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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
文章介绍了一种分布式网络指纹识别系统NBFIS(Network-BasedFingerprintIdentifyingSystem)。首先提出模型框架,并对其关键技术特别是指纹图像处理技术及面向对象的数据库技术进行讨论。实现了NBFIS系统的原型并给出实验和性能测试结果。 相似文献
82.
改进遗传算法搜索性能的研究 总被引:1,自引:0,他引:1
本文针对改进遗传算法的搜索性能,提出了一种新的变异算子-自适应多位变异算子,它根据每一代的每一个体在当代中的优劣程度,自适应地控制其发生变异的位数。适应度差的个体变异的位数多,一方面使差的模式生存机会少,另一方面增加了种群的多样性,同时也扩大了搜索范围。我们用模式定理证明了该算子的有效性,并且我们作的仿真实验也同样表明该算子能大大改进遗传算法的搜索性能。 相似文献
83.
Yufei Tao Xiaokui Xiao 《The VLDB Journal The International Journal on Very Large Data Bases》2008,17(5):1253-1270
The existing predictive spatiotemporal indexes can be classified into two categories, depending on whether they are based
on the primal or dual methodology. Although we have gained considerable empirical knowledge about various access methods, currently there is only
limited understanding on the theoretical characteristics of the two methodologies. In fact, the experimental results in different
papers even contradict each other, regarding the relative superiority of the primal and dual techniques. This paper presents
a careful study on the query performance of general primal and dual indexes, and reveals important insight into the behavior
of each technique. In particular, we mathematically establish the conditions that determine the superiority of each methodology,
and provide rigorous justification for well-known observations that have not been properly explained in the literature. Our
analytical findings also resolve the contradiction in the experiments of previous work. 相似文献
84.
It is still not very clear to what extent and how does the amino acid sequences of proteins determine their tertiary structures. In this paper, we report our investigations of the sequence-structure relations of the proteins in the beta-propeller fold family, which adopt highly symmetrical tertiary structures while their sequences appear "random". We analyzed the amino acid sequences by using a similarity matrix plus Pearson correlation method and found that the sequences can show the same symmetries as their tertiary structures only if we deduce the conditions of sequence similarity. This suggests that some key residues may play an important role in the formation of the tertiary structures of these proteins. 相似文献
85.
A study on combined manual materials-handling tasks performed on floors under three friction levels was conducted. Eight male subjects participated in the study. The maximum acceptable weight of handling, including lifting, carrying for 3m, lowering, and walking 3m back at twice per minute was determined. The subject then performed the same tasks for 10 min. Heart rate, Vo2, energy efficiency, perceived sense of slip, and rating of perceived exertion for whole body strain were measured. The results showed that the effects of friction level on the maximum acceptable weights of handling, perceived sense of slip, Vo2, and energy efficiency were statistically significant (p相似文献
86.
一种改进的GA变异算子及其数学分析 总被引:7,自引:0,他引:7
提出了一种改进的GA变异算子,并对其有效性作了数学分析。实例表明,该算子能改善GA的收敛性能。 相似文献
87.
给出了AutoCAD环境下的木工成型铣刀CAD系统中 ,用户输入的工件截形曲线通过坐标变换生成木工成型铣刀前刀面截形曲线的方法 ,并进一步讨论了样条曲线最值点的求法 相似文献
88.
供应链集成化模型与优化 总被引:2,自引:0,他引:2
本文建立了一个包括供应商、制造商、销售商
在内的集成化模型,这一模型含有线性状态方程和神经网络非线性模型,提出了库存成本、
供应成本、生产水平等在内的供应链目标函数和约束条件.对于供应链集成化模型采用模拟
退火方法进行优化,并以辽化公司为背景进行了初步条件的仿真工作. 相似文献
89.
90.
M. K. Vijaya Sankar E. Eisner A. Garofalo D. Gates T. H. Ivers R. Kombargi M. E. Mauel D. Maurer D. Nadle G. A. Navratil Q. Xiao 《Journal of Fusion Energy》1993,12(3):303-310
HBT-EP is a new research tokamak designed and built to investigate passive and active feedback techniques to control MHD instabilities. In particular, HBT-EP will be able to test techniques to control fast MHD instabilities occurring at high Troyon-normalized beta, N Ba/Ip [Tm/MA], since it is equipped with a thick, close-fitting, and adjustable conducting shell. The major goals of the initial operation of HBT-EP have been the achievement of high beta operation (N 3) using only ohmic heating and the observation of MHD instabilities. By using a unique fast startup technique, we have successfully achieved these goals. A variety of MHD phenomena were observed during the high beta operation of HBT-EP. At modest beta (N 2), discharges have been maintained for more than 10 msec, and these discharges exhibit saturated resistive instabilities. When N approaches 3, major disruptions occur preceded by oscillating, growing precursors. During start-up, one or more minor disruptions are usually observed. A 1-D transport code has been used to simulate the evolution of the current profile, and these early minor instabilities are predicted to be double tearing modes. The simulation also reproduces the observed high beta operation when saturated neo-Alcator energy confinement scaling is assumed. 相似文献