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【期刊论文】An Improved Dielectric Sensor for Determining Soil Water Content
孙宇瑞, Sun Yurui, Ma Daokun, Lin Jianhui
,-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 sensor for determining soil water content. Unlike other measurement principles, an index, which is independent of the output impedance and the amplitude of the oscillator but relies on the impedance of the multi-pin probe, was proposed. Moreover, a model for treating the impedance of the multi-pin probe was also discussed and the necessary experiment was conducted. Finally, the relationship between the proposed index and soil volumetric water content was linearly corrected.
Dielectric Constant, Impedance, Soil water content
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孙宇瑞, 汪懋华, 马道坤, 黄季平
农业机械学报,2001,32(4):48~50,-0001,():
-1年11月30日
根据精细农业研究的实际要求,首先在不考虑外部振动的情况下设计了一种基于冲量原理的谷物流量测量试验装置。该装置由自行研制的冲量传感器、数据采集器和谷物流动模拟箱体组成。试验结果表明这种装置测量误差的绝对值小于5%。在此基础上又进行了谷物产量实时监测系统的试验研究,试验结果表明,在引入外部机械振动的情况下经过滤波处理系统测量误差的绝对值小于8%。
冲量, 固体流量, 测量系统, 试验装置
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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】An assessment of three kinds of optical sensors for estimating soil water content
孙宇瑞, Yurui Sun, Schulze lammers and Lutz Damerow
,-0001,():
-1年11月30日
Three types of optical sensors at wavelength ranging from visible to NIR, were used in laboratory environment for determining soil moisture content. Some index was defined to reduce measurement error caused by scatter. Two different sands and clay were tested from air dry to saturated conditions. The test results demonstrated that all tested sensors were very sensitive to soil texture and particle-size distributions. Because the wavelength from visible to NIR varies within the sizes of sand and clay, soil should not be viewed as a material with homogeneous property under optical measurement methods.
soil, moisture content, optical sensor
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孙宇瑞, Y. Sun a, D. Maa, P. Schulze Lammers b, *, O. Schmittmann b, M. Rose b
Soil & Tillage Research 2 xxx(2005)xxx-xxx,-0001,():
-1年11月30日
A combined horizontal penetrometer was designed for the on-the-go and simultaneous measurement of soil water content and mechanical resistance. The maximum sampling rate for both sensors was 10 Hz and the maximum operating depth was 20 cm. For the water-content sensor, its measurement principle depends on the electric field of the fringe-capacitance. In order to evaluate the applicability of this combined penetrometer, four experiments in the field were carried out. These experiments included: (1) soil water content profiles test; (2) soil compaction measurement test; (3) effect of the operating velocity on the water content and resistant force measurement; (4) effect of operating depth on the force measurement. The experimental results show that the combined horizontal penetrometer is a practical tool since it can provide more useful information of soil physical properties.
Soil compaction, Water content, Penetrometer, On-the-gomeasurement
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