The optimization of a primary mirror support system is one of the most critical problems in the design of large telescopes. Here, we propose a hybrid optimizationmethodology of variable densities mesh model (HOMVDMM)...
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The optimization of a primary mirror support system is one of the most critical problems in the design of large telescopes. Here, we propose a hybrid optimizationmethodology of variable densities mesh model (HOMVDMM) for the axial supporting design, which has three key steps: (1) creating a variable densities mesh model, which will partition the mirror into several sparse mesh areas and several dense mesh areas;(2) global optimization based on the zero-order optimization method for the support of primary mirror with a large tolerance;(3) based on the optimization results of the second step, further optimization with first-orderoptimizationmethod in dense mesh areas by a small tolerance. HOMVDMM exploits the complementary merits of both the zero-and first-orderoptimizations, with the former in global scale and the latter in small scale. As an application, the axial support of the primary mirror of the 2.5-m wide-field survey telescope (WFST) is optimized by HOMVDMM. These three designs are obtained via a comparative study of different supporting points including 27 supporting points, 39 supporting points, and 54 supporting points. Their residual half-path length errors are 28.78, 9.32, and 5.29 nm. The latter two designs both meet the specification of WFST. In each of the three designs, a global optimization value with high accuracy will be obtained in an hour on an ordinary PC. As the results suggest, the overall performance of HOMVDMM is superior to the first-orderoptimizationmethod as well as the zero-order optimization method. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
Taking deformation of the main arch under dead load as the arch alignment control target, the overall cable force and pre-camber of multi-rib arch were calculated by zero-order optimization method. According to the in...
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ISBN:
(纸本)9783037851395
Taking deformation of the main arch under dead load as the arch alignment control target, the overall cable force and pre-camber of multi-rib arch were calculated by zero-order optimization method. According to the installation sequences of arch segments, taking deviation of cable tower, cables in one-time tensioning method and the section stress of arch chords as constraint conditions, the cable force and pre-camber for every segment were calculated by iterative method. This method is applied to the erection of a 400m steel truss arch bridge with three ribs, the calculated values of cable force are anastomosed with the measured ones, and the precision of arch alignment is high.
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