MULTIPLE LAYER BEHAVIOR OF BOUNDARY VALUE PROBLEM FOR SINGULARLY PERTURBED n-TH ORDER NONLINEAR DIFFERENTIAL EQUATION

In this paper,we study the singular perturbation of boundary value problem for a class of n-th order nonlinear differential equation,the solution is shown to exhibit multiple layer behavior.According to different layers and by introducing extended variable,we obtain the uniformly effective asymptotic expansion with different boundary layer correction term.     

一类非线性方程组的奇摄动问题

本文在较弱的假设下．用校正边界层的方法得到了一类非线性奇摄动方程组的一致有效渐近展开式．并得到了其渐近性态．     

薄膜测厚实验研究

用球坑法测量薄膜厚度的原理,文献[1]已有所叙述.其膜厚的表示式可写为:d=(D_2~2-D_1~2)/8R=[(x_1-x_4~2)-(x_2-x_3)~2]/8R,其中D_1,D_2分别表示小圆和大圆直径,x_1,x_2,x_3,x_4分别表示剖层圆环边缘在显微镜下的读数.运用上式测厚,需要考虑以下几个因素:首先,要设法避免始端情况,对于较薄和软膜,要使剖层清晰,存在两个困难,     

Effects of Si-doped GaAs layer on optical properties of InAs quantum dots

We have investigated the optical properties of InAs self-assembled quantum dots (SAQDs) with the Si-doped GaAs barrier layer. Two types of samples are fabricated according to the position of the Si-doped GaAs layer. For type A samples the Si-doped GaAs layer is grown below the QDs, whereas for type B samples the Si-doped GaAs layer is grown above the QDs. For both types of samples the excited-state emissions caused by state filling are observed in photoluminescence (PL) spectra at high excitation power densities. The bandgap renormalization of QDs can be found from the shift of the PL peak energy. Particularly, for type A samples the Si atoms act as nucleation centers during the growth of InAs QDs on the Si-doped GaAs layer and affect the density and the size of the QDs. The Si-doped GaAs layer in type A samples has more effects on the properties of QDs, such as state filling and bandgap renormalization than those of type B samples.     

Simulation numérique directe de l'influence de la forme aval d'une plaque séparatrice sur une couche de mélangeDirect-numerical simulation of the splitting-plate downstream-shape influence upon a mixing layer

In this Note, we present direct numerical simulation results of a spatial mixing layer generated behind an upstream plate separating two boundary layers. The effect of the shape of the trailing edge of the plate is considered through comparisons between flows obtained from a bevelled or a blunt plate. In the former case, a spatial mixing layer consistent with previous experimental and numerical observations is obtained. In the latter case, the self-excited state that establishes in the near wake region dominates primary and secondary instability mechanisms while understating the importance of inflow perturbations. This behaviour is interpreted in terms of convective or absolute instability. The effects on turbulent statistics are also discussed. To cite this article: S. Laizet, E. Lamballais, C. R. Mecanique 334 (2006).     

WIND observations of plasma waves inside the magnetic cloud boundary layers

Based on the WIND observational data for the plasma waves from thermal noise receptor （TNR） working on the frequency 4-256 kHz and the solar wind and the magnetic fields, we analyze the plasma wave activities in the 60 magnetic cloud＇s boundary layers （BLs） and find that there are often various plasma wave activities in the BLs, which are different from those in the adjacent solar wind （SW） and the magnetic clouds （MC）. The basic characteristics are that： （1） the enhancement of the Langmuir wave near the electronic plasma frequency （fpe） is a dominant wave activity, which occupies 75% investigated samples; （2） the events enhanced both in the langmuir and ion acustic （f〈fpe） waves are about 60% of investigated samples; （3） broadband, continuous enhancement events in the plasma wave activities were observed in the whole frequency band of TNR, and about 30% of the 60 samples, however, were not observed in the SW and the MC investigated events; （4） although the ratio of the temperatures between the electon and proton, Te/Tp ≤1, the ion caustic wave enhancement activities are still often observed in the BLs, which makes it difficult to explain them by the traditional plasma theory. New results reported in this paper further show that the magnetic cloud＇s BL is an important dynamic structure, which could provide useful diagnosis for understanding the cloud＇s BL physics and could expand a space developing space plasma wave theory.     

Elementary solution of contact problems for a transversely isotropic elastic layer bonded to a rigid foundation

The contact problem for an arbitrary punch acting on a transversely isotropic elastic layer bonded to a rigid foundation is solved by the generalized images method developed by the author earlier. The problem is reduced to that of an electrostatic problem of infinite row of coaxial charged disks in the shape of the domain of contact. The solution can be obtained by the method of iteration, collocations or any other standard procedure for solving integral equations. Exact inversion can be obtained in the case of a circular domain of contact. The mean value theorem can be used for estimation of the resultant force and tilting moment acting on a punch of arbitrary shape and circular domain of contact. A limiting case of general solution gives the solution for an isotropic layer. (Received: August 11, 2003)     

载流子迁移率对单层有机发光二极管复合效率的影响

建立了在单层有机发光二极管中电场强度不太大(E≤104Vcm)的情况下,载流子注入、传输和复合的理论模型.通过求解非线性Painleve方程得出了电场强度随坐标变化的解析函数关系式以及电流密度随电压变化关系,给出了电流密度以及器件的复合效率在不同的载流子迁移率情况下随电压变化关系图像.结果表明,复合效率受载流子迁移率影响较大,在器件中多数载流子应具有较低的迁移率,而少数载流子应具有较高的迁移率,这样有利于载流子的注入和传输,从而可提高发光效率.并且得出当空穴迁移率大于电子迁移率时,复合区域偏向阴极,反之亦 关键词： 单层有机发光二极管 复合效率 迁移率     

场致发射阳极用钨网的寿命特性分析

 通过扫描电镜分析和实验验证，分析了场致发射阳极用钨网被破坏的成因。对钨网进行淬火处理，使钨网表面形成一定厚度的氧化膜，可显著提高钨网使用寿命。不同的淬火温度,将使钨网表面形成不同厚度的氧化膜。实验结果表明，氧化膜厚度的改变，将明显影响钨网的使用寿命。当脉宽90ns、束流6kA、能量1MeV的电子束透过钨网时，钨网表面的氧化膜厚度选在0.4μm左右为宜。     

AN ACCURATE NUMERICAL SOLUTION OF A TWO DIMENSIONAL HEAT TRANSFER PROBLEM WITH A PARABOLIC BOUNDARY LAYER

1.IntroductionSingularlyperturbeddifferentialequationsarecharacterizedbythepresenceofasmallparameterEmultiplyingthehighestorderderivatives.Suchproblemsariseinmanyareasofappliedmathematics.Thesolutionsofsingularlyperturbeddifferentialequationstypicallyhave…