Recently people proved that every f∈C[0, 1] can be uniformly approximated by polynomial sequences {P_n}, {Q_n} such for any x∈[0,1] and n=1,2,…that Q_n(x)<Q_(n+1)(x)<f(x)<P_(n+1)(x)<P_n(x). For example...Recently people proved that every f∈C[0, 1] can be uniformly approximated by polynomial sequences {P_n}, {Q_n} such for any x∈[0,1] and n=1,2,…that Q_n(x)<Q_(n+1)(x)<f(x)<P_(n+1)(x)<P_n(x). For example, Xie and Zhou showed that one can construct such monotone polynomial sequences which do achieve the best uniform approximation rate for a continuous func- tion. Actually they obtained a result as ‖P_n(x)-Q_n(x)‖≤42E_n (f), (1) which essentially improved a conclusion in Gal and Szabados. The present paper, by optimal procedure, improves this inequality to ‖[P_n(x)-Q_n(x)‖≤(18+ε)E_n(f), where εis any positive real number.展开更多
Since it takes a long time to design an aircraft, the succession to or the acquirement of knowledges and technologies is a key to provide to aircraft design high quality and productivity. This paper describes a comput...Since it takes a long time to design an aircraft, the succession to or the acquirement of knowledges and technologies is a key to provide to aircraft design high quality and productivity. This paper describes a computer support system for wing design using a new tool based on an object-oriented approach. The system is programmed in a module of objects which represent design tasks or design knowledges. The modulated program gives advantages to maintain and extend the system easily. The system provides to users a flexible support with excellent user interface which consists of mouse, menu-driven system, and window system.展开更多
The 21st Century Business Herald,a leading Chinese finandal newspaper, recently sat down with Tian Guoqiang,Dean of the School of Economics, Shanghai University of Finance and Economics,and professor at Texas A&M ...The 21st Century Business Herald,a leading Chinese finandal newspaper, recently sat down with Tian Guoqiang,Dean of the School of Economics, Shanghai University of Finance and Economics,and professor at Texas A&M University (U.S.),to discuss the future outlook of China’s economic development.Excerpts follow:展开更多
In the summer of 2022,an unprecedented and long-lasting high temperature swept central-eastern China,causing significant societal effects.However,the sub-seasonal characteristics,causes and predictability of this extr...In the summer of 2022,an unprecedented and long-lasting high temperature swept central-eastern China,causing significant societal effects.However,the sub-seasonal characteristics,causes and predictability of this extreme high temperature event are not well explored.Based on the locations,intensities and causes of the high temperature,we divided it into three stages:early(13 June-3 July),sustained(4-28 July),and enhancement(29 July-30 August)stages.The high temperature during the early stage mainly occurred in north-central China with an anomaly of 2.5℃compared with climatology(1981-2010),while the last two stages occurred in the middle and lower Yangtze River Basin with anomalies of 2.8 and 3.8℃respectively.The high temperature during the three stages were all regulated by the strengthening and westward extension of the western Pacific subtropical high(WPSH)but involved different physical process.In the early stage,it was mainly caused by the anticyclones over the Mongolia and Northwest Pacific and enhanced by the minor impact of WPSH.In the sustained stage it was influenced by relatively more stronger WPSH and South Asia high(SAH)and the relatively minor impact of the anticyclone over the north-western South Asia.In the enhancement stage,the high temperature was mainly caused by a combination of the record-breaking WPSH and SAH and the strong European blocking high.Inside,the exceptionally powerful WPSH was well correlated with the sea surface temperature gradient induced by the developing La Niña.The ECMWF and NCEP models reasonably predicted the location and intensity of the high temperature in the early stage,but poorly predicted that in the sustained and enhancement stages partly because of the failure prediction of the WPSH's enhancement and westward extension.The ECMWF model's more accurate prediction of the WPSH may contribute to its better forecasting of the heatwaves.展开更多
文摘Recently people proved that every f∈C[0, 1] can be uniformly approximated by polynomial sequences {P_n}, {Q_n} such for any x∈[0,1] and n=1,2,…that Q_n(x)<Q_(n+1)(x)<f(x)<P_(n+1)(x)<P_n(x). For example, Xie and Zhou showed that one can construct such monotone polynomial sequences which do achieve the best uniform approximation rate for a continuous func- tion. Actually they obtained a result as ‖P_n(x)-Q_n(x)‖≤42E_n (f), (1) which essentially improved a conclusion in Gal and Szabados. The present paper, by optimal procedure, improves this inequality to ‖[P_n(x)-Q_n(x)‖≤(18+ε)E_n(f), where εis any positive real number.
文摘Since it takes a long time to design an aircraft, the succession to or the acquirement of knowledges and technologies is a key to provide to aircraft design high quality and productivity. This paper describes a computer support system for wing design using a new tool based on an object-oriented approach. The system is programmed in a module of objects which represent design tasks or design knowledges. The modulated program gives advantages to maintain and extend the system easily. The system provides to users a flexible support with excellent user interface which consists of mouse, menu-driven system, and window system.
文摘The 21st Century Business Herald,a leading Chinese finandal newspaper, recently sat down with Tian Guoqiang,Dean of the School of Economics, Shanghai University of Finance and Economics,and professor at Texas A&M University (U.S.),to discuss the future outlook of China’s economic development.Excerpts follow:
基金the support of National Natural Science Foundation of China(42275097)the Key Program of the National Natural Science Foundation of China(42130610)+1 种基金National Natural Science Foundation of China(42075091)the CAS Light of West China Program.
文摘In the summer of 2022,an unprecedented and long-lasting high temperature swept central-eastern China,causing significant societal effects.However,the sub-seasonal characteristics,causes and predictability of this extreme high temperature event are not well explored.Based on the locations,intensities and causes of the high temperature,we divided it into three stages:early(13 June-3 July),sustained(4-28 July),and enhancement(29 July-30 August)stages.The high temperature during the early stage mainly occurred in north-central China with an anomaly of 2.5℃compared with climatology(1981-2010),while the last two stages occurred in the middle and lower Yangtze River Basin with anomalies of 2.8 and 3.8℃respectively.The high temperature during the three stages were all regulated by the strengthening and westward extension of the western Pacific subtropical high(WPSH)but involved different physical process.In the early stage,it was mainly caused by the anticyclones over the Mongolia and Northwest Pacific and enhanced by the minor impact of WPSH.In the sustained stage it was influenced by relatively more stronger WPSH and South Asia high(SAH)and the relatively minor impact of the anticyclone over the north-western South Asia.In the enhancement stage,the high temperature was mainly caused by a combination of the record-breaking WPSH and SAH and the strong European blocking high.Inside,the exceptionally powerful WPSH was well correlated with the sea surface temperature gradient induced by the developing La Niña.The ECMWF and NCEP models reasonably predicted the location and intensity of the high temperature in the early stage,but poorly predicted that in the sustained and enhancement stages partly because of the failure prediction of the WPSH's enhancement and westward extension.The ECMWF model's more accurate prediction of the WPSH may contribute to its better forecasting of the heatwaves.
