首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1篇
  免费   2篇
物理学   3篇
  2011年   1篇
  2010年   1篇
  1997年   1篇
排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
收发分置水下目标声散射特性的实验研究   总被引:4,自引:0,他引:4  
本文对收发分置情况下,某潜艇模型的声散射特性进行了理论分析和实验研究。在声源、目标和接收机之间呈复杂的三角形关系条件下,找到了目标强度与入射角、分置角之间的关系。通过理论计算和水地测试,验证了理论的正确性。该研究成果可直接应用于收发分置的双基地或多基地水声探测系统。  相似文献   
2.
江凡  丁玮 《中国物理 B》2010,19(10):106101-106101
A previously published new rotation function has been improved by using a dynamic correlation coefficient as well as two new scoring functions of relative entropy and mean-square-residues to make the rotation function more robust and independent of a specific set of weights for scoring and ranking. The previously described new rotation function calculates the rotation function of molecular replacement by matching the search model directly with the Patterson vector map. The signal-to-noise ratio for the correct match was increased by averaging all the matching peaks. Several matching scores were employed to evaluate the goodness of matching. These matching scores were then combined into a single total score by optimizing a set of weights using the linear regression method. It was found that there exists an optimal set of weights that can be applied to the global rotation search and the correct solution can be ranked in the top 100 or less. However, this set of optimal weights in general is dependent on the search models and the crystal structures with different space groups and cell parameters. In this work, we try to solve this problem by designing a dynamic correlation coefficient. It is shown that the dynamic correlation coefficient works for a variety of space groups and cell parameters in the global search of rotation function. We also introduce two new matching scores: relative entropy and mean-square-residues. Last but not least, we discussed a valid method for the optimization of the adjustable parameters for matching vectors.  相似文献   
3.
丁玮  江凡 《物理学报》2011,60(4):46103-046103
将多元函数的变尺度法与两电子密度图的相关系数相结合,得到一种能够对蛋白质晶体结构进行刚体优化的新方法.初步测试结果表明,该方法能够明显地改善待测晶体的初始模型在晶胞中的取向和位置.而与最大似然方法相比,该方法可能更适用于搜索空间中存在大量局域极值点的情况. 关键词: 蛋白质晶体结构 刚体优化 多元函数的变尺度方法 电子密度图的相关系数  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号