Center positioning of circular interference fringe patterns for fine measurement

A kind of center positioning method of the circular interference fringe patterns was reported in this paper. The whole process was programmed by Matlab for processing the gray-scale images without denoising preprocessing and binary format transformation. The gradient vector field (GVF) based on a complex-valued cost function was used to extract the skeletons of circular interference fringe patterns, and the coordinate of the center was calculated by statistical method in which partial skeletons were selected to calculate the center according to the space topological relationship. Finally, subpixel accuracy and perfect anti-noise ability of the proposed method are demonstrated by the simulation and experimental fringe patterns, respectively. Thus the technique can be used in precision measurement and fine interferometry.     

Soliton interactions for coupled nonlinear Schrödinger equations with symbolic computation

Soliton interactions for the coupled nonlinear Schrödinger equations, governing the propagation of envelopes of electromagnetic waves in birefringent optical fibers, are investigated with symbolic computation. Based on the Hirota method, analytic two- and three-soliton solutions for this model are derived. Relevant interaction properties are discussed. Stationary bound vector solitons with the periodic attraction and repulsion are obtained. Soliton intensity could be reduced if the nonlinearity in optical fibers is enlarged, while the soliton period could be prolonged as the group velocity dispersion in the anomalous dispersion regime of optical fibers increases. Through the asymptotic analysis for the two-soliton solutions, interactions between two solitons are proven to be elastic. Besides, parallel soliton transmission systems without soliton interactions are presented. Moreover, interactions between the regular and bound vector solitons are studied. Dual complex structures and triple-soliton bound states are presented. Results could be of certain value to the studies on the soliton control and optical switching technologies.     

Types of coefficient constraints of coupled nonlinear Schrödinger equations for elastic and inelastic interactions between spatial solitons with symbolic computation

With symbolic computation and Hirota method, analytic two-soliton solutions for the coupled nonlinear Schrödinger (CNLS) equations, which describe the propagation of spatial solitons in an AlGaAs slab waveguide, are derived. Two types of coefficient constraints of the CNLS equations to distinguish the elastic and inelastic interactions between spatial solitons are obtained for the first time in this paper. Asymptotic analysis is made to investigate the spatial soliton interactions. The inelastic interactions are studied under the obtained coefficient constraints of the CNLS equations. The influences of parameters for the obtained soliton solutions are discussed. All-optical switching and soliton amplification are studied based on the dynamic properties of inelastic interactions between spatial solitons. Numerical simulations are in good agreement with the analytic results. The presented results have applications in the design of birefringence-managed switching architecture.     

原子荧光光谱法测定饲料添加剂中的汞

建立了原子荧光光谱法测定硫酸盐型饲料添加剂中汞的方法,讨论了共存离子的干扰情况。在最佳实验条件下.方法的检出限达到了0.0096ng/mL,加标回收率在97.2%—109.7%之间,相对标准偏差为1.03%,被分析的硫酸盐型饲料添加剂中的共存离子对汞的测定基本无干扰。方法可用于硫酸盐型饲料添加剂中的汞的测定。     

H2/Air/CO2点火过程中的热辐射和化学反应效应

本文采用基于详细化学反应机理的化学反应流自适应数值模拟技术,研究了添加二氧化碳对氢气/空气预混气体点火的影响,获得了不同当量比下最小点火能随稀释率的变化情况。本文引入最小点火能的热辐射敏感度与化学反应敏感度,重点分析了CO₂的热辐射效应和化学反应效应对最小点火能的影响。研究结果表明二氧化碳的热辐射效应和化学反应效应只有在接近极限稀释率时才会导致最小点火能有显著升高。     

Generation of dual-wavelength domain-wall rectangular-shape pulses in HNLF-based fiber ring laser

The generation of dual-wavelength domain-wall rectangular-shape pulses in a highly nonlinear fiber (HNLF)-based fiber ring laser is experimentally demonstrated. The dual-wavelength lasing operation is realized by employing the intracavity birefringence-induced spectral filtering effect. An 85 m long HNLF is introduced into the fiber ring laser to enhance the nonlinear effect, which is favorable for the cross coupling between the two lasing beams. Experimentally, it was found that the interval of two domain walls in the time domain could be adjusted by simply tuning the linear cavity phase delay, which results in the achievement of different output pulse shapes. By properly rotating the polarization controller (PC), the dual-wavelength rectangular-shape pulses could be efficiently obtained. The proposed fiber laser provides a simple and efficient way to generate rectangular-shape pulse.     

