斜纹结构的编织卷积码性能分析与仿真

主要研究了斜纹结构的编织卷积码(WCCs)在编码设计中活性距离和交织器对其性能的影响。通过系统仿真，结果表明在AWGN信道下，发现斜纹WCCs的系统性能将受到系统传输帧长、编码器归零方式及编码器个数的影响，因此适当地选择了编码器和交织器，能使其误码性能更加优越，且没有错误地板效应。     

基于对比度因子调节的快速分形解码算法

通过对搜寻码本设置门限的方法来调节对比度因子,提出了基于对比度因子调节的快速分形解码算法.实验结果表明,该算法获得了较基本分形算法质量高的第一次迭代后图像,在图像质量降质较小的情况下比基本分形解码明显地加快了收敛速度,从而可较好地满足需要超高速图像解码的应用场合(如实时视频传输).     

Recent progress in terahertz science and technology

The relatively new technique of coherent electromagnetic radiation, in the region of 1012 Hz, has potential to detect the nature of low energy processes in physics, chemistry and biomedicine. In this review article, an overview of recent progress of terahertz (THz) science and technology is presented. The development of the THz generation and detection system, the THz radiation applications which include THz time-domain spectroscopy and T-ray imaging, and the future potential of THz wave research are discussed.     

B.T.I.阅读模式与大学英语阅读教学

阅读是人们获取信息的一个极其复杂的综合心理言语过程 ,也是英语教学的主要手段。外国专家对阅读模式进行了研究 ,主要有三个阅读模式 :自下而上、自上而下、相互作用模式。笔者结合我国大学英语教学实际 ,提出对提高大学英语阅读教学的几点思考 :我们既不能照搬自上而下的模式 ,也不能照搬自上而下的模式 ,相比较而言相互作用的模式是目前较为理想的阅读模式。广大英语教师应采取切合实际的阅读教学模式以便使学生掌握真正的解码技能     

设计串联校正装置的一种解析方法

根据时域指标设计串联校正装置,一般使用根轨迹法(图解法)。此类方法无法将静态指标(如位置误差系数 K_p 或速度误差系数 K_r)与根轨迹作图有机结合,使设计计算复杂化。此处提出的解析法可免于这一问题,使设计计算更合理更简单,且物理概念清楚明了。     

利用对偶码的捕错译码

当g(r)是x~n+1的既约多项式,n为奇素数,g(x)是(n,(n+1)/2)循环码C的生成多项式,利用C的对偶码C′生成多项式(x+1)g(x)构造捕错译码器.该方法能提高原捕错译码器的纠错能力,可以识别C(x)中的码型(对偶码和非对偶码)。     

循环码关于软判决译码的一条性质

研究了循环码的性质，给出了并证明了关于编码率ｋ／ｎ〈（ｔ＋１）／（ｄ－１）的循环码的一条定理，该定理有利于降低软判决译码复杂度。     

Lagrange线性内插函数的实用表式及其推广应用

该文导出了两维四节点和三维八节点Ｌａｓｒａｎｇｅ线性内插函数、适用于编程和计算的实用表示式，并给出其在时域有限差分法（ＦＤ－ＴＤ）计算角点辐射边界条件（ＲＢＣ）中的推广应用．     

Optical Characterization of Iridescent Wings of <Emphasis Type="Italic">Morpho</Emphasis> Butterflies using a High Accuracy Nonstandard Finite-Difference Time-Domain Algorithm

In certain species of moths and butterflies iridescent colors arise from subwavelength diffractive surface corrugation of the wing-scales. The optical properties of such structures depend strongly on wavelength, incidence angle, and state of polarization of illuminating radiation, and the viewing angle. In this paper, we study the reflection spectra of the wings of the Morpho didius butterfly by simulating a double-layered model of a transverse cross-section comprised of the ground scale and the cover scale. Each layer contains a certain quasi-periodic arrangement of tree-like subwavelength microstructures. The simulation is done using a high accuracy nonstandard finite-difference time-domain (FDTD) method in two dimensions. We assume that the structure is made of a slightly lossy dielectric material. The wavelength dependence of the complex refractive index for the ground scale of Morpho didius is assumed to be similar to that of Morpho sulkowskyi. The complex refractive index in the latter case was obtained by comparing the computed reflection/transmission spectra with corresponding experimental measurements at normal incidence.     

3D FDTD Implementation for Scattering of Electric Anisotropic Dispersive Medium Using Recursive Convolution Method

The finite-difference time-domain method based on recursive convoltion method (RC-FDTD) for the electric anisotropic dispersive medium is discussed in detail. To exemplify the availability of the three-dimensional RC-FDTD algorithm, the backscattering Radar-Cross-Section(RCS) of a non-magnetized plasma sphere is computed, and the numerical results are the same as the one of the Shift Operater-FDTD method, and show that the RC-FDTD method is correct and efficient. In addition, the co-polarized and cross-polarized backscattering time-domain of a magnetized plasma sphere are obtained by the RC-FDTD algorithm. The results show that when the external magnetic field is implemented, the cross-polarized component appear, evidently.