Discontinuous and long-duration thunderstorm weather, which occurred at Guanghan in Sichuan Province, was analyzed and predicted using structural conversion of irregular information in phase-space from self-recording ...Discontinuous and long-duration thunderstorm weather, which occurred at Guanghan in Sichuan Province, was analyzed and predicted using structural conversion of irregular information in phase-space from self-recording “time sequence” records for predicting rain areas, as described in the “Non Destructive Information” method proposed by Professor OuYang Shoucheng. The results show that this method can reveal important changes of weather as well as, by using irregular self-recording information recorded every ten minutes, predict local thunderstorms with durations of only half an hour, and even predict intense convections 12 hours in advance. This is significant for civil and military aviation. It shows the necessity of full utilization of information from automatic weather stations and the necessity of improvements in recording modes in current automatic stations.展开更多
As one of the most important steps in the design of bearing-less rotor systems,the design of flexible beam has received much research attention.Because of the very complex working environment of helicopter,the flexibl...As one of the most important steps in the design of bearing-less rotor systems,the design of flexible beam has received much research attention.Because of the very complex working environment of helicopter,the flexible beam should satisfy both the strength and dynamic requirements.However,traditional optimization research focused only on either the strength or dynamical characteristics.To sufficiently improve the performance of the flexible beam,both aspects must be considered.This paper proposes a two-stage optimization method based on the Hamilton variational principle:Variational asymptotic beam section analysis(VABS)program and genetic algorithm(GA).Consequently,a two-part analysis model based on the Hamilton variational principle and VABS is established to calculate section characteristics and structural dynamics characteristics,respectively.Subsequently,the two parts are combined to establish a two-stage optimization process and search with GA to obtain the best dynamic characteristics combinations.Based on the primary optimization results,the section characteristics of the flexible beam are further optimized using GA.The optimization results show that the torsional stiffness decreases by 36.1%compared with the full 0°laying scheme without optimization and the dynamic requirements are achieved.The natural frequencies of flapping and torsion meet the requirements(0.5 away from the passing frequencies of the blade,0.25 away from the excitation force frequency,and the flapping and torsion frequencies keep a corresponding distance).The results indicate that the optimization method can significantly improve the performance of the flexible beam.展开更多
基金The project is funded by Youth Scientific Research Foundation of CAFUC (Q2003-23).
文摘Discontinuous and long-duration thunderstorm weather, which occurred at Guanghan in Sichuan Province, was analyzed and predicted using structural conversion of irregular information in phase-space from self-recording “time sequence” records for predicting rain areas, as described in the “Non Destructive Information” method proposed by Professor OuYang Shoucheng. The results show that this method can reveal important changes of weather as well as, by using irregular self-recording information recorded every ten minutes, predict local thunderstorms with durations of only half an hour, and even predict intense convections 12 hours in advance. This is significant for civil and military aviation. It shows the necessity of full utilization of information from automatic weather stations and the necessity of improvements in recording modes in current automatic stations.
基金supported by the Foundation of National Key Laboratory of Rotorcraft Aeromechanics,Nanjing University of Aeronautics and Astronautics(No.614222004030917)。
文摘As one of the most important steps in the design of bearing-less rotor systems,the design of flexible beam has received much research attention.Because of the very complex working environment of helicopter,the flexible beam should satisfy both the strength and dynamic requirements.However,traditional optimization research focused only on either the strength or dynamical characteristics.To sufficiently improve the performance of the flexible beam,both aspects must be considered.This paper proposes a two-stage optimization method based on the Hamilton variational principle:Variational asymptotic beam section analysis(VABS)program and genetic algorithm(GA).Consequently,a two-part analysis model based on the Hamilton variational principle and VABS is established to calculate section characteristics and structural dynamics characteristics,respectively.Subsequently,the two parts are combined to establish a two-stage optimization process and search with GA to obtain the best dynamic characteristics combinations.Based on the primary optimization results,the section characteristics of the flexible beam are further optimized using GA.The optimization results show that the torsional stiffness decreases by 36.1%compared with the full 0°laying scheme without optimization and the dynamic requirements are achieved.The natural frequencies of flapping and torsion meet the requirements(0.5 away from the passing frequencies of the blade,0.25 away from the excitation force frequency,and the flapping and torsion frequencies keep a corresponding distance).The results indicate that the optimization method can significantly improve the performance of the flexible beam.
