循环域

The m-sequence with Cyclic Prefix is inserted between OFDM symbols in time domain as training sequence. The cross-correlation is calculated between the received sequence with CP removed and the appointed circular shifted m-sequence, which takes reliability of the estimation of channel impulse response on account of the two-valued auto-correlation property of the m-sequence, thereby the channel frequency response can be advisably decided.

在时域OFDM符号之间插入附加循环前缀的m序列作为训练序列，在接收端将去掉循环前缀的接收序列与指定的循环移位m序列作相关运算，然后利用m序列的二值自相关特性获得信道的冲激响应估计，从而得到信道的频率响应估计。

A new frequency estimation algorithm for Time Domain Synchronization OEDM system is proposed, which utilizes the time domain circular characteristic of PN sequences to adjust frequency offset and then uses a variable step frequency scan scheme to estimate large frequency offset.

提出一种新的适用于TDS-OFDM系统的频偏估计算法，利用PN序列的时域循环特性进行预频偏调整，然后用变步长扫频进行大频偏的估计，定时同步之后再利用PN的时域循环特性进行细偏估计。

In 1957, Prange first began to study cyclic codes over field GF, and then the study of cyclic codes over GF was made great progress both on theory and on practice.

1957年普朗格首先开始在域GF上研究循环码，此后人们对域GF上循环码的研究在理论和实践方面都取得了很大进展。

In this paper, new classes of linear block codes over finite fields of the algebraicinteger ring of quadratic number fields Qd~(1/2 modulo irreducible elements with norm p or p~2 are presented. These codes can correct one error which takes from the cyclic subgroup of the multiplicative group of the finite fields. The results presented in this paper extend the corresponding results of previous papers.

在处理适用于二维信号的线性分组码时，我们考虑类数为1的有理数域二次扩域Qd~(1/2的代数整数环，利用范数为p或p~2的不可约元构造有限域，给出剩余类域的一组完全陪集代表元系，从而构造出一类有限域上的线性分组码，当错误取值于有限域乘法群的一个循环子群时，所得到的适用于二维信号的线性分组码可以纠单个错，推广了文[14-16]的结果。

Based on the second-order statistics, cyclic autocorrelation function , a method of demodulation is deduced.

推导了二阶循环统计量——循环自相关函数的解调方法，该方法通过搜索循环频率而将调制源分离在循环域的低频段，并且调幅和调频信号有不同的解调结果。

Based on the analytic method of cyclic spectrum density, the paper pointed out that the impact frequency could be extracted effectively with the help of scanning cyclic frequency domain.

通过对循环谱密度分析方法的特性分析，指出应用循环谱密度分析方法可以在循环频率域有效提取出滚动轴承的冲击故障频率。

The main contributions of the second part of this dissertation are focused on the cryptographic properties of logical functions over finite field, with the help of the properties of trace functions, and that of p-polynomials, as well as the permutation theory over finite field: The new definition of Chrestenson linear spectrum is given and the relation between the new Chrestenson linear spectrum and the Chrestenson cyclic spectrum is presented, followed by the inverse formula of logical function over finite field; The distribution for linear structures of the logical functions over finite field is discussed and the complete construction of logical functions taking on all vectors as linear structures is suggested, which leads to the conception of the extended affine functions over finite field, whose cryptographic properties is similar to that of the affine functions over field GF (2) and prime field F〓; The relationship between the degeneration of logical functions and the linear structures, the degeneration of logical functions and the support of Chrestenson spectrum, as well as the relation between the nonlinearity and the linear structures are discussed; Using the relation of the logical functions over finite field and the vector logical functions over its prime field, we reveal the relationship between the perfect nonlinear functions over finite field and the vector generalized Bent functions over its prime field; The existence or not of the perfect nonlinear functions with any variables over any finite fields is offered, and some methods are proposed to construct the perfect nonlinear functions by using the balanced p-polynomials over finite field.

重新定义了有限域上逻辑函数的Chrestenson线性谱，考察了新定义的Chrestenson线性谱和原来的Chrestenson循环谱的关系，并利用一组对偶基给出了有限域上逻辑函数的反演公式；给出了有限域上随机变量联合分布的分解式，并利用随机变量联合分布的分解式对有限域上逻辑函数的密码性质进行了研究；给出了有限域上逻辑函数与相应素域上向量逻辑函数的关系，探讨了它们之间密码性质的联系，如平衡性，相关免疫性，扩散性，线性结构以及非线性度等；讨论了有限域上逻辑函数各类线性结构之间的关系，并给出了任意点都是线性结构的逻辑函数的全部构造，由此引出了有限域上的"泛仿射函数"的概念；考察了有限域上逻辑函数的退化性与线性结构的关系、退化性与Chrestenson谱支集的关系；给出了有限域逻辑函数非线性度的定义，利用有限域上逻辑函数的非线性度与相应素域上向量逻辑函数非线性度的关系，考察了有限域上逻辑函数的非线性度与线性结构的关系；利用有限域上逻辑函数与相应素域上向量逻辑函数的关系，揭示了有限域上的广义Bent函数与相应素域上的广义Bent函数的关系，以及有限域上的完全非线性函数与相应素域上向量广义Bent函数之间的关系；给出了任意有限域上任意n元完全非线性函数存在性与否的完整证明，并利用有限域上平衡的p-多项式的性质给出了有限域上完全非线性函数的一些基本构造方法。

The algorithm is featured with insensitivity to Gaussian noise. The proposed algorithm can estimate DOAs without search and match problem.

因此，在阵元数相同的条件下，与传统的循环域DOA估计算法相比，DOA估计的分辨率和可估计源的个数均得到大幅度的提高。

We make use of a normal element and circular permutations to construct polynomials over the intermediate extension field between F_q and F_ denoted by F_ where s divides t. The polynomials we constructed are F_q-linearly independent and return elements in F_q when they are evaluated at elements of the extension fields.

结合Reed-Solomon码的构造特点，我们将Chaoping Xing与San Ling所构造的线性码的方法推广到有限域的任意次扩张上，首先利用正规元和循环排列来构造系数属于F_q和F_q的任意次扩域F_之间的中间域的具有特殊性质的多项式，中间域记为F_，其中s为t的真因子，由正规元的选择可以保证所构造多项式的F_q-线性无关性，并且这些多项式在扩域F_中取值都属于F_q，从而构造出一类q元线性码。

At last, By using the factorization properties of cyclotomic polynmials on finite fields and the construction characteristic of cyclic codes, we present the relation of the period distribution of cyclic codes and the period distribution of their dual codes, establish the explicit formula for the number of the codewords without inner-period of the cyclic codes and their dual codes, find the method for computing the dimension and the period distribution of narrow-sense primitive BCH codes,and study the inverse question of period distribution of cyclic codes.

最后，利用有限域上分圆多项式的分解特性和循环码的构造特点，揭示了循环码的周期分布与其对偶码周期分布之间的内在联系，确定了一般循环码及其对偶码内无内周期码字的精确计数公式，决定了狭义本原BCH码的维数与周期分布，讨论了循环码周期分布的反问题。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。