The northern edge of the East Asian summer monsoon （EASM） is identified using the pentad total column water vapor obtained from ERA-Interim reanalysis data during 1979-2015.Empirical orthogonal function analysis is ...The northern edge of the East Asian summer monsoon （EASM） is identified using the pentad total column water vapor obtained from ERA-Interim reanalysis data during 1979-2015.Empirical orthogonal function analysis is applied to study the meridional displacement of the northern edge of the EASM during the study period,and the results show an interdecadal southward shift around 1993/1994 and an indistinct northward displacement after 2007/2008.To focus on the interdecadal change around 1993/1994,composite analysis using the difference between 1979-1993 and 1994-2007 is employed.Through examination of the differences between these two periods,a significant anticyclonic anomaly is found over Mongolia,suggesting a pronounced interdecadal weakening of the Mongolian low during 1994-2007.Thus,northward advancement of the EASM may have been prevented by the anomalous northerly flow to the east of the weakened Mongolian low after 1993.Further study shows that the interdecadal weakening of the Mongolian low might be attributable to the meridional inhomogeneity of surface warming over the northern part of East Asia.Previous studies suggest that such meridional inhomogeneity would lead to a reduction in local atmospheric baroclinicity,and thus the suppression of extratropical cyclone activity over Mongolia,resulting in a southward withdrawal of the northern edge of the EASM on the interdecadal timescale.展开更多
Three new species of fossil woods are reported from the Upper,Jurassic to Lower Cretaceous in southeastern Mongolia, including Protaxodioxylon mongolense sp. nov. Circoporoxylon mongolen.;e sp. nov. Protocircoporoylon...Three new species of fossil woods are reported from the Upper,Jurassic to Lower Cretaceous in southeastern Mongolia, including Protaxodioxylon mongolense sp. nov. Circoporoxylon mongolen.;e sp. nov. Protocircoporoylon mongolense sp. nov. The anatomical characters of three new species are described in detail.展开更多
Ethnic style is one of the original and special styles in modem fashion. Search for aesthetic inspirations made many designers turn their attention to the rich artistic heritage of national, traditional and even primi...Ethnic style is one of the original and special styles in modem fashion. Search for aesthetic inspirations made many designers turn their attention to the rich artistic heritage of national, traditional and even primitive cultures. Ethnic style known as originated two centuries ago and now it＇ s experiencing second birth.展开更多
Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability ...Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability index based on maximum entropy (MaxEnt) principle. To achieve this goal, the complicated iteration of first order second moment (FOSM) method was replaced by the calculation of entropy density function. Local convergence of Newton iteration method utilized to calculate entropy density function was proved, which ensured the convergence of iteration when calculating reliability index. To promote calculation efficiency, Newton down-hill algorithm was incorporated into calculating entropy density function and Monte Carlo simulations (MCS) were performed to assess the efficiency of the presented method. Two numerical examples were presented to verify the validation of the presented method. Moreover, the execution and advantages of the presented method were explained. From Example 1, after seven times iteration, the proposed method is capable of calculating the reliability index when the performance function is strongly nonlinear and at the same time the proposed method can preserve the calculation accuracy; From Example 2, the reliability indices calculated using the proposed method, FOSM and MCS are 3.823 9, 3.813 0 and 3.827 6, respectively, and the according iteration times are 5, 36 and 10 6 , which shows that the presented method can improve calculation accuracy without increasing computational cost for the performance function of which the reliability index can be calculated using first order second moment (FOSM) method.展开更多
基金supported by National Key Basic Research and Development Projects of China[grant number 2016YFA0600601]the National Natural Science Foundation of China[grant numbers 41530503,41405045,and 41605027]
文摘The northern edge of the East Asian summer monsoon （EASM） is identified using the pentad total column water vapor obtained from ERA-Interim reanalysis data during 1979-2015.Empirical orthogonal function analysis is applied to study the meridional displacement of the northern edge of the EASM during the study period,and the results show an interdecadal southward shift around 1993/1994 and an indistinct northward displacement after 2007/2008.To focus on the interdecadal change around 1993/1994,composite analysis using the difference between 1979-1993 and 1994-2007 is employed.Through examination of the differences between these two periods,a significant anticyclonic anomaly is found over Mongolia,suggesting a pronounced interdecadal weakening of the Mongolian low during 1994-2007.Thus,northward advancement of the EASM may have been prevented by the anomalous northerly flow to the east of the weakened Mongolian low after 1993.Further study shows that the interdecadal weakening of the Mongolian low might be attributable to the meridional inhomogeneity of surface warming over the northern part of East Asia.Previous studies suggest that such meridional inhomogeneity would lead to a reduction in local atmospheric baroclinicity,and thus the suppression of extratropical cyclone activity over Mongolia,resulting in a southward withdrawal of the northern edge of the EASM on the interdecadal timescale.
文摘Three new species of fossil woods are reported from the Upper,Jurassic to Lower Cretaceous in southeastern Mongolia, including Protaxodioxylon mongolense sp. nov. Circoporoxylon mongolen.;e sp. nov. Protocircoporoylon mongolense sp. nov. The anatomical characters of three new species are described in detail.
文摘Ethnic style is one of the original and special styles in modem fashion. Search for aesthetic inspirations made many designers turn their attention to the rich artistic heritage of national, traditional and even primitive cultures. Ethnic style known as originated two centuries ago and now it＇ s experiencing second birth.
基金Project(50978112) supported by the National Natural Science Foundation of China
文摘Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability index based on maximum entropy (MaxEnt) principle. To achieve this goal, the complicated iteration of first order second moment (FOSM) method was replaced by the calculation of entropy density function. Local convergence of Newton iteration method utilized to calculate entropy density function was proved, which ensured the convergence of iteration when calculating reliability index. To promote calculation efficiency, Newton down-hill algorithm was incorporated into calculating entropy density function and Monte Carlo simulations (MCS) were performed to assess the efficiency of the presented method. Two numerical examples were presented to verify the validation of the presented method. Moreover, the execution and advantages of the presented method were explained. From Example 1, after seven times iteration, the proposed method is capable of calculating the reliability index when the performance function is strongly nonlinear and at the same time the proposed method can preserve the calculation accuracy; From Example 2, the reliability indices calculated using the proposed method, FOSM and MCS are 3.823 9, 3.813 0 and 3.827 6, respectively, and the according iteration times are 5, 36 and 10 6 , which shows that the presented method can improve calculation accuracy without increasing computational cost for the performance function of which the reliability index can be calculated using first order second moment (FOSM) method.
