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991.
本文以基于 Buchadhl 象差系数得到的点列图为目标函数,只需追迹少许光线就可得到近似点列图,大大减少了计算量;同时采用了目标函数对结构参数偏导数解析求导原理并应用于光学自动设计,这样得到的解析偏导数不仅不存在原理误差,同时极大地减少了求得所需的时间;最后给出了使用 DFP-BFGS 优化方法设计一个双高斯物镜的实例. 相似文献
992.
Summary We describe the simplest system which shows stochastic resonance. A linear(ized) theory for white and (almost) arbitrarily
coloured noise is presented. The presented new system has new, unique properties which originate from itsnon-dynamical character; for example, the strength and phase shift of periodic response of the system is independent of the frequency.
Experiments have been carried out with the following noise processes: (physical) white noise, (physical) Lorentzian noise
and (physical) 1/f noise. With a small extension of the system, its linear-response regime can be significantly increased. As the system is
similar to some simple models of neurones, the new results might have not only physical but also biological importance.
Paper presented at the International Workshop “Fluctuations in Physics and Biology: Stochastic Resonance, Signal Processing
and Related Phenomena”, Elba, 5–10 June 1994. 相似文献
993.
机械结构的模糊优化设计 总被引:2,自引:0,他引:2
本文阐述了机械结构模糊优化设计的必要性及方法,并以用于55千瓦风力发电机组的NGW92型行星齿轮传动为例,说明这一现代设计方法的实施及优良设计特性。 相似文献
994.
995.
Summary Strategies for computational association of molecular components entail a compromise between configurational exploration and accurate evaluation. Following the work of Meng et al. [Proteins, 17 (1993) 266], we investigate issues related to sampling and optimization in molecular docking within the context of the DOCK program. An extensive analysis of diverse sampling conditions for six receptor-ligand complexes has enabled us to evaluate the tractability and utility of on-the-fly force-field score minimization, as well as the method for configurational exploration. We find that the sampling scheme in DOCK is extremely robust in its ability to produce configurations near to those experimentally observed. Furthermore, despite the heavy resource demands of refinement, the incorporation of a rigid-body, grid-based simplex minimizer directly into the docking process results in a docking strategy that is more efficient at retrieving experimentally observed configurations than docking in the absence of optimization. We investigate the capacity for further performance enhancement by implementing a degeneracy checking protocol aimed at circumventing redundant optimizations of geometrically similar orientations. Finally, we present methods that assist in the selection of sampling levels appropriate to desired result quality and available computational resources. 相似文献
996.
T. D. J. Perkins J. E. J. Mills P. M. Dean 《Journal of computer-aided molecular design》1995,9(6):479-490
Summary Steric complementarity is a prerequisite for ligand-receptor recognition; this implies that drugs with a common receptor binding site should possess sterically similar binding surfaces. This principle is used as the basis for an automatic and unbiased method that superposes molecules. One molecule is rotated and translated to maximize the overlap between the two molecular surface volumes. A fast grid-based method is used to determine the extent of this overlap, and this is optimized using simulated annealing. Matches with high steric similarity scores are then sorted on the basis of both hydrogen-bond and electrostatic similarity between the matched molecules. Flexible molecules are treated as a set of rigid representative conformers. The algorithm has correctly predicted superpositions between a number of pairs of molecules, according to crystallographic data from ligands that have been co-crystallized at common enzyme binding sites. 相似文献
997.
998.
We introduce and discuss a combination of methods and options that aim at the aerodynamical optimization of a flow around an arbitrary aircraft shape. The flow is governed by the Euler equations, discretized by a mixed element-volume method on a fixed unstructured tetrahedrization. The shape parametrization relies on the skin of the above mesh through a hierarchical representation. Descent-type and one-shot algorithms are devised and adapted to the solution of a few model problems. 相似文献
999.
1000.
The selection of a monitoring network is formulated as a decision problem whose solutions would then be optimal. The theory is applied where the underlying field has a multivariate normal probability structure. 相似文献