2007 Annual Report 1a.Objectives (from AD-416) This is a component of a Cooperative Agreement funded by Cotton Incorporated. The objectives of this Specific Cooperative Agreement are to characterize cotton fiber length distribution, to establish the relationship between the original fiber length distribution and the length distribution measured by High Volume Instrument (HVI), to explore non-traditional cotton length parameters that may lead to better prediction of cotton quality, and to study fundamental theories of fiber length determination from rapid testing by use of fiber beards. The Agreement will be reviewed for possible extension in 2007. 1b.Approach (from AD-416) In order to obtain accurate measurements of the fiber length distribution, the relationship between the length of specimen fibers actually measured by the instrument and the original sample population has to be established. Three length distributions from specimen fibers, namely fibers selected by the HVI clamp, fibers held in the clamp (invisible for the instrument to measure) and fibers projecting from the clamp (actually measured by the instrument) will be obtained by AFIS (Advanced Fiber Information System) instrument. The relationships among the three distributions and the distribution of the original sample will be analyzed. Various non-traditional statistical parameters of cotton fiber length distributions will be obtained. Algorithm will be developed to obtain Lower Half Mean Length (LHML) that is a good parameter alterative to short fiber content (SFC). The effectiveness to predict cotton processability and yarn properties by use of these non-traditional length parameters will be studied. 3.Progress Report This report serves to document research conducted under a Reimbursable Cooperative Agreement between Agricultural Research Service (ARS) and University of New Orleans. Additional details of research can be found in the report for the in-house project 6435-44000-069-00D, “Improved Cotton Quality Measurements.” The methods used to monitor activities for this agreement were onsite visits, email and telephone communications, progress reports, presentations at scientific and industry meetings, and publications. Cooperatively with the Mathematic Department of University of New Orleans, we searched for the mathematic functional description for cotton fiber length distribution. Eight cotton samples with a wide range of fiber length are selected and tested on the Advanced Fiber Information System (AFIS) instrument. The measured single fiber length data are used for finding the underlying theoretical distribution of the cotton. It is found that none of the known distributions yielded satisfactory fit, but a mixture of two Weibull distributions fits the data very well. (Weibull distribution is named after its inventor Waloddi Weibull and is a widely used probability distribution function). Fiber length distributions by number and by weight are studied separately, and in both cases a mixed Weibull distribution shows a good fit to the data. Numerical comparisons for various parameters between the original distribution from the data and the fitted distribution were performed. We are applying this technique to a larger data set to explore the relationships among the parameters of the Weibull distributions and the qualities of cotton fiber and yarns.