混合层中柱状粒子运动的研究

本文在直接数值模拟混合层流场的基础上,求解柱状粒子运动方程而得到粒子运动轨迹,说明粒子在混合层中的不同区域,其运动轨迹也不同,有的呈现波状轨迹,有的呈现环状轨迹,有的是混合轨迹。粒子的混合程度与St数有关。文中结论对工程应用有指导意义。     

工作面顶板二次断裂的研究

本文通过对现场工作面来压所进行的预测预报所观测到的工作面顶板二次断裂现象进行分析,建立了工作面项板三次断裂的力学模型,研究表明对于各种不同的顶板三次断裂均有可能发生,它与顶板上覆岩层的变形特性和煤体或直接顶的变形特性有关并且提出通过提高工作面支架阻力是难以控制顶板二次断裂发生的,同时指出对于三次断裂不是控制其位置而在于采取安全措施通过三次断裂区域。图4,袁2,参3。     

Gas-Dynamic Methods of Temperature Stratification (a Review)

The known methods of gas-dynamic temperature stratification are reviewed. Attention is concentrated on an analysis of the possibilities of the gas dynamic stratification method proposed by the author. The method is based on the difference between the equilibrium temperature of a thermally insulated wall in supersonic flow and the adiabatic stagnation temperature of the gas. Certain possible practical applications of the method to various types of energy-converting apparatus are considered. The basic trends of fundamental and applied research in the field of gas-dynamic temperature stratification are formulated.     

MULTIPLE BOUNDARY LAYER PHENOMENA OF THE SOLUTION OF NONLINEAR HIGHER ORDER ELLIPTIC EQUATIONS WITH PERTURBATION BOTH IN BOUNDARY AND IN OPERATOR

1IntroductionInmanyproblemsofmechanicsandphysics,therefrequentlyappeartheellipticequationswiththederivativetermofthehigherordercontainingsmallparameters.Inengineering,thehigherorderellipticequationswithbothboundaryperturbationandoperatorperturbationoccurintheproblemsofcircularorellipticcoluxnnarshell(suchasthehullofasubmarineorthecolumnarshellroofetc.)withstiffeningribinthecirculnferentialdirection.Insuchcasesjthestudyofweldingstresscausedbyexternalpressureorself-weightduetoabnormalweldingposi…     

钩藤中异钩藤碱在TLC原位的FT-SERS研究

本文报道了将薄层色谱（TLC）与傅里叶变换表面增强拉曼散射（FT－SERS）联用，获得了中草药钩藤中的异钩藤碱光谱研究的新方法。研究表明，在薄层原位，2.5μg钩藤总碱可将异钩藤碱等8种生物碱完全分离。应用薄层原位的薄层色谱傅里叶变换表面增强拉曼散射（TLC－FT－SERS）技术，获得异钩藤碱分子的特征振动谱带，进而阐述了样品分子在银胶表面的吸附模式，异钩藤碱以分子中氧化吲哚基团上N原子的孤子电子对和吲哚环π电子共同吸附于银晶体微粒表面,1.615cm^-1与芳环骨架振动和氧化吲哚N－H变形振动相关的峰获得最大增强。说明TLC－FT－SERS对中草药化学成分进行高灵敏度示踪指纹检测的可靠性和优越性。     

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).