In this study, the kinetic energy formula of the projection curve under 1-parameter closed homothetic motion is expressed and as a result, theorem is given. Also some special cases are given related with that formula.
A formula for the calculation of critical shear stress of non-uniform sediment was developed by on river bed has been established while considering the relative degree expose of grains.The values of the Coeffi- cients...A formula for the calculation of critical shear stress of non-uniform sediment was developed by on river bed has been established while considering the relative degree expose of grains.The values of the Coeffi- cients in the formula have been obtained.The formula has been verified with prototype observation data, flumes data of both nature and lightweight sand.The computed results fully reflect the characteristics of thresh- old motion of non-uniform sediment.The result have been used in some physical mo...展开更多
Recent earthquakes in the Sichuan Province have contributed to significantly expand the existing ground-motion database for China with new,high-quality ground-motion records.This study investigated the compatibility o...Recent earthquakes in the Sichuan Province have contributed to significantly expand the existing ground-motion database for China with new,high-quality ground-motion records.This study investigated the compatibility of ground-motion prediction equations(GMPEs)established by the NGA-West2 project in the US and local GMPEs for China,with respect to magnitude scaling,distance scaling,and site scaling implied by recent Chinese strong-motion data.The NGA-West2 GMPEs for shallow crustal earthquakes in tectonically active regions are considerably more sophisticated than widely used previous models,particularly in China.Using a mixed-effects procedure,the study evaluated event terms(inter-event residuals)and intra-event residuals of Chinese data relative to the NGA-West2 GMPEs.Distance scaling was investigated by examining trends of intra-event residuals with source-to-site distance.Scaling with respect to site conditions was investigated by examining trends of intra-event residuals with soil type.The study also investigated other engineering characteristics of Chinese strong ground motions.In particular,the records were analyzed for evidence of pulse-like forward-directivity effects.The elastic median response spectra of the selected stations were compared to code-mandated design spectra for various mean return periods.Results showed that international and local GMPEs can be applied for seismic hazard analysis in Sichuan with minor modification of the regression coefficients related to the source-to-site distance and soil scaling.Specifically,the Chinese data attenuated faster than implied by the considered GMPEs and the differences were statistically significant in some cases.Near-source,pulse-like ground motions were identified at two recording stations for the 2008 Wenchuan earthquake,possibly implying rupture directivity.The median recorded spectra were consistent with the code-based spectra in terms of amplitude and shape.The new ground-motion data can be used to develop advanced ground-motion models for China and worldwide and,ultimately,for advancing probabilistic seismic hazard assessment(PSHA).展开更多
A real-time electronic image stabilization motion estimation method based on fast sub- block gray projection algorithm is proposed. In the method, each image is divided into a number of sub-blocks, and sub-blocks are ...A real-time electronic image stabilization motion estimation method based on fast sub- block gray projection algorithm is proposed. In the method, each image is divided into a number of sub-blocks, and sub-blocks are sifted with their gray gradients. After removing sub-blocks whose gray gradients are lower than the given threshold, the calculation amount of projection is reduced and the motion estimation accuracy is improved. Then gray projection is done in each remained sub- block, and global motion vector of the image is calculated according to the local motion vectors of sub-blocks and the affine motion model. The drawbacks as the local motions reducing the global mo- tion estimation accuracy and traditional gray projection algorithm could not deal with rotation are re- solved well by this algorithm. The experiment results show that the algorithm is more accurate and efficient than the gray projection algorithm.展开更多
文摘In this study, the kinetic energy formula of the projection curve under 1-parameter closed homothetic motion is expressed and as a result, theorem is given. Also some special cases are given related with that formula.
基金Supported by Doctorial Fund of Ministry of Education (2002-173) and (2003-172)
文摘A formula for the calculation of critical shear stress of non-uniform sediment was developed by on river bed has been established while considering the relative degree expose of grains.The values of the Coeffi- cients in the formula have been obtained.The formula has been verified with prototype observation data, flumes data of both nature and lightweight sand.The computed results fully reflect the characteristics of thresh- old motion of non-uniform sediment.The result have been used in some physical mo...
基金Community Based Disaster Management in Asia Programme Phase Ⅱ (CBDM Asia Phase Ⅱ) (00084327)
文摘Recent earthquakes in the Sichuan Province have contributed to significantly expand the existing ground-motion database for China with new,high-quality ground-motion records.This study investigated the compatibility of ground-motion prediction equations(GMPEs)established by the NGA-West2 project in the US and local GMPEs for China,with respect to magnitude scaling,distance scaling,and site scaling implied by recent Chinese strong-motion data.The NGA-West2 GMPEs for shallow crustal earthquakes in tectonically active regions are considerably more sophisticated than widely used previous models,particularly in China.Using a mixed-effects procedure,the study evaluated event terms(inter-event residuals)and intra-event residuals of Chinese data relative to the NGA-West2 GMPEs.Distance scaling was investigated by examining trends of intra-event residuals with source-to-site distance.Scaling with respect to site conditions was investigated by examining trends of intra-event residuals with soil type.The study also investigated other engineering characteristics of Chinese strong ground motions.In particular,the records were analyzed for evidence of pulse-like forward-directivity effects.The elastic median response spectra of the selected stations were compared to code-mandated design spectra for various mean return periods.Results showed that international and local GMPEs can be applied for seismic hazard analysis in Sichuan with minor modification of the regression coefficients related to the source-to-site distance and soil scaling.Specifically,the Chinese data attenuated faster than implied by the considered GMPEs and the differences were statistically significant in some cases.Near-source,pulse-like ground motions were identified at two recording stations for the 2008 Wenchuan earthquake,possibly implying rupture directivity.The median recorded spectra were consistent with the code-based spectra in terms of amplitude and shape.The new ground-motion data can be used to develop advanced ground-motion models for China and worldwide and,ultimately,for advancing probabilistic seismic hazard assessment(PSHA).
基金Supported by the National Defense Scientific Research Project （ B2220132013 ）
文摘A real-time electronic image stabilization motion estimation method based on fast sub- block gray projection algorithm is proposed. In the method, each image is divided into a number of sub-blocks, and sub-blocks are sifted with their gray gradients. After removing sub-blocks whose gray gradients are lower than the given threshold, the calculation amount of projection is reduced and the motion estimation accuracy is improved. Then gray projection is done in each remained sub- block, and global motion vector of the image is calculated according to the local motion vectors of sub-blocks and the affine motion model. The drawbacks as the local motions reducing the global mo- tion estimation accuracy and traditional gray projection algorithm could not deal with rotation are re- solved well by this algorithm. The experiment results show that the algorithm is more accurate and efficient than the gray projection algorithm.
