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孙宇瑞, 孙宇瑞①, 汪懋华
农业工程学报,2001,17(2):20~23,-0001,():
-1年11月30日
针对一种土壤电导率的测量方法——“电流-电压四端法”,从理论上深入探讨了该方法的测量原理,建立了对应的数学模型。关于Wenner分布、Schlumberger分布和Polar ipole分布3种测量组态计算公式的正确性也通过实验进行了检验。
土壤, 电导率, 测量, 建模
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【期刊论文】Measuring Soil Water Content Using the Principle of Standing-wave Ratio
孙宇瑞, Yurui Sun, Maohua Wang, Naiqian Zhang
,-0001,():
-1年11月30日
Determination of soil water content in situ is complicated due to variations in dielectric constant of porous media. Time domain reflectometry (TDR) may meet the need for measurement of soil moisture with high accuracy. However, TDR-type instruments are expensive. A theory, which is called standing-wave ratio (SWR) of transmission line, is proposed in this paper. This theory has been proven a valuable tool for measuring soil water content. A method for calculating the characteristic impedance of a four-wire probe was developed. Furthermore, a prototype of a SWR-type sensor equipped with a new soil probe was designed.The measurement error was found to be within
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【期刊论文】A dual sensor for simultaneous investigation of soil cone index and moisture content
孙宇瑞, Yurui Sun), Peter Schulze Lammers) and Lutz Damerow)
,-0001,():
-1年11月30日
A dual sensor combining dielectric and mechanic principles wasdeveloped. The geometric structure of this sensor has been designedaccording to the ASAE-standard for penetrometer cones, and the sensorcan provide a pair of output signals when inserted into soil. By analyzingboth signals, one can determine the correlation among cone index, soilbulk density, and moisture content. Some preliminary experiments wereperformed in a laboratory environment, and the sensor will be ready foruse in the field in the near future.
Cone index, soil moisture, bulk density, dielectrics, measurement
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【期刊论文】An improved FD-technique for determining soil water content*1
孙宇瑞, SUN Yu-Rui, MA Dao-Kun, LIN Jian-Hui, P. Schulzlammers, L. Damerow
,-0001,():
-1年11月30日
A soil moisture sensor with low-cost, reliability and sufficient accuracy has been desired for many years. This paper presented an improved measurement method based on FD principle for determining soil water content. Unlike other measurement principles, a new measurable index, which is independent of the output impedance and the amplitude of the oscillator but relies on the electric impedance of the multi-pin probe, was proposed. Moreover, a model for treating the impedance of the multi-pin soil probe was also discussed and several important electric properties were approached. In order to confirm the theoretical analysis, the necessary experiments were conducted. Finally, using obtained modeling, the relationship between the proposed index and soil volumetric water content was linearly corrected.
Dielectric Constant, Measurement, Soil water content
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孙宇瑞, 孙宇瑞①, 汪懋华, 赵燕东
农业工程学报,1999,15(2):37~41,-0001,():
-1年11月30日
土壤介电常数是影响土壤含水率快速、准确和可靠测量的关键参数。通过检测土壤介电常数换算出土壤含水率的测量方法已成功地应用在基于TDR原理的现代先进测量仪器中。文中依据传输线理论探讨了基于驻波比原理的土壤介电常数测量方法,解决多针探头特征阻抗的计算,实验结果证实了理论分析的正确。
介电常数, 驻波比, 传输线, 特征阻抗, 土壤含水率
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