随机细胞人工神经网络的稳定性

基于细胞神经网络输出函数饱和线性特性,采用分割状态空间为若干子区域的方法,对处于噪声环境下的细胞神经网络的几乎必然指数稳定性进行了分析.在噪声扰动项分别满足Lipschitz条件和线性条件下,依据平衡点所处子区域位置,得到了对应区域中仅依赖于网络参数构成的矩阵负定性的若干代数判别条件.特别地,如果平衡点为区域内点,所得结果是非常方便检验的.研究结果可供网络设计参考,并可用来计算网络抗干扰强度.     

基于EMD-小波随机消噪模型的GPS/INS组合导航

为提高GPS/INS组合导航精度,提出了EMD-小波INS随机误差削弱模型.首先分析了GPS/INS组合系统的误差特点,给出组合导航的基本原理.基于EMD的多尺度结构,结合小波分解理论,提出基于EMD-小波的GPS/INS组合导航技术路线.采集新南威尔士大学校园内的实测数据,分别选用1s与2s的GPS采样信息和100 Hz的INS数据,进行融合试验.用随机模型消噪前后的INS数据计算导航解,并与GPS测量的位置进行比较,分析误差分布情况.结果表明,滤波后的INS自主导航解要优于滤波前.当GPS更新周期为1 s时,X,Y,Z方向上导航精度分别提高9.07％,13.89％,35.14％,残差最大值分别减小2.62％,19.54％,31.23％.当GPS更新周期为2s时,X,Y,Z方向上导航精度分别提高17.82％,23.46％,22.48％,残差最大值分别减小14.34％,28.85％,17.48％.     

变时滞随机模糊细胞神经网络的全局指数稳定性

通过构造合适的Lyapunov泛函,利用It微分算子和不等式的分析技巧研究一类变时滞随机模糊细胞神经网络平衡点的全局指数稳定性,得到了该模型全局指数稳定的一个时滞独立和一个时滞依赖的充分条件.最后通过数值算例验证结论的有效性.     

S-分布时滞随机区间细胞神经网络的全局指数鲁棒稳定性

利用Lyapunov稳定性理论和随机分析的方法,给出了在均方意义下系统全局指数鲁棒稳定性的判据,并且给出了几乎必然指数稳定性的代数判据,通过仿真例子说明结果的实用性。     

变时滞随机模糊细胞神经网络的均方指数稳定性分析

利用Lyapunov泛函及随机分析技巧研究一类变时滞的随机模糊细胞平衡点的均方指数稳定性,得到了均方指数稳定性的充分条件.该模型同时考虑了模糊不确定性和随机不确定性,更加接近真实的神经网络.最后给出一个例子证明结论的有效性.     

S-分布时滞随机广义细胞神经网络的均方指数稳定性分析

利用Lyapunov泛函方法和随机分析技巧,研究了S-分布时滞随机广义细胞神经网络的全局均方指数稳定性。给出了稳定性判据。仿真实验验证了结论的正确性。     

Quadrupole transitions revealed by Borrmann spectroscopy

The Borrmann effect-a dramatic increase in transparency to X-ray beams-is observed when X-rays satisfying Bragg's law diffract through a perfect crystal. The minimization of absorption seen in the Borrmann effect has been explained by noting that the electric field of the X-ray beam approaches zero amplitude at the crystal planes, thus avoiding the atoms. Here we show experimentally that under conditions of absorption suppression, the weaker electric quadrupole absorption transitions are effectively enhanced to such a degree that they can dominate the absorption spectrum. This effect can be exploited as an atomic spectroscopy technique; we show that quadrupole transitions give rise to additional structure at the L(1), L(2) and L(3) absorption edges of gadolinium in gadolinium gallium garnet, which mark the onset of excitations from 2s, 2p(1/2) and 2p(3/2) atomic core levels, respectively. Although the Borrmann effect served to underpin the development of the theory of X-ray diffraction, this is potentially the most important experimental application of the phenomenon since its first observation seven decades ago. Identifying quadrupole features in X-ray absorption spectroscopy is central to the interpretation of 'pre-edge' spectra, which are often taken to be indicators of local symmetry, valence and atomic environment. Quadrupolar absorption isolates states of different symmetries to that of the dominant dipole spectrum, and typically reveals orbitals that dominate the electronic ground-state properties of lanthanides and 3d transition metals, including magnetism. Results from our Borrmann spectroscopy technique feed into contemporary discussions regarding resonant X-ray diffraction and the nature of pre-edge lines identified by inelastic X-ray scattering. Furthermore, because the Borrmann effect has been observed in photonic materials, it seems likely that the quadrupole enhancement reported here will play an important role in modern optics.     

