Linear analysis of degree correlations in complex networks

Many real-world networks such as the protein–protein interaction networks and metabolic networks often display nontrivial correlations between degrees of vertices connected by edges. Here, we analyse the statistical methods used usually to describe the degree correlation in the networks, and analytically give linear relation in the degree correlation. It provides a simple and interesting perspective on the analysis of the degree correlation in networks, which is usefully complementary to the existing methods for degree correlation in networks. Especially, the slope in the linear relation corresponds exactly to the degree correlation coefficient in networks, meaning that it can not only characterize the level of degree correlation in networks, but also reflects the speed that the average nearest neighbours’ degree varies with the vertex degree. Finally, we applied our results to several real-world networks, validating the conclusions of the linear analysis of degree correlation. We hope that the work in this paper can be helpful for further understanding the degree correlation in complex networks.     

钾原子中由四波,六波混频过程产生的相干辐射

当双光子共振激发钾原子于６Ｓ能级时，由光泵受激辐射，串级受激辐射参与的四波、六波混频以及电离复合的布居过程，产生了位于可见区的诸多相干辐射，文中对混频机制进行了分析和讨论，并对所测得的相干辐射进行了标识。     

Temperature Dependence of Dark Lines in Coherent Population Trapping

We measure the signal amplitude and linewidth of a dark line in coherent population trapping in the Rb vapour cell filled with mixed buffer gas N2 and Ar as a function of cell temperature. We find that the dark line signal amplitude increases with temperature up to a maximum at 49℃ and then drops at higher temperatures due to quenching effects of N2. The linewidth of the dark line remains basically constant, at 1080 Hz. We also measure the linewidth of the dark line as a function of laser intensity. The linewidth increases linearly with laser intensity. An intrinsic linewidth （FWHM=896 Hz at 3.4 GHz） of the Rb cell is obtained.     

快脉冲直线变压器驱动源模块的原理及实验

 介绍了直线型变压器驱动源（LTD）产生快脉冲的基本原理及技术优势,阐述了快脉冲LTD模块设计的要点,设计了输出脉冲上升时间小于100 ns的快脉冲LTD模块,并进行了初步的实验研究。实验得到该LTD模块充电±16 kV时,短路放电的电流峰值为23.7 kA,电流振荡1/4周期为69.6 ns;充电±50 kV驱动0.85 Ω负载时,电流峰值为41.4 kA,上升时间为36.8 ns（10%~90%）和60.8 ns（0~100%）。     

焊缝散射对板中超声水平剪切导波直线合成孔径阵列成像的影响

为探讨焊缝散射与板中超声导波阵列成像之间的关系,提出了将散射渡越时间矩阵作为分析工具用来开展焊缝散射对板中超声水平剪切(Shear horizontal,SH)导波直线合成孔径阵列成像影响的研究。运用散射因子和散射渡越时间矩阵描述焊缝散射,结合分析超声SH导波直线阵列信号所特有的圆锥曲线特征和合成孔径成像算法,从导波阵列信号和阵列成像机理出发,重点研究了焊缝散射因子和散射渡越时间矩阵在阵列成像中的作用。结果显示,焊缝散射易造成同一成像散射体反射声波的阵列信号形成\     

非等间距高频波导线阵列指向性研究

研究了非等间距高频波导组成的线阵列的远场垂直指向性。提出了更符合实际应用的高频波导线阵列非等间距排列模型。通过分析同相点声源阵列的指向性,结合扬声器线阵列乘积理论得到了计算所提出模型远场垂直指向性的方法,对模型进行了有限元仿真,并实验验证了理论计算值的准确性,最后分析了高频波导线阵列非等间距排列对指向性的影响。结果表明:该方法简单有效。在有效辐射率相等的情况下,非等间距高频波导线阵列与等间距线阵列的远场指向性主瓣差异很小。     

Wideband Antireflection Film Fabricated by Glancing Angle Deposition

Graded-index ZrO2 films has been fabricated on K9 glass by glancing angle deposition. Because the index mismatch at the interface has been reduced, the film results in wideband high-transmission antireflection. From 400nm to 1200nm, the film reflection is lower than 0.8% and the lowest value is 0.2% at 432nm.     

KDP晶体折射率非均匀性检测系统

基于正交偏振干涉法,建立了KDP晶体折射率非均匀性的检测系统,并可实现晶体相位失谐角的间接检测.波前检测系统实现了测试光偏振态的精密控制与切换,采用波长调谐相移的方法去除了测试过程中参考面倾斜引入的误差,优化了抗振动相移算法,提高了波前测试的测量准确度及重复性.通过折射率非均匀性分析算法的设计,解决了晶体厚度变化引入的误差等.小口径晶体元件的测试结果表明系统的折射率非均匀性检测准确度(均方根值)优于10~(-6).     

Exact Solutions for a Nonisospectral and Variable-Coefficient KdV Equation

The bilinear form for a nonisospectral and variable-coefficient KdV equation is obtained and some exact soliton solutions are derived through Hirota method and Wronskian technique. We also derive the bilinear transformation from its Lax pairs and find solutions with the help of the obtained bilinear transformation.     

光学渡越辐射测量中能量分辨精度分析

 基于光学渡越辐射原理的用于高能强流电子束束流参数在线测量及诊断系统,具有时间响应快、分辨率高等特点,可以测量电子束的束剖面、发散角、能量等多个参数。分析了测量系统的结构参数（包括了透镜的焦距、成像面位置、CCD像元尺寸）对电子束能量测量精度的影响,并在理论上模拟了电子束的发散角的影响。还根据系统数据的特点,阐述了数据噪声对能量测量结果精度的影响,指出了光学渡越辐射测量中电子束能量分辨精度受到多种因素的影响,需要在数据处理时考虑修正。