用拉曼光谱测量GeSbSe玻璃的热导率

本文根据斯托克斯和反斯托克斯拉曼光谱散射截面的不同,测量样品表面温度,并进一步提出了一种测量材料热导率的新方法.利用该方法系统地研究了GexSb10Se90-x,GexSb15Se85-x和GexSb20Se80-x三个系列的GeSbSe玻璃的热导率,从而证明该方法的实用性和可靠性,同时分析其化学组分对材料结构和热导率的影响.该方法测量获得的热导率与文献报道的热导率基本一致,表明拉曼光谱法测试材料的热导率简单、快捷,是一种实用的测量材料热导率的方法.结果表明每个系列硫系玻璃的热导率随着Ge浓度的增加而增加,在等于或近似化学配比组分处,硫系玻璃的热导率达到最大值,然后随着Ge含量的继续增加而降低.认为GeSbSe硫系玻璃热导率表现出的阈值现象归因于GeSbSe三元网络结构分离为二元结构的结果.     

基于Newmark算法的任意磁化方向铁氧体电磁散射时域有限差分分析

利用坐标系转换矩阵给出实验室坐标系中饱和磁化铁氧体的频域磁导系数张量,再通过频域到时域的转换关系jω→?/?t得到一个二阶微分方程形式的时域本构关系.然后采用Newmark方法求解时域本构关系从而给出一种适用于处理任意磁化方向铁氧体电磁问题的Newmark时域有限差分算法.利用此算法计算了饱和磁化铁氧体层的反(透)射系数和饱和磁化铁氧体球的后向雷达散射截面,所获得的结果验证了此算法的正确有效性.     

基于微扰近似的圆锥表面光散射*

由Hueygen原理出发,介绍了粗糙表面的光散射特性.基于微扰近似,在不考虑遮蔽效应和圆锥顶点的散射情况下,分析了圆锥物体的光散射特性,推导了圆锥物体对平面光的散射场解析表达式.计算了圆锥表面在高度起伏均方根不同情况下对1.06μm光波的散射,并且得到了入射角一定的情况下,不同观察方向的散射光强分布曲线.结果表明,在观察方位角不变时,圆锥的散射光强随观察角顶角的增加先增大后减小|在观测方位角一定时,散射光强随高度起伏均方根的增加而减小,且随观察方位角呈对称分布.     

基于支持向量描述的自适应高光谱异常检测算法

提出了一种应用于高光谱异常检测的自适应支持向量数据描述方法.根据高光谱数据和局部异常检测模型的特点,通过局部背景分波段二阶分布统计,分析了核参量与局部背景总体标准差的变化关系,构造了随检测背景变化的局部检测核参量,使得检测算法针对不同背景分布自适应地调整检测核参量.克服了传统支持向量描述算法由于采用固定核参量带来的复杂背景下检测性能下降的问题.通过模拟数据和真实高光谱数据的测试检验,接收机特性曲线表明该算法相对于传统固定核参量支持向量数据描述方法,在相同虚警概率下检测概率提高了10%.     

New Exact Solutions of （1 ＋ 1）-Dimensional Coupled Integrable Dispersionless System

This paper applies the exp-function method, which was originally proposed to find new exact travelling wave solutions of nonlinear evolution equations, to the Riccati equation, and some exact solutions of this equation are obtained. Based on the Riccati equation and its exact solutions, we find new and more generalvariable separation solutions with two arbitrary functions of (1+1)-dimensional coupled integrable dispersionless system. As some special examples, some new solutions can degenerate into variable separation solutions reported in open literatures. By choosing suitably two independent variables p(x) and q(t) inour solutions, the annihilation phenomena of the flat-basin soliton, arch-basin soliton, and flat-top soliton are discussed.     

