The weight hierarchy of a binary linear [n, k] code C is the sequence (d 1, d 2, . . . , d k ), where d r is the smallest support of an r-dimensional subcode of C. The codes of dimension 4 are collected in classes and...The weight hierarchy of a binary linear [n, k] code C is the sequence (d 1, d 2, . . . , d k ), where d r is the smallest support of an r-dimensional subcode of C. The codes of dimension 4 are collected in classes and the possible weight hierarchies in each class is determined by finite projective geometries. The possible weight hierarchies in class A, B, C, D are determined in Part (I). The possible weight hierarchies in class E, F, G, H, I are determined in Part (II).展开更多
A （v, k, λ） difference family （（v, k, λ）-DF in short） over an abelian group G of order v, is a collection F=（Bi｜i ∈ I} of k-subsets of G, called base blocks, such that any nonzero element of G can be repres...A （v, k, λ） difference family （（v, k, λ）-DF in short） over an abelian group G of order v, is a collection F=（Bi｜i ∈ I} of k-subsets of G, called base blocks, such that any nonzero element of G can be represented in precisely A ways as a difference of two elements lying in some base blocks in F. A （v, k, λ）-DDF is a difference family with disjoint blocks. In this paper, by using Weil＇s theorem on character sum estimates, it is proved that there exists a （p^n, 4, 1）-DDF, where p = 1 （rood 12） is a prime number and n ≥1.展开更多
肾小球滤过率GFR(glonerular filtration rate)是评价肾功能的重要指标,而肾动态图像中感兴趣区ROI(region of interest)的准确勾画又是影响GFR的重要因素。现有的肾动态定量分析软件的ROI仍需人工辅助勾画,主观性强。在综合了现有肾动...肾小球滤过率GFR(glonerular filtration rate)是评价肾功能的重要指标,而肾动态图像中感兴趣区ROI(region of interest)的准确勾画又是影响GFR的重要因素。现有的肾动态定量分析软件的ROI仍需人工辅助勾画,主观性强。在综合了现有肾动态图像ROI勾画方法的基础上进行了ROI自动提取的相关研究。首先用自适应滤波器对数字图像进行滤波,减小图像的噪声;再用ostu法自动确定阈值形成二值图,接着用交替顺序滤波法对二值图像滤波,提取双肾轮廓;然后采用链码和与差的方法修补边界,使轮廓平滑;最后针对象素进行本底ROI设置,从而实现自动提取肾脏和本底ROI。展开更多
当 A是特殊的 (n,1,n)等重码和 (n,n,1)等重等距码时 ,通过对两个旧码 A和 B构造一个新码 A B即直和码的分析 ,给出了 A B广义 Ham ming重量与 A、B的广义 Ham ming重量的关系 ;在 A、B是一般情形下 ,对直和码的广义 Ham ming重量进行...当 A是特殊的 (n,1,n)等重码和 (n,n,1)等重等距码时 ,通过对两个旧码 A和 B构造一个新码 A B即直和码的分析 ,给出了 A B广义 Ham ming重量与 A、B的广义 Ham ming重量的关系 ;在 A、B是一般情形下 ,对直和码的广义 Ham ming重量进行了研究。展开更多
基金supported by The Norwegian Research Councilthe National Science Foundation of China(10271116)
文摘The weight hierarchy of a binary linear [n, k] code C is the sequence (d 1, d 2, . . . , d k ), where d r is the smallest support of an r-dimensional subcode of C. The codes of dimension 4 are collected in classes and the possible weight hierarchies in each class is determined by finite projective geometries. The possible weight hierarchies in class A, B, C, D are determined in Part (I). The possible weight hierarchies in class E, F, G, H, I are determined in Part (II).
基金Supported by the National Natural Science Foundation of China(No.10561002)Guangxi Science Foundation(No.0640062)Innovation Project of Guangxi Graduate Education.
文摘A （v, k, λ） difference family （（v, k, λ）-DF in short） over an abelian group G of order v, is a collection F=（Bi｜i ∈ I} of k-subsets of G, called base blocks, such that any nonzero element of G can be represented in precisely A ways as a difference of two elements lying in some base blocks in F. A （v, k, λ）-DDF is a difference family with disjoint blocks. In this paper, by using Weil＇s theorem on character sum estimates, it is proved that there exists a （p^n, 4, 1）-DDF, where p = 1 （rood 12） is a prime number and n ≥1.
文摘肾小球滤过率GFR(glonerular filtration rate)是评价肾功能的重要指标,而肾动态图像中感兴趣区ROI(region of interest)的准确勾画又是影响GFR的重要因素。现有的肾动态定量分析软件的ROI仍需人工辅助勾画,主观性强。在综合了现有肾动态图像ROI勾画方法的基础上进行了ROI自动提取的相关研究。首先用自适应滤波器对数字图像进行滤波,减小图像的噪声;再用ostu法自动确定阈值形成二值图,接着用交替顺序滤波法对二值图像滤波,提取双肾轮廓;然后采用链码和与差的方法修补边界,使轮廓平滑;最后针对象素进行本底ROI设置,从而实现自动提取肾脏和本底ROI。
