To better understand the aerodynamic reasons for highly organized movements of flying organisms,the three-flapping wing system in tandem formation was studied numerically in this paper.Different from previous relevant...To better understand the aerodynamic reasons for highly organized movements of flying organisms,the three-flapping wing system in tandem formation was studied numerically in this paper.Different from previous relevant studies on the multiple flapping wings that are equally spaced,this study emphasizes the impact of unequal spacing between individuals on the aerodynamics of each individual wing as well as the whole system.It is found that swapping the distance between the first and second wing with the distance between the second wing and the rearmost wing does not affect the overall aerodynamic performance,but significantly changes the distribution of aerodynamic benefits across each wing.During the whole flapping cycle,three effects are at play.The narrow channel effect and the downwash effect can promote and weaken the wing lift,respectively,while the wake capture effect can boost the thrust.It also shows that these effects could be manipulated by changing the spacing between adjacent wings.These findings provide a novel way for flow control in tandem formation flight and are also inspiring for designing the formation flight of bionic aircraft.展开更多
We investigate consumption inequality in China both theoretically by constructing a theoretical model that delineates the transmission channels by which income shocks affect consumption and empirically through an Uneq...We investigate consumption inequality in China both theoretically by constructing a theoretical model that delineates the transmission channels by which income shocks affect consumption and empirically through an Unequally Spaced Dynamic Panel Data model estimation. We find that China is experiencing consumption inequality with the full partial insurance of consumption against both permanent and transitory income shocks, although the impact of both types of shock are larger than the case of the United States. The results are due to precautionary savings motives of the Chinese. We further document how income becomes more dispersed in China and show how the family background of a child affects his outcome to a large extent. Policy implications based on our findings are proposed.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12172276)Shaanxi key research and development program(Grant No.2022ZDLGY02-07).
文摘To better understand the aerodynamic reasons for highly organized movements of flying organisms,the three-flapping wing system in tandem formation was studied numerically in this paper.Different from previous relevant studies on the multiple flapping wings that are equally spaced,this study emphasizes the impact of unequal spacing between individuals on the aerodynamics of each individual wing as well as the whole system.It is found that swapping the distance between the first and second wing with the distance between the second wing and the rearmost wing does not affect the overall aerodynamic performance,but significantly changes the distribution of aerodynamic benefits across each wing.During the whole flapping cycle,three effects are at play.The narrow channel effect and the downwash effect can promote and weaken the wing lift,respectively,while the wake capture effect can boost the thrust.It also shows that these effects could be manipulated by changing the spacing between adjacent wings.These findings provide a novel way for flow control in tandem formation flight and are also inspiring for designing the formation flight of bionic aircraft.
文摘We investigate consumption inequality in China both theoretically by constructing a theoretical model that delineates the transmission channels by which income shocks affect consumption and empirically through an Unequally Spaced Dynamic Panel Data model estimation. We find that China is experiencing consumption inequality with the full partial insurance of consumption against both permanent and transitory income shocks, although the impact of both types of shock are larger than the case of the United States. The results are due to precautionary savings motives of the Chinese. We further document how income becomes more dispersed in China and show how the family background of a child affects his outcome to a large extent. Policy implications based on our findings are proposed.
