基于界面信号的扫频光学相干层析成像系统相位矫正方法

由于扫频光源的采集触发信号和采样时钟信号存在时间上的随机延时,导致扫频光学相干层析成像(SS-OCT)系统干涉信号光谱的整体错移,进而引发OCT空间域信号的相位跳变,阻碍了基于相位信息的功能成像.为了获得稳定的相位,便于开展功能OCT的研究,提出了一种基于界面信号的数字相位矫正方法.对界面附近相邻A-line间同一深度的相位信号进行差分运算,计算得到相位跳变的A-line位置与光谱错移量(以像素为单位),然后在原始干涉信号上对齐光谱,重新傅里叶逆变换,得到矫正后的复信号.该数字矫正算法不会引入额外的相位噪声,可以实现OCT信噪比受限的相位探测.通过对反射镜、荧光板和小鼠脑皮层血流的多普勒成像验证了该方法的可行性.     

关于y=√ax+b±√cx+d(ac≠0)的值域的统一解法

2009年武汉市高三年级二月调考理科试卷第9题是:y=√x-3 √x+1的最大值为( ) A.- √2 B.-2√3 C.-√3 D.-2√2 这道题给出的参考答案为D,在评析试卷时,笔者是按照三角代换的思路讲解的. 但有学生却反映说,我们以前不是用向量的数量积公式来做过这类型的题目吗? 为此, 我们一起做了类比思考, 最终寻求到统一解法.     

毫秒延时爆破等效单响药量计算及振速预测

毫秒延时爆破存在同段雷管离散及分段振波叠加效应,对单响药量取值及质点峰值振速的预报带来极大困扰。设计开展毫秒延时爆破试验,建立群孔齐发爆破振速的计算模型,研究并构建炮孔数目对齐发爆破等效药量影响及其取值方法;并基于单孔爆破回归分析结果,提出修正的质点峰值振速与比例距离关系公式。结果表明,群孔齐发爆破等效药量比名义单响药量小,可利用缩比系数和折算炮孔数目进行计算,缩比系数随炮孔数目增加呈指数形式衰减;修正的质点峰值振速与比例距离公式引入的振波叠加因子可反映振波叠加对速度的影响,依据该公式计算得到的质点峰值振速预测值与实测值间平均绝对误差、平均相对误差及均方根误差分别为0.05 cm/s、9.52%、0.059 cm/s,用于现场爆破振动预测切实可行。     

Density functional study of uranyl （VI） amidoxime complexes

Uranyl (Ⅵ) amidoxime complexes are investigated using relativistic density functional theory. The equilibrium structures, bond orders, and Mulliken populations of the complexes have been systematically investigated under a generalized gradient approximation (GGA). Comparison of (acet) uranyl amidoxime complexes ([UO 2 (AO) n ] 2 n , 1≤ n ≤4) with available experimental data shows an excellent agreement. In addition, the U-O(1), U-O(3), C(1)-N(2), and C(3)-N(4) bond lengths of [UO 2 (CH 3 AO) 4 ] 2 are longer than experimental data by about 0.088, 0.05, 0.1, and 0.056 A. The angles of N(3)-O(3)-U, O(2)-N(1)-C(1), N(3)-C(3)-N(4), N(4)-C(3)-C(4), and C(4)-C(3)-N(3) are different from each other, which is due to existing interaction between oxygen in uranyl and hydrogen in amino group. This interaction is found to be intra-molecular hydrogen bond. Studies on the bond orders, Mulliken charges, and Mulliken populations demonstrate that uranyl oxo group functions as hydrogen-bond acceptors and H atoms in ligands act as hydrogen-bond donors forming hydrogen bonds within the complex.     

小波计盒分形维数核爆电磁脉冲信号模糊识别

为了在现有禁核试验条件下开展核爆电磁脉冲探测技术研究,对实测的非均匀采样核爆电磁脉冲数据进行阈值检波、直流剔除、滤波、插值和归一化处理后,采用小波分析提取信号第四尺度小波系数能谱熵、第一尺度和第四尺度小波系数计盒分形维数特征值,在统计分析的基础上分别建立其专用隶属度函数;利用模糊识别理论,对核爆电磁脉冲信号和作为主要探测干扰信号源的闪电电磁脉冲信号进行了模糊识别,获得了总识别率为99.41%的识别效果。     

CCD摄像法采集激光光斑图像方法研究

为了测量大尺寸激光光斑图像,对CCD摄像法采集漫反射的激光光斑图像方法进行了研究。采用CCD摄像机捕获经漫反板反射的激光光斑图像,光斑图像进行去背景处理后,根据系统噪声特性对光斑图像进行提取,再利用透视投影原理对畸变的光斑图像进行了校正,最后根据人眼对彩色图像敏感的特性,利用灰度级一彩色变换法对光斑图像进行了伪彩色处理。结果表明,CCD漫反射法能够准确地测量大尺寸激光光斑图像。     

A general phase retrieval algorithm based on a ptychographical iterative engine for coherent diffractive imaging

Coherent diffractive imaging (CDI) is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine (PIE) is a CDI phase retrieval algorithm that uses multiple diffraction patterns obtained through the scan of a localized illumination on the specimen, which has been demonstrated successfully at optical and X-ray wavelengths. In this paper, a general PIE algorithm (gPIE) is presented and demonstrated with an He-Ne laser light diffraction dataset. This algorithm not only permits the removal of the accurate model of the illumination function in PIE, but also provides improved convergence speed and retrieval quality.     

Modified read-out system of the beam phase measurement system for CSNS

The customized beam phase measurement system can meet the requirement of beam loss control of the radio-frequency quadrupole (RFQ). However, its read-out part cannot satisfy the requirement of China Spallation Neutron Source (CSNS). CSNS uses the Experimental Physics and Industrial Control System (EPICS) as its control system. So it is necessary to develop the EPICS read-out system consisting of EPICS IOC databases, driver support and OPIs. The new system has been successfully tested in the RFQ. In the future, it will be applied to the beam diagnostics of CSNS.     

外激励作用下亚音速二维壁板的复杂响应研究

研究了亚音速流中二维壁板在外激励作用下的复杂响应问题。采用迦辽金方法将非线性运动控制方程离散为常微分方程组,采用数值方法进行计算,研究了壁板系统的复杂响应。应用最大李亚普诺夫指数和庞加莱截面方法对系统的运动性质进行了判定。结果表明,系统随着参数的变化呈现出复杂的响应,系统的周期运动与混沌运动会相间出现;系统由周期运动进...     

用李代数方法解析研究线性三原子分子振动的动力学纠缠

采用李代数方法研究了线性三原子分子非线性伸缩振动的动力学纠缠,给出了描述纠缠行为的线性熵和冯诺伊曼熵的解析表达式,并分别讨论了初态为Fock态和相干态下的HCN和DCN分子伸缩振动纠缠的动力学性质.