In some studies on landslide susceptibility mapping(LSM),landslide boundary and spatial shape characteristics have been expressed in the form of points or circles in the landslide inventory instead of the accurate pol...In some studies on landslide susceptibility mapping(LSM),landslide boundary and spatial shape characteristics have been expressed in the form of points or circles in the landslide inventory instead of the accurate polygon form.Different expressions of landslide boundaries and spatial shapes may lead to substantial differences in the distribution of predicted landslide susceptibility indexes(LSIs);moreover,the presence of irregular landslide boundaries and spatial shapes introduces uncertainties into the LSM.To address this issue by accurately drawing polygonal boundaries based on LSM,the uncertainty patterns of LSM modelling under two different landslide boundaries and spatial shapes,such as landslide points and circles,are compared.Within the research area of Ruijin City in China,a total of 370 landslides with accurate boundary information are obtained,and 10 environmental factors,such as slope and lithology,are selected.Then,correlation analyses between the landslide boundary shapes and selected environmental factors are performed via the frequency ratio(FR)method.Next,a support vector machine(SVM)and random forest(RF)based on landslide points,circles and accurate landslide polygons are constructed as point-,circle-and polygon-based SVM and RF models,respectively,to address LSM.Finally,the prediction capabilities of the above models are compared by computing their statistical accuracy using receiver operating characteristic analysis,and the uncertainties of the predicted LSIs under the above models are discussed.The results show that using polygonal surfaces with a higher reliability and accuracy to express the landslide boundary and spatial shape can provide a markedly improved LSM accuracy,compared to those based on the points and circles.Moreover,a higher degree of uncertainty of LSM modelling is present in the expression of points because there are too few grid units acting as model input variables.Additionally,the expression of the landslide boundary as circles introduces errors in measurement and is not a展开更多
For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a su...For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a surface-piercing body. The set of over-determined linear equations obtained from the method is modified into a normal set of linear equations by superposing a set of linear equations with zero solutions. Numerical experiments have also been carried out to find the optimum choice of the size of the auxiliary domain and the discretization on it.展开更多
In this paper a three-dimensional tidal current model has been used toexamine variations of local fluid field due to establishment of a dam. By imputing ten tides-K_1,O_1, P_1 , Q_1, M_2, S_2, N_2, K_2 , S_a and S_(sa...In this paper a three-dimensional tidal current model has been used toexamine variations of local fluid field due to establishment of a dam. By imputing ten tides-K_1,O_1, P_1 , Q_1, M_2, S_2, N_2, K_2 , S_a and S_(sa) through the open boundary of the Bohai straitand adopting 5′ x 5′ horizontal resolution the whole fluid field of the Bohai Sea was firstsimulated. The computed harmonic constants of m_1 and M_2 tides at seventeen observational stationsalong the coast of the Bohai Sea matched the observed values rather well. Taking the calculatednumerical results as open boundary conditions, the local fluid field in the Kendong Oil Field bymeans of 1′ x 1′ horizontal resolution was then investigated. In the course of calculation, finegrids were embedded in coarse grids so as to enhance the computational order. In addition, thelatest water-depth data of the Huanghe Delta coast area were adopted, thus topographic changesbecause of silt sediment in that region wouldn''t affect the computed results. In the end, byanalyzing the relative changes of the fluid field before and after the dam was established, that theeffect on the dynamic environment of the local sea area mainly concentrated on the adjacentpositions north and south of the dam was suggested.展开更多
基金funded by the National Natural Science Foundation of China(Nos.41807285,41972280,51679117)the National Science Foundation of Jiangxi Province,China(No.20192BAB216034)+1 种基金the China Postdoctoral Science Foundation(Nos.2019M652287,2020T130274)the Jiangxi Provincial Postdoctoral Science Foundation(No.2019KY08)。
文摘In some studies on landslide susceptibility mapping(LSM),landslide boundary and spatial shape characteristics have been expressed in the form of points or circles in the landslide inventory instead of the accurate polygon form.Different expressions of landslide boundaries and spatial shapes may lead to substantial differences in the distribution of predicted landslide susceptibility indexes(LSIs);moreover,the presence of irregular landslide boundaries and spatial shapes introduces uncertainties into the LSM.To address this issue by accurately drawing polygonal boundaries based on LSM,the uncertainty patterns of LSM modelling under two different landslide boundaries and spatial shapes,such as landslide points and circles,are compared.Within the research area of Ruijin City in China,a total of 370 landslides with accurate boundary information are obtained,and 10 environmental factors,such as slope and lithology,are selected.Then,correlation analyses between the landslide boundary shapes and selected environmental factors are performed via the frequency ratio(FR)method.Next,a support vector machine(SVM)and random forest(RF)based on landslide points,circles and accurate landslide polygons are constructed as point-,circle-and polygon-based SVM and RF models,respectively,to address LSM.Finally,the prediction capabilities of the above models are compared by computing their statistical accuracy using receiver operating characteristic analysis,and the uncertainties of the predicted LSIs under the above models are discussed.The results show that using polygonal surfaces with a higher reliability and accuracy to express the landslide boundary and spatial shape can provide a markedly improved LSM accuracy,compared to those based on the points and circles.Moreover,a higher degree of uncertainty of LSM modelling is present in the expression of points because there are too few grid units acting as model input variables.Additionally,the expression of the landslide boundary as circles introduces errors in measurement and is not a
基金This work is a part of the research project financially supported by the National Natural Science Foundation of China
文摘For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a surface-piercing body. The set of over-determined linear equations obtained from the method is modified into a normal set of linear equations by superposing a set of linear equations with zero solutions. Numerical experiments have also been carried out to find the optimum choice of the size of the auxiliary domain and the discretization on it.
文摘In this paper a three-dimensional tidal current model has been used toexamine variations of local fluid field due to establishment of a dam. By imputing ten tides-K_1,O_1, P_1 , Q_1, M_2, S_2, N_2, K_2 , S_a and S_(sa) through the open boundary of the Bohai straitand adopting 5′ x 5′ horizontal resolution the whole fluid field of the Bohai Sea was firstsimulated. The computed harmonic constants of m_1 and M_2 tides at seventeen observational stationsalong the coast of the Bohai Sea matched the observed values rather well. Taking the calculatednumerical results as open boundary conditions, the local fluid field in the Kendong Oil Field bymeans of 1′ x 1′ horizontal resolution was then investigated. In the course of calculation, finegrids were embedded in coarse grids so as to enhance the computational order. In addition, thelatest water-depth data of the Huanghe Delta coast area were adopted, thus topographic changesbecause of silt sediment in that region wouldn''t affect the computed results. In the end, byanalyzing the relative changes of the fluid field before and after the dam was established, that theeffect on the dynamic environment of the local sea area mainly concentrated on the adjacentpositions north and south of the dam was suggested.
