This paper numerically and analytically studies the onset of instability of a flag in uniform flow. The three-dimensional （3D） simulation is performed by using an immersed-boundary method coupled with a nonlinear fi...This paper numerically and analytically studies the onset of instability of a flag in uniform flow. The three-dimensional （3D） simulation is performed by using an immersed-boundary method coupled with a nonlinear finite element method. The global stability, bistability and instability are identified in the 3D simulations. The Squire＇s theorem is extended to analyze the stability of the fluid-flag system with 3D initial perturbations. It is found that if a parallel flow around the flag admits an unstable 3D disturbance for a certain value of the flutter speed, then a two-dimensional （2D） disturbance at a lower flutter speed is also adnfitted. In addition, the growth rate of 2D disturbance is larger than that of the 3D disturbance.展开更多
Based on some former studies of Chinese rural society, this paper summerizes the achievements and limitations of general Chinese rural studies and then proposes a social operation model in rural areas which is dominat...Based on some former studies of Chinese rural society, this paper summerizes the achievements and limitations of general Chinese rural studies and then proposes a social operation model in rural areas which is dominated by the squires. It uses some specific historical data and discoveries of feild sduty to further examine the profound influence of the squires on rural politcal construction in three different aspects： the model of clan and religion, the role as inter-mediator and the growth of basic armed forces. The study found that this special social group played a center role in Chinese rural political system from ancient to modem times, particularly, the research considers the decline of the squire society since the establishment of the new government in 1949. In the end, this paper points out the cultural guiding significance of this social model in the study to the rural construction in contemporay China by predicting the possiblity of renaissance展开更多
基金supported by the National Natural Science Foundation of China (10832010)the Innovation Project of the Chinese Academy of Sciences (KJCX2-YW-L05)the United States National Science Foundation(CBET-0954381)
文摘This paper numerically and analytically studies the onset of instability of a flag in uniform flow. The three-dimensional （3D） simulation is performed by using an immersed-boundary method coupled with a nonlinear finite element method. The global stability, bistability and instability are identified in the 3D simulations. The Squire＇s theorem is extended to analyze the stability of the fluid-flag system with 3D initial perturbations. It is found that if a parallel flow around the flag admits an unstable 3D disturbance for a certain value of the flutter speed, then a two-dimensional （2D） disturbance at a lower flutter speed is also adnfitted. In addition, the growth rate of 2D disturbance is larger than that of the 3D disturbance.
文摘Based on some former studies of Chinese rural society, this paper summerizes the achievements and limitations of general Chinese rural studies and then proposes a social operation model in rural areas which is dominated by the squires. It uses some specific historical data and discoveries of feild sduty to further examine the profound influence of the squires on rural politcal construction in three different aspects： the model of clan and religion, the role as inter-mediator and the growth of basic armed forces. The study found that this special social group played a center role in Chinese rural political system from ancient to modem times, particularly, the research considers the decline of the squire society since the establishment of the new government in 1949. In the end, this paper points out the cultural guiding significance of this social model in the study to the rural construction in contemporay China by predicting the possiblity of renaissance
