零级代数体函数的强Borel方向

该文证明了平面上满足一定条件的零级代数体函数至少存在一条强Borel方向,并且它还是通常的关于型函数的Borel方向.     

六层加侧混合型摇摆器磁场的理论计算与数值模拟

 利用文献[1，2]给出的结果，提供了六层加侧混合型摇摆器中永磁体磁场的计算公式和软铁磁场计算的积分方程式。对周期长度lw =1.6cm，磁极间隙g=0.5cm的情况，计算了单向聚焦和双向聚焦两种不同构形的磁场分布，并得到了g /lw =1/3条件下，峰值磁场Bw超过1特斯拉的设计指标。     

左手介质中电磁波的传播速度

在同向介质中,电磁波的群速度一般是能量传播的方向,并且电磁波的相速度和群速度在大部分情况下都满足瑞利关系.为了研究左手介质的电磁特性,本文从理论上导出了左手介质中电磁波的相速度、群速度及其关系,得出左手介质中电磁波的群速度为负,并介绍了左手介质的一些应用前景.     

Measurement of Principal-Stress Directions from Photoelastic Experiment Using Generalized Phase-Shift Method

A generalized phase-shift method is developed for automatic measurement of principal-stress directions in the whole field of a model from photoelastic experiments. This method uses a set of light intensities obtained from the rotation of polaroids in dark-field plane polariscopes at each point. To investigate the accuracy of the measurement, time-series light intensity curves with different noise and different numbers of data which constitute the curves are used in computer simulation. The error of the measurement of the principal-stress directions obtained by the method is not greatly affected by noise when the number of data exceeds 50. This method is applied to a circular disk subjected to a concentrated load. The principal-stress directions obtained by the method are found to be in good agreement with the theory.Presented at 1996 International Workshop on Interferometry (IWI ‘96), August 27–29, Saitama, Japan.     

非线性规划的摄动可行方向法

本文提出了二类新的摄动可行方向法,发展和完善了这类方法.新方法形式简单而且不必用Polak程序.适当选择算法中有关参数可减少计算量,还可加快算法的收敛速度.     

非欧椭圆几何的若干度量问题

本文用新方法讨论解决了n维椭圆空间Sⁿ中若干几何问题。给出了关于n维球面单形的余弦定理、高的公式、内切及外接球半径r,R以及内心I与外心Q间的距离公式。同时将著名的欧拉不等式推广到Sⁿ中。     

镁铁双羟基复合金属氧化物的可控合成及晶面生长特征研究

采用成核 /晶化隔离法合成镁铁双羟基复合金属氧化物MgFe LDH ,考察了Mg∶Fe摩尔比对MgFe LDH晶形的影响 ,探讨了晶化温度及晶化时间对晶面生长选择性及晶粒尺寸的影响规律 .结果表明 ,随Mg∶Fe摩尔比增大 ,层板阳离子排列更为规整 .晶化温度对晶粒尺寸的影响显著大于晶化时间的影响 .晶化温度相同 ,随晶化时间延长 ,MgFe LDH的晶体结构趋于完整 ,晶粒尺寸变化不大 ;晶化时间相同 ,随晶化温度升高 ,晶体结构趋于完整 ,晶粒尺寸明显增大 .所得到的MgFe LDH沿a轴方向的晶粒尺寸对晶化温度变化的敏感程度远大于对晶化时间变化的敏感程度 ,但总是沿a轴方向的晶粒尺寸大于沿c轴方向的尺寸 ,即 [110 ]晶面的生长速率比[0 0 2 ]晶面的生长速率快     

Alternating direction algorithms for solving Hamilton-Jacobi-Bellman equations

We focus on numerically solving a typical type of Hamilton-Jacobi-Bellman (HJB) equations arising from a class of optimal controls with a standard multidimensional diffusion model. Solving such an equation results in the value function and an optimal feedback control law. The Bellman's curse of dimensionality seems to be the main obstacle to applicability of most numerical algorithms for solving HJB. We decompose HJB into a number of lower-dimensional problems, and discuss how the usual alternating direction method can be extended for solving HJB. We present some convergence results, as well as preliminary experimental outcomes.This research was funded in part by an RGC grant from the University of Alabama.     

亚纯函数的正规定则与奇异方向

本文讨论了亚纯函数的正规定则与Ｊｕｌｉａ型方向间的联系．     

On diagonally preconditioning the truncated Newton method for super-scale linearly constrained nonlinear programming

We present an algorithm for super-scale linearly constrained nonlinear programming (LCNP) based on Newton's method. In large-scale programming solving the Newton equation at each iteration can be expensive and may not be justified when far from a local solution. For super-scale problems, the truncated Newton method (where an inaccurate solution is computed by using the conjugate-gradient method) is recommended; a diagonal BFGS preconditioning of the gradient is used, so that the number of iterations to solve the equation is reduced. The procedure for updating that preconditioning is described for LCNP when the set of active constraints or the partition of basic, superbasic and nonbasic (structural) variables have been changed.