针对斑点鬣狗优化算法(spotted hyena optimizer,SHO)容易陷入局部最优解、求解质量低等缺点,本文提出使用Lévy飞行和单纯形搜索算法改进SHO(spotted hyena optimizer based on simplex method and Lévy flight,Lévy_SM_...针对斑点鬣狗优化算法(spotted hyena optimizer,SHO)容易陷入局部最优解、求解质量低等缺点,本文提出使用Lévy飞行和单纯形搜索算法改进SHO(spotted hyena optimizer based on simplex method and Lévy flight,Lévy_SM_SHO)。将Lévy_SM_SHO与Lévy飞行斑点鬣狗优化算法(spotted hyena optimizer based on Lévy flight,Lévy_SHO)、单纯形搜索斑点鬣狗优化算法(spotted hyena optimizer based on simplex method,SM_SHO)和SHO在测试函数上结果进行对比,实验证明改进算法能够取得较好的优化结果。并将Lévy_SM_SHO算法用于红外图像阈值分割问题,通过与粒子群算法(particle swarm optimization,PSO)分割结果对比,证明Lévy_SM_SHO算法能够取得较好的阈值分割结果。展开更多
Rendezvous in circular or near circular orbits has been investigated in great detail, while rendezvous in arbitrary eccentricity elliptical orbits is not sufficiently explored. Among the various optimization methods p...Rendezvous in circular or near circular orbits has been investigated in great detail, while rendezvous in arbitrary eccentricity elliptical orbits is not sufficiently explored. Among the various optimization methods proposed for fuel optimal orbital rendezvous, Lawden＇s primer vector theory is favored by many researchers with its clear physical concept and simplicity in solu- tion. Prussing has applied the primer vector optimization theory to minimum-fuel, multiple-impulse, time-fixed orbital ren- dezvous in a near circular orbit and achieved great success. Extending Prussing＇s work, this paper will employ the primer vec- tor theory to study trajectory optimization problems of arbitrary eccentricity elliptical orbit rendezvous. Based on linearized equations of relative motion on elliptical reference orbit （referred to as T-H equations）, the primer vector theory is used to deal with time-fixed multiple-impulse optimal rendezvous between two coplanar, coaxial elliptical orbits with arbitrary large ec- centricity. A parameter adjustment method is developed for the prime vector to satisfy the Lawden＇s necessary condition for the optimal solution. Finally, the optimal multiple-impulse rendezvous solution including the time, direction and magnitudes of the impulse is obtained by solving the two-point boundary value problem. The rendezvous error of the linearized equation is also analyzed. The simulation results confirmed the analyzed results that the rendezvous error is small for the small eccentric- ity case and is large for the higher eccentricity. For better rendezvous accuracy of high eccentricity orbits, a combined method of multiplier penalty function with the simplex search method is used for local optimization. The simplex search method is sensitive to the initial values of optimization variables, but the simulation results show that initial values with the primer vector theory, and the local optimization algorithm can improve the rendezvous accuracy effectively with fast convergence, because the optimal results obtained by the primer vector theory are already very close to the actual optimal solution.展开更多
文摘针对斑点鬣狗优化算法(spotted hyena optimizer,SHO)容易陷入局部最优解、求解质量低等缺点,本文提出使用Lévy飞行和单纯形搜索算法改进SHO(spotted hyena optimizer based on simplex method and Lévy flight,Lévy_SM_SHO)。将Lévy_SM_SHO与Lévy飞行斑点鬣狗优化算法(spotted hyena optimizer based on Lévy flight,Lévy_SHO)、单纯形搜索斑点鬣狗优化算法(spotted hyena optimizer based on simplex method,SM_SHO)和SHO在测试函数上结果进行对比,实验证明改进算法能够取得较好的优化结果。并将Lévy_SM_SHO算法用于红外图像阈值分割问题,通过与粒子群算法(particle swarm optimization,PSO)分割结果对比,证明Lévy_SM_SHO算法能够取得较好的阈值分割结果。
基金supported by the National Natural Science Foundation of China(Grant Nos. 10832004 and 11072122)
文摘Rendezvous in circular or near circular orbits has been investigated in great detail, while rendezvous in arbitrary eccentricity elliptical orbits is not sufficiently explored. Among the various optimization methods proposed for fuel optimal orbital rendezvous, Lawden＇s primer vector theory is favored by many researchers with its clear physical concept and simplicity in solu- tion. Prussing has applied the primer vector optimization theory to minimum-fuel, multiple-impulse, time-fixed orbital ren- dezvous in a near circular orbit and achieved great success. Extending Prussing＇s work, this paper will employ the primer vec- tor theory to study trajectory optimization problems of arbitrary eccentricity elliptical orbit rendezvous. Based on linearized equations of relative motion on elliptical reference orbit （referred to as T-H equations）, the primer vector theory is used to deal with time-fixed multiple-impulse optimal rendezvous between two coplanar, coaxial elliptical orbits with arbitrary large ec- centricity. A parameter adjustment method is developed for the prime vector to satisfy the Lawden＇s necessary condition for the optimal solution. Finally, the optimal multiple-impulse rendezvous solution including the time, direction and magnitudes of the impulse is obtained by solving the two-point boundary value problem. The rendezvous error of the linearized equation is also analyzed. The simulation results confirmed the analyzed results that the rendezvous error is small for the small eccentric- ity case and is large for the higher eccentricity. For better rendezvous accuracy of high eccentricity orbits, a combined method of multiplier penalty function with the simplex search method is used for local optimization. The simplex search method is sensitive to the initial values of optimization variables, but the simulation results show that initial values with the primer vector theory, and the local optimization algorithm can improve the rendezvous accuracy effectively with fast convergence, because the optimal results obtained by the primer vector theory are already very close to the actual optimal solution.
