Numerical analysis of the As2Se3 chalcogenide glass multi-ring photonic crystal fiber

A novel kind of As₂Se₃ chalcogenide glass multi-ring photonic crystal fiber is proposed. The characteristics of multi-ring photonic crystal fiber have been studied by the finite element method. Compared with another two kinds of single-core photonic crystal fibers, the multi-ring PCF can make the perfect combination of the effective mode area, the nonlinearity coefficient and multi-zero dispersion. It can achieve high power supercontinuum generation in middle infrared band; It also can be used in high-power pulsed laser fiber amplifier and high-power ultra-short pulse laser transmission in far infrared band.     

Characterizing the rotation of non symmetric objects in an optical tweezer

We present an optical tweezer based study of the rotation of microscopic objects with shape asymmetry. Thermal fluctuations and rotations are simultaneously monitored through laser back scattering. The rotation causes a modulation in intensity of the back scattered light incident on a quadrant photo detector. The resulting power spectrum is a modified Lorentzian with additional peaks located at the fundamental rotational frequency of the object and at the integer harmonics. The manifestation of these peaks reveals that the rotations are periodic but with varying angular velocity. We model our experimental results to illustrate the hydrodynamic interplay between the rotor and the surrounding medium that results in the time dependence of the angular speed of the former. Further, we demonstrate the use of video microscopy for characterization of low reflectivity rotors, such as biological cells. We propose through these studies that an analysis of these rotations can provide insights into the role of hydrodynamics at micron levels.     

Multichannel double-polarization bandpass optical filter utilizing evanescent wave

A multichannel double-polarization bandpass optical filter, which has the performance of variable channel interval, is theoretically proposed. The filter consists of a stack of two one-dimensional photonic crystals (1D PCs). Based on the resonant couple of evanescent waves localized at the interfaces between neighboring layers, the linear transmission properties of the filter are numerically simulated by the transfer matrix method. The simulation results show that channel number of the filter can be changed by varying the thickness of the middle layer in the centrosymmetric 1D PC structure, while the bandwidth and wavelength of the channel can be adjusted by the incident angle of light. This work may be helpful in designing multichannel double-polarization bandpass optical filter in optical communication systems.     

Simultaneous chromatic dispersion monitoring,extinction ratio enhancement and wavelength conversion using four-wave mixing

This paper presents a multi-functional all-optical device performs simultaneous chromatic dispersion (CD) monitoring, extinction ratio (ER) improvement and tunable wavelength conversion using four-wave mixing (FWM) in a single piece of highly nonlinear optical fiber (HNLF). The multi-functional ability arises from the nonlinear power transfer function (PTF) between the input signal and the output idler wave, which not only maps the CD information of the signal onto the average power of idler wave, but also transfers the data information to the idler wave with ER enhancement, making the device compact and cost effective. Furthermore within the wavelength tuning range the monitoring sensitivity and output ER can be much higher compared to all optical monitors and regenerators proposed before. Numerical simulations are then used to demonstrate the efficiency of this method.     

二元Block-Basu型指数分布的独立性与不相关性

若（X,Y）服从二元Block-Basu型指数分布,则X,Y相互独立与不相关是等价的．还给出了X,Y的相关系数和尾部相关系数．     

黑鱾（Girellaleonina）淀粉酶与蛋白酶的活力研究

通过测定1＋龄黑鱾的胃、盲囊、肝脏和肠道4个消化组织中蛋白酶和淀粉酶活性,并研究其与温度及pH值的关系,可以为黑纪的合理投饵提供理论依据．实验设9个温度梯度（10～50℃）和14个pH缓冲液梯度（pH2．0～9．0）,用淀粉-碘显色法测淀粉酶活力,用福林-酚试剂法测蛋白酶活力．结果表明：黑纪盲囊、肠道中淀粉酶和蛋白酶活力均较高,最适温度为35℃,淀粉酶最高活力为每克鲜组织46．02U和42．61U蛋白酶最高活力为每克鲜组织156．52u和147．79U;胃中酶的最适温度为40℃,肝脏中淀粉酶温度要求稍低,最适温度为30℃,酶活力值也最低;胃淀粉酶和胃蛋白酶最适pH值分别为6．5和3．5,盲囊、肠道和肝脏组织中的最适pH值相近,为7．0-8．0．可以认为黑鲍胃中主要存在着酸性蛋白酶,胃是食物蛋白质初步分解消化的场所;Q10值充分反映了温度对消化酶活力的影响,当温度从10℃上升至20℃时。2种消化酶活力增幅显著,可作为开始投饵的温度指标．     

