基于二阶矩的直扩信号伪码周期估计算法

直接序列扩频信号(DSSS)具有抗干扰抗截获等特性,对其参数的有效估计具有重要意义。针对直扩信号的伪码周期估计的问题,在现有的自相关估计方法基础上引入二阶矩概念,提出了一种基于二阶矩的伪码周期估计算法,并对其进行了理论分析和实验仿真。仿真结果表明,该算法能适用于低信噪比情况,并且与自相关估计方法相比,估计性能更好。     

基于扫描线的新型车牌定位方法研究

针对车牌定位易受光照、场景等因素的影响,无法准确定位的问题,研究并提出了一种基于扫描线的车牌定位方法。首先增强图像并去噪,改善图像质量;接着通过水平边缘检测和行扫描粗定位车牌区域,通过扫描线聚类增长固定候选车牌区域;最后通过水平投影和倾斜校正精确定位车牌。通过多组不同条件下车牌的对比实验,验证了该方法能够适应各种条件下拍摄的车牌图像定位,具有较高的鲁棒性。     

S盒变换规则融合雅克比椭圆混沌映射的图像加密算法研究

由于当前的基于混沌映射的图像加密算法存在瞬态效应,且在像素扩散阶段都没有使用完整的随机密码序列,从而降低了加密系统的安全性,无法抵御各类明文与密文攻击。对此,设计了一个完整的随机密码序列和新的雅克比椭圆映射,并定义了一个S盒变换规则;构造了预混淆-混淆-扩散结构,提出了S盒变换规则耦合雅克比椭圆混沌映射的图像加密算法。首先利用S盒变换规则对初始图像进行预混淆;再根据Logistic混沌映射与代数变换模型所生成的外部密钥迭代雅克比椭圆混沌映射,以消除瞬态效应;改变初始外部密钥,再次迭代雅克比椭圆混沌映射,用序列修正函数对迭代得到的伪随机序列进行修正,产生的新序列在混淆机制下改变预混淆图像像素值;根据密钥流机制和新序列来设计一个完整的随机密码序列,对混淆像素进行扩散。在MATLAB仿真平台上测试结果表明:该算法高度安全,拥有很强的密钥敏感性,密钥空间巨大。     

一种改进偏微分方程扩散系数的图像去噪方法

在偏微分方程P-M模型图像去噪过程中,扩散系数的选择会影响图像去噪的效果,为此提出了一个新的扩散系数模型来实现图像去噪。首先分析讨论了P-M模型中扩散系数和梯度阈值的选取对图像去噪的重要性,并对比了两个扩散系数的优点和缺点;在此基础上提出一个新的扩散系数,并应用到CLMC模型进行数值离散实验。实验结果表明,采用新的扩散系数得到的信噪比和峰值信噪比要比P-M方程中所给出的两个扩散系数得到的信噪比和峰值信噪比好。提出的扩散系数能够有效地进行图像去噪。     

关于3x+1问题的一点注记

给出了3x 1问题的三个等价命题,其中构造数列{T^(k)(n)2∑^k-1i=0i^x(n)}k=1 ∞,证明它是一个单调递减下有界数列。     

一种基于Lucas序列的盲签名方案

根据Ｌｕｃａｓ序列的特点,设计了一种新的盲签名方案,其安全性是基于大数分解问题的。该方案签名和验证过程简单,通信成本低,因而有较高的安全性和实用性。     

An important reference criterion for the selection of GSSP

A study on the relationship between biostratigraphy and sequence stratigraphy in several designated global boundary stratotypes shows that the best way may be to take the GSSP at a point coincident with the base of the first widespread Leading Group biozone above the first flooding surface (FFS) of the relevant third-order sequence. It is suggested that the first flooding surface of the sequence should be an important reference criterion for the selection of GSSP. As the base of the first widespread Leading Group biozone chosen for the definition of GSSP could not be lower than the first flooding surface of the referred sequence, the latter surface may be an important criterion for the recognition and correlation of the chronostratigraphic boundaries.     

Molecular characterization of a K+ channel blocker in the scorpionButhus martensii Karsch

K⁺ channel blockers of scorpion venoms are of important value in studying pharmacology and physiology of specific K⁺ channel of cells. Based on the amino acid sequences of BmP01 previously characterized as a small-conductance Ca²⁺-activated K⁺ channel blocker, two “back to back” degenarate primers have been designed and synthesized for inverse PCR strategy, its full-length cDNA has been cloned from the venom gland of the Chinese scorpionButhus martensii. The cDNA is composed of 3 parts: 5′ UTR, ORF and 3′ UTR. The flanking sequence of translation initiation codon ATG is AAAATGA, which is highly conserved in scorpion Na⁺ channel toxin and protozoan genes, suggesting that these genes may have followed a common mechanism for translation initiation. The 3′ UTR contains poly(A) signal AATAAA. The open reading frame encodes a precursor of 57 residues with a signal peptide of 28 residues and a mature peptide of 29 residues. The signal peptide is rich in hydrophobic amino acid residues and its length is significantly different from that of the determined scorpion Na⁺ channel toxin. The deduced amino acid sequence of mature peptide is completely consistent with BmP01 previously determined by primary structure analysis.     

巨野煤田含煤地层层序单元划分

运用当代层序地层学的理论和方法体系,通过对区内近２００个钻孔岩心的详细研究,根据石岩－二叠系沉积旋回特点,系统地分析了沉积体系、层序地层及其内部构成特点,建立了研究区陆表海盆地和陆相盆地的层地层格架。研究表明,巨野煤田石岩－二叠系共划分为２个构造层序,７个Ⅲ级层序和４２个准层序。     

多值单调型算子不动点带有误差项的Ishikawa迭代逼近

在一致光滑Ｂａｎａｃｈ空间中,证明了带有误差项的Ｉｓｈｉｋａｗａ迭代序列强收敛于一类多值单调型算子的唯一不动点。这些结果改进和推广了Ｄｕｎｎ,Ｃｈｉｄｕｍｅ,Ｄｅｎｇ－Ｄｉｎｇ,丁协平,Ｃｈａｎｇ－Ｔａｎ等人的最新结果。