针对目标在形状、外观和光照条件发生较大变化时产生的检测率低的问题,以牛体检测为例提出了基于Gentle AdaBoost算法的牛体检测。利用bag of features(BOF)的思想创建特征词典,然后通过词典对牛体目标进行特征提取,最后通过Gentle AdaB...针对目标在形状、外观和光照条件发生较大变化时产生的检测率低的问题,以牛体检测为例提出了基于Gentle AdaBoost算法的牛体检测。利用bag of features(BOF)的思想创建特征词典,然后通过词典对牛体目标进行特征提取,最后通过Gentle AdaBoost算法对训练集的BOF特征向量进行训练分类,获得目标对象和场景的分类模型。实验结果表明,该算法训练的检测器在牛体目标存在光照不均匀、形变时均可实现可靠的检测。展开更多
Characteristics of soil erosion change along a long slope in the gentle hilly areas in black soil region in Northeast China are discussed. A simplified slope model based on segments was used to analyze the runoff data...Characteristics of soil erosion change along a long slope in the gentle hilly areas in black soil region in Northeast China are discussed. A simplified slope model based on segments was used to analyze the runoff data and soil erosion data observed between 2003 and 2004 over 10 field plots with different slope length in Heshan Farm, Heilongjiang Province. We found that soil erosion rate over long slopes in the black soil region changed alternatively along the slope and creates alternative zones of intensive erosion and week erosion.The exact place of each zone is different for different rainfall conditions. In a year with less and mild precipitation, rill cannot happen within the top 50 m, while in a year with large and intensive precipitation, rill can be formed starting even at 15 m from the top of the slope.展开更多
The effects of slope surface material, slope gradient, block shape, and block mass conditions on rockfall rolling velocity were estimated with orthogonal test approach. Visual analysis shows that the importance of the...The effects of slope surface material, slope gradient, block shape, and block mass conditions on rockfall rolling velocity were estimated with orthogonal test approach. Visual analysis shows that the importance of the factors is slope surface material > slope gradient > block shape > block mass. All the factors except block mass have the F value greater than the critical value, suggesting that these three factors are the key factors affecting the rockfall rolling velocity. Factor interaction analysis shows that the effect of the slope gradient relies largely on the slope surface conditions, and the block shape has little influence if the slope gradient is larger than a critical value. An empirical model considering the three key factors is proposed to estimate the rolling velocity, of which the error is limited to 5% of the testing value. This model is validated by 73 field tests, and the prediction shows excellent correlation with the site test. Thus, this analysis can be used as a tool in the rockfall behavior analysis.展开更多
Potential tsunami generated in the Okinawa Trench or the Manila Trench may attack the southeast coast of China. The continental shelves with extremely gentle slope in the China Seas affect the evolvement of tsunami wa...Potential tsunami generated in the Okinawa Trench or the Manila Trench may attack the southeast coast of China. The continental shelves with extremely gentle slope in the China Seas affect the evolvement of tsunami waves. In this paper, we carry out the simulation of tsunami propagation based on the fully nonlinear and highly dispersive Boussinesq model, which could describe the nonlinearity and dispersion of water waves quite well. So the undulation characters could be well presented. In terms of the real topographies of the East China Sea and the South China Sea, we take some typical profiles to simulate the hypothetical tsunamis generated in the Okinawa Trench and the Manila Trench. Different waveforms in the near shore regions are obtained. The N-shape tsunami waves will evolve into long wave trains, undular bores or solitons near the coastal area. The numerical results of the near shore waveform provide essential conditions for the further studies of tsunami runup and inundation.展开更多
Regular wave deformation and breaking on very gentle slopes is calculated by Mixed-Eulerian-Lagrangian procedure. The velocity potentials and their normal derivatives on the boundary are calculated through the mixed 0...Regular wave deformation and breaking on very gentle slopes is calculated by Mixed-Eulerian-Lagrangian procedure. The velocity potentials and their normal derivatives on the boundary are calculated through the mixed 0-1 boundary element method. The wave elevation and the potentials of Lime-stepping integration are determined by the 2nd-order Taylor expansion at the nodes of free surface boundary elements. During calculation the x-coordinates of the free surface element nodes are supposed to remain unchanged, i.e. the partial derivatives of wave elevation and potentials with respect to x are considered as zero. The numerical results of asymmetric parameters of breaking waves are verified by experimental study. It is shown that when the wave asymmetry is weak, the maximum horizontal velocity of water particales occurs at the wave peak and, the average ratio of this maximum velocity to wave celerity is 0.96. However, when the wave asymmetry is strong, the maximum horizontal velocity of water particles occurs just before the wave crest, and the average ratio of the maximum velocity to wave celerity is about 0.98. The numerical results also show that the asymmetry of wave profiles affects the value of the wave breaking index (H/d) (b), that is, when the asymmetric characteristics are weak, the value of wave breaking index coincides with that given by Goda; on the contrary, when the asymmetry of wave profiles is notable, the value of wave breaking index is close to Nelson's result. The experimental study gives the same conclusions.展开更多
