子束排列方式对固体激光器光束合成特性的影响

建立了固体激光器矩形光斑光束合成的理论模型,对诺·格公司给出的2束、4束、8束合成实验结果进行分析,并通过数值模拟,得到了不同子束排列方式下合成光斑的远场图形。通过仿真模拟可以得出:排列结构影响远场光斑的形状;子束间距决定了合成光束远场光斑的衍射旁瓣的大小和多少。采用环围能量进行分析,研究了远场光斑中主瓣能量随激光阵列占空比的变化。结果显示,远场光束环围功率随子束间距的增大而逐渐下降,而且参与相干合成子束越多,下降越大。     

Turbulent liquid metal flow in rectangular shaped contraction nozzles for target applications

Owing to the high beam power densities envisaged in advanced nuclear targets, liquid metal-operated free surface targets are conceived as one feasible option. There, the free surface is formed by an adequately shaped upstream located nozzle. Target boundary conditions necessitate a detailed knowledge on the turbulent flow in contraction nozzles in order to identify turbulence models accurately predicting experimental findings within the velocity range of interest for nuclear target and hence can then act as design optimisation tools. In this context, a combined experimental and numerical study is conducted on the basis of the turbulent flow in the contraction nozzle of the Super-FRS target. Two aspects determining the turbulent flow in the nozzle have been investigated. The first is a potential relaminarisation of the boundary layer caused by the acceleration within the contraction and the second is a development of the secondary flows due to the pressure gradient in the rectangular shaped ducts cross-section. Regarding the three different turbulence models investigated here only the V2F model exhibited the capability to predict the relaminarisation of the turbulent boundary layer both qualitatively and quantitatively. All turbulence models are able to predict the development of secondary flows induced by pressure gradients in transverse direction with an acceptable accuracy.     

不连续随机算子随机不动点定理及其应用

该文利用半序理论和随机压缩映象原理,得到了一类不连续随机增算子随机不动点的唯一存在定理.作为应用,考虑了R~n中含间断项的一阶随机微分积分方程初值问题.     

利用非平行矩形板电容器测量金属的线胀系数

根据非平行矩形板电容器测量弹性模量的实验原理,提出了用非平行矩形板电容器测量金属线胀系数,并对实验装置进行了改进,提高了实验的灵敏度,降低了相对非线性误差.     

4.5 GPa静水压活塞圆筒式高压装置的压力检测分析及压力校正

 本文提供了提高现有活塞圆筒式高压装置流体静压强的一种实验方法。成功地制作了锰铜丝压力计，并利用铋丝相变准确地做了压力校正。各箍的应力检测分析和相对位移测量都表明：无论压腔空载或充液时，在0.000 1~3.08 GPa均不显示出同步箍紧作用；上下缸的压强差偏大带来高压暴露的危险。为把流体静压强提高到3.08 GPa以上，建议改进设计；（1）内箍中箍合二为一，外箍分为上下二层，将增加箍力；（2）调整各箍之间接触圆锥面的面积，将有助于同步箍紧；（3）增大密封套圈的无支承面，将减少上下缸压差，有利于安全运行。     

Dynamically tunable multiband plasmon-induced transparency effect based on graphene nanoribbon waveguide coupled with rectangle cavities system

A dynamically tunable multiband plasmon-induced transparency (PIT) effect in a series of rectangle cavities coupled with a graphene nanoribbon waveguide system is investigated theoretically and numerically by tuning the Fermi level of the graphene rectangle cavity. A single-PIT effect is realized using two different methods: one is the direct destructive interference between bright and dark modes, and the other is the indirect coupling through a graphene nanoribbon waveguide. Moreover, dual-PIT effect is obtained by three rectangle cavities side-coupled with a graphene nanoribbon waveguide. Results show that the magnitude of the dual-PIT window can be controlled between 0.21 and 0.74, and the corresponding group index is controlled between 143.2 and 108.6. Furthermore, the triple-PIT effect is achieved by the combination of bright-dark mode coupling and the cavities side-coupled with waveguide mechanism. Thus, sharp PIT windows can be formed, a high transmission is maintained between 0.51 and 0.74, and the corresponding group index is controlled between 161.4 and 115.8. Compared with previously proposed graphene-based PIT effects, the size of the introduced structure is less than 0.5 μm². Particularly, the slow light effect is crucial in the current research. Therefore, a novel approach is introduced toward the realization of optical sensors, optical filters, and slow light and light storage devices with ultra-compact, multiband, and dynamic tunable.     

一种分析楔形光纤的等效矩形近似-阶梯串联法

楔形光纤(WSF)是实现平面光波光路芯片入出端口与光纤高效连接的核心部件. 采用数值模拟方法分析其中光波传输演化过程,是优化设计光子器件耦合结构的重要基础. 提出基于等效矩形近似的三维阶梯串联法(ERA-SCM),将楔端沿传输方向细分,引入矩形波导近似,给出了细分后各段近似矩形波导的等效折射率;在此基础上,建立了阶梯串联法分析模型,分级给出WSF中光波传输过程与模场演变. 数值分析结果表明,ERA-SCM比有限差分束传播法(FD-BPM)能够更精确地分析非对称光纤和波导结构,描述其中光模场的演化. WSF出射光场实测结果表明,ERA-SCM数值模拟结果与实验结果的误差为1.9%,而FD-BPM的误差为4.5%. ERA-SCM是分析非对称光波导光波传输与模场演变的有效方法. 关键词： 平面光波光路 楔形光纤 等效矩形近似 阶梯串联法     

关于一些数值求积公式的渐近性

该文给出了一些数值求积公式的渐近性质,这些公式包括求积分的矩形法则、梯形法则和抛物线法则,包含于余项中的中介点的位置当积分区间的长度趋于零时被确定,对应于该法则的校正公式被得到,它们具有较高的代数精度,我们也进行了一些数值试验,得到较满意的数值结果。