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形心搜索法测量桥梁位移
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作者 刘亚双 《四川建筑》 2010年第4期226-227,共2页
研究了桥梁位移的远距离测量新技术——形心搜索法的基本原理,将形心搜索方法应用于天津解放桥称重顶升检测,同时应用百分表校核,结果表明利用形心搜索法所编程序计算出的顶升位移与百分表所检测位移值最大误差仅为6.48%。
关键词 桥梁 形心搜索法 位移
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数字图像处理技术在桥梁检测中的应用 被引量:5
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作者 金波 李鸿琦 刘祥君 《机床与液压》 北大核心 2004年第9期110-112,共3页
本文提出了利用数字图像处理技术即形心搜索法测量梁体局部表面位移的光力学检测方法。并且 ,把形心搜索法和有限元位移模式相结合进一步求出了梁体局部表面位移场和应变场。较其他光学测试方法如云纹干涉法 。
关键词 数字图像 形心搜索法 桥梁 局部应变 有限元 位移模式
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Optimal four-impulse rendezvous between coplanar elliptical orbits 被引量:6
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作者 WANG JianXia BAOYIN HeXi +1 位作者 LI JunFeng SUN FuChun 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第4期792-802,共11页
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
关键词 If the initial values are taken randomly it is difficult to converge to the optimal solution. elliptical orbit rendezvous primer vector fuel optimal
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