摘要:

AbstractThe direct trilinear decomposition method (DTDM) is an algorithm for performing quantitative curve resolution of three‐dimensional data that follow the so‐called trilinear model, e.g. chromatography–spectroscopy or emission‐excitation fluorescence. Under certain coditions complex eigenvalues and eigenvectors emerge when the generalized eigenproblem is solved in DTDM. Previous publications never treated those cases. In this paper we show how similarity transformations can be used to eliminate the imaginary part of the complex eigenvalues and eigenvectors, thereby increasing the usefulness of DTDM in practical applications. The similarity transformation technique was first used by our laboratory to solve the similar problem in the generalized rank annihilation method (GRAM). Because unique elution profiles and spectra can be derived by using data matrices from three or more samples simultaneously, DTDM with similarity transformations is more efficient than GRAM in the case where there are many samples to be inves

ISSN:0886-9383    

DOI:10.1002/cem.1180070202

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractWindow factor analysis (WFA) is a self‐modeling chemometric technique for obtaining the concentration profiles of components from evolutionary processes such as chromotography, titration and reaction kinetics. By specifying the ‘window’, i.e. the region along the evolutionary axis indigenous to a component, the concentration profile of the component can be obtained without recourse to any information concerning the other components. Mathematical expressions required to perform such computations are derived. The method is applied to the investigation of copper(II) complexation with ethylenediaminetetraacetate (EDTA) by recording and factor analyzing the ultraviolet spectra of aqueous solutions containing a fixed amount of the disodium salt of EDTA and varying amounts of CuCl2. Evidence for four different species of EDTA is obtained. Clues concerning the stoichiometry of the species are garnered from the concentration pro

ISSN:0886-9383    

DOI:10.1002/cem.1180070203

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractRegularized discriminant analysis has proven to be a most effective classifier for problems where traditional classifiers fail because of a lack of sufficient training samples, as is often the case in highdimensional settings. However, it has been shown that the model selection procedure of regularized discriminant analysis, determining the degree of regularization, has some deficiencies associated with it. We propose a modified model selection procedure base on a new appreciation function. By means of an extensive simulation it was shown that the new model selection procedure performs better than the original one. We also propose that one of the control parameters of regularized discriminant analysis be allowed to take on negative values. This extension leads to an improved performance in certain situations. The results are confirmed using two chemical data sets.

ISSN:0886-9383    

DOI:10.1002/cem.1180070204

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSeveral multivariate methods are now available for the calibration of second‐order or hyphenated instruments (e.g. GC/MS). When applied to bilinear data, it has been shown that calibration can be performed in the presence of unknown interferences ‐ a significant advantage over first‐order calibration. In this paper, non‐bilinear rank annihilation (NBRA), a method which has the potential of handling, second‐order non‐bi‐linear data, is studied through theoretical analysis and computer simulation. It is found that the second‐order advantage can be carried over to non‐bilinear data if a property defined as net analyte rank (NAR) holds for the analyte of interest. The net analyte signal (NAS) is defined accordingly for second‐order calibration and the analogy to and difference from lower‐order calibration are discussed. With NAS, some analytical figures of merit such as signal‐to noise ratio, selectivity, sensitivity and limit of determination can be calculated for second order calibration. An application to M

ISSN:0886-9383    

DOI:10.1002/cem.1180070205

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThere are many chemical products where product conformity is decided upon by qualitative human judgements of overall product quality. Nowadays, quantitative instrumentally determined quality parameters become available which are intended to replace such qualitative judgements by means of automatic decision rules using multivariate specification limits. Six classification methods to derive such limits are compared in terms of their power to predict corresponding human judgemets on overall color conformity of 17 dyestuffs based on historical quality data. Standard statistical classification methods turned out to be unacceptable for the routine generation of decision rules because of the frequent distinct suboptimality of their predictive power. Instead, a simple non‐statistical classification method utilizinga prioriknowledge about the underlying data structure yielded uniformly satisfactory decision rule

ISSN:0886-9383    

DOI:10.1002/cem.1180070206

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0886-9383    

DOI:10.1002/cem.1180070207

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0886-9383    

DOI:10.1002/cem.1180070208

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0886-9383    

DOI:10.1002/cem.1180070201

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY