This paper aims to investigate experimentally the disengagement of needle thread from rotating hook in an industrial single-needle lockstitch sewing machine with respect to tightening tension.For this purpose, the disengagement of the thread from rotating hook was photographically observed, and the resultant changes in needle thread tension were recorded simultaneously. A rotating hook, manufactured by Hirose Manufacturing Co., Ltd., model HSL-B was used, which was provided with a rotating hook section jib. Sewing speed was 2,250 spm, and the sewing threads used were cotton, and filament threads of polyester and nylon.The experimental investigation above revealed that the timing of the disengagement of needle thread from rotating hook is affected by the elongation properties of the sewing threads.If the cotton thread low in elongation was used, the needle thread first slips out of the jib and thereafter slips out of the `rotating hook bobbin case holder position bracket'. This is because when the needle thread becomes tight the rotating hook is beyond the correct angular position. The needle thread behavior therefore is abnormal. In this case, it is estimated that if the shortage of needle thread slack can not be compensated by the thread take-up spring or by thread elongation, the thread is frequently drawn out of the tension disc to result in an insufficient tightening tension.When polyester or nylon threads higher in elongation than cotton are used disengagement of needle thread from the rotating hook is normal since the needle thread first slips out of the bracket and thereafter slips out of the jib. When the disengagement occurs in this order the timing of disengagement has no effect on the tightening tension.

To investigate the effects of heat of sorption per se induced by sweating on thermoregulatory responses in clothed subjects, two experiments were carried out. In experiment 1 [ambient temperature (Ta) 27.2 degrees C, 50% relative humidity (r.h.)], seven female subjects immersed their lower-legs in a water bath at a temperature raised between 35-41 degrees C during 70 min wearing garments made for the experiment of either 100% cotton (C) or 100% polyester (P). Skin blood flow at the forearm was significantly greater in C than in P (P < 0.05). The increase of mean skin temperature (Tsk) and clothing surface and clothing microclimate temperatures were significantly higher in C than that of P after the onset of sweating (P < 0.05). Furthermore, these responses were accompanied by warmer and more uncomfortable sensations in C than in P despite a lower rectal temperature in C compared with P and identical mean body temperature in both sets of garments. In experiment 2, to simulate the clothing microclimate after the onset of sweating, C and P garments were exposed in the climate chamber to r.h. raised from 50% to 95% at a constant Ta of 27.2 degrees C. The clothing surface temperature rose by 2.2 degrees C for C and by 0.5 degree C for P after the increase of r.h. These results clearly showed a more marked increase in heat of sorption in C than in P. These results indicated that the heat of sorption per se after the onset of an increasing clothing microclimate vapour pressure, mimicking the onset of sweating, enhanced thermoregulatory responses such as skin blood flow, (Tsk) and subjective voting in C.

An experiment was conducted for revealing the aerodynamic characteristics of cylinders clothed with fabrics. Pressure distributions on the outer and inner surfaces of cylinders and velocity distributions around these cylinders were measured. The results showed that the outer pressure distributions on the cylinders clothed with different fabrics were identical, but that they were different from that on a naked cylinder. This is because the air flow around the clothed cylinder separates from the surface earlier than that around the naked one. The inner pressure distribution were strongly affected by the fabrics of low permeability, but they were scarcely influenced in the case of high permeability. Measured velocity distributions indicated the forward shift of the separation point and they were found to be influenced seriously by the fabrics of high permeability; the boundary layer on the outer surface became thick and the turbulence level in the layer was high. In the case of low permeability, however, the velocity distribution was hardly influenced by clothing except the shift of the separation point.

Geotextiles used as reinforcing elements in soil structures transfer a majority of the shear stress from the soil to the reinforcement by friction. The interfacing ability manifested by soil/geotextile frictional contact is thus very important in the perfor mance of reinforced soil structures. In this study, the interaction criteria of geotextiles with soil are evaluated by conducting model pull-out friction tests in a laboratory. The study includes an investigation of the influence of surface roughness of different woven geotextiles embedded in glass beads on interfacial friction under varying normal stresses. Pull-out friction tests on embossed acrylic plates are also done in the same manner to support beads/geotextile friction test results. The surface roughness of woven geotextiles can influence in-soil frictional behavior depending on the relationship between soil particle size and surface asperity of the geotextile: the closest fit of soil particles into the surface irregularities gives the maximum frictional resistance.

The velocity distribution in the inner flow field around a solid cylinder that was covered with a cloth and immersed in an air flow was studied experimentally by hot-wire anemometry. The cicumferential distribution of the velocity was detected by a hot-wire probe which was inserted into the clearance between the inner surface of the covering cloth and the surface of the cylinder. The results suggested that, with being away from the frontal stagnation point, the inner flow was accelerated to a maximum point positioned at about 45 degrees distant along the cylinder circumference from the starting point, and then decelerated to zero velocity at a 90-degree point. It was confirmed that the inner air flow blew off from the inner field in the region between these two positions and that the maximum velocity increased linearly with the permeability of the covering cloth. The effects of doubling the covering and of changing the thickness of the inner flow region were also investigated. It was shown, as the result, that the flow permeation into the inner region could be strongly suppressed by covering doubly, and that increasing the clearance raised the inner flow velocity.