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991.
静园草坪灌溉系统的改进 总被引:3,自引:3,他引:0
焦莹 《数学的实践与认识》2000,30(2):150-152
在本文中 ,我将讨论一个从自己的实际观察中总结出来的数学模型——静园草坪的灌溉系统问题 .文中证明了灌溉系统的最大效率是 3 32π .这个结论还可以应用于其他的一些领域 .这实际上是一个决策问题 ,它归结为用小块的图形去覆盖平面区域 .我们需要找到一种最佳的覆盖方法 ,使得重叠的部分最少 .这样 ,我们就有两个问题要解决 ,首先是如何评价覆盖方法的优劣 ,其次是如何找到最佳的覆盖方法 .文中给出了合理的评价准则 ,并且提出了一些深入研究的方向和建议 . 相似文献
992.
We give efficiency estimates for proximal bundle methods for finding f*minXf, where f and X are convex. We show that, for any accuracy <0, these methods find a point xkX such that f(xk)–f* after at most k=O(1/3) objective and subgradient evaluations. 相似文献
993.
Global Multiobjective Optimization Using Evolutionary Algorithms 总被引:2,自引:0,他引:2
Thomas Hanne 《Journal of Heuristics》2000,6(3):347-360
Since the 60s, several approaches (genetic algorithms, evolution strategies etc.) have been developed which apply evolutionary concepts for simulation and optimization purposes. Also in the area of multiobjective programming, such approaches (mainly genetic algorithms) have already been used (Evolutionary Computation 3(1), 1–16).In our presentation, we consider a generalization of common approaches like evolution strategies: a multiobjective evolutionary algorithm (MOEA) for analyzing decision problems with alternatives taken from a real-valued vector space and evaluated according to several objective functions. The algorithm is implemented within the Learning Object-Oriented Problem Solver (LOOPS) framework developed by the author. Various test problems are analyzed using the MOEA: (multiobjective) linear programming, convex programming, and global programming. Especially for hard problems with disconnected or local efficient regions, the algorithms seems to be a useful tool. 相似文献
994.
995.
996.
Y B S R Prasad V K Senecha H C Pant M P Kamath G S Solanki P K Tripathi A P Kulkarni S Gupta R Pareek A S Joshi N Sreedhar Sameer Nigam C P Navathe 《Pramana》2000,55(5-6):797-802
The x-ray emission from slab targets of copper irradiated by Nd:glass laser (1.054 μm, 5 and 15 ns) at intensities between 1012 and 1011W/cm2 has been studied. The x-ray emissions were monitored with the help of high quantum efficiency x-ray silicon photo diodes
and vacuum photo diodes, all covered with aluminium filters of different thickness. The x-ray intensity vs the laser intensity
has a scaling factor of (1.2–1.92). The relative x-ray conversion efficiency follows an empirical relationship which is in
close agreement with the one reported by Babonneau et al. The ion velocities were monitored using Langmuir probes placed at different angles and radial distances from the target
position. The variation of the ion velocity with the laser intensity follows a scaling of the form Φ
β
where β ∼0.22 which is in good agreement with the reported scaling factor values. The results on the x-ray emission from Cu plasma
are reported. 相似文献
997.
氟化物体系三价铬镀铬工艺的研究 总被引:2,自引:0,他引:2
采用恒电位法在氟化物体系中镀铬,以铅银合金为阳极,20号不锈钢片为阴极,探讨了电流密度、温度、pH值、时间等因素对电镀效率的影响.研究表明:在氟化物体系中,镀液温度为30-40℃,pH=1.65,电流密度=30 A/dm2,反应时间在15 m in时,即能得到细致光亮结合力牢固的金属铬镀层,并且电镀效率达到29.46%. 相似文献
998.
Amarjot Kaur Harshinder Singh 《Annals of the Institute of Statistical Mathematics》1991,43(2):347-356
Let random samples of equal sizes be drawn from two exponential distributions with ordered means
i
. The maximum likelihood estimator
i
* of
i
is shown to have a smaller mean square error than that of the usual estimator Xi, for each i=1,2. The asymptotic efficiency of
i
* relative to Xi has also been found. 相似文献
999.
The present paper examines the sequential location—allocation problems of public facilities in one- and two-dimensional space under several policies. It is shown that the efficiency loss due to the adoption of a myopic policy is not so large, contrary to common belief, provided that the efficiency can be measured by the total transportation cost of users and by the total capacity of facilities. If the total serving area is sufficiently narrow, then the spatial allocations of optimal solutions in two-dimensional problems can be closely approximated by those in one-dimensional problems. 相似文献
1000.
石墨管内被测原子间的平衡关系 总被引:1,自引:0,他引:1
本文探讨了石墨管内被测原子间的平衡关系,从理论上推导了基态原子数与吸光度之间的系数β,计算了部分元素的理论特征量N值. 相似文献