This study investigated the perceptual and physiological responses of 10 college-aged subjects to square wave airflows of different cycles (2 min, 10 min and 30 min) under different temperature levels (28 and 32 ). Main conclusions are as follows:(1) The mean pleasantness was highest in the condition of 32℃ air temperature with square-wave airflow (10-min cycle).(2) The mean thermal sensations reported by subjects were lower than corresponding PMV values, indicating the cooling effect of dynamic airflows on human thermal comfort in warm environment.

No abstract

The sensing of acoustic emission (AE) is efficiently used for the detection of the crack initiation of brittle materials and defects in plastic forming and other manufacturing processes. We carried out circular hole punching tests using carbon steel S45C plates of 5 or 6 mm thickness. The objective was to capture the occurrence of cracks as a predictive phenomenon of punch fracture and their propagation during punching by using an AE sensor. The impulsive stress acting on the punch due to the sudden drop in punch force at the fracture of the plate was also measured using strain gages. This stress induced fracture at the stepped portion of the punch. The maximum tensile stress of the punch depended on the fillet radius at the stepped portion. A reciprocal punching test using both plates alternately was performed to evaluate the detection of crack initiation using an AE waveform. Features in the AE waveform due to crack initiation and the frictional behavior of the crack were captured.