表面对流冷却下非稳腔激光窗口温升分布的计算

 用有限差分法计算了强迫对流冷却下非稳腔激光器CaF₂输出窗口在不同换热系数、不同激光功率和不同窗口厚度下的温升分布、温升随时间的变化及温度梯度沿激光输出方向的分布,分析了各个参数对激光器窗口温升的影响。     

非稳腔傍轴波动方程高斯球面波修正方法的数值研究

在分析用差分方法求解虚共焦非稳腔三维傍轴波动方程,及用数值积分方法与快速付氏变换(FFT)方法求解三维菲涅耳积分方程优缺点的基础上,从激光束在虚共焦非稳腔中以修正高斯球面波形式传输的特征出发,经坐标变换把发散(或会聚)的光束拉直成平行光束,然后用FFT方法求解了在新坐标系中修正函数满足的傍轴波动方程.把相同条件下得到的结果与国内外文献给出的结果进行了比较;计算COIL实验非稳腔给出的近远场结果图象合理正确.     

Unstable resonator and output-coupling design study for diffraction radiation generator near-mm sources

Configurations of unstable resonators that could be used for diffraction radiation generators (DRG's) are presented. The output coupling of a negative branch unstable resonator exhibits an extreme sensitivity to mirror radius and appears to be unsuited to DRG use. The positive branch resonator does not exhibit this sensitivity to mirror radius, and the mirror radii that are needed to give output couplings of a few percent appear practical.Work conducted at the Harry Diamond Laboratories.     

多元件共焦型非稳腔的特征

本文首次使用牛顿成像方程对多元件共焦型非稳腔的基模给出了公式化描述,揭示出这类光腔的重要特征.对本文所用方法和其它方法的比较亦作了讨论.     

Simple model for the instabilities in the aggregation of silica sols in a sol-gel process

A simple kinetic model based on the Prigogine's Brusselator model was used to explain some unstable non-linear oscillations found in the particle size profile of sols in a sol-gel process. These oscillations were explained, in some previous papers, by using the stability criterion from the non-linear irreversible thermodynamics; it is the excess entropy production that characterizes the stability of a system and the occurrence of new structures. In the solgel reaction considered here, one of the steps is auto-catalytic; this fact produces local gradients in the concentration of one of the chemical components, forming a wide variety of new unstable structures. With this model we obtained a relationship for the reaction constants that determines the unstable character of the reaction, and the dependence of the frequency of oscillations on the reactant concentrations. The dependence of the oscillation frequency on water and ethanol concentrations obtained from the experimental data, were well explained by using this model.     

FAZIA: Prototyping a next-generation 4π array for nuclear reaction-dynamics studies

The international FAZIA (Four π A and Z Identification Array) Collaboration, presently involving researchers and institutions from France, Italy, Poland, Romania, Spain, India, Canada and USA, is currently investigating the use of new detector types/configurations (nTD Si detectors, single chip telescope) and new electronics (charge/current preamplifiers, digital sampling and signal processing) in view of defining a next-generation detection array with improved particle identification capability to study nuclear reaction dynamics and thermodynamics exploiting the Radioactive Nuclear Beam (RNB) facilities. The present main R&D activities inside the Collaboration are brielfly described.     

均匀化位相的常规非稳腔的分析与实验

对常规非稳腔的输出镜面进行改造,在原来不透光的中央区域引入增透膜,使之能部分透过,使输出耦合能的比例得到提高;同时加敷适当的位相膜,使中央区与环带区波面位相拉平些.着重报导了均匀化相位常规非稳腔的系列实验和分析,从而使常规非稳腔的环带输出引起的中央不透明区与外环带输出波面的位相突变得到改善,克服了远场能量分布出现较严重离散的问题,使远场中央亮斑能量更集中.     

基于Foliation条件的离散动力系统二维流形计算

研究离散动力系统双曲不动点的二维流形计算,利用不变流形轨道上Jacobian矩阵能够传递导数这一特殊性质,提出一种新的一维流形计算方法,通过预测-校正两个步骤迅速确定流形上新网格点,避免重复计算,并简化精度控制条件.在此基础上,将基于流形面Foliation条件进行推广,推广后的Foliation条件能够控制二维流形上的一维子流形的增长速度,从而实现二维流形在各个方向上的均匀增长.此外,算法可以同时用于二维稳定和不稳定流形的计算.以超混沌三维Hénon映射和具有蝶形吸引子的Lorenz系统为例验证了算法的有效性.     

化学氧碘激光器非稳腔的研究

设计并研究了适合于连续波超音速化学氧碘激光器的正支共焦非稳腔，给出了放大率、输出功率和光束质量的实验结果。     

血管支架随机均匀性扩展问题的模型和应用

从力学上提出了随机失稳结构串联扩展的均匀性问题,建立了描述该问题的数学模型,提出了均匀性指标概念和该指标的概率计算公式和方法. 针对两个扩展单元构成的串联结构,详细考察了筋厚度发生随机时对于扩展均匀性指标的影响,得到均匀性指标概率与筋厚度随机范围、载荷和强化系数等的变化关系. 研究发现当总扩展位移一定的情况下,强化系数的改变对于均匀性有重大影响.关键字:血管支架 均匀性 随机 失稳 串联