Study of passive Q-switching for flash-lamp-pumped 1.34-μm Nd:GdVO4 laser

The static laser performance of a-growth Nd:GdVO4 crystal (a-cut, 4 × 4 × 25 (mm)) at 1.34μm pumped by flash-lamp is investigated with different transmissions of output couplers. With the output coupler transmission of T = 30%, the static output energy of 148 mJ is obtained when the pump energy is 35.2 J,and the corresponding electric-optical conversion efficiency is 0.42%. The Q-switched output of lasers with the output wavelength ranging from 1.3 to 1.6 μm can be realized by using Co2+ :LaMgAl11O19 (Co:LMA)as saturable absorber. A flash-lamp-pumped, passively Q-switched Nd:GdVO4 laser with Co:LMA as saturable absorber is demonstrated in plano-concave laser cavity. With the cavity length of 16.3 cm and pump energy of 19.8 J, the single-pulse output energy, pulse width, and peak power are obtained to be 4m J, 80 ns, and 5 × 104 W, respectively.     

Investigation of neutron emission from relativistic heavy ion interactions by nuclear tracks

Fast neutrons produced in 44 and 22 GeV ¹²C+Cu interactions have been recorded and analysed with a CR-39 detector stack. The irradiation of the CR-39 stack to fast neutrons was carried out at the accelerator Synchrophasotron, Joint Institute for Nuclear Research, Dubna, Russia. Areal and volume densities of tracks induced by fast neutrons in the CR-39 at different positions and for different etching time have been measured. The neutron production ratio of 44 GeV to 22 GeV ¹²C+Cu interactions has been obtained, which is 2.17 ± 0.30 by areal track density, or 2. 12±0.33 by step etch technique, or 2.03±0.34 by volume track density measurement. These results confirm that the production rate at 44 GeV ¹²C+Cu interactions is more than theoretical estimation.     

Large-Time Behaviour of Energy in Elasticity

This paper is concerned with the large-time behaviour of energy for the n-dimensional nonhomogeneous and anisotropic elastic system with a locally reacting boundary subject to small oscillations. Under reasonable assumptions, the polynomial decay for the energy of such a model has been established. Multiplicative techniques and the energy method are used.     

Synthesis, electronic, and photophysical properties of cruciform OPE/OPV hybrid oligomer bridged bisfullerene triads

A series of cruciform-shaped phenyleneethynylene and phenylenevinylene hybrid oligomers was prepared via a sequence of Sonogashira reactions. Using an in situ ethynylation protocol, these oligomers were end-functionalized with bis(fullerenyl) groups at the termini of the oligomers. Spectroscopic and electrochemical properties of these novel bisfullerene triads were studied in detail by UV-vis, fluorescence, and cyclic voltammetric analyses, and the results of these investigations are reported.     

拟圆周与交比

设(z_1,z_2,z_3,z_4)=((z_1-z_3)(z_2-z_4))/((z_1-z_4)(z_2-z_3))表示扩充复平面■~2上互不相同有序四点z_1,z_2,z_3,z_4的交比,利用交比刻画了圆周与拟圆周的几何性质,得到(1)■~2上的Jordan曲线Γ是圆周(或直线)当且仅当Γ上任意互不相同的有序四点z_1,z_2,z_3,z_4,满足|(z_1,z_4,z_2,z_3)| |(z_1,z_2,z_4,z_3)|=1; (2)■~2上的Jordan曲线Γ是拟圆周当且仅当存在常数c≥1,对Γ上任意互不相同的有序四点z_1,z_2,z_3,z_4,满足|(z_1,z_4,z_2,z_3)| |(z_1,z_2,z_4,z_3)|≤c．     

DWDM用薄膜窄带滤光片的容差特性模拟分析

讨论了用于DWDM系统的薄膜窄带滤光片在镀制过程中的监控方法及误差产生的机理,利用自行建立的计算机膜厚容差模拟程序,分析了多FabryPerot腔窄带滤光片的容差特性.发现多腔窄带滤光片各腔的误差灵敏度与腔的位置有关,且各腔间隔层组成材料不同,其对误差最敏感的膜层位置也不相同.     

拟圆的三个充要条件

设D是R2中的Jordan域,D*=R2＼D是D的外部,本文证明了拟圆的下面三个充要条件:(1)D是拟圆当且仅当D和D*都是弱拟凸域;(2)D是拟圆当且仅当D和D*都是弱Cigar域;(3)D是拟圆当且仅当D是弱一致域.     

由对苯二酚合成2,5—二甲氧基对苯二苄氯锍盐

以对苯二酚为基本原料，通过改进的甲氧基化、氯甲基化、锍化３个反应合成，得到（２，５－二甲氧基对苯乙炔）单体双锍盐２，５－二甲氧基对苯二苄氯锍盐，且产率达８４％，并对每步反应的合成条件及原因进行了解释，运用色谱／质谱联用仪和核磁共振仪对每步产物进行了表征     

关于n阶微分方程边值问题（Ⅲ）——奇摄动的渐近展开

本文研究n阶非线性过值问题(NB)的奇异摄动。在较一般的条件下,应用高阶微分不等式理论证明了摄动解的存在性,并给出了摄动解直到n阶导函数的一致有效渐近展开式,推广和改进了已有的结果。     

非线性波动方程经典解的整体存在性

该文证明了波动方程uu－△u＝F（u，Du）的Cauchy问题整体经典解的存在性唯一性，并对方程中出现的每项u，Du，D2u的某种范数均得到了与齐次方程相同的衰减估计，其结果补充和丰富了[4]中F不显含u时的结果．