<p>The objective of this research is to develop a procedure for detectingfaults in a particular process by analyzing data generated by theprocess on a compressed wavelet scale. In order to compress the data,three different methods are compared for reducing the number ofwavelet coefficients needed to obtain an accurate representation ofthe data. One method is ultimately chosen to compress all data usedin this study. This method, which involves minimizing the relativereconstruction error, effectively balances model parsimony againstreconstruction error. The compressed data from seven in-control runsis used to define a standard, or baseline, by which to compare newdata sets. The compressed baseline process is defined by forming theunion set of the top, or coarsest, coefficient positions selected bythe relative reconstruction error method for each of the seven runs.In order to determine if a new, compressed data set differssignificantly from the baseline, a variant of Hotelling'sT²-statistic for two-sample problems is formulated. This statisticis tested by applying it to four induced-fault data sets, as well asto 21 in-control data sets. The results provide substantial evidenceof the statistic's effectiveness in detecting process faults fromcompressed data. It is also shown that traditional bootstrappingmethods cannot be implemented in this case.<P>
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-20000404-160239 |
| Date | 06 April 2000 |
| Creators | Lada, Emily Kate |
| Contributors | J.-C. Lu, C. E. Smith, J. R. Wilson |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-20000404-160239 |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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