Acoustic Vibration Method Research Articles

Measurement of ripening speed and determination of the optimum ripeness of melons by a nondestructive acoustic vibration method

The ripening speed of the melon cultivar ‘Miyabi-Haruaki’ was determined by monitoring its elasticity index (EI) with a nondestructive acoustic vibration method. EI was determined by the formula EI = f 2 2 ⋅ m 2 / 3 , where f 2 is the second resonance frequency of a melon sample, and m is the mass of the sample. The speed of ripening, i.e., ΔEI/day, was determined to be 0.36 × 10 4 kg 2/3 Hz 2 d −1, which was lower than the ripening speeds of previously studied melon cultivars ‘Andes’ and ‘Quincy’ (0.39 × 10 4 kg 2/3 Hz 2 d −1 and 0.50 × 10 4 kg 2/3 Hz 2 d −1, respectively). Using a sensory panel test, the period of optimum ripeness of the melons was determined to be 5.3–7.1 × 10 4 kg 2/3 Hz 2. Nondestructive determination of the period of optimum ripeness in terms of the EI can be useful for estimating the shelf-life of melons. In addition, by determining the ripening speed, the time required for a melon to reach optimum ripeness can be predicted.

Determination of the Young's Modulus and Loss Factor by Acoustic Bending Vibration Methods

A new acoustic bending vibration method of determining the resonance frequency, Young’s modulus and loss factor applicable for both metallic and non-metallic materials is proposed. Measurements were conducted by using both conventional electromagnetic excitation method specified by ASTM E 756 and ISO 6721 and our method for conductive metallic specimen of stainless steel and non-metallic polypropylene specimen. Difference in the mechanical properties observed between both methods is attributed to the presence of a metal disk attached to the non-metallic sample for electromagnetic. However, the good agreement between the results obtained by both methods for the metallic sample ascertains the reliability and advantages of the method.

新しい音響振動法によるキュウリの肉質評価

新しい音響振動法によるキュウリの肉質評価