基于介电特性的花椒湿基含水率预测研究

Study on Prediction of Chinese Prickly Ash Wet Basis Moisture Content Based on Dielectric Properties

含水率是花椒干燥的重要品质指标。然而,传统的精确含水率测量耗时、繁琐且投入较大,已与精确农业背景下的作业过程与数据需求不相适应。为此,以花椒湿基含水率与其介电特性参数之间关系出发,寻求间接但易获取的含水率测量新途径。首先,基于LCR数字电桥,温度与测量频率对电阻R_(Q)、复阻抗Z_(Q)、损耗系数D、单重品质因数Q这四个介电参数测量值的影响被关注,发现干燥温度为40℃、检测频率为1 kHz的组合对花椒品质的无损检测较为理想。进而,利用多项式回归方程对花椒的不同介电参数与湿基含水率W进行相关性分析,基于决定系数R^(2),得出了损耗系数D与湿基含水率W的相关性更明显的结论。试验数据表明,基于损耗系数D预测的花椒湿基含水率最大误差为2.1%,这对工程应用的精度已经足够。

Moisture content is an important quality index of Chinese prickly ash drying.However,the traditional accurate moisture content measurement is time-consuming,cumbersome and involves large investment,which doesn’t adapt to the operation process and data demand against the background of precision agriculture.Therefore,from the perspective of the relationship between the water content of Chinese prickly ash and its dielectric characteristic parameters,this study seeks a new indirect but easy way to obtain moisture content.First of all,based on a LCR digital bridge,the influence of temperature and measurement frequency on the measured values of four dielectric parameters,i.e.resistance R_(Q),complex impedance Z_(Q),loss coefficient D,single quality factor Q attracted attention.It was found that the combination of drying temperature of 40℃and detection frequency of 1kHz was relatively ideal for wet basis moisture content detection.Furthermore,the correlation between different dielectric parameters and wet basis moisture content W were analyzed using polynomial regression equation.Based on the determination coefficient R^(2),the conclusion that the loss coefficient D had more obvious correlation with wet basis moisture content W was drawn.The test data show that the maximum error of Chinese prickly ash wet base moisture content predicted based on loss coefficient D was 2.1%,and it is enough for engineering application.