Neural networks in multivariate calibration.
Neural networks in multivariate calibration.
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DOI:
10.1039/a805562i
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发表时间:
1998
期刊:
影响因子:
--
通讯作者:
F. Despagne;D. Massart
中科院分区:
文献类型:
--
作者:
F. Despagne;D. Massart
Artificial neural networks (NNs) have now gained acceptance in numerous areas of chemistry, as illustrated by the number of applications mentioned by Zupan and Gasteiger1 in their review. In the 1996 Chemometrics fundamental review, 2 NN applications were reported in sections concerning signal processing, curve resolution, calibration, parameter estimation, QSAR, pattern recognition and of course artificial intelligence. Tutorials on NNs in chemistry were proposed by Smits et al. 3 and Svozil et al. 4 (the latter contains an extensive list of Internet resources for NNs) and different types of applications of NNs to spectroscopy were reviewed by Cirovic. 5 This tutorial is restricted to the application of NNs for multivariate calibration with chemical data, which is an important source of publications in chemometrics. The potential of NNs as modelling tools for multivariate calibration is well established, and efforts must now focus on developing proper methodologies to ensure that NNs are always used in ideal conditions; this is the goal of this tutorial. Bos et al. 6 presented an excellent overview of practical aspects of NNs in quantitative analysis. Most of these aspects will be presented again here, in particular in order to establish the terminology, and we will include some recommendations according to recent results obtained in NN research. We will restrict ourselves to NNs of the multi-layer feed-forward type (also called multi-layer perceptron, MLP) with the error back-propagation learning rule that is the most popular.The tutorial is organised as follows. In Section 2, we remind readers how NNs came on to the scene and explain their basic principles. Section 3 is dedicated to the possibilities offered by NNs to analytical chemists. We present some of the most general aspects of NNs (flexibility, black-box aspect) and emphasise their main limitations. In Section 4 we consider more technical aspects and propose a methodology for the development of calibration models with NNs. A non-negligible part of this methodology is dedicated to data handling, and we try to outline the pitfalls specific to NN modelling. We consider topology optimisation and introduce techniques that can help in developing and interpreting NN models. The different aspects discussed in the tutorial are illustrated with examples of applications from the literature.