能谱涨落统计特征稳定性分析

通过引入权重,并用一能级数等于简并谱的无趋向性序列为标准去衡量 简并邻间距谱的趋向性,由此建立分析简并谱涨落统计特征稳定性的MKS无参量试验法;根 据该方法,具体分析、比较了H2O分子低激发态与高激发态振动能谱涨落统计特征,找出 了从低激发态向高激发态过度时涨落统计特征明显改变点。     

可积量子系统的能谱涨落统计特征

运用简单的模型，进行了数值计算和研究了可积量子系统的能谱涨落统计特征，揭示了其特征可能出现的低或高Ｐｏｉｓｓｏｎ律行为。     

一种可能的简并谱NNS分布

利用随机矩阵理论,通过对一特殊情形的简并谱展开研究,得到了简并谱一种可能的最小相邻间距NNS分布函数．研究表明,由于简并的存在,简并谱不仅可分解成随机谱和规则谱两个子谱,同时还影响其规则谱,使规则谱的能级斥力减少．     

C6H6分子振动能谱的涨落统计特征

分析了C6 H6 分子振动能谱的涨落统计特征 .研究结果显示 ,C6 H6 分子振动能谱的涨落统计特征属于低Poisson型 ,即谱刚度值大于Poisson型与Wigner型 ,而能谱分维函数值则小于Poisson型与Wigner型 ,这是一种与通常的Poisson型、Wigner型完全不同的类型 ,该特性在一定程度上反映了C6 H6 分子结构的特殊性 .     

三原子分子体系振动能谱的涨落统计特征

文中对一系列三原子分子模型体系的振动能量本征值谱进行了涨落统计分析，探讨了组成原子质量和键角因素对能谱涨落统计特征的影响及规律。计算结果表明，折合质量的增大，键角的减小等分子结构特征，都将导致能谱结构混沌化程度的增高。     

三原子分子体系振能谱的涨落统计特征

文中对一系列三原子分子模型体系的振动能量本征值谱进行了涨落统计分析，探讨了组成原子质量和键角因素对能谱小组涨落统计特征的影响及规律。计算结果表明，折合质量的增大，键角的减小等分子结构特征，都将导致能谱结构混沌化程度的增高。     

非结构网格生成Bowyer—Watson方法的改进

完善了应用Ｄｅｌａｎｎａｙ原理生成非结构网格的Ｂｏｗｙｅｒ－Ｗａｔｓｏｎ方法。通过求解简化Ｐｏｉｓｓｉｏｎ方程，灵活地控制网格的疏密，通过网格层次的区分，提高了网络的贴体性能；并通过分区，实现了适用于粘流计算的网格生成。     

基于加权TV正则化的X射线CT系统能谱估计方法

在CT硬化伪影校正、双能CT图像重建以及CT辐射剂量计算等实际应用中,X射线的能谱信息具有重要的作用。然而,由于透射测量方程组系数矩阵的病态性、X光子的统计涨落和噪声的干扰,使得EM等能谱估计方法难以获得较精细的能谱刻画。针对该问题,提出一种基于加权TV正则化的X射线CT系统能谱估计方法。首先采用能谱能量范围内带有不同K-edge的材料作为体模以降低投影测量方程之间的相关性。然后,利用CT成像系统的几何参数来获取投影测量数据所对应的准确透射长度信息来减小投影方程的测量误差。最后,综合利用透射衰减测量数据的保真性、轫致辐射能谱部分的连续性、特征辐射能谱部分的离散性、能谱的非负性和归一性以及平均有效衰减系数等信息,使用加权TV正则化方法建立目标函数,利用正则化理论中的L曲线准则通过黄金分割参数搜索策略求得最优正则化参数及对应的能谱估计结果。分别通过不同统计波动模型下的仿真能谱和实际测量数据对算法性能进行了验证,结果表明该方法与EM等方法相比,不受初始能谱的影响,有效提高了能谱估计结果的稳定性和准确性。     

高Q Kerr介质腔中非简并双光子Jaynes－Cummings模型中原子的辐射谱

本文对高Q Kerr介质腔中单个二能级原子与双模腔场非简并双光子相互作用的辐射谱进行了系统研究,在数值计算的基础上,详细分析了Kerr效应对原子辐射谱的影响,从而揭示出一系列重要的新特征.     

准粒子特征与奇奇核的能谱统计

用粒子转子理论模型计算奇奇核⁸⁴Y的能谱,通过分析能谱的最近邻能级间距分布函数和能谱刚性度的变化特点,研究了准粒子特征对奇奇核⁸⁴Y能谱统计特点的影响,发现奇奇核⁸⁴Y的能谱总体上接近混沌;在采用的理论模型中,准粒子特征通过反冲项和科氏力作用项影响能谱,同时能谱具有随着费米能和能隙参量的减小从接近混沌逐渐转变到接近规则的特点 关键词： 奇奇核 粒子转子模型 准粒子特征 能谱统计 NNS分布函数 能谱刚性度     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.