Pattern recognition definition

Definition the electronic tongue is an analytical instrarment including an array of low-selective chemical sensors and appropriate pattern recognition tool, capable to recognize quantitative and qualitative compositions of simple and complex solutions . 

There is a tendency to think of medicinal chemistry as primarily a logical exercise. A specific and trivial example would be the much maligned QSAR exploration of methyl, ethyl, butyl, futile. This author believes that equating medicinal chemistry with QSAR is incorrect. There is a definite place for what might for want of a better term be called high-order pattern recognition. A specific example is the time tested... 

From both a theoretical and practical view, it is ideal to use Bayesian Decision Theory because it represents an optimal classifier. From a theoretical perspective, Bayesian Decision Theory offers a general definition of the pattern recognition problem and, with appropriate assumptions, it can be shown to be the basis of many of the so-called non-PDF approaches. In practice, however, it is typically treated as a separate method because it places strong data availability requirements for direct use compared to other approaches. 

Advanced mathematical and statistical techniques used in analytical chemistry are often referred to under the umbrella term of chemometrics. This is a loose definition, and chemometrics are not readily distinguished from the more rudimentary techniques discussed in the earlier parts of this chapter, except in terms of sophistication. The techniques are applied to the development and assessment of analytical methods as well as to the assessment and interpretation of results. Once the province of the mathematician, the computational powers of the personal computer now make such techniques routinely accessible to analysts. Hence, although it would be inappropriate to consider the detail of the methods in a book at this level, it is nevertheless important to introduce some of the salient features to give an indication of their value. Two important applications in analytical chemistry are in method optimization and pattern recognition of results. 

In qualitative analysis, the unknown spectrum is compared with a known spectrum in a library. Each gas is definitively determined by its spectrum. The comparison with library data is a simple pattern recognition process. Depending on the availability, the comparison may be made using any of a number ancillary aids. So, for example, in accordance with the position, size and sequence of the five or ten highest peaks. Naturally, comparison is possible only after the spectrum has been standardized, by setting the height of the highest line equal to 100 or 1000 (see Table 4.5 as an example). 

Data, computer versus human view, 56-58 Data sets, see Example data sets DCLS, seeDirea da ical least squares (DCLS) Decision trees defining the problem, 9-11 muiiivaiiate calibration, 186-188 pattern recognition. 62-64 Definitions. 5-7 Degrees of freedom PLS F-test. 304 SLMCA F-test. 152-153 Dendrogram construaion of. 65-71 definition of 65... 

A spectrum contains an enormous quantity of information. This information can only be used when definitive feature-by-feature correspondences with a known spectrum can be established or, when the spectrum contains previously unobserved transitions, if the spectrum can be assigned. Some form of pattern recognition is essential. Every improvement in the accuracy of the frequency calibration will be rewarded by more facile identification and unambiguous assignment of the spectrum. 

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