频数分布

This model can provide the good base of adaptive modulation and coding and automatic repeat request as well as dynamic resource allocation.

首先分析了正交频分复用技术频域信道统计特性，说明了Nakagami-m分布能更好地描述衰落信道；然后针对高速移动及OFDM信号传输的特点，采用状态持续时间相等法建立了OFDM频域信道有限状态马尔可夫模型，分别给出了计算持续时间、状态门限及状态数、转移概率、状态差错率的一般方法及m=0.5\1\2典型值的闭式解，该模型能为自适应模型控制、混合自动重传请求 HARQ、动态资源分配等技术提供良好的基础。

By time-varying filtering, we realize the signal selectivity and interference suppression, especially for the signals with time-varying power spectrum. It is shown herein that conventional eigenstructure based methods are lower dimensional special case of the time-frequency subspace fitting method. The closed-form array response estimation algorithms for blind source separation in wireless communication is also developed in the dissertation by exploiting the data structure of second-order statistics of the array output in the presence of multipath. The proposed method achieves array response estimation with little constraint on signal property and propagation environment such as scatters or angular spread. Moreover, the array utilized here can be of arbitrary geometry and even uncalibrated. Since the closed-form solution is obtained, no misconvergency may occur and large amount of computation can be saved. The equivalent feed model and corresponding optimization designation are proposed to realize the downlink multi-user selective transmission. By coherent and non-coherent superposition of the electromagnetical field, multiple beams can be formed using a single array, so that each co-channel user signal is transmitted in each beam and will not interfered with each other. The proposed system scheme implements the digital beamforming and the channel allocation in the base band, therefore is suitable for the utilization of the radio software technology. The feasibility and effectiveness of the proposed model are proved by the RF experiment.

在窄带条件下，GSC－SSF方法还可以提高阵列的虚拟孔径，从而提高估计的性能；可以证明，Cyclic DOA 和SC-SSF方法可看作该方法的特例或近似； 3、提出了二维GSC－SSF方法和宽带谱相关DOA矩阵方法，利用信号的循环平稳特性解决了宽带条件下二维 DOA 估计问题，并具有阵元数少、计算量较小的特点； 4、提出了时频子空间拟合和宽带时频DOA估计算法，将联合时频分析的理论和方法引入到阵列信号的空间谱估计研究中，利用时变滤波实现信号选择性测向和干扰抑制，特别适合于谱时变信号；可以证明传统特征结构法可看作是时频子空间拟合方法的特例； 5、提出了多用户环境下阵列响应的估计方法——CARE方法，该方法对信号结构和传播参数（主要是散射源分布与角度散布）的约束较少，适用于各种几何结构的阵列甚至未校准的阵列，能够直接得到阵列响应的闭式解，因此计算量小、稳健性好，不存在收敛问题； 6、提出了针对多用户下行选择性发送的阵列等效激励模型、优化设计方法及其系统实现方案，通过空间场的相干叠加与非相干叠加使得单一阵列能够形成多个波束，并保证各波束内的用户信号各不相同且相互干扰最小；其系统方案具有在基带实现数字波束成形、信道分配并便于软件无线电实现的特点，其有效性已得到外场实测数据的证实。

Results: There was significant difference in the haplotype of the 4 SNPs frequency between two groups.

结果：联合统计发现，PRODH基因的4个位点的单倍型频数两组分布差异有统计学意义(P05)。

And the parameters inversed by using the GA are in agreement with those of real media.

此外，本文最后为了与频率波数分析的结果进行对比，研究了时频分析方法-魏格纳维尔分布，用数值模拟和实验结果分析了层状介质中瑞利波的频散曲线。

The mechanism of oscillation overvoltage and induction overvoltage produced in transformer windings under impulse voltage conditions, the principle of the simulation of impulse voltage distribution in transformer windings, and the experience of winding insulation design using the simulation software are theoretically summarized.

在工频电压和操作电压作用下，电力变压器绕组匝间和饼间的电压差值近似按匝数平均分布。但在雷电冲击作用下，由于电压波形的波前等值频率高达数百千赫兹，绕组匝间和饼间的电容和绕组对地的电容影响已不能忽略。

Pseudo-random multi-frequency signal is invented and named by academician He Jishan. The bandwidth of PRMF signal is controllable, it's energy concentrates on several frequencies, which are equally spaced on log scale coordinates.

何继善院士发明和命名的伪随机多频信号，由于其带宽可控，能量主要集中在数个在对数坐标上呈等间距分布的频率上，是电法勘探的理想场源。

Pseudo-random multi-frequency signal is invented and named by academician He Jishan. The bandwidth of PRMF signal is controllable, it's energy concentrates on several frequencies, which are equally spaced on log scale coordinates. It is ideal excitation source for electrical exploration.

中文题名伪随机多频电磁法观测系统研究副题名外文题名 The study on pseudo-random multi-frequency electromagnetic prospecting system 论文作者陈儒军导师何继善学科专业地球探测与信息技术研究领域\研究方向学位级别博士学位授予单位中南大学学位授予日期2003 论文页码总数165页关键词电法勘探电磁法伪随机多频信号馆藏号BSLW /2003 /P631.3 /4 伪随机多频信号由何继善院士发明和命名，该信号带宽可控，其能量集中在数个在对数坐标上呈等间距分布的频率上，是电法勘探的理想场源。

Keywords original position statistic distribution analysis;aluminum inclusion;frequency of abnormal spark;spectral intensity of abnormal spark

原位统计分布分析；铝夹杂物；异常火花频数；异常火花强度

Lugalbanda was a god and shepherd king of Uruk where he was worshipped for over a thousand years.

Lugalbanda 是神和被崇拜了一千年多 Uruk古埃及喜克索王朝国王。

I am coming just now,' and went on perfuming himself with Hunut, then he came and sat.

我来只是现在，'歼灭战perfuming自己与胡努特，那麼，他来到和SAT 。