| บทคัดย่อ(English) |
The nondestructive determination of the durian maturity is an important process for quality control. Since durian has specific properties, such as the thickness of peel, nonuniformity of shape, roughness of prickle skin, largeness of size etc., the nondestructive determination of maturity is required, but it is hard to perform. This thesis proposes two methods for determining maturity of durian by using nondestructive force vibration and ultrasonic. In vibration method, the constant vibration is transferred directly through durian in the region between prickles located at the middle of durian. The measurement of frequency responses from vibration of durian is done by using light-intensity measure set. The signal is transformed into high frequency components by Discrete Wavelets Transform, then their correlation with PSD (Power Spectral Density) are matched to the template for maturity determination. The experiment results are compared with percent of dry-weight that is claimed as the standard measurement in destructive way. They reveal 75.92 percent of accuracy. In ultrasonic method, the ultrasonic signal from piezo-electric of transmission set is transferred directly through durian in the region between prickles located at the middle of durian. The frequency responses from durian are then collected by piezo-electric of receiver set. Then the signal is transformed into high frequency components. Finally, their correlations with PSD are matched to the template for maturity determination related to absorption of ultrasonic signal. The results of experiment with 81 durian fruits show 93.93 percent of accuracy compared with percent of dryweight. |
