The evaluation of the performance of distribution uniformity by linearly moved irrigation system(LMIS)should consider the impacts of non uniformity of the water on crop yield.With increasing pressures to improve water...The evaluation of the performance of distribution uniformity by linearly moved irrigation system(LMIS)should consider the impacts of non uniformity of the water on crop yield.With increasing pressures to improve water use efficiency,plant productivity and farm profitability,questions continue to be raised concerning the future direction of irrigated agriculture.This study therefore aimed at evaluating water distribution under LMIS newly designed by the National Research Centre of Fluid Machinery Engineering and Technology,Jiangsu University,China.This article reports the real distribution of irrigation water under the LMIS with respect to sprinkler height above the ground surface as well as the consequence of different operating pressures.Water distribution coefficients used in the performance assessment were Christiansen’s coefficient of uniformity(CU),distribution uniformity(DU),scheduling coefficients(Sc)and the coefficient of variation(CV).The results showed that the mean CU ranged from 82.30%to 93.17%,and mean DU ranged from 70.39%to 88.44%.Also Sc values ranged from 1.13 to 1.42 with CV values ranging from 10.3%to 22.5%.The optimum method and results in this study can provide a reference to the operations for saving water and cost in the application of LMIS.展开更多
To capture the grading-dependence of the shear stiffness of heterogeneous granular aggregates, a new grading parameter that considered the size distribution of the entire aggregates was developed. Both the coefficient...To capture the grading-dependence of the shear stiffness of heterogeneous granular aggregates, a new grading parameter that considered the size distribution of the entire aggregates was developed. Both the coefficient of uniformity and median particle size decreased with increasing the grading parameter. A general increase of the shear stiffness with increasing the grading parameter was observed. Compari- son with experimental results revealed that the proposed grading parameter had a stronger correlation with the material constants of Hardin＇s stiffness formula than the coefficient of uniformity, which is a traditional grading parameter.展开更多
基金the National Key Research and Development Program of China(No.2016YFC0400202)the Project of New Agricultural Machinery in Jiangsu Province(No.NJ2016-11)+1 种基金the Postdoctoral Science Foundation Special Support of China(No.2016T90428)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The evaluation of the performance of distribution uniformity by linearly moved irrigation system(LMIS)should consider the impacts of non uniformity of the water on crop yield.With increasing pressures to improve water use efficiency,plant productivity and farm profitability,questions continue to be raised concerning the future direction of irrigated agriculture.This study therefore aimed at evaluating water distribution under LMIS newly designed by the National Research Centre of Fluid Machinery Engineering and Technology,Jiangsu University,China.This article reports the real distribution of irrigation water under the LMIS with respect to sprinkler height above the ground surface as well as the consequence of different operating pressures.Water distribution coefficients used in the performance assessment were Christiansen’s coefficient of uniformity(CU),distribution uniformity(DU),scheduling coefficients(Sc)and the coefficient of variation(CV).The results showed that the mean CU ranged from 82.30%to 93.17%,and mean DU ranged from 70.39%to 88.44%.Also Sc values ranged from 1.13 to 1.42 with CV values ranging from 10.3%to 22.5%.The optimum method and results in this study can provide a reference to the operations for saving water and cost in the application of LMIS.
基金The financial support provided by the Fundamental Research Funds for the Central Universities （Grant no, 2017B05214）, the National Natural Science Foundation of China （Grant No. 51479060） and the Priority Academic Program Development of Jiangsu Higher Education Institutions are appreciated.
文摘To capture the grading-dependence of the shear stiffness of heterogeneous granular aggregates, a new grading parameter that considered the size distribution of the entire aggregates was developed. Both the coefficient of uniformity and median particle size decreased with increasing the grading parameter. A general increase of the shear stiffness with increasing the grading parameter was observed. Compari- son with experimental results revealed that the proposed grading parameter had a stronger correlation with the material constants of Hardin＇s stiffness formula than the coefficient of uniformity, which is a traditional grading parameter.
