Quantitative reconstructions of the mean July temperature and annual precipitation are performed based on pollen percentage contents from surface and stratum pollen samples,together with vertical meteorological observ...Quantitative reconstructions of the mean July temperature and annual precipitation are performed based on pollen percentage contents from surface and stratum pollen samples,together with vertical meteorological observations across 700-2800 m in Dajiuhu,Shennongjia in Hubei Province of China.Canonical correspondence analysis and robust locally weighted regression of surface pollen samples are employed to investigate the relationship between plants and climate,and to build the seven pollen-climate response surface functions. Reconstructed results of the stable type assemblage exhibit the climate evolution since the Late-Glacial Period, including the B（？）lling-Aller（？）d warm episode,Younger Dryas cold episode,Climatic Optimum,and cold events in 8 and 6.5 ka BP.The ranges of the mean July temperature and annual precipitation have been about 5℃and 300 mm since the Late-Glacial Period.Analysis of temperature and humidity reveals that Climatic Optimum with high temperature and precipitation occurred during early Holocene and former mid-Holocene,corresponding to the high resolution records in the low latitude region.The results indicate that the pollen-climate response surface functions are capable to valuate the comprehensive influence of temperature and precipitation on pollen content and can be used to reconstruct the past climate from pollen data.展开更多
In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the...In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the integrated modal method and the multi-body system dynamics method.By using the Monte Carlo method,the random sample values of the dynamic parameters were obtained and Lagrange dynamics differential equations were solved for each random sample value which revealed their displacement,speed and acceleration.On this basis,dynamic stresses and deformations were obtained.By taking the maximum values of the stresses and the deformations as output responses and the random sample values of dynamic parameters as input quantities,extremum response surface functions were established.A number of random samples were then obtained by using the Monte Carlo method and then the reliability was analyzed by using the extremum response surface method.The results show that the extremum response surface method is an efficient and fast reliability analysis method with high-accuracy for the two-link flexible robot manipulator.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.40875043 and 40631002the Science Fund for Creative Research Groups from NSFC under Grant No.41021002
文摘Quantitative reconstructions of the mean July temperature and annual precipitation are performed based on pollen percentage contents from surface and stratum pollen samples,together with vertical meteorological observations across 700-2800 m in Dajiuhu,Shennongjia in Hubei Province of China.Canonical correspondence analysis and robust locally weighted regression of surface pollen samples are employed to investigate the relationship between plants and climate,and to build the seven pollen-climate response surface functions. Reconstructed results of the stable type assemblage exhibit the climate evolution since the Late-Glacial Period, including the B（？）lling-Aller（？）d warm episode,Younger Dryas cold episode,Climatic Optimum,and cold events in 8 and 6.5 ka BP.The ranges of the mean July temperature and annual precipitation have been about 5℃and 300 mm since the Late-Glacial Period.Analysis of temperature and humidity reveals that Climatic Optimum with high temperature and precipitation occurred during early Holocene and former mid-Holocene,corresponding to the high resolution records in the low latitude region.The results indicate that the pollen-climate response surface functions are capable to valuate the comprehensive influence of temperature and precipitation on pollen content and can be used to reconstruct the past climate from pollen data.
基金Project(2006AA04Z405)supported by the National High Technology Research and Development Program of ChinaProject(3102019)supported by Beijing Municipal Natural Science Foundation,China
文摘In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the integrated modal method and the multi-body system dynamics method.By using the Monte Carlo method,the random sample values of the dynamic parameters were obtained and Lagrange dynamics differential equations were solved for each random sample value which revealed their displacement,speed and acceleration.On this basis,dynamic stresses and deformations were obtained.By taking the maximum values of the stresses and the deformations as output responses and the random sample values of dynamic parameters as input quantities,extremum response surface functions were established.A number of random samples were then obtained by using the Monte Carlo method and then the reliability was analyzed by using the extremum response surface method.The results show that the extremum response surface method is an efficient and fast reliability analysis method with high-accuracy for the two-link flexible robot manipulator.
