山茶属植物EST-SSR序列分析

研究通过SSR、EST-SSR分子标记技术对179种山茶属植物进行亲缘关系分析。采用改良的CTAB法提取茶花基因组DNA,用1%的琼脂糖凝胶电泳检测DNA纯度,用2%的琼脂糖凝胶电泳检测PCR扩增产物。扩增产物测序结果显示,EST-SSR序列片段大小为194 bp,序列最长的是崇左金花茶,长度为210 bp,序列最短为凹脉金花茶,长度为152 bp。在NCBI上寻找同源系列,用Cluster软件进行系列比对,发现不同山茶属植物EST-SSR系列差异较大,其中缺失位点为1752个,突变位点813个。用MEGA6.0软件画系统树,对茶花进行亲缘关系分析,39种茶花聚为红山茶组、金花茶组、糙果茶组、连蕊茶组四组,结果与张宏达形态学分类结果基本一致。结论:EST-SSR分子标记用于茶花系统分类及物种鉴定效果较好。

A coupled Legendre-Laguerre polynomial method with analytical integration for the Rayleigh waves in a quasicrystal layered half-space with an imperfect interface

The Laguerre polynomial method has been successfully used to investigate the dynamic responses of a half-space.However,it fails to obtain the correct stress at the interfaces in a layered half-space,especially when there are significant differences in material properties.Therefore,a coupled Legendre-Laguerre polynomial method with analytical integration is proposed.The Rayleigh waves in a one-dimensional(1D)hexagonal quasicrystal(QC)layered half-space with an imperfect interface are investigated.The correctness is validated by comparison with available results.Its computation efficiency is analyzed.The dispersion curves of the phase velocity,displacement distributions,and stress distributions are illustrated.The effects of the phonon-phason coupling and imperfect interface coefficients on the wave characteristics are investigated.Some novel findings reveal that the proposed method is highly efficient for addressing the Rayleigh waves in a QC layered half-space.It can save over 99%of the computation time.This method can be expanded to investigate waves in various layered half-spaces,including earth-layered media and surface acoustic wave(SAW)devices.

功能梯度圆柱板中的周向衰逝导波

与传播波模态不同,衰逝波模态波数为纯虚数或复数,它们随传播距离呈指数或阻尼式衰减.具有复波数的衰逝波对结构缺陷形状和尺寸的导波检测具有重要作用,但其求解却是非常困难的,通常要借助于各种迭代技术.论文提出一种计算求解衰逝波问题的改进的Legendre正交多项式方法,该方法可将复杂的变系数微分方程组计算转换为特征值求解问题,无需迭代便能计算得到包含实波数域、虚波数域和复波数域的完整的频散曲线.通过具体算例验证了提出方法的正确性.应用提出方法计算了不同梯度圆柱板中的衰逝导波,绘制了三维频散曲线,研究了不同径厚比和梯度场对衰逝导波频散的影响,分析了衰逝导波的位移和应力分布,讨论了衰逝导波的传播特性.

GUIDED WAVES IN MULTILAYERED PLATES: AN IMPROVED ORTHOGONAL POLYNOMIAL APPROACH

Conventional orthogonal polynomial approach can solve the multilayered plate only when the material properties of two adjacent layers do not change significantly. This paper de- veloped an improved orthogonal polynomial approach to solve wave propagation in multilayered plates with very dissimilar material properties. Through numerical comparisons among the exact solution, the results from the conventional polynomial approach and from the improved poly- nomial approach, the validity of the improved polynomial approach is illustrated. Finally, it is shown that the conventional polynomial approach can not yield correct continuous normal stress profiles. The improved orthogonul polynomial approach has overcome this drawback.

GUIDED THERMOELASTIC WAVE PROPAGATION IN LAYERED PLATES WITHOUT ENERGY DISSIPATION

In this paper, the propagation of guided thermoelastic waves in laminated orthotropic plates subjected to stress-free, isothermal boundary conditions is investigated in the context of the Green-Naghdi （GN） generalized thermoelastic theory （without energy dissipation）. The coupled wave equations and heat conduction equation are solved by the Legendre orthogonal polynomial series expansion approach. The validity of the method is confirmed through a comparison. The dispersion curves of thermal modes and elastic modes are illustrated simultaneously. Dispersion curves of the corresponding pure elastic plate are also shown to analyze the influence of the thermoelasticity on elastic modes. The displacement and temperature distributions are shown to discuss the differences between the elastic modes and thermal modes.

Wave Propagation in Viscoelastic Functionally Graded Nanoplates:Comparison of the Integral and Differential Nonlocal Models

As one of the popular non-classical continuum theories in functionally graded material(FGM)nanostructures,the modified nonlocal theory(MNT)has been applied in various mechanical problems.However,due to the difficult solution process,the original integral formulation of MNT(IMNT)is transformed into a differential formulation of MNT(DMNT),which results in an inevitable approximation error.To clarify the consistency and difference between two formulations,the Lamb wave characteristics in viscoelastic FGM nanoplates are investigated.Two mathematical models are established based on the IMNT and DMNT,and solved by the proposed displacement-based and strain-based Legendre polynomial series approaches(LPSAs),respectively.Comparisons with the available data verify the validates of the presented LPSAs.Numerical examples indicate that the results from the DMNT and IMNT are significantly different at high frequencies.Several important differences are discovered.For example,the escape frequency only appears in the results from DMNT,but not in IMNT.In addition to comparing with classical structures,more attention should be paid to the attenuation characteristics of nonlocal nanostructures.