Tangling strengths represent the preservation characteristic of tangling parts of interlaced yarns subjected to force. The number of tangles, tangling angle, lengths of tangling and non-tangling parts, yarn diameter and so on are structural characteristics of interlaced yarns. They are important characteristics of interlaced yarns. However, the relation between tangling strengths and structures has not been clarified yet. In this study, for the purpose of evaluating and controlling interlaced yarns, we discussed the two followings : the effects of interlacing factors (supplied air pressures, yarn speeds and feed ratios) on the tangling strength, and the relation between the tangling strength and the structure. Results obtained are as follows.
(1) When the supplied air pressure is high, an air force acting on a yarn is great. When the yarn speed is low, a time for which an air jet acts on a yarn of a unit length is long. When the feed ratio is large, a great amount of filaments is fed to tangling production. Hence, these cases give large tangling strengths to interlaced yarns.
(2) Modified tangling angles are defined by tangling angles divided by dimensionless cross-sectional areas of tangling parts (ratios of average apparent cross-sectional areas of tangling parts to average apparent crosssectional areas of raw yarns). Then, the tangling strength has a linear relation to the modified tangling angle, in one-to-one correspondence independent of processing factors (supplied air pressures, yarn speeds and feed ratios). The tangling strength increases with the modified tangling angle. This is because filaments in tangling parts are long for large tangling angles, tangling is strong for small apparent cross-sectional areas of tangling parts, and frictional force between filaments is large for large yarn counts with wide contact areas.
(3) It was suggested that the tangling strength can be evaluated, on an on-line real time system because both tangling angles and dimensionless cross-sectional areas of tangling parts can be measured on an on-line real time system.

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Alumina ceramics precursor was coated on the glass fibers by sol-gel method using metal alkoxide solution. The optimum coating condition for the concentration of metal alkoxide and silane coupling agent make it possible to uniformly coat alumina precursor film on the glass fiber. The organic contents in alumina precursor on the glass fiber increased with the concentration of metal alkoxide. The addition of silane coupling agent led adhesive force between glass fiber and ceramics precursor films to be higher. The alkali-resistance, heat resistance and tensile strength of ceramics precursor coating glass fibers were superior to original glass fiber. The surface of glass fiber was eroded by curing in NaOH aqueous solution at 40°C. However, the morphology of fiber coated by alumina precursor was retained in NaOH aqueous solution. The crack on the surface of glass fiber was formed by heating at 800°C, but, the crack was not observed in the glass fiber coated by alumina precursor. The tensile strength of glass fiber and alumina precursor coating fiber was 60×10³and80×10³kgf/cm², respectively. The tensile stren of glass fiber and alumina precursor coating fiber increased with the concentration of silane coupling agent.

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A measurement system was developed to measure the density of knit fabrics automatically without destruc tion, and the applicability was discussed. The density of knit fabrics is concerned greatly with the appearance of the finish, so the measurement is very important for the design and reproduction. Computer image processing and information analysis were implemented in the system to measure the density. The surface images of knit fabrics were scanned by an image scanner and saved to disk on a computer. The threshold processing and histogram processing were performed to determine the positions of courses and wales. Then, the system counted the number of stitches in a course. The density, the number of courses and wales per the unit length, were measured for some plane stitch knit fabrics. The density measurement was successful for relatively coarse fabrics such as five gauges and was good for gauge of less than or equal to 12, but was sometimes incorrect for fine fabrics such as 20 gauge. This is caused by the resolution of the image scanner. If the resolution of the image increase, the measurements become successful. This system can be used instead of the current manual measurement using a textile analysis glass.

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