The analysis of the transient temperature distribution of double-slab Nd:YAG laser medium

A novel double-slab Nd:YAG laser, which uses face-pumped slab medium cooled by liquid with different temperatures on both sides, is proposed. The thermal distortion of wavefront caused by the non-uniform temperature distribution in the laser gain media can be self-compensated. According to the method of operation, the models of the temperature distribution and stress are presented, and the analytic solutions for the model are derived. Furthermore, the numerical simulations with pulse pumping energy of 10 J and repetition frequencies of 500 and 1000 Hz are calculated respectively for Nd:YAG laser medium. The simulation results show that the temperature gradient remains the approximative linearity, and the heat stress is within the extreme range. Then the absorption coefficient is also discussed. The result indicates that the doping concentration cannot be too large for the high repetition frequency laser. It has been proved that the high repetition frequency, high laser beam quality, and high average output power of the order of kilowatt of Nd: YAG slab laser can be achieved in this structure.     

利用啁啾光纤光栅色散特性实现波长可调谐的主动锁模掺铒光纤环行腔激光器

在环形腔主动锁模光纤激光器中引入啁啾光纤光栅，利用啁啾光纤光栅的大色散特性，通过调节调制频率，实现波长调谐，调谐范围2nm。所得脉冲为重复频率2．5GHz，脉宽约60ps的正啁啾脉冲，。     

陶瓷刀具材料增强增韧机制的研究

用透射电子显微镜和扫描电子显微镜研究了金属陶瓷增强增韧机制,并用高压电子显微镜动态拉伸研究了第二相粒子对裂纹扩展的影响.     

Some new results in Waring's problem

LetG(k) denote the smallest numbers such that every sufficiently large natural number is the sum of, at most,s k-th powers of natural numbers. In this paper, we give new bounds forG(12),G(13) andG(19).     

基于最优保存和自适应性的混合遗传算法

1 引 言遗传算法（Genetic Algorithm,GA）是由Michigan大学Holland等创立的.常用的遗传算法一般有以下三种:简单遗传算法（Simple Genetic Algorithm,SGA）或称标准遗传算法（Canonical Genetic Algorithm,CGA）、最优保存简单遗传算法（Optimum MaintainingSimple Genetric Algorithm,OMSGA）和自适应遗传算法（Adaptive Genetic Algorithm,AGA）.     

Almost all Cayley graphs are hamiltonian

It has been conjectured that there is a hamiltonian cycle in every finite connected Cayley graph. In spite of the difficulty in proving this conjecture, we show that almost all Cayley graphs are hamiltonian. That is, as the order n of a groupG approaches infinity, the ratio of the number of hamiltonian Cayley graphs ofG to the total number of Cayley graphs ofG approaches 1.Supported by the National Natural Science Foundation of China, Xinjiang Educational Committee and Xinjiang University.     

一种全光纤波长可调谐环路反射镜

介绍了一种全光纤波长可调谐环路反射镜。在试验温度改变140℃时，反射波长调谐了36nm，覆盖了光纤通信的C波段。对全光纤波长可调谐反射镜的反射波长的测试及调谐原理进行了分析。     

Microwave-assisted Allylic Oxidation at C-13 Position of 14-Deoxysinenxan A

Microwave-assisted allylic oxidation at C-13 position of 14-deoxysinenxan A was described. This new method (150℃/10 min/5 bar on microwave synthesizer) led to a better yield of compound 1 and shorter reaction time.     

一种含势阱具有混合交换势形式的平均原子模型

对传统的简单平均原子模型（AAM）作了改进：1使用了动态自由电子判据；2将自由电子分为三种类型，分别用分波法和统计方法加以处理；3应用变分原理给出了一种混合形式的交换势取代了Slater势；4应用材料常态常数标定了原子结构中的参数.作为算例，计算并与实验比较了Fe,Ni,Cu的零温电子压强. 关键词： 平均原子结构 交换势 电子压强     

The exponent of the primitive Cayley digraphs on finite Abelian groups

Let G be finite group and let S be a subset of G. We prove a necessary and sufficient condition for the Cayley digraph X_{(G, S)} to be primitive when S contains the central elements of G. As an immediate consequence we obtain that a Cayley digraph X_{(G, S)} on an Abelian group is primitive if and only if S^−1S is a generating set for G. Moreover, it is shown that if a Cayley digraph X_{(G, S)} on an Abelian group is primitive, then its exponent either is or is not exceeding . Finally, we also characterize those Cayley digraphs on Abelian groups with exponent . In particular, we generalize a number of well-known results for the primitive circulant matrices.