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標題: 利用聲波檢測鴨蛋外殼裂痕之研究
The Study of Eggshells' Crack Detection by Acoustics
作者: Shih-Yu Pai
Wei-Min Jee
Chung-Wei Li
Ching-Wei Cheng
關鍵字: Duck egg;蛋;acoustics;natural frequency;聲波檢測;諧振頻率
出版社: 臺中巿: 國立中興大學農學院
Project: 農林學報, Volume 50, Issue 4, Page(s) 79-102.

The purpose of this study is to offer a method for using acoustics detecting eggshells' crack in order to make an effective application to the development of the eggshells' detecting automatic detecting system. This experiment used different length of closed brass tubes to find the frequencies and wavelengths of air in the tube. According to the response spectrum, it was observed that the first natural frequency was the same as that in the brass tube. Besides, the frequency amplitude was decreased due to the existed cracks. Then, using the sound-gathering tube with a steel ball in front of tube to knock at the eggshells, the microphone received a sound-wave signal from the air in the tube. By means of the swift the FFT, it showed that the frequency amplitude was also decreased due to the existed cracks. Therefore, this experiment used oscilloscope to compare the amplitudes and to justify weather the cracks was existed or not. The experimental results showed that the amplitude of eggs with crack was lower that without crack. It also showed that all the ratio of the second peak to the first peak for the eggs without crack was ranged 70% to 90%. However, for the eggs with crack, the ratio was ranged 30% to 40% when knocking at the point of crack, and 50% to 60% when knocking at the point near the crack. The amplitude of the first natural frequency at the crack was under -30dB, between -27.1dB and -28.7dB. When the shell is perfect and between -28.7dB and -30dB beside the crack. The results will be identified as the base of detecting the eggshells' cracks.
Appears in Collections:第50卷 第04期

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