To investigate the longitudinal motion stability of aircraft maneuvers conveniently, a new stability analysis approach is presented in this paper. Based on describing longitudinal aerodynamics at high angle-of-attack ...To investigate the longitudinal motion stability of aircraft maneuvers conveniently, a new stability analysis approach is presented in this paper. Based on describing longitudinal aerodynamics at high angle-of-attack （a ＆lt; 50 ） motion by polynomials, a union structure of two-order differential equation is suggested. By means of nonlinear theory and method, analytical and global bifurcation analyses of the polynomial differential systems are provided for the study of the nonlinear phenomena of high angle-of-attack flight. Applying the theories of bifurcations, many kinds of bifurcations, such as equilibrium, Hopf, homoclinic （heteroclinic） orbit and double limit cycle bifurcations are discussed and the existence conditions for these bifurcations as well as formulas for calculating bifurcation curves are derived. The bifurcation curves divide the parameter plane into several regions; moreover, the complete bifurcation diagrams and phase portraits in different regions are obtained. Finally, our conclusions are applied to analyzing the stability and bifurcations of a practical example of a high angle-of-attack flight as well as the effects of elevator deflection on the asymptotic stability regions of equilibrium. The model and analytical methods presented in this paper can be used to study the nonlinear flight dynamic of longitudinal stall at high angle of attack.展开更多
The basic theory of the axial drifting of the cylinder on a welding roller ded is introduced in the the paper,at,the same time,experiment and study for the mechanism of axial drifting of the cylinder have been done on...The basic theory of the axial drifting of the cylinder on a welding roller ded is introduced in the the paper,at,the same time,experiment and study for the mechanism of axial drifting of the cylinder have been done on an experimental of the welding roller bed.It shows that the main cause of the axial drifting of the cylinder lies in the existence of spiral angle between cylinder and rollers.the relative axial motions between rollers and cylinder are composed of spiral motion,elastic slide and frictional slide.The theory of the compatible motion and the non-compatible one is put forward for the exial motions of the cylinder.The relative axial motion between rollers and cylinder is coordinated by elastic slides and frictional slides between two ones.展开更多
基金supported by National Natural Science Foundation of China (No. 61134004)
文摘To investigate the longitudinal motion stability of aircraft maneuvers conveniently, a new stability analysis approach is presented in this paper. Based on describing longitudinal aerodynamics at high angle-of-attack （a ＆lt; 50 ） motion by polynomials, a union structure of two-order differential equation is suggested. By means of nonlinear theory and method, analytical and global bifurcation analyses of the polynomial differential systems are provided for the study of the nonlinear phenomena of high angle-of-attack flight. Applying the theories of bifurcations, many kinds of bifurcations, such as equilibrium, Hopf, homoclinic （heteroclinic） orbit and double limit cycle bifurcations are discussed and the existence conditions for these bifurcations as well as formulas for calculating bifurcation curves are derived. The bifurcation curves divide the parameter plane into several regions; moreover, the complete bifurcation diagrams and phase portraits in different regions are obtained. Finally, our conclusions are applied to analyzing the stability and bifurcations of a practical example of a high angle-of-attack flight as well as the effects of elevator deflection on the asymptotic stability regions of equilibrium. The model and analytical methods presented in this paper can be used to study the nonlinear flight dynamic of longitudinal stall at high angle of attack.
文摘The basic theory of the axial drifting of the cylinder on a welding roller ded is introduced in the the paper,at,the same time,experiment and study for the mechanism of axial drifting of the cylinder have been done on an experimental of the welding roller bed.It shows that the main cause of the axial drifting of the cylinder lies in the existence of spiral angle between cylinder and rollers.the relative axial motions between rollers and cylinder are composed of spiral motion,elastic slide and frictional slide.The theory of the compatible motion and the non-compatible one is put forward for the exial motions of the cylinder.The relative axial motion between rollers and cylinder is coordinated by elastic slides and frictional slides between two ones.
