Relationship between three cotton trash measurements: High Volume Instrumentation (HVI), Shirley Analyzer (SA), and Advanced Fiber Information System (AFIS)

Authors: Liu, Yongliang; Thibodeaux, Devron; Gamble, Gary

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/8/2012
Publication Date: 4/16/2012
Citation: Liu, Y., Thibodeaux, D.P., Gamble, G.R. 2012. Relationship between three cotton trash measurements: High Volume Instrumentation (HVI), Shirley Analyzer (SA), and Advanced Fiber Information System (AFIS). National Cotton Council Beltwide Cotton Conference. p. 1276-1285.

Interpretive Summary: Presence of trash in commercial cotton bales at varying amounts degrades their market values and further influences the end-use qualities. In order to ensure a fair trading, USDA’s AMS has introduced the high volume instrument (HVI) measurement as an universal standard index. Compare to HVI’s geometric method that represents the trash portion only on samples’ surface, gravimetric-based Shirley analyzer (SA) and advanced fiber information system (AFIS) have also been utilized to yield the trash contents considerably in cotton industry. With the increasing acceptance of HVI readings in the domestic and international trading, there is a continued interest in the relationship between HVI trash and SA trash from cotton customers and regulators. Due to the complexity of not only trash type, size, and presence but also the nature of HVI and SA tests, it is understandable that there has been no such a study available trying to bridge two types of trash readings and, apparently, this is a challenge. Further, with the suggestion from Dr. James Knowlton of AMS, who talked his latest foreign trip to promote the HVI and mentioned one concern on HVI trash during the 2011 Beltwide Cotton Conference, we voluntarily performed this study by analyzing the data collected over a 4-year span at the house. As a result of new strategy, we not only proposed the conversion between HVI and SA trash from the simple statistic approach, but also confirmed this tactic from independent NIR measurement. The outcome provides cotton fiber / textile engineers, researchers, ginners, and regulators an innovative way in understanding HVI and SA trash.

Technical Abstract: Presence of non-lint materials (trashes) in commercial cotton bales at various amounts degrades the market values and further influences the end-use qualities. In order to ensure a fair trading, the USDA’s AMS has introduced the high volume instrument (HVI) measurement as a universal standard index. Trash contents are generated by one of three HVI modules and represent the trash portion only detectable on samples’ surfaces. In additional to HVI’s geometric method, gravimetric-based Shirley analyzer (SA) and advanced fiber information system (AFIS) have also been utilized to yield the trash contents. With the increasing acceptance of HVI readings in the domestic and international trading, there is a continued interest in the relationship between HVI trash and SA trash from cotton fiber customers and regulators. Due to the complexity of not only trash type, size, and its weight distribution but also the nature of HVI and SA tests, it is understandable that there is few study available trying to bridge two types of trash readings and, apparently, this is a challenge. This study first investigated the correlations between two HVI trash readings, and revealed a general conversion of HVIcount=104.5*HVIarea among low trash samples (HVIarea = 0.40). Then, correlations between the HVI and SA trash and also against AFIS trash were examined, and a stronger relationship between HVI and SA trash than between HVI and AFIS trash was observed. Next, the samples were sub-grouped subjectively according to the ratios of HVIarea/SAvisible (or HVIcount/SAvisible), and from the plots with the least intercepts, it was proposed two general conversions of SAvisible = 6.82*HVIarea and SAvisible = 0.069*HVIcount. In order to verify the likely conversion, NIR spectra were correlated with HVIarea readings. Considering the heterogeneous distribution of trashes in fibers and different sampling specimens between NIR spectral and HVI reference measurement, a 90% confidence interval was applied to exclude outlier samples from the calibration and validation sets. The recalibrated models revealed different response to validation samples in various subsets. Remarkably, the model from samples with the HVIarea/SAvisible ratio of 0.12-0.18 suggested the highest r2, RPD, and means/SEP, indicating the most appropriate references for the samples in this subset and echoing the earlier finding from simple descriptive approach of least intercept. Unquestionably, conversion constant might change with relative amount of trash size and type and also their weight distribution.