Depressions in landscapes function as buffers for water and sediment. A landscape with depressions has less runoff, less erosion and more sedimentation than that without depressions. Sinks in digital elevation models ...Depressions in landscapes function as buffers for water and sediment. A landscape with depressions has less runoff, less erosion and more sedimentation than that without depressions. Sinks in digital elevation models （DEMs） can be considered the real features that represent depressions in actual landscapes or spurious features that result from errors in DEM creation. In many hydrological and erosion models, all sinks are considered as spurious features and, as a result, these models do not deal with the sinks that represent real depressions. Consequently, the surface runoff and erosion are overestimated due to removing the depressions. Aiming at this problem, this paper presents a new method, which deal with the sinks that represent real depressions. The drainage network is extracted without changing the original DEM. The method includes four steps： detecting pits, detecting depressions, merging depressions, and extracting drainage network. Because the elevations of grid cells are not changed, the method can also avoid producing new fiat areas, which are always produced by the conventional filling methods. The proposed method was applied to the Xihanshui River basin, the upper reach of the Jialingjiang River basin, China, to automatically extract the drainage network based on DEM. The extracted drainage network agrees well with the reality and can be used for further hydrologic analysis and erosion estimation.展开更多
为研究某大口径火炮身管的自紧残余应力场和发射中极端循环热冲击导致的热力耦合场,采用ABAQUS软件分析了考虑炮钢材料卸载线性硬化及鲍兴格效应的自紧过程,在此基础上进一步对发射过程进行仿真,获得了该自紧身管发射炮弹时的热力耦合...为研究某大口径火炮身管的自紧残余应力场和发射中极端循环热冲击导致的热力耦合场,采用ABAQUS软件分析了考虑炮钢材料卸载线性硬化及鲍兴格效应的自紧过程,在此基础上进一步对发射过程进行仿真,获得了该自紧身管发射炮弹时的热力耦合响应。最后采用三维疲劳裂纹仿真软件—ALOF(Analyses Laboratory of Fracture),探明了药室部内膛表面二维直裂纹和斜裂纹扩展情况。研究结果为保障身管强度和可靠性及进一步确定服役寿命提供重要科学依据。展开更多
基金supported by the Project of the National Natural Science Foundation of China (40671025)the Knowledge Innovation Project of the Chinese Academy of Sciences (No. KZCX2-YW-302)
文摘Depressions in landscapes function as buffers for water and sediment. A landscape with depressions has less runoff, less erosion and more sedimentation than that without depressions. Sinks in digital elevation models （DEMs） can be considered the real features that represent depressions in actual landscapes or spurious features that result from errors in DEM creation. In many hydrological and erosion models, all sinks are considered as spurious features and, as a result, these models do not deal with the sinks that represent real depressions. Consequently, the surface runoff and erosion are overestimated due to removing the depressions. Aiming at this problem, this paper presents a new method, which deal with the sinks that represent real depressions. The drainage network is extracted without changing the original DEM. The method includes four steps： detecting pits, detecting depressions, merging depressions, and extracting drainage network. Because the elevations of grid cells are not changed, the method can also avoid producing new fiat areas, which are always produced by the conventional filling methods. The proposed method was applied to the Xihanshui River basin, the upper reach of the Jialingjiang River basin, China, to automatically extract the drainage network based on DEM. The extracted drainage network agrees well with the reality and can be used for further hydrologic analysis and erosion estimation.
文摘为研究某大口径火炮身管的自紧残余应力场和发射中极端循环热冲击导致的热力耦合场,采用ABAQUS软件分析了考虑炮钢材料卸载线性硬化及鲍兴格效应的自紧过程,在此基础上进一步对发射过程进行仿真,获得了该自紧身管发射炮弹时的热力耦合响应。最后采用三维疲劳裂纹仿真软件—ALOF(Analyses Laboratory of Fracture),探明了药室部内膛表面二维直裂纹和斜裂纹扩展情况。研究结果为保障身管强度和可靠性及进一步确定服役寿命提供重要科学依据。
