Based upon the covariant prolongation structures theory, we construct the sl（2, R）×R（p） prolongation structure for Konno-Asai-Kakuhata equation. By taking two and one-dimensional prolongation spaces, we obtai...Based upon the covariant prolongation structures theory, we construct the sl（2, R）×R（p） prolongation structure for Konno-Asai-Kakuhata equation. By taking two and one-dimensional prolongation spaces, we obtain the inverse scattering equations given by Konno et al. and the corresponding Riccati equation. The Baecklund transformations are also presented.展开更多
The rural settlements accounted for a great proportion of overall building land in China,but it still expanded in recent years along with urbanization and gradually decreasing rural population.To explore the reason fo...The rural settlements accounted for a great proportion of overall building land in China,but it still expanded in recent years along with urbanization and gradually decreasing rural population.To explore the reason for this phenomenon,an analy- sis has been made based on the investigation in a traditional agri- cultural region.This study found that socioeconomic factors,in- cluding the scale of families and its quantity,the improvement of rural public infrastructure,the change of population and the pres- sure of arable land,have effects on the expansion.The view on land tenure which has shaped in farmers minds in the long haul makes them dispose their houses cautiously,and this was the main cause of the fact that one household own more than one plot.In addition,the limitations of rural land institution are unconducive to inspiriting the transfer of farmers' building land and redevel- opment of the idle housing land.展开更多
A novel twin-rotor piston engine （TRPE） mechanism with high volumetric output and power density was introduced. This new engine comprises an energy conversion system and a differential velocity drive mechanism （DVD...A novel twin-rotor piston engine （TRPE） mechanism with high volumetric output and power density was introduced. This new engine comprises an energy conversion system and a differential velocity drive mechanism （DVDM）. Two special geared four-bar mechanisms, DVDM-1 and DVDM-2, were utilized and compared. Based on the closed loop vector method, a mathematical model for position, velocity, and acceleration of the two mechanisms was established. Numerical examples illustrate that the kinematic characteristics were presented. Expression of the displacement and compression ratio of the two engine mechanisms were derived and compared. It is concluded that both DVDM-1 and DVDM-2 adopted in the proposed TRPE with six vane pistons create thirty-six power strokes per revolution of the output shaft, and the summation of two angles covered by each rocker is always 2x/N as the output shaft rotates an angle of x/N. In DVDM-1, the span angle of a vane piston should be designed to be 10.2°, and the compression ratio should be equal to 10; in DVDM-2, the span angle of a vane piston should be designed to be 10.6°, and the compression ratio should be equal to 4.3.展开更多
文摘Based upon the covariant prolongation structures theory, we construct the sl（2, R）×R（p） prolongation structure for Konno-Asai-Kakuhata equation. By taking two and one-dimensional prolongation spaces, we obtain the inverse scattering equations given by Konno et al. and the corresponding Riccati equation. The Baecklund transformations are also presented.
文摘The rural settlements accounted for a great proportion of overall building land in China,but it still expanded in recent years along with urbanization and gradually decreasing rural population.To explore the reason for this phenomenon,an analy- sis has been made based on the investigation in a traditional agri- cultural region.This study found that socioeconomic factors,in- cluding the scale of families and its quantity,the improvement of rural public infrastructure,the change of population and the pres- sure of arable land,have effects on the expansion.The view on land tenure which has shaped in farmers minds in the long haul makes them dispose their houses cautiously,and this was the main cause of the fact that one household own more than one plot.In addition,the limitations of rural land institution are unconducive to inspiriting the transfer of farmers' building land and redevel- opment of the idle housing land.
基金Project(7131109) supported the by National Defense Pre-research Foundation of ChinaProject(50975278) supported by National the Natural Science Foundation of China
文摘A novel twin-rotor piston engine （TRPE） mechanism with high volumetric output and power density was introduced. This new engine comprises an energy conversion system and a differential velocity drive mechanism （DVDM）. Two special geared four-bar mechanisms, DVDM-1 and DVDM-2, were utilized and compared. Based on the closed loop vector method, a mathematical model for position, velocity, and acceleration of the two mechanisms was established. Numerical examples illustrate that the kinematic characteristics were presented. Expression of the displacement and compression ratio of the two engine mechanisms were derived and compared. It is concluded that both DVDM-1 and DVDM-2 adopted in the proposed TRPE with six vane pistons create thirty-six power strokes per revolution of the output shaft, and the summation of two angles covered by each rocker is always 2x/N as the output shaft rotates an angle of x/N. In DVDM-1, the span angle of a vane piston should be designed to be 10.2°, and the compression ratio should be equal to 10; in DVDM-2, the span angle of a vane piston should be designed to be 10.6°, and the compression ratio should be equal to 4.3.
