Papers by Author: Li Yao

Abstract: Soil moisture sensor probe is the basic and key part of the automated water-saving irrigation equipment. It can measure soil moisture accurately and in real-timely, while metal probes have a serious problem of corrosion and passivation as working in the soil which is a severe environment of the soil of high humidity and complex chemical compositions. Graphite gelling of different content of graphite composite material under both wet and dry conditions, the experimental study, by testing the experimental data of its resistivity contrast to identify the proportion of the composite material of graphite content suitable for the production of a new probe.

Abstract: A novel technique using solar power to irrigation was proposed. In order to obtain better sensitivity, small dense probe, single strand copper probe, bifilar winding type probe and rectangular cross section type probe were designed. Through the experiments, the electrical resistance of four kinds of probe structure was determined. Test results show that conductivity of small dense probe is the worst, conductivity of single strand copper probe is better. Graphite content has great influence to probe resistance value, resistance and graphite content in the relationship is not linear.

Abstract: It presents a new structure of soil moisture probe which is designed for the solar automatic water-saving irrigation. DC two-probe method is used to measure resistivity of the new probe with different content of graphite under wet and dry conditions. The results show the resistance variation of the composite material with more than 25% graphite content is very small, its suitable for the production of two-pin probe; the conduction of composite material with less than 15% graphite content are greatly affected by the cement, its suited for the production of one-pin probe. The research results can be used as reference for choosing moisture probe according to different soil.

Abstract: Soil moisture detective probe is an important part of automatic irrigation system. Soil moisture probe is usually made of metal material which is easy to be corroded and passivated as long-term working in the damp soil, especially containing acid, alkali and salt. We developed a new soil moisture probe material - the graphite-based cementitious material. The mechanical properties and the conductive properties of the material were tested and we found the graphite-based cementitious material which contains 30% to 50% of graphite could be an applicable material for the soil moisture probe.