光纤Bragg光栅的饱和效应

光纤 Bragg光栅的饱和效应可引起二阶衍射,并使一阶衍射的峰值反射率下降.本文利用折射率变化模型和耦合模理论,模拟了饱和情况下 Bragg光栅的一阶和二阶衍射谱,并讨论了饱和系数对一阶和二阶衍射的 Bragg波长和峰值反射率的影响.数值模拟结果与参考文献中的实验结果相吻合.     

Fast stepwise procedures of selection of variables by using AIC and BIC criteria

Fast stepwise procedures of selection of variables by using AIC and BIC criteria are proposed in this paper. We shall use a short name “FSP” for these new procedures. FSP are similar to the well-known stepwise regression procedures in computing steps. But FSP have two advantages. One of these advantages is that FSP are definitely convergent with a faster rate in finite computing steps. Another advantage is that FSP can be used for large number of candidate variables. In this paper we also show some asymptotic properties of FSP, and some simulation results.     

Synthesis of a S-linked heparan sulfate trisaccharide as the substrate mimic of heparanase

An approach to the construction of the β-(1→4)-S-linkage between a glucuronic and a glucosamine unit, and then to the synthesis of a heparan sulfate trisaccharide containing such a linkage (1) as a nonhydrolyzable substrate mimic of heparanase was developed.     

Inverse regression method in data structure analysis

In order to explore the nonlinear structure hidden in high-dimensional data, some dimension reduction techniques have been developed, such as the Projection Pursuit technique (PP). However, PP will involve enormous computational load. To overcome this, an inverse regression method is proposed. In this paper, we discuss and develop this method. To seek the interesting projective direction, the minimization of the residual sum of squares is used as a criterion, and spline functions are applied to approximate the general nonlinear transform function. The algorithm is simple, and saves the computational load. Under certain proper conditions, consistency of the estimators of the interesting direction is shown.This project is supported by the National Natural Science Foundation of China.In Commemoration of the 15th Anniversary of the Acta Mathematicae Applicatae Sinica.     

Continuous synthesis of CdSe-ZnS composite nanoparticles in a microfluidic reactor

ZnS-coated CdSe composite particles have been continuously synthesized in a microfluidic reactor. By using this system, CdSe particles and a ZnS coating can be produced in sequence, and the particle size and layer thickness can be directly adjusted by the residence time. It demonstrated that the continuous synthesis in the microreactor was a simple and efficient way to prepare composite particles with different structures and determine the optimized experimental conditions.     

Modified micro-space using self-organized nanoparticles for reduction of methylene blue

By using silica layers bound to the surface of the inner wall of the microchannel via a self-assembly technique which relies on capillary forces to organize the colloids, TiO2 particles were attached to the inner surface of a microcapillary. The reduction rate of methylene blue increased by more than 150 times in the SiO2/TiO2 modified micro-space compared to that in a batch system.     

线性平稳序列的自相关分析

本文的目的在于,对于线性平稳时间序列的样本、自协方差、自相关和偏相关函数的渐近性质,给出一个比较系统的描述.以下内容将是被论及到的,上述样本函数的矩的性质,渐近正态分布,强相容性和几乎处处收敛的速度等.我们将给出在上述诸方面的某些重要的新的成果,这些结果都是在时间序列分析的文献中被建立起来的,与此同时,我们还对其中比较深的结果给出详细的数学推导.文中的绝大部分内容,都曾做为硕士研究生的时间序列课程的一部分被使用过.     

广义线性模型拟合方法的相容性(Ⅲ)

广义性模型包括了回归、自回归及其混合型的线性模型,是一种比较广泛的统计模型.对它的拟合,主要包括了对参数的最小二乘估计,以及对自变元的选择估计.本文的目的在于,综述近十余年在此领域中的重要研究成果,其中也包括介绍某些主要结论的证明方法.     

μPC1477C集成电路在卫星广播接收机中的应用

集成电路μPC1477C是具有广泛用途的锁相环型的FM解调器,是近年来国外开发生产的新型的电子器件.本文具体地介绍了它的工作原理,并把它应用到卫星广播接收机中,有效地提高了接收机的性能.     

Effect of Cr on the electronic structure of Co3Al intermetallic compound: A first-principles study

The effect of doping with Cr on the electronic structure and magnetism of Co₃Al has been studied by density functional calculations. It has been found that the Cr atom has a strong site preference for the B-site in Co₃Al. With the substitution of Cr for Co, the total densities of states (DOS) change obviously: A DOS peak appears at E_F in the majority spin states and an energy gap is opened in the minority spin states. The effect of Cr in Co₃Al is mainly to push the antibonding peak of the Co (A,C) atoms high on the energy scale and to form the energy gap around E_F, and also to contribute to the large DOS peak at E_F in the majority spin direction. The calculations indicate a ferromagnetic alignment between the Co and Cr spin moments. The calculated total magnetic moment decreases and becomes closer to the Slater–Pauling curve with increasing Cr content. This is mainly due to the decrease of the Co (A,C) spin moments. At the same time, the moments of Co (B) and Cr (B) only change slightly.