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191.
设计IIR数字滤波器的遗传优化算法 总被引:2,自引:0,他引:2
提出了IIR数字滤波器设计的遗传优化法。这是一种模拟自然遗传和达尔文进化理论的随机并行优化算法。首先,详细描述了遗传算法并给出了计算步骤,然后将遗传算法用于IIR数字滤波器的优化设计,最后给出了模拟计算结果。 相似文献
192.
基于光子晶体的红外隐身材料,主要采取一维层层堆叠结构和三维木堆结构等来实现对红外波段电磁波辐射性能的调控.本文报道了一种操作简易、成本低廉的光子晶体红外隐身材料制备方法.通过优化的垂直沉积法,微米级SiO_2胶体微球自组装成高质量的蛋白石型光子晶体结构.对SiO_2胶体微球进行优选,成功制备了禁带位于2.8—3.5μm,8.0—10.0μm的SiO_2胶体晶体蛋白石型光子晶体材料.该材料可改变目标相应波段的红外辐射特征,具有目标红外波段的隐身效果. 相似文献
193.
Vivek F. Farias 《Operations Research Letters》2006,34(2):180-190
We consider a problem of allocating limited quantities of M types of resources among N independent activities that evolve over T epochs. In each epoch, we assign to each activity a task which consumes resources, generates utility, and determines the subsequent state of the activity. We study the complexity of, and approximation algorithms for, maximizing average utility. 相似文献
194.
In this work we devise efficient algorithms for finding the search directions for interior point methods applied to linear programming problems. There are two innovations. The first is the use of updating of preconditioners computed for previous barrier parameters. The second is an adaptive automated procedure for determining whether to use a direct or iterative solver, whether to reinitialize or update the preconditioner, and how many updates to apply. These decisions are based on predictions of the cost of using the different solvers to determine the next search direction, given costs in determining earlier directions. We summarize earlier results using a modified version of the OB1-R code of Lustig, Marsten, and Shanno, and we present results from a predictor–corrector code PCx modified to use adaptive iteration. If a direct method is appropriate for the problem, then our procedure chooses it, but when an iterative procedure is helpful, substantial gains in efficiency can be obtained. 相似文献
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酶作为生物催化剂参与很多重要的生理过程,同时也是一类重要的生物分子。酶的活性分析对于疾病诊断和治疗具有重要意义。基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)具有操作简单、分析速度快、灵敏度高和易于实现高通量分析的特点,已被广泛用于各种组学研究和生物分子的检测,在酶的检测和活性分析中亦发挥了重要作用。该文综述了国内外利用MALDI-TOF MS分析酶活性和进行药物筛选的策略,总结了各种方法的优缺点,提出了MALDI质谱技术在酶活性分析领域存在的问题和挑战,并对其发展前景进行了展望。 相似文献
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199.
The metabolic profiling of kiwifruit (Actinidia deliciosa, Hayward cultivar) aqueous extracts and the water status of entire kiwifruits were monitored over the season (June-December) using nuclear magnetic resonance (NMR) methodologies. The metabolic profiling of aqueous kiwifruit extracts was investigated by means of high field NMR spectroscopy. A large number of water-soluble metabolites were assigned by means of 1D and 2D NMR experiments. The change in the metabolic profiles monitored over the season allowed the kiwifruit development to be investigated. Specific temporal trends of aminoacids, sugars, organic acids and other metabolites were observed.The water status of kiwifruits was monitored directly on the intact fruit measuring the T2 spin-spin relaxation time by means of a portable unilateral NMR instrument, fully non-invasive. Again, clear trends of the relaxation time were observed during the monitoring period.The results show that the monitoring of the metabolic profiling and the monitoring of the water status are two complementary means suitable to have a complete view of the investigated fruit. 相似文献
200.
Simulated annealing and genetic algorithms for minimizing mean flow time in an open shop 总被引:1,自引:0,他引:1
Michael Andresen Heidemarie Brsel Marc Mrig Jan Tusch Frank Werner Per Willenius 《Mathematical and Computer Modelling》2008,48(7-8):1279-1293
This paper considers the problem of scheduling n jobs on m machines in an open shop environment so that the sum of completion times or mean flow time becomes minimal. It continues recent work by Bräsel et al. [H. Bräsel, A. Herms, M. Mörig, T. Tautenhahn, T. Tusch, F. Werner, Heuristic constructive algorithms for open shop scheduling to minmize mean flow time, European J. Oper. Res., in press (doi.10.1016/j.ejor.2007.02.057)] on constructive algorithms. For this strongly NP-hard problem, we present two iterative algorithms, namely a simulated annealing and a genetic algorithm. For the simulated annealing algorithm, several neighborhoods are suggested and tested together with the control parameters of the algorithm. For the genetic algorithm, new genetic operators are suggested based on the representation of a solution by the rank matrix describing the job and machine orders. Extensive computational results are presented for problems with up to 50 jobs and 50 machines, respectively. The algorithms are compared relative to each other, and the quality of the results is also estimated partially by a lower bound for the corresponding preemptive open shop problem. For most of the problems, the genetic algorithm is superior when fixing the same number of 30 000 generated solutions for each algorithm. However, in contrast to makespan minimization problems, where the focus is on problems with an equal number of jobs and machines, it turns out that problems with a larger number of jobs than machines are the hardest problems. 相似文献