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扁平颗粒乳剂微晶体的形态比对其感光性能有重要的影响。本文制备了三个不同形态比的卤化银乳剂,用介电损耗法和微波光导法分别测定了它们的离子电导和光电导衰变动力学。结果表明:离子电导随着形态比的增大而加大,光电导随形态比增加而降低,光电子衰变动力学由单阶段向双阶段图式过渡。 相似文献
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强外场中类He体系基态能的计算是非常复杂和困难的 ,利用MCI方法将体系的状态波函数用later基展开 ,用演化算法优化波函数中的变分参数 ,再求解相应的定态Schr dinger方程 ,获得了类He体系基态能高精度的结果 ,该工作表明由于使用了演化算法获得了最优参数 ,从而正确地确定了一组基 ,对类He体系基态能计算结果的准确性与可靠性方面起了重要作用 相似文献
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A novel algorithm for bridge recognition of median synthetic aperture radar (SAR) images using histogram entropy presented by Pun is proposed. Firstly, Lee filter and histogram proportion are used to denoise the original image and to make the target evident. Then, water regions are gained through histogram segmentation and the contours of water regions axe extracted. After these, the potential bridge targets are obtained based on the space relativity between bridges and water regions using improved contour search. At last, bridges are recognized by extracting the feature of Pun histogram entropy (PHE) of these potential bridge targets. Experimental results show the good qualities of the algorithm, such as fast speed, high rate of recognition, and low rate of false target. 相似文献
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微动损伤常见于工程中,可使紧固件松动,疲劳寿命减少和腐蚀增加,造成较大的安全隐患和经济损失.微动损伤的试验耗时耗力,还不宜损伤的直接观察,辅以计算模拟和分析十分必要.本文重点介绍微动磨损和微动疲劳寿命计算的一些方法和分析准则.其中,微动磨损计算主要介绍基于Archard公式,结合有限元计算的分析方法,以及相应的多层节点更新方法.对于微动疲劳寿命的计算和分析,主要介绍基于多轴疲劳临界面准则的判别准则,尤其是基于能量准则的Smith-Watson-Topper参数.重点介绍如何在微动条件下实现磨损与疲劳寿命的耦合求解,以及损伤的累积和破坏的判定.通过一个简单算例说明了微动磨损对其疲劳寿命可有很大的影响. 相似文献
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First principles study on the charge density and the bulk modulus of the transition metals and their carbides and nitrides
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A first principles study of the electronic properties and bulk modulus (B0) of the fcc and bcc transition metals, transition metal carbides and nitrides is presented. The calculations were performed by plane-wave pseudopotential method in the framework of the density functional theory with local density approximation. The density of states and the valence charge densities of these solids are plotted. The results show that B0 does not vary monotonically when the number of the valence d electrons increases. B0 reaches a maximum and then decreases for each of the four sorts of solids. It is related to the occupation of the bonding and anti-bonding states in the solid. The value of the valence charge density at the midpoint between the two nearest metal atoms tends to be proportional to B0. 相似文献
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