叶轮机械设计自变数在内外环壁面上的限制条件及轴流式叶轮机械S1流面的翘曲

本文利用中心流面法的概念,指出叶轮机械的设计白变数在内、外环壁面上应有附加的限制条件,并导得其具体简明方程。同时,还定性地分析了S₁流面的翘曲情况。     

超导临界温度理论(Ⅰ)

本文求出了Eliashberg方程在T=T_c时的解,得到了下面的临界温度级数表示式: 其中α₀(μ^*),α₁(μ^*)等系数是μ^*的函数.此式表明,T_c不仅依赖于λ,〈ω²〉和μ^*,而且依赖于有效声子谱α²F(ω)的各级矩〈ω²n〉.这是区别于前人的T_c公式最重要的一点。这说明像McMillan以及Allen和Dynes的T_c公式不仅是近似的,而主要是他们没有能正确地概括出α²F(ω)对T_c的影响.     

On the Location of Zeros of Certain Classes of Polynomials with Applications to Numerical Analysis

A polynomial is said to be of type (p₁, p₂, p₃) relative tothe unit circle if it has p₁ zeros interior to, p₂ on, and p₃exterior to the unit circle. Stability criteria frequently arisewhere a polynomial or a family of polynomials must be shownto be of type (p₁, p₂, 0) or of type (p₁, 0, 0). Here we reconsiderthe practical problem of showing that a polynomial is of oneor other of these types, and we show that the testing of a polynomialof degree n may always be reduced to the testing of one of degreen–1. The simplicity of the method is illustrated by itsapplication to several well known difference schemes for partialdifferential equations.     

A Finite Element Moving Boundary Computation with an Adaptive Mesh

The finite element method is used to obtain an accurate approximationto the solution of a well-known moving boundary problem. Thealgorithm uses the projective nature of the approximate solutionto follow the movement of the boundary, and the element notesare adapted as the region of the solution changes.     

Monte Carlo simulations of an amphiphilic polymer at a hydrophobic/hydrophilic interface

Monte Carlo simulations have been carried out for an off-lattice model of an amphiphilic polymer at a hydrophobic/hydrophilic interface. The model system consists of a polynorbornene backbone with poly(ethylene oxide) (PEO) grafts modelled atomistically at an idealized interface between hydrophobic and hydrophilic regions, which are represented by external potentials. Results are presented for the distribution of PEO chain ends, and the density of PEO segments perpendicular to the surface. The latter is used to provide predictions for neutron reflectivity profiles normal to the surface as a function of the lateral confinement of the PEO grafts. At low surface coverage the simulation results are found to be in good agreement with experimental neutron scattering results from similar polymers studied at the water/air interface.     

使用色散可调啁啾光纤光栅在常规单模光纤中实现超过100km,10Gb/s的转输 *

报道了用简单的应力方法使均匀光栅成为线性啁啾光纤光栅的技术 ,并推导出了相应理论 ,发现最大色散补偿带宽与色散的乘积近似为常数 .在常规单模光纤G652,10Gb/s系统中实现超过100km的色散补偿 .     

三维光存储中折射率失配引起的球差补偿

为实现三维光存储中折射率失配引起的球差补偿,建立了光学存储系统模型,获得了折射率失配引起的波前偏差函数与存储深度的表达式.采用泽尔尼克循环多项式对波前偏差函数进行补偿展开.在双光子荧光和单光子共焦荧光读出方式下,均可获得读出荧光强度与存储深度的关系:在折射率失配引起的球差未得到补偿矫正的情况下,存储深度在200 μm左右读出荧光强度基本上下降为零;当折射率失配引起的初级球差被补偿矫正后,读出荧光强度随存储深度的下降得到较好改善;当折射率失配引起的二级球差被补偿矫正后,存储深度在1 mm内存储点强度随深度基本上没有明显地变化.并且对像差补偿方法进行了具体地分析.     

高温高密度氦的压缩特性及其结构的分子动力学模拟

用分子动力学方法和不同参数的指数 6势函数计算了T =30 4K的高密度氦的等温压缩线和能量分布 .给出了能精确描述高密度氦原子间相互作用的指数 6势函数优化参数 .并用优化的势函数计算了高密度氦T =30 0K和T =2 98K的等温压缩线 ,计算结果和实验值非常吻合 .进一步用优化的势函数模拟了高温高密度氦的状态方程及其结构 ,发现当把 ρ限定为 1 .6 0g /cm³ 时 ,其径向分布函数的第 2个峰将在 2 0 0 0～ 30 40K区间消失 ,表明此时发生了固 液相变过程 .     

多尺度B样条小波边缘检测算子

基于B样条理论提出了一类新的多尺度小波变换,通过其零交叉或模极值能有效地表示和检测信号或图象的边缘,对任意n次B样条,导出了相应的分解和重建的快速算法,对应的用于分解和重建的滤波器的时域和频域响应也被精确地给出.从时频局部化的角度对不同次数的B样条作了分析,认为3次B样条小波在边缘提取等实际应用中是渐近最优的,结果也为B样条小波在立体视觉匹配、滤噪等方面的进一步应用提供了基础.