厚非线性介质瞬态热光非线性效应的研究

瞬态热光非线性效应是指由脉冲宽度可以和非线性效应的建立时间相比拟的纳秒脉冲激光入射产生的热光非线性效应.用Zscan法测量了不同厚度、不同束腰半径碘的酒精溶液的瞬态热光非线性效应曲线.从声波的传播方程和光波的非线性传播方程出发,用数值计算方法模拟了这一非线性过程.并对实验结果和数值模拟结果进行了比较 关键词： 瞬态热光非线性效应 非线性光学 数值计算     

XRF测定铅锌矿选矿流程中铅,锌,铜

本文叙述一个ＸＲＦ粉末法测定铅锌矿选矿流程中铅，锌，铜的方法，选用精，中矿和原，尾矿两个标准系列。ＲｈＫａ康普顿散射线作内标克服质量吸收系数变化带来的影响，用经验系数法校正基体效应，与化学分析方法相比，本法县有测定组分含量范围广，简便，快速，准确和成本低等特点，配合选矿试验大大加快造矿周期，提高工效数倍。     

外加电场对光折变高阶响应影响的微扰分析

应用微扰展开法了“跳跃模型”给出了空间电荷场前三阶分量随时间，外加电场等变化的解析表达式，同时讨论了外加电场对各阶空间电荷场建立的影响，当扩散与外加电场可比拟时，外加电场对空间电荷场的影响不大，随着空间电荷场阶数的提高，其达到最大饱和值所需的外加电磁越小，在外加电场作用下，空间电荷场各阶分量随时间呈振荡衰减，直到达到饱和，外加是场越大，振荡越强烈，周期越短，在考虑高阶分量的贡献后，空间电荷场的振荡     

Microstructure and photoluminescence of a-SiO x :H

Two strong photoluminescence (PL) bands in the spectral range of 550–900 nm have been observed at room temperature from a series of a-SiO _x :H films fabricated by plasma-enhanced chemical vapor deposition (PECVD) technique. One is composed of a main band in the red-light region and a shoulder; the other is located at about 850 nm, only found after 1170°C annealing in N₂ atmosphere. In conjunction with infrared (IR) and micro-Raman spectra, it is thought that the two PL bands are associated with a-Si clusters in the SiO _x network and nanocrystalline silicon in SiO₂, respectively. Project supported by the National Natural Science Foundation of China (Grant No. 69576025).     

gb→tH－的超对称QCD单圈修正和非退耦效应

在最小超对称标准模型的框架内计算了gb→tH^－过程产生截面的单圈超对称QCD修正.结果发现:若胶子质量和超对称软破缺参数μ或A_t,A_b同量级且趋于很大,就会出现超对称QCD的非退耦效应.大的tanβ值可以提高非退耦的贡献,因此大tanβ情况下,较大的修正结果可能在Tevatron和LHC上观测到.非退耦行为的根本原因在于圈图中的某些耦合顶角正比于超对称质量参数.     

Stability of strain gradient elastic bars in tension

Equilibrium of a bar under uniaxial tension is considered as optimization problem of the total potential energy. Uniaxial deformations are considered for a material with linear constitutive law of strain second gradient elasticity. Applying tension on an elastic bar, necking is shown up in high strains. That means the axial strain forms two homogeneously deformed sections in the ends of the bars and a section in the middle with high variable strain. The interactions of the intrinsic (material) lengths with the non linear strain displacement relations develop critical states of bifurcation with continuous Fourier’s spectrum. Critical conditions and post-critical deformations are defined with the help of multiple scales perturbation method. An erratum to this article can be found at     

On the solution of indefinite systems arising in nonlinear programming problems

This work is concerned with the convergence properties and the numerical analysis of the preconditioned conjugate gradient (PCG) method applied to the solution of indefinite linear systems arising in nonlinear optimization. Our approach is based on the choice of quasidefinite preconditioners and of a suitable factorization routine. Some theoretical and numerical results about these preconditioners are obtained. Furthermore, we show the behaviour of the PCG method for different formulations of the indefinite system and we compare the effectiveness of the proposed variants. Copyright © 2007 John Wiley & Sons, Ltd.     

Line integrals and Green's formula on time scales

In this paper we study curves parametrized by a time scale parameter, introduce line delta and nabla integrals along time scale curves, and obtain an analog of Green's formula in the time scale setting.     

An experimental comparison between the aqueous pH scale and the electron donicity scale

We have made an experimental comparison of the aqueous pH scale with the Lewis base donicity scale. This requires an indicator that can function in both kinds of system. We find that the zeta-potential zero charge point for certain oxide materials provides a suitable indicator. The materials are: SiO₂, Al₂O₃, TiO₂, and MgO. For each material, we measure the zeta potential in aqueous media as a function of pH. In each case, the zeta potential varies systematically with pH, and changes sign at some value of pH, that we refer to as the zero charge point. We then do similar measurements in a series of organic liquids having different donicities. In this case, the zeta potential varies systematically with the donicity and may change sign. In such cases, we determine the donicity that corresponds to the zero charge point. For a given oxide material, we can then relate a zero charge point on the pH scale to one on the donicity scale. This gives us a consistent experimental alignment of the pH and donicity scales, relative to one another. We compare our results with thermodynamic data, relating to the pH scale, and the hydrogen electrode, and find good agreement.