调频信号的单模激光线性模型随机共振

对单模激光增益模型的光强方程加入调频信号,用线性化近似方法计算了以δ函数形式关联的两白噪声驱动下光强的输出功率谱及信噪比. 结果表明,信噪比随抽运噪声和量子噪声强度的变化可出现典型随机共振,受调制信号振幅的影响,信噪比随载波信号频率和调制信号频率的变化出现抑制、单调上升、共振、抑制和共振等几种情况. 关键词： 抽运噪声 单模激光 随机共振 调频信号     

超光谱成像仪狭缝热光谱特性的分析

介绍了在狭缝超光谱成像仪中的重要作用。推导出在温度水平变化时,狭缝宽度尺寸的变化对超光谱成像仪光谱带宽与信噪比的影响,得到了超光谱成像仪狭缝的热光谱特性。比较了两类常见狭缝的热光谱特性,得出热特征尺寸与其导热率乘积越小的狭缝热光谱特性也越好的结论。     

扫描型热像系统均匀性校正方法研究

随着热像系统时域噪声等效温差（NETD）的不断下降,残余固定图形噪声（RFPN）的不稳定性成为制约系统性能,特别是制约系统识别能力的一个关键因素。通过分析热像系统响应非均匀性产生的机理,介绍一种扫描型热像系统获得场景平均辐照度点的方法,实现了以场景平均辐照度点为校正基准点的动态校正。采用该方法研制的热像系统在（0～50）℃场景动态范围内可使系统的RFPN小于15mK。通过样机冬、夏两季外场试验以及各种环境试验,验证了该校正方法在热像系统温度发生变化以及场景辐照度发生变化时具有良好的适应性。     

System Size Resonance Associated with Canard Phenomenon in a Biological Cell System

通过研究发现,内噪声对细胞内钙振荡是有影响的,当体系处于由确定性方程所确定的稳定区域时,如果考虑内噪声的作用,就会有随机的钙振荡发生. 并且这种振荡的行为随着体系尺度的变化出现两个最大值,表明了尺度共振现象的发生. 这种行为是与体系的Canard现象密切相关的. 最佳的体系尺度与真实的细胞体积是相吻合的,并且这种吻合基本不随控制参数的改变而改变.     

热噪声对约瑟夫森结I-V特性及微波感应台阶的影响研究

采用数值仿真的方法研究了热噪声对约瑟夫森结I-V特性及微波感应台阶的影响。研究表明,热噪声导致约瑟夫森结的I-V特性曲线呈现"圆拱化",也使得微波感应台阶高度减小。得出了取不同约瑟夫森结临界电流和结电阻时,热噪声对台阶的影响规律     

基于GA-BP神经网络的加速工况车内声品质研究

遴选出15辆乘用车三挡全油门加速工况车内噪声,选择专业评审者进行主观评价试验,选择具有噪声时变特征的4个客观评价参量,基于GA-BP神经网络建立精准的预测模型,同时将用该模型与多元线性回归模型得出的结果进行对比。研究表明,GA-BP神经网络模型更适合描述车内噪声品质评价的复杂性和非线性,可以获得更好的预测结果,可较大程度的提高预测精度。     

Vacuum-gap-based lumped element Josephson parametric amplifier

We propose a lumped element Josephson parametric amplifier with vacuum-gap-based capacitor.The capacitor is made of quasi-floating aluminum pad and on-chip ground.We take a fabrication process compatible with air-bridge technology,which makes our design adaptable for future on-chip integrated quantum computing system.Further engineering the input impedance,we obtain a gain above 20 dB over 162-MHz bandwidth,along with a quasi quantum-limit noise performance.This work should facilitate the development of quantum information processing and integrated superconducting circuit design.     

Gold-Catalyzed Cross-Coupling Reactions: An Overview of Design Strategies,Mechanistic Studies,and Applications

Transition-metal-catalyzed cross-coupling reactions are central to many organic synthesis methodologies. Traditionally, Pd, Ni, Cu, and Fe catalysts are used to promote these reactions. Recently, many studies have showed that both homogeneous and heterogeneous Au catalysts can be used for activating selective cross-coupling reactions. Here, an overview of the past studies, current trends, and future directions in the field of gold-catalyzed coupling reactions is presented. Design strategies to accomplish selective homocoupling and cross-coupling reactions under both homogeneous and heterogeneous conditions, computational and experimental mechanistic studies, and their applications in diverse fields are critically reviewed. Specific topics covered are: oxidant-assisted and oxidant-free reactions; strain-assisted reactions; dual Au and photoredox catalysis; bimetallic synergistic reactions; mechanisms of reductive elimination processes; enzyme-mimicking Au chemistry; cluster and surface reactions; and plasmonic catalysis. In the relevant sections, theoretical and computational studies of Au^I/Au^III chemistry are discussed and the predictions from the calculations are compared with the experimental observations to derive useful design strategies.