized to N-mode Hamiltonian with kinetic couplings case. Work supported by the National Natural Science Foundation of China under grant 10475056 and Foundation of President of Chinese Academy of Science.     

浅析相关系数的显著性检验

本文用最小二乘法作直线拟合,给出相关系数显著性检验的判断方法,指出了用概率理论判断线性相关的必要性。