安全模型既是可信信息系统的核心内容,也是可信计算研究的重要领域.基于对角色访问控制(RBAC:Role Based Access Control)和安全操作系统标准的深入研究,提出了同名角色的概念,扩展了RBAC中角色的控制范畴,便于灵活地权衡控制粒度与空...安全模型既是可信信息系统的核心内容,也是可信计算研究的重要领域.基于对角色访问控制(RBAC:Role Based Access Control)和安全操作系统标准的深入研究,提出了同名角色的概念,扩展了RBAC中角色的控制范畴,便于灵活地权衡控制粒度与空间需求的对立关系,实施细粒度的访问控制;同时根据同名角色的思想,为自主存取控制(DAC:Discretionary Ac-cess Control)系统提供了同名控制域的能力.最后,在FreeBSD操作系统中设计实现了同名控制域,提高了访问控制的灵活性.展开更多
提出一种高分辨率SAR图像与光学图像之间的自动配准方法,首先利用仿射变换进行SAR图像和光学图像粗匹配,简化整体算法的处理复杂度;然后使用边缘检测算子分别对光学图像和SAR图像进行特征提取,为后续精匹配作好数据准备;最后基于归一化...提出一种高分辨率SAR图像与光学图像之间的自动配准方法,首先利用仿射变换进行SAR图像和光学图像粗匹配,简化整体算法的处理复杂度;然后使用边缘检测算子分别对光学图像和SAR图像进行特征提取,为后续精匹配作好数据准备;最后基于归一化互相关原理进行图像之间的同名点精匹配。引入的比值边缘检测算子(ROA)与传统光学检测算子相比,可以较好地克服SAR斑点噪声,提取出的SAR特征图像与光学特征图像非常相似,提高了算法的准确性和鲁棒性。以星载3 m TerraSar数据和1 m SPOT数据为例进行算法验证,试验结果表明该算法能实现自动的异源图像之间的像素级匹配。展开更多
Hibiscus syriacus is one of the flower trees that were known and used most early in Chinese history.With the development of Hibiscus syriacus culture,its many another names appeared.At the same time,several homonyms a...Hibiscus syriacus is one of the flower trees that were known and used most early in Chinese history.With the development of Hibiscus syriacus culture,its many another names appeared.At the same time,several homonyms about it appeared too,which was because of word evolvement,one similar attribute,similar species,or error during the transfer of culture.This brought some obstacles for persons when they read ancient literature about Hibiscus syriacus.In order to help people to consult ancient literature about Hibiscus syriacus,a distinction on homonyms was made in the paper.展开更多
文摘提出一种高分辨率SAR图像与光学图像之间的自动配准方法,首先利用仿射变换进行SAR图像和光学图像粗匹配,简化整体算法的处理复杂度;然后使用边缘检测算子分别对光学图像和SAR图像进行特征提取,为后续精匹配作好数据准备;最后基于归一化互相关原理进行图像之间的同名点精匹配。引入的比值边缘检测算子(ROA)与传统光学检测算子相比,可以较好地克服SAR斑点噪声,提取出的SAR特征图像与光学特征图像非常相似,提高了算法的准确性和鲁棒性。以星载3 m TerraSar数据和1 m SPOT数据为例进行算法验证,试验结果表明该算法能实现自动的异源图像之间的像素级匹配。
文摘Hibiscus syriacus is one of the flower trees that were known and used most early in Chinese history.With the development of Hibiscus syriacus culture,its many another names appeared.At the same time,several homonyms about it appeared too,which was because of word evolvement,one similar attribute,similar species,or error during the transfer of culture.This brought some obstacles for persons when they read ancient literature about Hibiscus syriacus.In order to help people to consult ancient literature about Hibiscus syriacus,a distinction on homonyms was made in the paper.