文摘针对目标在形状、外观和光照条件发生较大变化时产生的检测率低的问题,以牛体检测为例提出了基于Gentle AdaBoost算法的牛体检测。利用bag of features(BOF)的思想创建特征词典,然后通过词典对牛体目标进行特征提取,最后通过Gentle AdaBoost算法对训练集的BOF特征向量进行训练分类,获得目标对象和场景的分类模型。实验结果表明,该算法训练的检测器在牛体目标存在光照不均匀、形变时均可实现可靠的检测。
基金National Basic Research Program of China, No.2007CB407207Knowledge Innovation Project of Institute of Geographic Sciences and Natural Resources Research,CAS,No.CXIOG-A04-10the support from CAS through its "One Hundred Talent" program
文摘Characteristics of soil erosion change along a long slope in the gentle hilly areas in black soil region in Northeast China are discussed. A simplified slope model based on segments was used to analyze the runoff data and soil erosion data observed between 2003 and 2004 over 10 field plots with different slope length in Heshan Farm, Heilongjiang Province. We found that soil erosion rate over long slopes in the black soil region changed alternatively along the slope and creates alternative zones of intensive erosion and week erosion.The exact place of each zone is different for different rainfall conditions. In a year with less and mild precipitation, rill cannot happen within the top 50 m, while in a year with large and intensive precipitation, rill can be formed starting even at 15 m from the top of the slope.
基金supported by the National Science Foundation of China (Grant No. 41572302)the Funds for Creative Research Groups of China (Grant No. 41521002)
文摘The effects of slope surface material, slope gradient, block shape, and block mass conditions on rockfall rolling velocity were estimated with orthogonal test approach. Visual analysis shows that the importance of the factors is slope surface material > slope gradient > block shape > block mass. All the factors except block mass have the F value greater than the critical value, suggesting that these three factors are the key factors affecting the rockfall rolling velocity. Factor interaction analysis shows that the effect of the slope gradient relies largely on the slope surface conditions, and the block shape has little influence if the slope gradient is larger than a critical value. An empirical model considering the three key factors is proposed to estimate the rolling velocity, of which the error is limited to 5% of the testing value. This model is validated by 73 field tests, and the prediction shows excellent correlation with the site test. Thus, this analysis can be used as a tool in the rockfall behavior analysis.
基金supported by the National Natural Science Foundation of China (11202130 )the Doctoral Program Foundation of Higher Education (20060248046)
文摘Potential tsunami generated in the Okinawa Trench or the Manila Trench may attack the southeast coast of China. The continental shelves with extremely gentle slope in the China Seas affect the evolvement of tsunami waves. In this paper, we carry out the simulation of tsunami propagation based on the fully nonlinear and highly dispersive Boussinesq model, which could describe the nonlinearity and dispersion of water waves quite well. So the undulation characters could be well presented. In terms of the real topographies of the East China Sea and the South China Sea, we take some typical profiles to simulate the hypothetical tsunamis generated in the Okinawa Trench and the Manila Trench. Different waveforms in the near shore regions are obtained. The N-shape tsunami waves will evolve into long wave trains, undular bores or solitons near the coastal area. The numerical results of the near shore waveform provide essential conditions for the further studies of tsunami runup and inundation.
基金This project was supported financially by National Natural Science Foundation of China(Grant No.49876026)
文摘Regular wave deformation and breaking on very gentle slopes is calculated by Mixed-Eulerian-Lagrangian procedure. The velocity potentials and their normal derivatives on the boundary are calculated through the mixed 0-1 boundary element method. The wave elevation and the potentials of Lime-stepping integration are determined by the 2nd-order Taylor expansion at the nodes of free surface boundary elements. During calculation the x-coordinates of the free surface element nodes are supposed to remain unchanged, i.e. the partial derivatives of wave elevation and potentials with respect to x are considered as zero. The numerical results of asymmetric parameters of breaking waves are verified by experimental study. It is shown that when the wave asymmetry is weak, the maximum horizontal velocity of water particales occurs at the wave peak and, the average ratio of this maximum velocity to wave celerity is 0.96. However, when the wave asymmetry is strong, the maximum horizontal velocity of water particles occurs just before the wave crest, and the average ratio of the maximum velocity to wave celerity is about 0.98. The numerical results also show that the asymmetry of wave profiles affects the value of the wave breaking index (H/d) (b), that is, when the asymmetric characteristics are weak, the value of wave breaking index coincides with that given by Goda; on the contrary, when the asymmetry of wave profiles is notable, the value of wave breaking index is close to Nelson's result. The experimental study gives the same conclusions.
