Spectral hole-burning of Eu3+: Y2SiO5 crystal at 579.62 mm

By using an Ar+ ion laser, a tunable Rh 6G dye laser(Linewidth : 0.5 cm(-1)) and a Coherent 899-21 dye laser as light sources and using a monochromator and a phase-locking amplifier, the optical properties of Eu3+ : Y2SiO5 crystal were detected. Persistent spectral hole burning (PSHB) were also observed in (5)Do-(7)Fo transition in the crystal at the temperature of 16 K. For 15 mW dye laser (Wavelength : 579.62 nm) burning the crystal for 0.1 s a spectral hole with about 80 MHz hole width were detected and the hole can been keep for longer than 10 h.

579．62nm波长处Y2SiO5：Eu^3＋晶体永久性光谱烧孔

分别利用氩离子激光，二倍频YAG：Nd激光泵浦的诺明6G可调谐窄线宽（0．5cm^-1）染料激光和899-21可调谐染料激光作为光源，以单色仪-锁相放大器-光电倍增管-计算机数据采集系统记录光谱，对Y2SiO5：Eu^3＋晶体进行了光谱和光谱烧孔研究。在常温和液氮温度下测量了晶体的激发光谱、荧光光谱等。在16K温度下对晶体进行了光谱烧孔研究，得到了孔宽约80MHz并能保存10h的永久性光谱孔。

改进型液排渣煤粉燃烧器实验研究

对传统的液排渣型锅炉煤粉燃烧器进行了优化设计，并用五孔探针对改进后的燃烧室流场进行了冷态试验研究，测定了空气动力场特性。并对不同配风参数进行了热态实验，测量了室内温度场分布。试验表明，燃烧室有较高的燃烧强度和灰渣熔化率，该燃烧室内的温度水平基本达到国外同类设备水平。

水波作用下浮体的稳定

<正> 本文在理想流体假设下,计及线性水波对浮体的影响,应用连续系统Lyopunov直接方法得到了一般情形下浮体的稳定条件。以往的静稳定条件可作为特例导出。 浮体的平衡和稳定问题是船舶力学和经典流体静力学长期研究过的课题。随着近年来海洋工程的发展,对这个问题有了新的兴趣。以往所有稳定性方面研究都是按静力学处理,没有考虑水波对浮体的影响。John最先研究了浮体和水波的相互作用。Wehansen重新给

一个推广Virial定理的数学方法和应用

本文在提出广义Gauss定理的思路下,提出了广义Stokes定理和一个推广Virial定理的新方法,后者应用于天体磁流体力学和引力平衡问题时得到的结果有:(1)气体具有运动时的平衡系统的判据,(2)磁场对气团形态的影响。应用于实验室等离子体平衡问题时,其结果有:(1)包围在气体中孤立磁场的特性,(2)发现内包无力场必须外包一有力场,(3)无力场的形态,应用于Tokmak等离子体环时的结果有:(1)环的胖瘦对环表面磁压的影响,(2)两个外加磁场分量分别和气压、环的胖瘦,截面形态、环电流分布和逆磁或顺磁的平衡关系,搞清楚了外加磁场约束等离子体总体平衡的物理机制。

Effects of stochastic extension in ideal microcrack system

The effects of stochastic extension on the statistical evolution of the ideal microcrack system are discussed. First, a general theoretical formulation and an expression for the transition probability of extension process are presented, then the features of evolution in stochastic model are demonstrated by several numerical results and compared with that in deterministic model.

计算平面Ⅰ、Ⅱ型复合应力强度因子的半权函数法

给出计算一般平面裂纹问题应力强度因子的半权函数方法。该方法引入两个满足裂纹面零应力条件、平衡方程以及裂尖位移具有r- 1 2 奇异性的虚拟位移与应力函数的解析表达式 ,即半权函数。从功能互等定理出发 ,结合从裂纹下缘到上缘绕裂尖任意路径的位移与应力的近似值 ,得到Ⅰ、Ⅱ复合型应力强度因子KⅠ 和KⅡ 积分形式的表达式。由于在积分中避开了裂尖的奇异性 ,因此即使采用较粗糙的模型或方法得到的近似值 ,也可以得到精度较高的KⅠ 、KⅡ 。相对于权函数法 ,本方法的限制条件较少 ,半权函数易于获得 ,实用性强 ;相对于有限元法计算量小 ,模型建立简便。

Analysis of dispersion compensation by chirped fiber grating in directly and externally modulated CATV systems

The dispersion compensation effect of the chirped fiber grating (CFG) is analyzed theoretically, and analytic expressions are derived for composite second-order (CSO) distortion in analog modulated sub-carrier multiplexed (AM-SCM) cable television (CATV) systems with externally and directly modulated transmitters. Simulations are given for the two kinds of modulations and for standard single mode fiber and non-zero dispersion shift fiber (NZDSF) systems. The results show that CFG could be used as a dispersion compensator in directly modulated systems, but its dispersion coefficient should be adjusted much more precisely than the externally modulated system. The requirements for the NZDSF system could be loosened much. It is proposed that directly modulated source may be used as a transmitter in CATV systems combined with tunable CFG dispersion compensator being adjusted precisely, which may be more cost-effective than externally modulation technology. (c) 2006 Elsevier GmbH. All rights reserved.

长脉冲激光作用下薄膜表面鼓包的形成机理

在光学薄膜的激光损伤实验中,可以在显微镜下观测到激光辐照引起的尺寸较大、形状对称性很好的鼓包。从杂质气化的角度，应用弹性力学的球壳受压膨胀模型，分析薄膜表面鼓包的形成机制，同时得到了相应情况下薄膜的损伤机制。结果表明，半径越大杂质在激光辐照下越容易引起薄膜破坏,填埋得越浅的杂质也越容易引起薄膜破坏。杂质诱导破坏机制下,薄膜的裂纹首先出现在杂质附近的薄膜基体中。在薄膜中出现裂纹的临界状态时，半径越大、填埋得越深的杂质所引起的鼓包尺寸越大、高度越高。这种热力耦合模型，弥补了现有理论的不足。进一步完善了现有理论