Conservation Laws and Analytic Soliton Solutions for Coupled Integrable Dispersionless Equations with Symbolic Computation

Under investigation in this paper are two coupled integrable dispersionless (CID) equations modeling the dynamics of the current-fed string within an external magnetic field. Through a set of the dependent variable transformations, the bilinear forms for the CID equations are derived. Based on the Hirota method and symbolic computation, the analytic N-soliton solutions are presented. Infinitely many conservation laws for the CID equations are given through the known spectral problem. Propagationcharacteristics and interaction behaviors of the solitons are analyzed graphically.     

单粒子表面增强拉曼光谱的二维成像研究

以单个椭球形Fe₂O₃@Au核壳粒子作为SERS活性基底, 苯硫酚(TP)作为探针分子, 研究了椭球形粒子表面SERS效应的分布, 对比了粒子尖端以及中间SERS效应的差别. 为了得到单个粒子表面不同部分对SERS强度的贡献差别, 通过数学模拟和解析了探针分子SERS的二维成像(2D-mapping)信号, 获得了粒子边缘不同点的SERS效应. 模拟分析结果表明, 当xy平面内粒子在垂直入射(z轴)平面波作用下, 单个椭球形Fe₂O₃@Au核壳粒子表面单位面积上的SERS强度相差极大, 粒子长轴方向端点附近单位面积上的SERS效应最大, 而其它表面部分较弱, 其中与短轴平行方向的表面附近为最弱, 差异可达到约2~3个数量级. 若考虑SERS增强主要为电磁场增强的尖端效应, 则单个椭球形粒子尖端的局域感应电磁场为垂直方向的5倍.     

叶蜡石的有机活化及其对对苯二酚的吸附

采用湿法活化工艺选择不同类型的有机活化剂对叶蜡石粉体进行了活化处理,并进行了对水中极性有机物对苯二酚的吸附实验.结果表明,有机活化处理后的叶蜡石能明显提高对对苯二酚的吸附能力,可使水溶液中对苯二酚的去除率从26.8%提高到83.1%.优选的叶蜡石原土的吸附条件为;室温,粒径<7.9μm,pH值为6.05～6.25,固液比为1:8,振荡时间25min.叶腊石活化条件为:活化剂用量1%,活化温度75℃,活化时间2h;活化叶腊石的吸附条件为:室温,固液比为1:8,振荡时间为30min,溶液pH值为6～7.同时还利用XRD、IR和SEM等分析方法测试了改性前、后叶蜡石粉体的结构,并探讨了叶蜡石的活化机理.     

Isospin Effects in the Isospin Fractionation Process in Intermediate Energy HeavyIon Collisions

Based on the isospin dependent quantum molecular dynamics model we investigated the isospin effects of isospin fractionation (N/Z)_gas/(N/Z)_liq from the neutron-proton ratio of colliding system and impact parameter. Here (N/Z)_gasand (N/Z)_liq is the neutron-proton ratio of nucleon emission for gas phase and that of fragment emission for liquid phase, respectively. Our results show that the (N/Z)_gas/(N/Z)_liq increases with the neutron-proton ratio of colliding systems when the system mass, incident energy and impact parameters are fixed. For the neutron-rich systems, the (N/Z)_gas/(N/Z)_liq depends sensitively to the form of symmetry potential and weakly on the isospin effect of the in-medium nucleon-nucleon cross section; For the neutron-poor colliding system, however, the (N/Z)_gas/(N/Z)_liq is not sensitive to both the form of symmetry potential and the isospin effect of the in-medium nucleon-nucleon cross section. We also found that the dependence of (N/Z)_gas/(N/Z)_liq on the impact parameter is not obvious. Detailed discussion and explanation for leading to these results are presented in the paper. According to these results, we propose that (N/Z)_gas/(N/Z)_liq can be directly compared with the experimental data to get the information about symmetry potential.