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Subject: search.filters.subject.Dielectric constant variation

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    Dual-Frequency Sensor for Thick Rind Fruit Quality Assessment
    (2020-10-01)
    Kittiyanpunya, Chainarong
    ;
    Phongcharoenpanich, Chuwong
    ;
    Krairiksh, Monai
    This article proposes a novel multibeam dual-frequency sensor system to assess the quality of thick rind fruits based on phase difference between lower- and higher-frequency reflection coefficients ( Φ {12} ). The proposed sensor system consists of five dual-band antennas and a customized circuit that approximates lower- and higher-frequency phase difference. The main components of the customized circuit are down-conversion mixers and a phase detector module. For comparison, simulations were initially carried out using single- (1 GHz) and dual-frequency (1 GHz/2.3 GHz) sensor systems, and results indicated lower accuracy in classification of thick rind fruits of the single-frequency scheme. As a result, a dual-frequency sensor prototype was fabricated and experimented with normal and granulated plastic pomelo models and real pomelo fruits. The experimental results revealed that the average Φ{12} of the normal and granulated pomelos are almost identical, while the standard deviation (SD) of Φ 12 of the granulated pomelo is significantly larger than the normal pomelo. SD is thus used as the determinant of pomelo quality. The multibeam 1-GHz/2.3-GHz dual-frequency sensor system efficiently differentiates between normal and granulated pomelo fruits. As such, the proposed sensor system is operationally appropriate for quality control of thick rind fruits.
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    Nondestructive Determination of the Maturity of the Durian Fruit in the Frequency Domain Using the Change in the Natural Frequency
    (2016-05-01)
    Tantisopharak, Tanawut
    ;
    Moon, Hongsik
    ;
    Youryon, Pannipa
    ;
    Bunya-Athichart, Kanokpon
    ;
    Krairiksh, Monai
    This paper proposes a nondestructive technique to determine the stages of maturity of durian fruits. The presented methodology utilizes the electromagnetic scattering properties from the fruits over time for identification of the stage of maturity using its natural frequencies. Both simulation and experimental results show that the natural frequencies in the scattering responses change with the maturity of the durian fruit. Particularly, the change in the fundamental resonant frequency is used as a possible identification criterion for characterization of the stage of maturity. This is because the dielectric constant of the core of the fruit changes with its degree of maturity. In addition, the experimental results indicate that the variation of the dominant resonant frequency of durian fruits varies at different stages of maturity and this has the potential to be applied as a criterion to identify the stages of maturity.