存在外部光反馈的半导体激光器的相位噪声

本文在理论上研究了由于外部光反馈引起的半导体激光器的相位噪声.理论分析是通过引入一个反馈耦合率K和线性化速率方程,导出了半导体激光器相位噪声功率谱密度的表达式.这表明相位噪声功率谱密度随外腔长度而周期性地漂移,且功率谱密度的峰值随外部反馈耦合率而发生很大的变化.     

Noise Factor of Optically Controlled GaAs Field-Effect Transistors

The influence of IR radiation on the noise factor of GaAs field-effect transistors has been analyzed. It is shown that the noise factor of the indicated transistors decreases under IR irradiation. It has been established that a decrease in the noise factor of the field-effect transistors under IR irradiation is mainly due to an increase in the low-field mobility of electrons in them.     

ELASTO-PLASTIC DYNAMIC BUCKLING AND POSTBUCKLING OF SQUARE PLATES UNDER SOLID-FLUID SLAMMING

The elasto-plastic dynamic buckling and postbuckling phenomena ofsquare plates subjected to in-plane solid-fluid slamming are investigated.According tothe plate's response,the critical criteria for dynamic buckling,dynamic plasticity andplasti(?)collapse are defined,and the corresponding critical impulses are presented.Meanwhile,dynamic buckling modes and collapse models are observed.The effects ofdifferent boundary conditions and loading histories on the properties of buckling andpostbuckling are discussed.     

分布式光纤温度传感器APD最佳倍增因子的分析

本文分析了分布式光纤温度传感器中光电接收用雪崩光电二极管倍增因子对接收信号的信噪比的影响，给出依据使传感系统光电接收电路输出信号信噪比最大这一最佳意义下ＡＰＤ雪崩因子的表达式，并对此结果进行了分析。     

Effect of external fluctuations on the Fréedericksz transition in an analogue simulator

The influence of multiplicative external fluctuations (noise) on the phenomenological equation describing the Fréedericksz transition has been studied by means of an electronic analogue simulator. Measurements were made of the stationary probability density for a wide range of fluctuation intensities and correlation times, for both dichotomous and Gaussianly distributed noise. For dichotomous forcing, the resultant phase diagrams at particular values of the field intensity parameter were found to be in satisfactory agreement with exact theoretical predictions by Horsthemkeet al. In the (physically more realistic) case of Gaussian fluctuations, for which no theory is currently available, the results obtained were distinctively different. A physically motivated discussion is given to account for the interesting differences and similarities of behavior found for the two types of external noise.     

基于相空间重构的降噪技术研究

探讨了基于相空间重构的局部线性映射算法在非线性时间序列降噪技术中的应用,并给出了算法中主要参数的选取方法.实验结果表明,该算法的降噪效果明显优于传统的线性信号滤波技术.并且针对多数实测数据的原始动态模型未知的特点,提出通过计算降噪前后时序信号的关联维数作为评判降噪效果的工具,克服了已有方法中无法计算该类时序信号降噪水平的缺点.     

FTIR spectroscopy of ethyl benzoate-titanium tetrachloride complexes with application to supported Ziegler-Natta catalysts

Several methods using linear predictionz-transformation and autoregression have been applied to FTIR spectral analysis to reduce noise and improve resolution of an emission spectrum obtained from the truncated interferogram.     

粒子成像测速法中询问域大小的选择与粒子位移量的关系

通过分析询问域大小对底片乳剂颗粒产生的散斑噪声及其散斑噪声对干涉条纹识别的影响,推导出了询问域大小的选择与被测粒子位移量之间的关系,并详细讨论和分析了询问域的大小对所能探测的粒子位移量最大值的限止,以及合理选择询问域大小的依据.     

染料激光中的饱和效应和倍增噪声

研究了单模激光中的倍增噪声和饱和效应,导出了定态激光强度的平均值和归一化方差.同实验值相比较,理论与实验在阈值附近符合得很好.而在远高于阈值时,含有饱和效应的激光模型能更好地描述实际应用中的激光.