小型全内腔脉冲Ar~＋激光管的研制

介绍一种小型全内腔脉冲Ａｒ＋激光管的设计和结构。并对不同阴极，放电管直径，激励电压及Ａｒ气压等对输出功率及激光管寿命的影响作了一系列的实验，试制出结构简单，使用方便，价格便宜的有一定实用价值的小型全内脏脉冲Ａｒ＋激光管。     

全新冷却方式双椭圆泵浦腔的实验研究

报导一种全新冷却方式的双椭圆泵浦腔，具有较高的泵浦效率和光学均匀性。１．０６μｍ调Ｑ脉冲输出能量总转换效率η＞０．７５％     

高功率板条固体激光器研究的进展

本文对高功率板条固体激光器研究的进展和应用前景作了综合评述。结合作者部分工作,对板条激光器的热效应、聚光器和光学谐振腔等关键问题和技术进行了物理分析。     

基于声光偏频法的激光频率无调制锁定

为了进一步提高1.5 μm波段激光器的频率稳定性,利用声光调制器(AOM)的频移特性使激光发生频移,将乙炔(~(12)C_2H_2)v_1+v_3带的P9支吸收峰作为参考频率,通过两条频移的吸收谱线产生类色散鉴频曲线,实现对外腔半导体激光器的无调制频率锁定.实验中把以前直接对激光器的调制转移到声光调制器上,避免了直接调制所引入的额外噪声,通过闭环锁定,50 s内典型的频率起伏达到5.8 MHz以内,激光器的频率起伏较自由运转时明显得到抑制,实现了激光频率的稳定.     

不同多相流模型在航行体出水流场数值模拟中的应用

基于VOF和Mixture两种均相流模型,并结合输运方程类空化模型、k-ε湍流模型和动网格技术,针对圆柱形航行体出水过程进行了数值模拟,获得了无空化、带空泡两种状态下航行体出水过程中的多相流物理景象和表面压力变化历程。根据计算结果分析了VOF模型、Mixture模型在多相流界面捕捉、压力计算等方面的异同,并给出了两种模型的适用范围,在理论研究和工程应用上都具有重要意义。     

筒式连续过滤机过滤特性研究

筒式连续过滤机采用了动态过滤技术，单位面积的过滤速率大大增加，处理能力大大提高，且具有薄滤饼过滤和连续出渣两大特点，整个过滤过程不仅满足过滤基本方程，而且实现物料平衡条件。着重阐述了过滤机的结构及工作原理，对其试验系统，即试验装置、过滤介质和主要技术参数作了详细介绍。对过滤机的过滤特性进行分析和试验的结果表明，过滤介质、料浆特性以及工艺和结构参数对过滤特性的影响很大。     

Buckling of thin‐walled cylindrical shells under axial compression

Lightweight thin‐walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. The buckling of an axially compressed shell is studied using analytical, numerical and semi‐empirical models. An analytical model is developed using the classical shell small deflection theory. A semi‐empirical model is obtained by employing experimental correction factors based on the available test data in the theoretical model. Numerical model is built using ANSYS finite element analysis code for the same shell. The comparison reveals that the analytical and numerical linear model results match closely with each other but are higher than the empirical values. To investigate this discrepancy, non‐linear buckling analyses with large deflection effect and geometric imperfections are carried out. These analyses show that the effects of non‐linearity and geometric imperfections are responsible for the mismatch between theoretical and experimental results. The effect of shell thickness, radius and length variation on buckling load and buckling mode has also been studied. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of non-planar geometry on diffusion kinetics during brazing repair process

A new finite difference numerical model is used to study the influence of non-planar (cylindrical and spherical) solid–liquid interface geometry on the kinetics of isothermal solidification during diffusion brazing or transient liquid phase repair process. Notwithstanding that limited work had been reported on non-planar systems, this study shows that non-planarity of the solid–liquid interface can have significant effects on the kinetics of solid–liquid phase transformation during the repair process, which are crucial to the understanding and optimisation of the repair process in non-planar systems.     

Study on postbuckling of axial compressed elastoplastic functionally graded cylindrical shells

Postbuckling of plates and shells is an important and cumbersome problem in the structural stability field. Presently, postbuckling behaviors of elastoplastic functionally graded cylindrical shells are investigated by a numerical simulation. The elastoplastic material properties are assumed to be of a multilinear hardening type, according to the constituent distributions, and are modeled using the laminate method. The Riks algorithm is used to obtain the equilibrium path. The postbuckling deformation and stain history of elastoplastic functionally graded cylindrical shells are investigated and various effects of the shell thickness and the constituent distributions are discussed. The results show material unloading effects in the postbuckling state.     

局部开口对封闭柱面网壳风荷载影响

局部开口对封闭大跨度空间结构风荷载影响很大,通过刚性模型测压风洞试验对底部和顶部有局部开口的两端封闭三心圆柱面网壳结构的风荷载分布进行了研究,对比不同开口状况下结构的力系数及风荷载分布,给出了局部开口对风荷载及其分布的影响规律,如强负压区的局部开口能有效的减小结构表面的风吸力,而正压区域的局部开口会增大结构表面的风吸力,这些规律为类似结构的抗风设计及防风措施提供了合理的建议。