Effect on Intensity Correlation Time by Input Signal in a Single-Mode Laser with Bias Signal Modulation

The effect on intensity correlation time T by input signal is studied for gain-noise model of a single-mode laser driven by colored pump noise and colored quantum noise with colored cross-correlation with a bias signal modulation in this paper. By using the linear approximation method, we detect that there exists maximum （i.e., resonance） in the curve of the intensity correlation time T upon bias current io when the noise correlation coefficient λ is positive; and there exists minimum （i.e., suppression） in the T-io curve when λ is negative. And whenλ is zero, T increases monotonously with increasing io. Furthermore, the curve of T upon the signal frequency Ω is also studied. Our study shows that no matter what the value of λ is, there exists minimum （i.e., suppression） in the T-Ω curve.     

基于周期调节的随机共振算法对化学弱信号的检测研究

提出了一种新的随机共振算法,通过对系统的周期进行调节以实现系统的共振.讨论了实现共振的系统参数,并对模拟信号和拉曼光谱实验信号进行了处理.结果表明,该方法不仅可方便地用于弱化学信号的处理,克服检出信号的滞后现象,而且对不同噪声水平的信号均有良好的适用性.     

适用于高维数据的正交信号校正预处理方法

建立了一种高维正交信号校正方法,基于二维PLS到高维PLS的发展思想,把适用于二维数据预处理的正交信号校正方法发展成适用于高维数据预处理的方法.不仅在理论上扩展了正交信号校正方法,而且在实际应用中也能通过与高维PLS的联用产生更有效的高维数据校正方法.     

Physical mechanism of the chaotic detection of the unknown frequency of weak harmonic signal and effects of damping ratio on the detection results

In the zero-order approximation, we use the perturbation method of parameter with small magnitude to prove that the harmonic frequency in the solution of the equation is close to that of the driving force when the chaotic system from Duffing－Holmes equation stays in the stable periodic state, which is the physical mechanism of the detection of the unknown frequency of weak harmonic signal using the chaotic theory. The result of the simulation experiment shows that the method proposed in this paper, by which one can determine the frequency of the stable system from the number of circulation change of the phase state directionally across a fixed phase state point (x,\dot{x}) in fixed simulation time period, is successful. Analyzing the effects of the damping ratio on the chaotic detection result, one can see that for different frequency ranges it is necessary to carefully choose corresponding damping ratio α.     

Influences of nonlinear interactions of polaritons in uniaxial crystals

We have analysed theoretically the polarization and dielectric constant of uniaxial ionic crystals,including the effect of the nonlinear interactions between ions.The spectrum of polaritons(coupling modes of photons and optical phonons) under nonlinear interactions was developed.A new branch of dispersion relations emerges in the original frequency gap.     

基于DSP实现的数字化闭环光纤陀螺

提出一种基于高速数字信号处理专用DSP芯片使用的数字化闭环光纤陀螺系统方案,并着重讨论其数字快速算法的实现。这种快速算法采用多抽样率数字信号系统中抽取的高效结构实现,能够在保证系统的实时性和精度的条件下,极大地减少了DSP系统的运算量和存储量。     

奇异值分解在海洋回波多普勒信息提取中的应用

运用矩阵奇异值分解原理,分析了功率谱估计对探测海洋表面信息和硬目标信号的意义,对接收信号的自相关矩阵进行分解以提高谱估计的分辨率,并将处理后的方法对实测数据进行功率谱的估计,与处理前的回波谱图进行比较,实验证明,得出的奇异值分解方法可以改善多普勒回波功率谱的性能,满足高频地波雷达的目标探测要求。     

嗜盐嗜碱芽孢杆菌NTT76启动子和信号肽序列的克隆及表达

利用启动子信号肽探测型质粒pGPB14,从嗜盐碱芽孢杆菌NTT76的总基因组中克隆具有启动子和信号肽功能的NDA片段,共得到41个转化子,其氨苄青霉素抗性水平在1000－12000mg/L之间,从3个不同抗性不平的转化子中提取重组质粒,酶切显示,外源插入片段在100－500bp之间,将重组粒质转化枯草芽孢杆菌,也同样使枯草芽孢杆菌具有分泌β－丙酰胺酶的功能,β－丙酰胺酶活力测定表明,大肠杆菌产生的酶主要积累在周质空间,而枯草芽孢杆菌产生的酶主要分泌在胞外,对外源插入片段进行定列测定发现,所有片段均含有启动子区、核糖体结合位点和信号肽编码区域。     

非线性动力学系统的辨识：时频滤波与骨架曲线

利用非平稳信号的时频分析方法研究了一类非线性系统的频率特性和阻尼特性随运动形态的变化规律,得到了能简洁、直观地反映系统基本非线性动力学特性的广义骨架线性系统（简称GSLS）和骨架曲线。在此基础上,利用时频滤波方法根据系统非平稳响应信号对非线性系统进行辨识。该项工作为非线性系统反问题的研究提供了一条新的途径。     

Three-dimensional elastic–plastic finite element analysis for orthogonal cutting with discontinuous chip of 6-4 brass

An elastic–plastic finite element model is developed for 3D orthogonal cutting of discontinuous chips. The tool is P20 while the workpiece is made of 6-4 brass. Examined under the condition of low cutting speed are the initial crack location, the direction of crack growth and variations of discrete chips. These predictions are made possible by application of the strain energy density (SED) theory. The initial crack was formed above the tool tip and grew progressively along the stationary values of the SED function until the trajectory intersects with the free surface. The plastic deformation and friction result in a high equivalent stress in the secondary deformation zone of the first longitudinal chip. Stresses are also high at the location of crack initiation. The chip node near the tool face is sensitive to the contact of the tool face. As more residual stress prevails after the first longitudinal cut, degradation of the workpiece surface prevails and should be accounted for.