基于模糊集合的无线通信跳频扩谱方法

为解决无线通信抗干扰性能，笔者讨论了不同于依赖伪随机码的基于模糊集合的无线通信跳频扩谱方法．介绍了可加性模糊系统通过数据来学习规则并起到伪随机数发生器(PN)的作用，由均匀分布随机数发生器提供训练样本，自适应模式可学习当前样本与以前样本之间的联系并将其以模糊规则形式编码．讨论了模糊系统的输入模糊集、模糊规则及自适应规则产生的方法，基于模糊集合的无线通信控制器设计．仿真结果表明模糊系统具有较低的X^2值，因此可提供均匀的或“随机”的无线通信传输频带．     

Effects of specimen refractive index on confocal imaging

The aberrations introduced when focusing within a specimen with a refractive index equal to that of water using an oil-immersion objective are investigated theoretically. The peak intensity in the confocal point spread function drops by a factor of two for focusing less than 10 μm into the specimen. The effects on scaling of dimensions in the resulting images are discussed. The image exhibits an axial stretching by a factor of about 1.12.     

最低限度通信中多普勒频偏估计算法

针对最低限度通信中多普勒频偏估计范围不足、估计精度较低的问题,提出一种改进的基于相关FFT的直扩信号同步捕获算法.该算法通过补零运算提高算法的估计精度、采用正交扩频序列优化算法的性能.数值分析表明,在低信噪比环境下,改进后的算法能够以较高的精度捕获较大频偏.     

高密度双谱分析技术在LSH深水地震资料中的应用研究

深水区的地震资料是采用长排列拖缆采集的,工区面积大,速度变化敏感,各向异性明显,传统人工速度分析技术不能满足工区的勘探开发需求,经研究,采用CGGVeritas的高密度双谱分析技术可以较好解决动校正问题,高效率高品质,提高了LSH深水地震资料的速度精度和密度,在全区得到推广应用,取得了很好的效果.     

混沌直接序列扩频(DS/SS)通信系统

本文讨论了混沌序列在直接序列扩频通信系统中的应用。针对简单混沌序列轨迹周期短以及存在误差传播现象,提出了一种改进的混沌扩频序列产生方法。并对混沌扩频序列的特性进行了分析和研究。     

基于Walsh序列扩频的图像信息隐藏

为了提高在高噪声条件下信息隐藏的可靠性,提出了一种将Walsh序列用于信息隐藏的嵌入算法,利用5-32Walsh序列的特性,以多位二进制信息为单位对嵌入二值图像进行扩频调制,然后将调制信号替换载体图像离散余弦变换域的低频系数.Walsh序列的应用使算法可以采用较长的扩频序列,从而提高了鲁棒性.实验表明,该算法在低信噪比的信道条件,具有较强的优势.     

LS模型下信用价差看跌期权定价研究

Vasicek模型是一个具有均值回归特征的仿射结构型短期随机利率模型,Black-Scholes期权定价模型假设无风险利率是常数,标的股票价格服从对数正态分布,对这些假设条件进行改进。假设无风险利率和标的资产信用价差都满足Vasicek模型,在此假设下首先给出几何平均执行价亚式信用价差看跌期权的定价公式,然后对定价公式...     

45号钢柱体内置裂纹扩展的动态响应

采用人工预测裂纹方法,分析高速减压条件下45号钢柱体内置裂纹展的动态响应行为,用弹塑性波理论很好地解释了钢体裂纹扩展过程。结果表明,在快速镦粗过程中预制内部裂纹具有稳定扩展特征,塑性等效应变速率εp基本不变。     

Modeling and finite element analysis of rod and wire steel rolling process

Two thermomechanical coupled elastic-plastic finite element （FE） models were developed for predicting the 12-pass continuous rolling process of GCrl 5 rod and wire steel. The distances between stands in the proposed models were set according to the actual values, and the billets were shortened in the models to reduce the calculation time. To keep the continuity of simulation, a technique was developed to transfer temperature data between the meshes of different models in terms of nodal parameters by interpolation functions. The different process variables related to the rolling process, such as temperature, total equivalent plastic strain, equivalent plastic strain rate, and contact friction force, were analyzed. Also, the proposed models were applied to analyze the reason for the occurrence of an excessive spread in width. Meanwhile, it was also utilized to assess the influence of the roll diameter change on the simulated results such as temperature and rolling force. The simulated results of temperature are found to agree well with the measured results.     

基于多小波变换的混合水印应用研究

扩频和量化技术是数字水印中两种基本的技术,扩频水印有鲁棒性强的特点,而量化水印具有更大的容量,考虑到两者之间存在互补性,论文在图像多小波变换统计特征和视觉掩蔽模型基础上,提出了一种新颖的图像多小波变换域内基于扩频和量化的混合数字水印方案。实验结果表明所提出的算法既具有较高的嵌入容量,又具有较强的鲁棒性,特别是在高压缩比下具有较高的性能。