Force and acceleration are the most well-known signals for the monitoring of milling vibration. However, the noncontact and low-cost microphone is also a potential choice for cutting vibration measurement. The superior detection sensitivity of the microphone against milling dynamics was preliminarily verified. However, the limitations of microphones to record milling vibration have also been reported over the past two decades, such as the vibration identification accuracy under the influence of environmental noise. In this work, the microphone signal beyond 5 kHz is employed in the milling stability analysis to diminish the effect of low-frequency environmental noise. In addition, almost all current studies for cutting noise analyses are conducted without cutting fluid (dry cutting). This is far from most practical manufacturing processes. The cutting fluid is used in this work and a waterproof device is particularly designed to ensure the microphone operation against the cutting fluid. The microphone signal is analyzed on the basis of the scatter diagram of time domain (SDTD) to discuss the variation trend due to the milling stability. In addition, both the fast Fourier transform (FFT) and short-time Fourier transform (STFT) were employed to clarify the signal characteristics in the frequency domain. Finally, the finished workpiece surface was examined with the stability lobe diagram (SLD) to verify the acoustic analysis results.

Abstract. Different physiological structure between genders reflects on daily life, in which "going to toilet" is mostly concerned. Going to toilet is an important triviality every day but is closely related to personal health. Since toilet seats directly contact with the skin, the cleanness presents critical influence on physiological health and psychological comfort. It is common to share a set of sanitary equipment in the family, where females reveal several times higher probability on contacting with toilet seats. Aiming at home toilet seats being easily polluted, an improvement program is proposed in this study to reduce gender conflict with a simple mechanism design, which is improved through experiments. Keywords: female population advantage, toilet seat, female right, convenient design of toilet, use efficiency of toilet.