排序方式: 共有4条查询结果,搜索用时 15 毫秒
1
1.
2.
一种描述RBAC角色层次关系和互斥关系的模型及实现 总被引:1,自引:1,他引:0
RBAC角色访问控制逐渐被软件业所认同,在概述了目前的RBAC模型的特点后,对其角色的继承关系和互斥关系进行了讨论,并提出了一种逻辑模型和实现方法,最后给出了一个实例。 相似文献
3.
短峰波和海流广泛分布于海洋之中,但二者的相互作用直到近些年才逐渐受到关注,根据速度势函数理论,推导二维均匀流与重力短峰波的相互作用,区别于之前的研究,推导时不考虑波面的毛细影响,避免了将位置变量(x)与时间变量(t)绑定的假设,使得二阶速度势函数包含了的时间(t)一阶项,从而给出了完整的二维流与短峰波交互作用的二阶解析解,对比结果说明上述考虑对于波流共同作用结果有影响,尤其是在波高较大时,影响更加明显,所得结果,可用于高波浪条件下海洋波浪与流相互作用的计算. 相似文献
4.
Wavelength Red-Shift of Long Wavelength InGaN/GaN Multi-Quantum Well by Using an InGaN Underlying Layer 下载免费PDF全文
Long-wavelength Ga2N based light-emitting diodes are of importance in full color displays, monofithic white lightemitting diodes and solid-state lighting, etc. However, their epitaxial growth faces great challenges because high indium (In) compositions of lnGaN are difficult to grow. In order to enhance In incorporation and lengthen the emission wavelength of a InGaN/GaN multi-quantum well (MQW), we insert an InGaN underlying layer underneath the MQW. InGaN/GaN MQWs with various InGaN underlying layers, such as graded InyGal-yN material with linearly increasing In content, or InyGa1-yN with fixed In content but different thicknesses, are grown by metal-organic chemical vapor deposition. Experimental results demonstrate the enhancement of In incorporation and the emission wavelength redshift by the insertion of an InGaN underlying layer. 相似文献
1