基于PLS投影分析的光谱波段选择方法

光谱测量数据需要对其进行波长选择以提高模型预测精度和简化模型。文章提出了一种基于PLS投影相关系数的快速、 准确的波段选择方法,它计算某波长点光谱数据对待测组分浓度向量的影响时,考虑了该波长点光谱数据的变化量与光谱PLS回归系数向量在该波长点的投影分量的共同影响。与传统相关系数方法想比较,该方法明显地改善了分析模型的稳健性并大幅度地压缩了建模所需的波长点数。对208个汽油样本的实验表明,经过PLS投影相关系数方法进行光谱波段选择后的光谱波长点数占全谱的比例下降至30%,交互验证均方根偏差(root mean square error of cross validation, RMSECV)由未经过波长选择时的0.44降至0.34。该方法可广泛应用于各类光谱定量分析中的波长选择与数据压缩。     

CHCl3电子吸附速率常数的离子迁移谱

The dissociative electron attachment process for CHCl₃ at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry (CD-IMS). The corresponding electron attachment rate constants varied from 1.26×10^-8 cm³/(molecules s) to 8.24×10^-9 cm³/(molecules s) as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region,the attachment rate constants are also detected at different sample concentration. The ion-molecule reaction rate constants for the further reaction between Cl^- and CHCl₃ are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl^- and CHCl₃ are the first time detected using CD-IMS.     

大气压电解液阴极辉光放电发射光谱检测水体中的金属残留

水环境中的金属残留严重威胁人类的健康安全,急需快速、高效的金属残留检测技术。文章报道了自行建立的大气压电解液阴极辉光放电发射光谱装置。利用待测液体作为放电阴极进行大气压辉光放电实现了水体中金属离子的痕量检测。对配制的标准样品进行了定量测量,基于背景发射光谱的3σ计算,获得了大气压电解液阴极辉光放电光谱装置对Na, Li, Cu, Pb和Mn等5种金属元素的检测限,分别为0.008, 0.005, 1.1, 2.06和1.95 mg·L-1。该装置在金属残留的实时在线检测领域具有应用前景。     

SU(2)格点规范场热力学Monte-Carlo模拟的改进——实现连续物理极限的一种途径

本文首次在非对称点阵(ξ>1)上模拟了SU(2)纯规范场系统的热力学量,并讨论了有限大小效应和实现连续物理极限问题.结果表明:利用非对称点阵易于模拟格点规范场的热力学行为,也易于讨论趋向连续物理的各种极限.本文还把纠偏抽样技巧用于格点规范场的Monte-Carlo模拟,不但提高了计算效率,还能更好地计算热容C_v的温度行为.     

楊輝三角形的推广

笔者偶然翻阅一本英文书《数学发现》第1卷(G.Polya著,Mathematical discovery,vol.1;1962),看到书中提起三项式系数和莱布尼茲的调和三角形,两者性质均与杨辉三角形十分类似。从三项式系数使我们想到可以进一步推广到四项式系数、五项式系数等等。由于它们本身还可能有一些实用价值,所以笔者结合个人体会,将它们作一简单介绍。有关事实都不难推证,所以多半述而不证。 (一) 三项式系数杨辉三角形可以由如下两条规则完全确定(参考图1): 1.边界条件:每一行开始和结尾的数都是1。 2.递推法则:内部的每个数都等于肩上的两个数的和。杨辉三角形第n+1行的各数顺次等于(1+x)~n展开式按升冪或降冪排列时各项的系数。     

电子与正电子散射的辐射修正

With the Mφller's theory of scattering between the electrons and the Dirac's hole theory, Bhabha has obtained the formula for the scattering of the electrons and the positrons. The experimental evidence of this phenomenon was discovered by Ho (何泽慧), and she has studied this phenomenon by means of the β⁺-radioactivity of the β⁺ sources such as Mn⁵², and F¹⁸ in the cloud chamber. The comparison of the theory and the experiment was done (see reference [2], [3], [4], [5] and [6].) by Ho, O. Ritter et al, R. R. Roy and L. Groven, G. R. Hoke and A. Ashkin et al.The purpose of the present work is to show the effect of the radiative corrections to the scattering of the electrons and the positrons by the method in the quantum electrodynamics developed by S. Tomonaga, J. Schwinger, R. P. Feynman and F. J. Dyson.In the above-mentioned electron and positron scattering experiments, the contributions to the scattering cross-section are mostly due to the positrons of low energies (about 0.1 to 0.2 Mev). In this energy range, the exchange effect in Bhabha's theory is small. In this work for the radiative corrections to the scattering of the electrons and the positrons, we have neglected this exchange effect. The ratio of the correction of the scattering cross-section due to the radiative corrections to the scattering cross-section of Bhabha's theory at this energy range does not exceed 1%. For experiments of the low energy positrons and of the higher energy positrons (e.g positrons with energies of 0.5 Mev to 1 Mev as in the experiment of Ashkin et al) with small exchanges of energy between the electrons and the positrons during scattering, our calculation is adequate. But for positrons of higher energies and with large exchanges during scattering, our calculation should be improved by considering the exchange effect.     

红外伪装遮障技术的物理基础

从能量 守恒定律和斯特藩－玻耳兹曼定律出发，推导出红外伪装遮障设计的理论依据，并介绍了红外伪装障技术的发展前景。     

Ar与SO2混合放电产生SO(c1Σ-)电子态的光谱研究

在流动余辉装置上 ,利用Ar与SO2 混合气体的空心阴极放电 ,在放电区的下游观察到一系列光谱 ,将 4 0 0～ 6 0 0nm波长范围内的发射谱带归属为SO(c1Σ-→X3 Σ-)跃迁 ,并得到该跃迁的ν0 0 =2 85 0 0cm-1。这是气相SO自由基c1Σ-电子态的首次直接的光谱观测。     

相变乳状液在蛇形管中的流动和传热特性

用正十四烷、复合表面活化剂和水制成O/W型相变乳状液作为相变蓄冷及传热介质,对其作为非牛顿流体和固液两相流的流动和传热特点进行了分析,通过测试得出不同浓度乳状液在蛇形管道中的对流换热Nυ数和摩擦系数,并给出了换热和阻力的无量纲关联式。指出了对这类特殊相变蓄冷材料作进一步研究的方向。     

非常热的余核系统破碎瞬时的体积效应

本文对非常热的余核系统破碎问题中的库仑相互作用,作了简化,不但节省了大量的计算时间;而且结果与实验符合得更好.对破碎问题中的另一个重要效应-破碎体积的效应也作了研究,结果表明:用合理选择的破碎体积权重的高斯分布平均后的质量分布,与实验符合得也很好.该高斯分布的中心位置和宽度,反映了气液共存相的区域.质量分布的形状和平均碎块数等随破碎体积变化的规律,呈现出了气液相变的迹象.还要指出,库仑能的简化,使研究破碎系统的状态方程成为现实,它的一个极端情形非常类似于理想气体的状态方程.