Extended Dual Composite Sphere Model for Determining Dielectric Permittivity of Andisols
Extended Dual Composite Sphere Model for Determining Dielectric Permittivity of Andisols
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DOI：
10.2136/sssaj2005.0931
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发表时间：
2005-05
影响因子：
2.9
通讯作者：
T. Miyamoto;T. Annaka;J. Chikushi
中科院分区：
文献类型：
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作者：
T. Miyamoto;T. Annaka;J. Chikushi
介电混合模型用于了解介电常数对含水量和土壤物理性质的依赖性。我们使用了混合模型来解释总结构的体积含水量（0）和介电常数（e）的Andisols之间的关系的影响。我们的目标是确定混合模型的适用性来描述团聚体土壤的介电常数。对Friedman提出的双复合球模型进行了扩展，考虑了团聚体土壤中水分的分布以及团聚体内部孔隙和团聚体之间孔隙的充水过程。因此，我们的扩展模型包括四相复合球和S形函数作为模型中的权重函数。两种湿骨料（直径为0.1-0.25和1.0-2.0 mm）的实验数据并以日本熊本和宫崎的两个安地土为例，验证了模型的适用性。在复合球体模型中增加一个额外的层，改善了在低于临界含水量的湿度范围内θ-e关系模型的可预测性。与弗里德曼模型相比，该模型估计的θ-de/ dθ曲线与实验数据更符合。特别是，在高于临界含水量的含水量范围内，应用S形权函数可改善θ-de/dθ曲线的估计。我们调整后的模型有助于提高对团聚体土壤的物理性质和介电常数之间关系的理解。
A dielectric mixing model was used for understanding the dependency of dielectric permittivity on water content and soil physical properties. We used a mixing model to interpret aggregate structural effects on the relationship between volumetric water content (0) and dielectric permittivity (e) of Andisols. Our objective was to determine the applicability of a mixing model to describe the dielectric permittivity of aggregated soil. A dual composite sphere model, proposed by Friedman in 1998, was extended by taking into account water distribution in aggregated soil and the processes of water filling in intra-and interaggregate pores. Hence, our extended model includes four-phase composite spheres and sigmoidal functions as a weight function in the model. Experimental data for two wet aggregates (0.1-0.25 and 1.0-2.0 mm in diam.) and two Andisols taken from Kumamoto and Miyazaki in Japan were used for the demonstration of model applicability. The addition of an additional layer in the composite sphere model improved the predictability of the model for the θ-e relationship in a moisture range of less-than-critical water content. The θ-de/ dθ curves estimated by the model were in better agreement with the experimental data than those of Friedman's model. In particular, applying the sigmoidal weight functions improved the estimation of θ-de/dθ curves in a moisture range higher than that of critical water content. Our adjusted model serves to improve the understanding of the relationship between the physical properties of aggregated soils and their dielectric permittivity.