深圳城市气溶胶物理光学特性的观测研究

气溶胶是影响气候变化和空气污染的重要因子.在深圳地区展开气溶胶观测实验,可以获得可靠的光学物理特征,进而有助于准确评估气溶胶在新型超极城市区域的气像和环境效应.本文利用2010年12月至2011年8月太阳光度计、黑碳和浊度计等气溶胶观测资料,分析了新型超级城市深圳地区的气溶胶物理光学特性.深圳地区气溶胶呈明显季节变化,冬、春季由于城市污染性气溶胶的影响,气溶胶光学厚度和Angstrom波长指数都较大,夏季受海盐气溶胶的影响,光学厚度较小,Angstrom波长指数也较小.光学厚度与Angstrom 波长指数对比表明城市综合性污染是引起深圳气溶胶高光学厚度的主要原因.深圳地区气溶胶的散射系数、吸收系数的平均值(标准偏差)分别为178.7×10^-6 m^-1(126.6×10^-6 m^-1)和32.5×10^-6 m^-1(18.1×10^-6 m^-1),均低于珠三角腹地多年观测平均值的二分之一和国内其他大型城市观测值.而单次散射反照率为0.81,与珠三角其他地区得到的结果接近.此外,气溶胶吸收、散射和单次散射反照率呈明显日变化,可能主要受大气边界层变化的影响.     

Semiclassical calculation of the recurrence spectra of He Rydberg atom in perpendicular electric and magnetic fields

Closed orbit theory is a semiclassical technique for explaining the spectra of Rydberg atoms in external fields. By developing the closed orbit theory from two degrees of freedom to three non-separable degrees of freedom, we calculated the recurrence spectra of He Rydberg atom in perpendicular electric and magnetic fields. The closed orbits in the corresponding classical system have also been obtained. Fourier transformed spectra of He atoms have allowed direct comparison between the resonance peaks and the scaled action values of closed orbits, whereas the nonhydrogenic resonance can be explained in terms of the new orbits created by the core scattering. The semiclassical result is in good agreement with the quantum spectra, which suggests that our method is correct.     

Light-induced scattering in SBN：Cr crystal under external electric fields and its suppression

In this paper, the enhancement of light-induced scattering in congruent SBN:Cr (Sr_{0.61}Ba_{0.39}Nb_2O_6:Cr) crystals in the presence of an externally applied electric field and its suppression are studied. If a coherent image is focalized in SBN:Cr crystal without applying external electric field, the output image will remain clear, because of the weak photorefractive effect in the crystal. When a field is applied properly along the crystal axis, markedly enhanced scattering from the signal beam and the output image dispersion can be observed due to the increase of the photorefractive two-beam coupling gain and the light-induced index change in SBN:Cr crystals. By introducing a coherent or incoherent beam with higher intensity the light-induced scattering can be suppressed through the erasure of scattering gratings. The difference between coherent and incoherent beam is that the former can also amplify the signal beam as the scattered light is removed, whereas the latter can only make the signal beam revert to its initial state. The results obtained under different experimental conditions are consistent with theoretical analysis.     

An approach to the detection of underwater remote target

An approach to the detection of underwater remote target by estimating its backscattering coefficient is presented. The key to this approach is that the echo signal is represented in state-variable model and the back-scattering coefficients of target are contained in dynamic noise of this model, thus underwater target can be detected by estimating this dynamic noise, i.e., deconvolving this model. When all noise statistics are a priori known, an optimum deconvolution algorithm based on the optimum state filter is derived, or else, an adaptive deconvolution algorithm based on the adaptive state filter of alternatively estimating the vector state and the noise statistics is developed. In the final simulation test, an echo signal with SNR equal to -6.1 dB is proceeded using the aforementioned two deconvolution algorithms, respectively, and the results demonstrate good performance of the approach.     

一种用表面增强拉曼光谱进行免疫检测的方法

一种结合表面增强拉曼(SERS)技术和纳米粒子标记技术,通过银增强来实现免疫检测的方法。将p-巯基苯甲酸(MBA)作为探针,固定在免疫金溶胶粒子表面形成纳米标记,其与被基底捕获抗原分子发生免疫识别。通过银增强技术,在"三明治"结构对探针进行拉曼检测。