In this study, combed ring spun and compact spun cotton yarns with different counts were selected from different textile mills to conduct singeing treatment. Yarn properties including hairiness, fineness, unevenness and tensile properties were tested after the treatment and the results were compared with those before treatment. Hairiness was greatly removed after singeing, especially for short hairs with length less than 3 mm. Compact ring spun cotton yarns showed higher tex values and lower weight loss than combed ring spun cotton yarns under the same counts. Coefficient of variation of yarns increased slightly after singeing treatment. The unevenness of yarn was divided into two parts: basic unevenness of yarn body and hairiness unevenness, to explain the worse yarn evenness after singeing treatment. In this way, the effect of singeing on yarn properties was investigated thoroughly so as to improve yarn quality with less hairiness and good evenness.

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Jerk is directly related to a physical mutation process of structural damage and human comfort. A fiber optic jerk sensor (FOJS) based on a fiber optic differentiating Mach–Zehnder interferometer is proposed. It can directly measure jerk by demodulating the phase of interference light, which avoids the high-frequency noise interference caused by differentiating the acceleration. The sensing theory and sensor design are given in detail. The experimental and theoretical results agree, demonstrating that the FOJS has a high sensitivity, an ultralow phase noise floor, a wide measuring range, and good linearity. The impact test shows that the FOJS can directly measure jerk and has good consistency with a standard piezoelectric accelerometer. The FOJS has potential applications in earthquake engineering, comfort evaluations, and railway design. This is the first time that directly measuring jerk with an optical sensor is reported.

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