In order to clarify the working mechanism of an air suction gun, yarn motion in the air suction gun was captured with a high-speed video camera, then characteristics of the yarn motion in the air suction gun and the geometrical effects on the yarn motion were investigated. A yarn moves forward with a high-speed rotation in a yarn propulsion tube, and performs a helical motion more regularly in a de Laval tube than in a straight tube. The motion path is different from the yarn posture. The yarn motion is unsteady and considerably affected by the friction from the tube wall, which causes a large reduction in the yarn circumferential velocity component v_yc. The changes in the geometrical parameters mainly produce changes in v_yc with a negligible effect on the yarn axial velocity component. v_yc increases with an increase in the compressed-air inflow angle and with a decrease in the throat diameter of de Laval tube. An increase in the convergence angle of de Laval tube causes v_yc to increase in the de Laval tube. Yarn motion is almost independent of the passage divergence angle of nozzle. It is mainly determined by the circumferential component of air velocity v_ac and bears less relationship to the axial one. Yarn suction force F_m is associated with various effects, and depends on v_yc in particular. For achieving a high F_m, the swirl intensity of helical airflow, namely v_ac, needs to be controlled at an appropriate level because an increment of v_ac increases both air drag on the yarn and friction between the yarn and the tube wall.

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Based on the structural analysis of sample knitted fabrics and the knit geometric theory, we have built an algorithm that can make three-dimensional structure models for weft knitted fabrics such as welt stitches, tuck stitches, cross stitches, rib stitches and purl stitches. In order to reduce computational complexity, we have set the anchoring point on the diametral plane of yarn in the knitting chart. Drawing from the beginning knitting point to the finished knitting point, a smooth knit curve model can be obtained with the cardinal spline curve. Using this algorithm, we have developed the weft knit three-dimensional structure modeling software that can display the three-dimensional model of knitted fabrics including welt stitches; tuck stitches, cross stitches, rib stitches and purl stitches.
Our work confirms 3-D modeling of three foundation knits of weft knit (plain stitches, purl stitches, rib stitches), tuck stitches, welt stitches and cross stitches with a commercially available PC. This software can be used by someone with no understanding of knitting to gain an understanding of the knitting process, and determine the structure of a knitted fabric product.

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The segmented polyurethane films having different composition ratios of PTMG and PEG in the soft segments were prepared. The films with different water absorbability were dyed with CI Acid Red 114 and CI Direct Red 28, respectively. Dye uptake of CI Acid Red 114 in the films increased by adding formic acid into dye bath. On the other hand, dye uptake of CI Direct Red 28 in the films increased by the addition of sodium chloride into dye bath. In any combination of the dyes and the films, the resulting sorption isotherms might indicate the Freundlich-type dye mechanics. Dyeing properties of the segmented polyurethane films containing polyethylene glycol with acid dye and direct dye were as follows ; (1) The dyeing was performed mainly in soft segments of the segmented polyurethane. (2) The segmented polyurethane films were dyed into the hydrophobic parts composed of urethane bonds in the neighborhood of hydrophilic PEG component. (3) The hydrophobic interaction between the dye and the segmented polyurethane became the big power as to the dyeing of the segmented polyurethane having the hydrophilic soft segment consisting of PEG. The effect of the dyeing by van der Waals forces on the segmented polyurethane seemed to be big as to the dyeing of the polyurethane.

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The long-term goal of this study is to design sportswear for the elderly. Previously, we reported dressing motion and muscle activity on young and dummy elderly persons while they are putting on four different styles of sportswear: long-sleeved, sleeveless, zippered, and zipper-less. In the part of the study reported in the present paper, we photographed their movements while they were putting on the four styles of sportswear and measured the wearing time, maximum working area, and muscle activity. Further, we investigated how the sportswear style influenced the psychological burden. From motion analysis, we found that, when the dummy elderly persons pass an arm through the sportswear at process (2), the wearing times for sleeveless sportswear were lower than those for long-sleeved sportswear. In addition, the maximum working area and %MVC (percentage maximum voluntary contraction) values for zippered sportswear were higher than those for zipper -less sportswear. When wearing the sportswear at process (3), the maximum working area and %MVC values for zipper-less sportswear were higher than those for zippered sportswear. From these results, it was concluded that the sportswear style influences wearing time, maximum working area, and muscle activity.

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