Ga对β基Co-Ni-Al铁磁性形状记忆合金马氏体和磁性转变的影响

借助光学金相、示差热分析、振动样品磁强计和x-射线能谱分析等分析方法，研究Ga含量对Co41Ni32-Al27-xGax合金马氏体相变和Curie点的影响。研究结果表明：合金马氏体相变温度与Ga含量成正比，在1573和1623K淬火时，X增加1，马氏体相变温度提高25K，但Ga含量对Curie点影响不大；在1573K淬火时，具有高有序度的马氏体相比B2结构相的Curie点高32K，说明结构有序度对Curie点影响较大；淬火温度升高会显著提高合金的马氏体相变温度和Curie点，当淬火温度从1573K升高到1623K时，马氏体相变温度升高43～69K，Curie点平均升高41K；随着Ga含量的增加，合金的熔点降低，在1623K淬火时Co41Ni32Al18Ga9合金发生部分熔化。     

沉淀-漫反射光谱法测定还原糖

通过测定还原糖与斐林试剂反应生成的Cu2O，建立测定还原糖的沉淀—漫反射光谱分析方法．该方法具有操作方便，灵敏度高，试剂用量少(＜1mL)等优点．还原糖在20—120μg范围有良好的线性关系，用于实际样品测定，结果满意．     

减少化验次数的一个优化模型

依据数学理论证明在一定条件下，可以减少化验次数；并给出了选择方法；建立了一个减少化验次数的优化模型。     

金属锌离子对胆绿素的荧光增强作用

研究了不同条件下Ｚｎ２＋对胆绿素（ｂｉｌｉｖｅｒｄｉｎ,ＢＶ）荧光性质的影响作用。发现在无水乙醇、甲醇、ＮＨ３－ＮＨ４Ｃｌ缓冲体系和ＮａＯＨ水溶液中,Ｚｎ２＋均对ＢＶ有显著的荧光增强作用。在ＮａＯＨ水溶液中,在表面活性剂（ｃｅｔｙｌｔｒｉｍｅｔｈｙｌａｍｍｏｎｉｕｍｂｒｏｍｉｄｅ,ＣＴＡＢ）存在下,Ｚｎ２＋与ＢＶ的摩尔比率为２,荧光增强作用达到最大值。借助这一荧光增强技术,可以在室温下使胆绿素水溶液产生特征强荧光（λｅｘ＝４６５ｎｍ,λｅｍ＝５２５ｎｍ）。     

Enhancement of Aminoacylase Activity by Sodium Citrate

IntroductionEnzyme activation is a common phenomenon inbiological studies. Many experiments havesuggested that enzyme activation is caused by theconformational change of the enzyme activesites[14 ] . Other papers have showed that theenhancement of enzyme activity is associated withsecondary or tertiary structural changes[5] .This study analyses aminoacylase (N-acylamino acid amidohydrolase,EC3 .5 .1 .1 4) ,adimeric protein,consisting of two identicalsubunits each with an active site. The zin…     

降低动叶与静叶互干扰噪声研究

本文分析旋转噪声的产生机理，采用增大动叶和静叶轴向间距的降噪方法进行试验，结果表明，适当增大轴向间距，可降低风机的噪声，并且在保证风机气动特性前提下，有一个最佳的间距，使风机的噪声最低。     

镥对铕-诺氟沙星体系的荧光增强效应

研究了Lu-Eu-诺氟沙星(NFLX)-十二烷基硫酸钠(SLS)组成的共发光体系。研究发现Lu3 的加入,使Eu-NFLX-SLS体系的荧光强度提高了7倍。在最佳试验条件下,Eu3 的线性范围是3.0×10-8~1.0×10-6mol/L,当信噪比为3时,Eu3 的检出限为4.4×10-9mol/L,建立了一种较灵敏的Eu3 的测定方法。     

Local conformation transitions of linear DNA induced by cisplatin

Cisplatin is the most successful anti-tumor drug, and its pharmacological property is generally considered to derive from the modification of DNA molecules. Structural modifications of short DNA induced by cisplatin have already been investigated. However, the conformation transitions induced by cisplatin are not clear. In the present letter, we have studied the effect of low-concentration cisplatin on DNA conformation by using AFM imaging. We observed formations of micro-rod structures of linear DNA induced by cisplatin. A method is presented to quantitatively analyze the occurrence of micro-rod structures. We found that the formation of micro-rod structures depends on the DNA sequence. Based on the results, we proposed a physical mechanism to explain the local conformation transitions of DNA molecules under the influence of cisplatin.