基于连续投影算法的光谱主成分组合优化方法研究

应用连续投影算法(successive projections algorithm, SPA)选择由主成分分析(principal component analysis,PCA)得到主成分的最佳组合。首先对奶粉的短波近红外光谱进行PCA分析, 然后通过SPA得到的脂肪和蛋白质含量预测最佳主成分组合分别为主成分1,2,4,5,6和7以及主成分1,2,3,4,5和8。通过最小二乘支持向量机(Least-squares support vector machine, LS-SVM)对奶粉中脂肪和蛋白质含量进行预测, SPA选择得到的主成分组合均优于分别采用前4个到前8个主成分。 基于SPA得到的主成分组合得到脂肪含量预测结果的确定系数(R2p),预测误差均方根(root mean square error for prediction, RMSEP)和剩余预测偏差(residual predictive deviation, RPD)分别为0.989 0,0.170 3和9.534 3。而蛋白质含量预测结果的R2p,RMSEP和RPD分别为0.987 6,0.134 8和8.927 4。说明SPA能够用于快速有效选取最佳的主成分数, 寻优过程简单快速,并且不用对大量参数进行调试。     

大孔-介孔Ag/PDA/MMS复合材料的制备及其催化性能

用双模板法制备了介孔纳米薄膜构筑的毫米级尺寸的大孔-介孔SiO₂(MMS),通过多巴胺(DA)在其孔道表面氧化自聚合成聚多巴胺(PDA),得到PDA修饰的MMS(PDA/MMS),再经PDA原位还原Ag+制得大孔-介孔Ag/PDA/MMS复合材料。应用扫描电镜、透射电镜、N2吸附-脱附、X射线光电子能谱、X射线衍射、UV-Vis、FT-IR和热重技术对所制得的材料进行表征。结果表明,MMS兼具纳米介孔材料和宏观尺寸大孔材料的优点。Ag/PDA/MMS在催化还原对硝基苯酚(4-NP)反应中展现出高催化活性,转化频率(TOF)达2.97 min^-1。这归因于其独特的结构：相互连通的大孔孔道大大降低了传质阻力,短孔道的介孔显著增加了活性位点的可达性,大的比表面积为反应物提供了大量的活性位点。而且,毫米级尺寸的Ag/PDA/MMS可以很容易从反应体系中分离出来,在5次循环后仍能将4-NP完全转化为对氨基苯酚(4-AP)。另外,Ag/PDA/MMS对亚甲基蓝(MB)的还原也有良好的催化效果。     

SHPB实验中的端面凹陷修正

提出了一种关于霍普金森压杆(SHPB)实验中压杆端面凹陷的分析方法,并在此基础上提出了修 正该凹陷的数据处理技术。将该技术与其他数据处理技术相结合,可提高SHPB实验中应变的计算精度。 该技术使SHPB可以用于小应变范围测试,并使利用SHPB测得完整的、精度及可靠性可与准静态测试相当 的材料动态应力应变曲线成为可能。     

新老混凝土粘结的抗压强度塑性极限分析

对新老混凝土粘结试块进行了抗压强度研究,发现新老混凝土粘结在竖向受压情况下,其抗压强度远低于整浇混凝土的抗压强度.因此,对新老混凝土粘结试块的竖向抗压强度进行相关理论分析,并根据试验,提出了新老混凝土粘结的受压破坏机构;又利用塑性极限分析中的上限定理,得到了新老混凝土粘结抗压强度的理论解.对比理论解与试验值,发现理论解高于试验值,在详细分析原因后,对理论解进行了相应修正.