阻尼最小二乘法用于激光诱导击穿光谱重叠特征谱线分离提取

近年来,激光诱导击穿广谱技术发展迅速。作为一种用于物质成分探测的新技术,它具有简单、快速、无需复杂样品制备、多种元素同时检测等优点,可实现待测样品物质成分现场、在线的检测,在很多领域都极具应用前景。激光诱导击穿光谱特征谱线的分离拟合提取是光谱特征识别与后续元素浓度定量反演研究的基础。为实现激光诱导击穿光谱重叠特征谱线的有效分离拟合提取,采用阻尼最小二乘法,分析并确定了迭代前的初始拟合参数值,实现了在重叠特征谱线情况下对某火力发电厂粉煤灰中的铬元素特征谱线的分离提取。阻尼最小二乘法基于高斯-牛顿迭代,在迭代步长中引入阻尼因子,在迭代的过程中根据每一步迭代后所反馈的信息动态的调整迭代步长,从而有效防止了迭代的发散,保证了迭代的快速收敛,最终使得元素特征谱线拟合提取的效果更佳、所得到的特征谱线强度值更准确。分别采用阻尼最小二乘法和最小二乘法对不同浓度的样品中铬元素特征谱线进行分离拟合提取并给出特征谱线的强度值,作出特征谱线强度值关于元素浓度的定标曲线并对比两种方法所得结果的线性相关性。结果表明,阻尼最小二乘法所得结果的线性相关性更高,该方法稳定、可靠,适用于激光诱导击穿光谱重叠特征谱线的分离拟合提取。     

GexSi1—x／Si应变层超晶格的结构特性与器件应用

近年来,Ge_xSi_(1-x)/Si 应变层超晶格的研究日渐活跃与成熟。本文试从半导体物理与器件应用的角度出发,着重介绍了这种超晶格的各种结构特性,并简要评述了以 Ge_xSi_(1-x)/Si 异质结形成的各种新型半导体器件的研究进展。     

软件企业知识共享影响因素模式研究

知识被认为是企业最重要的战略资源，企业成功与否取决于知识管理的成败。知识共享是企业实施知识管理活动的重要议题。本文详细分析了软件企业员工知识的特点，识别出影响员工知识共享的关键因素，提出了影响软件企业知识共享的基本模式。     

A Neutron Diffraction Study for the Crystal Structure of the Deuterium（hydrogen） L－Arginine Phosphate Monohydrate

ＡＮｅｕｔｒｏｎＤｉｆｆｒａｃｔｉｏｎＳｔｕｄｙｆｏｒｔｈｅＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆｔｈｅＤｅｕｔｅｒｉｕｍ（ｈｙｄｒｏｇｅｎ）Ｌ－ＡｒｇｉｎｉｎｅＰｈｏｓｐｈａｔｅＭｏｎｏｈｙｄｒａｔｅＣｈｅｎｇＺｈｉ－Ｘｕ；ＣｈｅｎｇＹｕＦｅｎ；Ｇｕ...     

CHARACTERISTIC EXPONENTS FOR SECONDORDER PERIODIC LINEAR DIFFERENTIAL EQUATION

1IntroductionandMainResultsItiswellknownthatwhenp'--4q>0,secondorderautonomoussystemhastwocharacteristicexponentsfsothefollowingpropositionsareobvious.Proposition1Assumeq<0,then(1.1)hastwocharacteristicexponentswithoppositesigns.Proposition2Assumeq>0andp'…     

不同类型石油卟啉标志物的光谱、质谱及色谱特征

本文利用紫外－可见光谱、质谱及色谱对ETIO、DPEP及Rhodo型石油卟啉标志物的特征性和相关性进行了研究，结果指出，在可见光谱带四个特征峰的吸收强度ETIO型为Ⅳ＞Ⅲ＞Ⅱ＞Ⅰ，DPEP型为Ⅳ＞Ⅱ＞Ⅲ＞ⅠRhodo型为Ⅲ＞Ⅱ＞Ⅳ＞Ⅰ，在反相高效液相色谱的体系中流出顺序为，先流出的是Rhodo型卟啉，其次是ETIO和DPEP型。不同类型卟啉的质谱特征是，各卟啉化合物基本以分子离子峰出现，极少碎片峰，同类卟啉化合物按正态分布。     

光缆拉伸应变分布测量的新方法：布里渊光纤时域分析技术

通信光缆拉伸应变分布测量对于保证光纤通信线路的长期可靠性具有十分重要的意义。文章论述了布里渊光纤时域分析技术的背景、现状、描述了该技术的基本原理，存在的问题以及目前研究的最新进展。     

On computing the entropy of the Henon attractor

In a recent article D. Ruelle [inLecture Notes in Physics, No. 80 (Springer, Berlin, 1978)] has conjectured that for the Hénon attractor its measure theoretic entropy should be equal to its characteristic exponent. This result is known to be true for systems which satisfy Smale's Axiom A. In this article we report the results of our computations which suggest that Ruelle's conjecture may be true for the Hénon attractor. Further, in our study we are confronted with fundamental questions which suggest that certain existence theorems from ergodic theory are not sufficient from a computational point of view.     

Cumulants are universal homomorphisms into Hausdorff groups

This is a contribution to the theory of sums of independent random variables at an algebraico-analytical level: Let Prob denote the convolution semigroup of all probability measures on with all moments finite, topologized by polynomially weighted total variation. We prove that the cumulant sequence regarded as a function from Prob into the additive topological group ofall real sequences, is universal among continuous homomorphisms from Prob into Hausdorff topological groups, in the usual sense that every other such homomorphism factorizes uniquely through . An analogous result, referring to just the first cumulants,holds for the semigroup of all probability measures with existing rth moments. In particular, there is no nontrivial continuous homomorphism from the convolution semigroup of all probability measures, topologized by the total variation metric, into any Hausdorff topological group.Mathematics Subject Classification (2000): 60B15, 60E10, 60G50