利用音波檢測西瓜內部品質－成熟度、空洞之存在與方位

Acoustic Evaluation of Watermelon Internal Quality-Maturity, Cavity Existence and Orientation

艾群(Chyung Ay)

《農業機械學刊》 5卷4期 (1996/12) Pp. 56-71

https://doi.org/10.30062/JAM.199612.0006

摘要

傳統農民利用手拍打西瓜，由拍打聲得知其品質－成熟度與是否有空洞，此技術需有多年經驗之專家始可為之。本研究利用衝擊拍打所造成之聲音進行非破壞性音波檢測技術來探討西瓜內部品質－成熟度、空洞有無及方位。本研究探討西瓜振動之共振頻率；且利用彈性圓球理論求出彈性模數，推導出一成熟度指標因子。由實驗結果得知，西瓜成熟度與成熟度指標因子有相關性；且由FFT的共振頻率可以探測西瓜內部是否有空洞及其方位，由音波探測西瓜內部空洞之方式較之傳統十幾年經驗之農民還要精確。

關鍵字

西瓜 ； 音波 ； 空洞方位 ； 非破壞性技術 ； 成熟度

並列摘要

The internal quality of watermelon, maturity and cavity existence, can be detected by traditional expert farmers who has more than 10 years experience. They tapped the watermelon by hand and listened the produced sound from watermelon to judge their qualities. This study is to evaluate the internal quality of watermelon, maturity, cavity existence and orientation, using a nondestructive technology-acoustics. An impulse vibration was produced with hammer to apply to the watermelon. The resonant frequency of watermelon after striking was found from acquired signal. The ripeness index was derived from the elastic sphere model to determine elastic modulus. From experimental results, there is a correlation between the maturity of watermelon and ripeness index. The cavity existence and orientation of watermelon can be evaluated by the resonant frequency of vibrational signal of watermelon through FFT. This technology of acoustics to evaluate the cavity existence is more reliable and accurate than the expert farmer.

並列關鍵字

Watermelon ； Acoustics ； Cavity orientation ； Non-destructive technology ； Maturity