总烃峰面积积分法与峰高法的线性比较

在环境空气中总烃的测定的研究发现,对于使用气相色谱仪填充柱分析环境大气总烃时,峰高的定量分析方法能够得到更好的精密度.     

General Regular Variation of n-th Order and the 2nd Order Edgeworth Expansion of the Extreme Value Distribution （Ⅰ）

In Part Ⅰ the concept of the general regular variation of n-th order is proposed and its construction is discussed. The uniqueness of the standard expression and the higher order regularity of the auxiliary functions are proved.     

A VARIATIONAL EXPECTATION-MAXIMIZATION METHOD FOR THE INVERSE BLACK BODY RADIATION PROBLEM

The inverse black body radiation problem, which is to reconstruct the area temperature distribution from the measurement of power spectrum distribution, is a well-known ill-posed problem. In this paper, a variational expectation-maximization （EM） method is developed and its convergence is studied. Numerical experiments demonstrate that the variational EM method is more efficient and accurate than the traditional methods, including the Tikhonov regularization method, the Landweber method and the conjugate gradient method.     

A novel efficient synthetic method for 2,2＇,3,3＇-biphenyltetracarboxylic dianhydride

A novel approach to the synthesis of 2,2',3,3'-biphenyltetracarboxylic dianhydride is described. The target compound was prepared by a nickel-catalyzed coupling reaction of dimethy 3-chlorophthalate (3-DMCP) for 4 h at 70-80℃, followed by subsequent hydrolysis of tetra-ester in acid solution and dehydration of tetra-acid, with overall yield of 68%. The structures of the products were characterized by IR, ¹H NMR and ¹³C NMR respectively.     

正多边形的最优分割问题

记平面边长为1的正m边形为S_m,将S_m剖分成n块:S_(m1),S_(m2),…,S_(mn),这样的剖分称S_m的n剖分,并以T(m,n)表示.以d_(mi)表示区域S_(mi)(i=1,2,…,n)的直径(即区域S_(mi)任意两点之间距离的最大者).记D(m,n)=max{d_(m1),d_(m2),…,d_(mn)}及Ψ(m,n)=■{D(m,n)}.本文将估计Ψ(m,n)的上下界.证明Ψ(6,3)=3/2,Ψ(6,4)=3-3~(1/2),Ψ(6.6)=1,Ψ(6,7)=3/2,估计Ψ(6,n)的渐进性.提出几个猜想.     

飞机的噪声环境及其结构的声振疲劳

本文简述了对某类机动飞机进行噪声环境测量及其数据归纳的方法;根据编制的噪声载荷谱和受载特点,选择适当的噪声源,进行声疲劳试验,考核飞机结构声疲劳特性,并对测量、试验结果进行分析,评定了几种抗声疲劳性能较高的结构形式。     

临界 h 棱连通图的最大棱数及其极值图

对于给定的正整数 p 和 h,p≥h+1且 h≥4,本文给出了 p 阶临界 h棱连通图的最大棱数并且确定了所有达到最大棱数的 p 阶临界 h 棱连通图.     

基于FDTD的时域混合方法及其在天线前门耦合数值模拟中的应用

强电磁脉冲环境下的平台-机载天线一体化耦合计算属于典型多尺度时域电磁计算问题,采用传统的FDTD方法数值模拟时,由于精细结构的存在导致网格量巨大,计算效率低下。介绍了一种将非均匀FDTD方法与细导线FDTD方法以及多网格集总元件FDTD方法相结合的时域混合方法,能够有效降低计算开销,结合并行计算技术,快速计算得到天线端口上耦合产生的瞬态电压和电流响应,并将该方法成功应用于无人机平台-天线一体化前门耦合数值模拟中。     

广义增量法在三维扁平桁架结构的弹塑性屈曲分析中的应用

本文利用广义逆矩阵,提出了解决非线性屈曲问题的广义增量法。并用该法分析了非线性荷载-位移关系曲线(其中包括极值点)。最后,给出一数值算例—三维扁平桁架结构的弹塑性屈曲分析,证明了本文方法的正确性和实用性。     

魔芋总生物碱量的测定

用酸性染料比色法测定魔芋总生物碱量,以盐酸金刚烷胺计,在2—10μg/mL范围内线性关系良好。设计正交试验选择总生物碱的最佳提取条件为：料液比1：12,乙醇浓度85%,索氏提取4h。