An investigation of the sampling bias of the beard method as used in HVI ™

In this paper, an economical way for accurately determining weight-based short fiber contents in raw cotton and semi-finished slivers by utilizing special bilateral beard specimens and image processing was introduced. In the specimen preparation, cotton fibers were drawn by a manual device into a sliver, then the sliver was combed to form a bilateral beard specimen, and finally the bilateral beard was scanned to generate a grayscale image from which a relative fiber number curve was extracted. An algorithm for calculating the weight-based short fiber contents based on the curve was proposed. Five types of cottons were repetitively measured to investigate the robustness of the results of [Formula: see text] and [Formula: see text], with the weight ratio of fibers shorter than 12.7 and 16 mm, respectively. The results showed that measuring two bilateral beards for each sample could keep the error rate lower than 15%, while four specimens kept the error rate lower than 10%. Compared with AFIS Pro 2, this Image-based Bilateral Beard Method provided results with lower standard deviations and variable coefficients, signifying its analogous or better robustness. In addition, 37 samples from some of the world’s major producing areas were measured by this method and AFIS Pro 2, and a Bland–Altman analysis confirmed a good agreement between the results from the two methods. As only a manual fiber drawing device and an office scanner are needed, this Image-based Bilateral Beard Method is clearly a cheap approach for accurately determining the short fiber contents in raw cotton and semi-finished slivers.

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confidence: 99%

Image-based Bilateral Beard Method for measuring weight-based short fiber contents in raw cotton and semi-finished slivers

Lang

Zhang

Wang³

et al. 2021

“…In the HVI, a bundle of cotton fibers is grabbed from the raw cotton, simply combed, and then scanned to generate the fibrogram for length parameter calculation. 24 The feature of high-speed and automatic measurement makes HVI a prevalent system in the international cotton trade. Nevertheless, the physical meaning of the HVI fibrogram is still unclear, leading to the failure of computing length frequency distribution from the fibrogram.…”

mentioning

confidence: 99%

Algorithm for measuring fiber length distributions of raw cotton and combed wool using dual-beard image method

Lang

Pan

et al. 2020

The dual-beard image method, which has been developed in recent years as a fast and economical method for fiber length measurement, consists of dual-beard specimen preparation, image processing, fibrogram extraction, and length parameter calculations. However, one of the shortcomings of this method is that it can only produce extremely limited length parameters such as mean length, coefficient of variation, modal length, and quality length (UHML, upper half mean length). This study introduces a new algorithm for converting the dual-beard fibrogram into a length distribution histogram which can be used to calculate most of the current length parameters. The algorithm is based on the short fiber content formulae but modified by theoretical analysis and experimental comparison. The length distributions of 24 cotton samples and 12 wool samples are measured by dual-beard image method with the new algorithm, and Advanced Fiber Information System (AFIS) and Almeter are employed for comparison. Comparative analysis shows that the peaks and ranges of the distribution histograms using the dual-beard method are similar to those from the reference methods, and the shapes of histograms from difference methods match well with one another. In addition, five length parameters calculated from the dual-beard distributions are verified to be consistent with those measured by AFIS and Almeter. The new algorithm employed in the dual-beard image method avoids the differential operation which amplifies the curve error, giving the dual-beard image method the ability to output more comprehensive length information.

“…However, many studies have indicated that possible fiber breakages in the opening process may bring a bias into the measurement. [6][7][8][9][10][11][12][13] As an instrumental image-based method, the fibrograph, a curve transformed from the transmission image of a single-beard sample, has been utilized to determine fiber length parameters. 14 The High Volume Instrument (HVI; Charlotte, NC) is a highspeed and multifunctional system whose length module is originated from the traditional fibrograph in which fibers are held by a row of needles and scanned by a light slit to generate a transmission image.…”

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confidence: 99%

Extracting fiber length distributions from dual-beard fibrographs with the Levenberg–Marquardt algorithm

Zhou

Wang

Wei

et al. 2019

Fiber length is a critical cotton fiber property that impacts yarn strength, yarn evenness, and ultimately fabric strength and appearance. In this paper, a new fiber fibrograph method was presented for accurate measurements of fiber length distributions (FLDs). The method, called the dual-beard fibrograph (DBF), was based on the transmission image of a combed sample with two tapered fiber ends/beards, and the approximation of the fibrograph with a series of triangular base functions. A desktop scanner was used to generate the transmission image of a dual-beard sample, and essential image-processing algorithms were utilized to mitigate image differences originating from variations in the scanning condition (e.g., brightness, resolution) and the sample condition (e.g., weight, orientation). The fibrograph approximation was implemented by minimizing a cost function that contains the sum of squared errors between the DBF and the ensemble of the weighted triangular base functions, and the regularization term that stabilizes the optimization with the Levenberg–Marquardt algorithm. The minimization eventually determined the optimal weights of the triangular base functions, which defined the FLDs of the scanned image. Important length measurements currently used in the industry can be easily calculated from the FLD. It was found that the DBF could correctly detect fiber lengths cut from 5 to 10 mm, respectively, and it could measure the short fiber content change after a known number of short fibers was added to an existing sample. When compared with an existing fiber testing instrument, the DBF was able to output more reasonable cotton length distributions.