Vertical electrical sounding (VES) was carried out in the east of the River Nile. The main objectives of the resistivity survey are to determine the types and thicknesses of sedimentary units in the area, to define th...Vertical electrical sounding (VES) was carried out in the east of the River Nile. The main objectives of the resistivity survey are to determine the types and thicknesses of sedimentary units in the area, to define the contact separating the sediments from the crystalline basement complex, and to determine the structural features of the subsurface formations. Several local depressions, whose maximum depth to the basement surface is about 160 m, are revealed as an outcome of the VES method, and suggested to have been infilled with undifferentiated units of the Nubian Group in particular Omdurman Formation. Thus, a depth to the basement complex is calculated and the associated structural map of the east of the River Nile is drawn. The map is useful for the groundwater drilling, as far as the presence or absence of the aquifer is concerned.展开更多
The numerical simulation of internal features,such as inclusions and voids,is important to analyze their impact on the performance of composite materials.However,the complex geometries of internal features and the ind...The numerical simulation of internal features,such as inclusions and voids,is important to analyze their impact on the performance of composite materials.However,the complex geometries of internal features and the induced continuous-discontinuous(C-D)deformation fields are challenges to their numerical simulation.In this study,a 3D approach using a simple mesh to simulate irregular internal geometries is developed for the first time.With the help of a developed voxel crack model,image models that are efficient when recording complex geometries are directly imported into the simulation.Surface reconstructions,which are usually labor-intensive,are excluded from this approach.Moreover,using image models as the geometric input,image processing techniques are applied to detect material interfaces and develop contact pairs.Then,the C-D deformations of the complex internal features are directly calculated based on the numerical manifold method.The accuracy and convergence of the developed3D approach are examined based on multiple benchmarks.Successful 3D C-D simulation of sandstones with naturally formed complex microfeatures demonstrates the capability of the developed approach.展开更多
提出面向合成孔径雷达(Synthetic Aperture Radar,SAR)回波数据的复杂结构特征增强算法(Complex Structure Feature Enhancement Algorithm,CEA),面向SAR成像目标的复杂结构特征,算法利用高阶方向全变分(High-order Total Direction Var...提出面向合成孔径雷达(Synthetic Aperture Radar,SAR)回波数据的复杂结构特征增强算法(Complex Structure Feature Enhancement Algorithm,CEA),面向SAR成像目标的复杂结构特征,算法利用高阶方向全变分(High-order Total Direction Variation,HOTDV)正则算子表示,面向SAR成像目标的稀疏特征,算法用ℓ_(1)正则算子表示。算法利用交替方向多乘子法(Alternating Direction Method of Multipliers,ADMM)建立多正则约束优化框架,设计复杂结构分裂变量和稀疏分裂变量,并求出分裂变量解析更新解以实现SAR成像目标的复杂结构特征与稀疏特征的增强。多正则约束优化框架中的对偶分解保证多特征多任务处理能力,增广拉格朗日项的使用则保证了算法的收敛性和稳健性。最后,设计了仿真和实测SAR数据特征增强实验以验证算法的有效性,对比多种传统结构特征增强算法以验证所提复杂结构特征增强算法的优越性。展开更多
文摘Vertical electrical sounding (VES) was carried out in the east of the River Nile. The main objectives of the resistivity survey are to determine the types and thicknesses of sedimentary units in the area, to define the contact separating the sediments from the crystalline basement complex, and to determine the structural features of the subsurface formations. Several local depressions, whose maximum depth to the basement surface is about 160 m, are revealed as an outcome of the VES method, and suggested to have been infilled with undifferentiated units of the Nubian Group in particular Omdurman Formation. Thus, a depth to the basement complex is calculated and the associated structural map of the east of the River Nile is drawn. The map is useful for the groundwater drilling, as far as the presence or absence of the aquifer is concerned.
基金supported by the National Natural Science Foundation of China(Grant Nos.41807277,42172306,and U1965204)the Natural Science Foundation of Hebei Province(Grant No.D2019202440)。
文摘The numerical simulation of internal features,such as inclusions and voids,is important to analyze their impact on the performance of composite materials.However,the complex geometries of internal features and the induced continuous-discontinuous(C-D)deformation fields are challenges to their numerical simulation.In this study,a 3D approach using a simple mesh to simulate irregular internal geometries is developed for the first time.With the help of a developed voxel crack model,image models that are efficient when recording complex geometries are directly imported into the simulation.Surface reconstructions,which are usually labor-intensive,are excluded from this approach.Moreover,using image models as the geometric input,image processing techniques are applied to detect material interfaces and develop contact pairs.Then,the C-D deformations of the complex internal features are directly calculated based on the numerical manifold method.The accuracy and convergence of the developed3D approach are examined based on multiple benchmarks.Successful 3D C-D simulation of sandstones with naturally formed complex microfeatures demonstrates the capability of the developed approach.
文摘提出面向合成孔径雷达(Synthetic Aperture Radar,SAR)回波数据的复杂结构特征增强算法(Complex Structure Feature Enhancement Algorithm,CEA),面向SAR成像目标的复杂结构特征,算法利用高阶方向全变分(High-order Total Direction Variation,HOTDV)正则算子表示,面向SAR成像目标的稀疏特征,算法用ℓ_(1)正则算子表示。算法利用交替方向多乘子法(Alternating Direction Method of Multipliers,ADMM)建立多正则约束优化框架,设计复杂结构分裂变量和稀疏分裂变量,并求出分裂变量解析更新解以实现SAR成像目标的复杂结构特征与稀疏特征的增强。多正则约束优化框架中的对偶分解保证多特征多任务处理能力,增广拉格朗日项的使用则保证了算法的收敛性和稳健性。最后,设计了仿真和实测SAR数据特征增强实验以验证算法的有效性,对比多种传统结构特征增强算法以验证所提复杂结构特征增强算法的优越性。
