一种适用于同轴放电环形增益区的多光程谐振腔

本文给出了由两块环形球面镜组成的适用于同轴放电环形增益区的多光程振荡器的设计及光束特性.在该类型的多光程谐振腔中,在环形球面镜表面的不同转折点上,光束尺寸量周期性地变化.如果这种类型的多光程谐振腔与假设所有转折镜都为平面镜的情况比较,前者的激活体积比后者要小得多.因此,该类型多光程谐振腔更加适用于具有较小电极间隙的同轴放电激光器.     

磁电弹性圆环板的三个解析解

从磁电弹性介质控制方程的一般解出发，用调和函数的一些函数作线性组合，给出了磁电弹性圆环板的纯弯曲问题和侧面受均匀径向电位移或磁感应强度问题的解析解。此方法也可应用于磁电弹性圆板的同样问题。     

Numerical study of hysteresis in annular swirling jets with a stepped‐conical nozzle

This study investigates the experimentally observed hysteresis in the mean flow field of an annular swirling jet with a stepped‐conical nozzle. The flow is simulated using the Reynolds‐averaged Navier–Stokes (RANS) approach for incompressible flow with a k–ε and a Reynolds stress transport (RSTM) turbulence model. Four different flow structures are observed depending on the swirl number: ‘closed jet flow’, ‘open jet flow low swirl’, ‘open jet flow high swirl’ and ‘coanda jet flow’. These flow patterns change with varying swirl number and hysteresis at low and intermediate swirl numbers is revealed when increasing and subsequently decreasing the swirl. The influence of the inlet velocity profile on the transitional swirl numbers is investigated. When comparing computational fluid dynamics with experiments, the results show that both turbulence models predict the four different flow structures and the associated hysteresis and multiple solutions at low and intermediate swirl numbers. Therefore, a good agreement exists between experiments and numerics. Copyright © 2006 John Wiley & Sons, Ltd.     

高Rayleigh数条件下竖圆环夹层内自然对流换热的实验研究

对内壁维持恒热流和外壁向环境冷却的大高宽比竖圆环夹层内自然对流换热进行了实验研究。实验装置高宽比分别为２３５和６６６７，半径比分别为２．０３和３．９２。实验数据整理考虑了热辐射影响以获得对流规律。由于已有工作均未考虑高Ｒａ数区域，首次得到Ｒａ数高达１０￣９的区域内平均Ｎｕ数的换热准则式。在低Ｒａ数区域，亦取得了与前人工作一致的结论。本文结果改进了高Ｒａ数区域换热规律的预测能力。     

Radially isospectral annular membranes

^** Email: h.gottlieb{at}griffith.edu.au By utilizing transformations of both the radial coordinate andthe radial wave function, densities of annular membranes whichare radially isospectral to any given radial density are produced.In particular, new families of annular membrane densities arefound which are radially isospectral to a uniform membrane.Some new generalizations for completely isospectral annularmembranes (including angle-dependent densities) are also given.     

Electroelastic behaviour of an annular interfacial crack between dissimilar piezoelectric layers

An annular interfacial crack between dissimilar piezoelectric layers subjected to electroelastic loadings was investigated under an electrically impermeable boundary condition on the crack surface by using the Hankel transform technique and the Cauchy singular integral equation method. The stress intensity factors and energy release rates were determined. Numerical results reveal the effects of crack configuration, electric loads and material parameters on crack propagation and growth. The results should be useful for the design of piezoelectric composite structures and devices of high performance.     

An accurate mathematical study on the free vibration of stepped thickness circular/annular Mindlin functionally graded plates

An analytical solution based on a new exact closed form procedure is presented for free vibration analysis of stepped circular and annular FG plates via first order shear deformation plate theory of Mindlin. The material properties change continuously through the thickness of the plate, which can vary according to a power-law distribution of the volume fraction of the constituents, whereas Poisson’s ratio is set to be constant. Based on the domain decomposition technique, five highly coupled governing partial differential equations of motion for freely vibrating FG plates were exactly solved by introducing the new potential functions as well as using the method of separation of variables. Several comparison studies were presented by those reported in the literature and the FEM analysis, for various thickness values and combinations of stepped thickness variations of circular/annular FG plates to demonstrate highly stability and accuracy of present exact procedure. The effect of the geometrical and material plate parameters such as step thickness ratios, step locations and the power law index on the natural frequencies of FG plates is investigated.     

光束通过含环形光阑的光学系统的传输特性研究

采用将环形光阑的窗口函数展开的傅里叶级数与复高斯函数的乘积的方法,推导出平面波经过含环形光阑光学系统的近似解析传输公式。利用该公式对光束通过含环形光阑的光学系统的传输进行了数值模拟,计算并分析了不同遮拦比下轴上光强分布和横向光强分布的特点。结果表明：轴上光强分布和横向光强分布与环形光阑的遮拦比有关。该研究方法和结果可推广到其他光阑,对控制光束和光学系统设计具有一定的参考价值。     

Combined static electromagnetic radiation and plant extract contribute to the biosynthesis of instable nanosilver responsible for the growth of microstructures

The instant biosynthesis of silver nanoparticles under static electromagnetic induction, its antibacterial activity and its post exposure monitoring were reported here. A mix of silver nitrate solution and Ruta chalepensis leaf extract was irradiated by a static electromagnetic field (SMF) of 200 mT. The characteristics and stability of the biosynthesized silver nanoparticles (Ag NPs) were determined. Compared to the non-irradiated exposure, the morphology and state of the obtained material change once the exposition to SMF is turned off. Shifting from 453 to 473 nm, the percentage of the needles shaped silver nanoparticles increased and continue to win and dominate the biomixture toward the spherical silver nanoparticles. TEM microscopy showed a wide range of silver materials designed in different nanoscale morphology and beyond where they undergo major changes affecting mainly the size, shape and form (dispersity) of nanosilver.     

Thermal-buckling of thin annular plates under multiple loads

On the basis of Von Kármán equations,the thermal-buckling of thin annular platessubjected to a field of non-uniform axisymmetric temperature and a variety of boundaryconditions is discussed.The linearized problem is analyzed and stability boundaries whichcharacterize instability of a plate are obtained by means of numerical and analysis methods.