The critical rainfall of runoff-initiated debris flows is utmost importance for local early hazard forecasting.This paper presents research on the critical rainfall of runoff-initiated debris flows through comparisons...The critical rainfall of runoff-initiated debris flows is utmost importance for local early hazard forecasting.This paper presents research on the critical rainfall of runoff-initiated debris flows through comparisons between slope gradients and three key factors,including topographic contributing area,dimensionless discharge,and Shields stress.The rainfall amount was estimated by utilizing in-situ rainfall records and a slope-dependent Shields stress model was created.The created model can predict critical Shields stress more accurately than the other two models.Furthermore,a new dimensionless discharge equation was proposed based on the corresponding discharge-gradient datasets.The new equation,along with factors such as contributing area above bed failure sites,channel width,and mean diameter of debris flow deposits,predicts a smaller rainfall amount than the in-situ measured records.Although the slope-dependent Shields stress model performs well and the estimated rainfall amount is lower than the in-situ records,the sediment initiation in the experiments falls within sheet flow regime due to a large Shields stress.Therefore,further sediment initiation experiments at a steeper slope range are expected in the future to ensure that the sediment transport belongs to mass failure regime characterized by a low level of Shields stress.Finally,a more accurate hazard forecast on the runoff-initiated debris flow holds promise when the corresponding critical slope-dependent dimensionless discharge of no motion,fluvial sediment transport,mass flow regime,and sheet flow regime are considered.展开更多
对于传统马尔可夫随机场而言,先验能量的势能函数中的先验参数通常是根据经验手动选取大于零的值,没有考虑像元之间的距离,也没有充分考虑图像局部邻域先验特征,针对上述问题,提出一种结合标号场先验特征和像元距离动态估计先验参数的方...对于传统马尔可夫随机场而言,先验能量的势能函数中的先验参数通常是根据经验手动选取大于零的值,没有考虑像元之间的距离,也没有充分考虑图像局部邻域先验特征,针对上述问题,提出一种结合标号场先验特征和像元距离动态估计先验参数的方法,并在先验能量中定义了观测场像元之间的影响系数,似然能量函数中引入Sobel算子描述观测场像元之间的关系,最后结合分水岭算法消除碎屑小区域进一步优化分割结果。通过Merced Land Use Dataset场景分类数据集进行了相关实验,结果表明该方法可以有效应用于遥感图像分割工作中。展开更多
Excitation functions have been measured for the dissipative products of 4≤Z≤12 in ^(19)F+^(45)Sc reaction from 102 to ^(108)MeV by a step of 300keV at θl=42°.The energy coherence widths have been extracted and...Excitation functions have been measured for the dissipative products of 4≤Z≤12 in ^(19)F+^(45)Sc reaction from 102 to ^(108)MeV by a step of 300keV at θl=42°.The energy coherence widths have been extracted and the dinuclear system lifetimes of the order of 10^(-21 ) s have been deduced by analysing the cross section Auctuations.展开更多
Excitation functions for projectile-like fragments from ^(19)F+^(51)V reaction have been measured at 102.25 to 109.50MeV in 250keV steps.A TOF+(ΔE-E)telescope atθ_(L)=21.7°is used to identify atomic number Z an...Excitation functions for projectile-like fragments from ^(19)F+^(51)V reaction have been measured at 102.25 to 109.50MeV in 250keV steps.A TOF+(ΔE-E)telescope atθ_(L)=21.7°is used to identify atomic number Z and mass number A of ejectiles simultaneously.Fluctuations of the dissipative cross section for a series of isotopes are observed.Their coherence energy widths are extracted by generalized statistical fluctuation analysis and the dependence on mass number and on N/Z values are observed for the first time.展开更多
The particle-particle(P-P)correlation functions are investigated in 46.7MeV/u^(12)C induced reactions,the correlation functions are greatly enhanced at q~20 MeV/c when the sum of the energies of two correlated protons...The particle-particle(P-P)correlation functions are investigated in 46.7MeV/u^(12)C induced reactions,the correlation functions are greatly enhanced at q~20 MeV/c when the sum of the energies of two correlated protons are high and almost independent on the targets.On the contrast,a strongly target dependent effect is observed for the P-P correlation functions when the sum energies are low.展开更多
基金supported by the by the Second Tibetan Plateau Scientific Expedition and Research Program (Grant No. 2019QZKK0902)Beijing Municipal Science and Technology Project (Z191100001419015)
文摘The critical rainfall of runoff-initiated debris flows is utmost importance for local early hazard forecasting.This paper presents research on the critical rainfall of runoff-initiated debris flows through comparisons between slope gradients and three key factors,including topographic contributing area,dimensionless discharge,and Shields stress.The rainfall amount was estimated by utilizing in-situ rainfall records and a slope-dependent Shields stress model was created.The created model can predict critical Shields stress more accurately than the other two models.Furthermore,a new dimensionless discharge equation was proposed based on the corresponding discharge-gradient datasets.The new equation,along with factors such as contributing area above bed failure sites,channel width,and mean diameter of debris flow deposits,predicts a smaller rainfall amount than the in-situ measured records.Although the slope-dependent Shields stress model performs well and the estimated rainfall amount is lower than the in-situ records,the sediment initiation in the experiments falls within sheet flow regime due to a large Shields stress.Therefore,further sediment initiation experiments at a steeper slope range are expected in the future to ensure that the sediment transport belongs to mass failure regime characterized by a low level of Shields stress.Finally,a more accurate hazard forecast on the runoff-initiated debris flow holds promise when the corresponding critical slope-dependent dimensionless discharge of no motion,fluvial sediment transport,mass flow regime,and sheet flow regime are considered.
文摘对于传统马尔可夫随机场而言,先验能量的势能函数中的先验参数通常是根据经验手动选取大于零的值,没有考虑像元之间的距离,也没有充分考虑图像局部邻域先验特征,针对上述问题,提出一种结合标号场先验特征和像元距离动态估计先验参数的方法,并在先验能量中定义了观测场像元之间的影响系数,似然能量函数中引入Sobel算子描述观测场像元之间的关系,最后结合分水岭算法消除碎屑小区域进一步优化分割结果。通过Merced Land Use Dataset场景分类数据集进行了相关实验,结果表明该方法可以有效应用于遥感图像分割工作中。
基金Supported by the National Natural Science Foundation of China.
文摘Excitation functions have been measured for the dissipative products of 4≤Z≤12 in ^(19)F+^(45)Sc reaction from 102 to ^(108)MeV by a step of 300keV at θl=42°.The energy coherence widths have been extracted and the dinuclear system lifetimes of the order of 10^(-21 ) s have been deduced by analysing the cross section Auctuations.
基金Supported by the National Natural Science Foundation of China.
文摘Excitation functions for projectile-like fragments from ^(19)F+^(51)V reaction have been measured at 102.25 to 109.50MeV in 250keV steps.A TOF+(ΔE-E)telescope atθ_(L)=21.7°is used to identify atomic number Z and mass number A of ejectiles simultaneously.Fluctuations of the dissipative cross section for a series of isotopes are observed.Their coherence energy widths are extracted by generalized statistical fluctuation analysis and the dependence on mass number and on N/Z values are observed for the first time.
文摘The particle-particle(P-P)correlation functions are investigated in 46.7MeV/u^(12)C induced reactions,the correlation functions are greatly enhanced at q~20 MeV/c when the sum of the energies of two correlated protons are high and almost independent on the targets.On the contrast,a strongly target dependent effect is observed for the P-P correlation functions when the sum energies are low.
