Philip’s two-term infiltration equation has been widely used to infer soil saturated hydraulic conductivity(Ks),the accuracy of which is usually influenced by the size of infiltration rings and soil conditions.Previo...Philip’s two-term infiltration equation has been widely used to infer soil saturated hydraulic conductivity(Ks),the accuracy of which is usually influenced by the size of infiltration rings and soil conditions.Previous studies have primarily focused on exploring the ring-size dependence of Ks estimations under specific soil conditions(e.g.,soil isotropy and/or uniform initial water content).This study aimed to provide a comprehensive analysis by systematically considering eight heterogeneous and anisotropic soils with nonuniform initial water contents.Specifically,we examined the validity of Philip’s infiltration equation as well as the recently proposed two forms(i.e.,infiltration and time forms)of Parlange’s infiltration equation both theoretically and in practical applications of double-ring infiltration.Then the time form of Parlange’s equation was applied to infer Ks using double-ring infiltrometer measurements with different combinations of six inner ring diameters(10,20,40,80,120,and 200 cm)and three buffer index(defined as the ratio of the difference between inner and outer ring diameters to the outer ring diameter)values(0.20,0.33,and 0.50).For each infiltrometer set,20 stochastic Ks fields were randomly generated by adopting five standard deviation values(0.1,0.3,0.5,0.7,and 0.9).Furthermore,we investigated the effects of five horizontal correlation lengths(30,60,150,300,and 600 cm)on Ks estimations.The results demonstrated that Parlange’s equation,compared to Philip’s equation,was more universal in describing the cumulative infiltration relationship for the test soils.The combination of inner ring diameter and buffer index of 40 cm and 0.2,respectively,which satisfied most of the practical requirements for determining Ks in the Soil Water Infiltration Global(SWIG)database was optimal.When the horizontal correlation length exceeded a threshold(i.e.,150 cm in our study),the inner ring diameter was required to increase to 80 cm.Our findings contribute to accurate Ks estimations of different soils using double-ring infiltrometers.展开更多
International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater...International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater sound field gener- ated by an airborne source, i.e., the ray theory, the wave solution, the normal-mode theory and the wavenumber integration approach, are introduced. Effects of two special conditions, i.e., the moving airborne source or medium and the rough air-water interface, on the air-to-water sound transmission are reviewed. In experimental studies, the depth and range distributions of the underwater sound field created by different kinds of airborne sources in near-field and far-field, the longitudinal horizontal correlation of underwater sound field and application methods for inverse problems are reviewed.展开更多
The spatial coherence of sound field in the reflection area of deep-water bottom is studied by analyzing the data of an acoustic propagation experiment conducted in the South China Sea. Some different oscillation patt...The spatial coherence of sound field in the reflection area of deep-water bottom is studied by analyzing the data of an acoustic propagation experiment conducted in the South China Sea. Some different oscillation patterns of the measured horizontal longitudinal correla- tions of acoustic field are observed for two different tracks in the flat bottom and the uneven bottom environments when the source distance ranges from 29 km to 35 km. Numerical analysis based on the ray theory is carried on to explain the causes of the differences. The experimental and mlmerical results show that the travel time differences between the one-bottom-reflection （1BR） rays, which make a major contribution to the sound field of the 1BR area in flat bottom environment, decrease gradually with increasing horizontal distance. Then the phase of the interference cyclically changes within 27r, leading to the correlations＇ periodical oscillation in deep water with flat bottom. In the uneven bottom environment, however, due to the reflection- blockage effects of the sea hill on the 1BR sound beams, the sound transmission losses （TLs） in- crease significantly in the reflection area of the sea hill. What＇s more, the horizontal-longitudinal correlations decreasing slightly in general don＇t show obvious cyclical oscillation any longer in the corresponding reflection area because of the complex interference of the relatively more eigenrays. This work is of significance to analyze the detection performance of the sonar array in deep water with the complicated bathymetry environment.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42107066 and 42007004)the Natural Science Foundation of Jiangsu Province,China(No.BK20201105)。
文摘Philip’s two-term infiltration equation has been widely used to infer soil saturated hydraulic conductivity(Ks),the accuracy of which is usually influenced by the size of infiltration rings and soil conditions.Previous studies have primarily focused on exploring the ring-size dependence of Ks estimations under specific soil conditions(e.g.,soil isotropy and/or uniform initial water content).This study aimed to provide a comprehensive analysis by systematically considering eight heterogeneous and anisotropic soils with nonuniform initial water contents.Specifically,we examined the validity of Philip’s infiltration equation as well as the recently proposed two forms(i.e.,infiltration and time forms)of Parlange’s infiltration equation both theoretically and in practical applications of double-ring infiltration.Then the time form of Parlange’s equation was applied to infer Ks using double-ring infiltrometer measurements with different combinations of six inner ring diameters(10,20,40,80,120,and 200 cm)and three buffer index(defined as the ratio of the difference between inner and outer ring diameters to the outer ring diameter)values(0.20,0.33,and 0.50).For each infiltrometer set,20 stochastic Ks fields were randomly generated by adopting five standard deviation values(0.1,0.3,0.5,0.7,and 0.9).Furthermore,we investigated the effects of five horizontal correlation lengths(30,60,150,300,and 600 cm)on Ks estimations.The results demonstrated that Parlange’s equation,compared to Philip’s equation,was more universal in describing the cumulative infiltration relationship for the test soils.The combination of inner ring diameter and buffer index of 40 cm and 0.2,respectively,which satisfied most of the practical requirements for determining Ks in the Soil Water Infiltration Global(SWIG)database was optimal.When the horizontal correlation length exceeded a threshold(i.e.,150 cm in our study),the inner ring diameter was required to increase to 80 cm.Our findings contribute to accurate Ks estimations of different soils using double-ring infiltrometers.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11434012 and 11674349)
文摘International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater sound field gener- ated by an airborne source, i.e., the ray theory, the wave solution, the normal-mode theory and the wavenumber integration approach, are introduced. Effects of two special conditions, i.e., the moving airborne source or medium and the rough air-water interface, on the air-to-water sound transmission are reviewed. In experimental studies, the depth and range distributions of the underwater sound field created by different kinds of airborne sources in near-field and far-field, the longitudinal horizontal correlation of underwater sound field and application methods for inverse problems are reviewed.
基金supported by the National Natural Science Foundation of China(11434012,41561144006,11404366)
文摘The spatial coherence of sound field in the reflection area of deep-water bottom is studied by analyzing the data of an acoustic propagation experiment conducted in the South China Sea. Some different oscillation patterns of the measured horizontal longitudinal correla- tions of acoustic field are observed for two different tracks in the flat bottom and the uneven bottom environments when the source distance ranges from 29 km to 35 km. Numerical analysis based on the ray theory is carried on to explain the causes of the differences. The experimental and mlmerical results show that the travel time differences between the one-bottom-reflection （1BR） rays, which make a major contribution to the sound field of the 1BR area in flat bottom environment, decrease gradually with increasing horizontal distance. Then the phase of the interference cyclically changes within 27r, leading to the correlations＇ periodical oscillation in deep water with flat bottom. In the uneven bottom environment, however, due to the reflection- blockage effects of the sea hill on the 1BR sound beams, the sound transmission losses （TLs） in- crease significantly in the reflection area of the sea hill. What＇s more, the horizontal-longitudinal correlations decreasing slightly in general don＇t show obvious cyclical oscillation any longer in the corresponding reflection area because of the complex interference of the relatively more eigenrays. This work is of significance to analyze the detection performance of the sonar array in deep water with the complicated bathymetry environment.
