Nondestructive Internal Defect Detection of Agricultural Products Using Ultrasonic Secondary Wave

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The purpose of present work is to establish the fundamentals of a method of nondestructive defect detection of various agricultural products using ultrasonic secondary wave.It was experimented on the internal defect of Japanese radish (longish common type), Japanese radish (cv. Sakurajima) and watermelon, and on the quality of kiwi fruits. Results obtained wave as follows :(1) The amplitude of waveform with the axis of time for a pithiness of common type radish was smaller than that of a normal radish without pithiness, and there were some differences in power spectra of the both. As a result of above mentioned, it was able to evaluate a pithiness of Japanese radish.(2) It was able to evaluate a pithiness of cv. Sakurajima as well as common type radish.(3) In case of watermelon, the amplitude of waveform with the axis of time for a sample with defects was smaller than that of a normal sample, and it was able to evaluate by means of the standard of distinction. The optimum frequency to detect internal defects of watermelon was 2 kHz.(5) There were some correlation between the largest amplitude of waveform with the axis of time and hardness of kiwi fruit.