共查询到19条相似文献,搜索用时 109 毫秒
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本文评述了各向同性和横向各向同性柱状分层固体声散射理论和实验研究进展 ,介绍了描述圆柱状界面薄层特性的弹簧模型 ,也讨论了该领域中有待进一步研究的一些问题。 相似文献
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各向同性谐振子是量子理论中能够严格求解的可解势场之一.对它的研究和讨论,在理论上和实际的应用中都有重要意义.本文推导出了N维(N≥2)各向同性谐振子径向矩阵元〈nrl|rk|nr′l′〉的递推公式,在此基础上得到了平均值的递推公式,并且讨论了维各向同性谐振子径向矩阵元的递推公式的一般性,而文献[3]与[4]所给出的各向同性谐振子径向矩阵元的递推公式只是本文结论的特例. 相似文献
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静止时线性、均匀、各向同性的介质,当它运动时变得不再各向同性,其标志是光线和波法线分离,波面形状由球面变成椭球面.本文给出了非各向同性介质与介质运动速度间的定量关系,导出了电磁波在运动介质表面反射和折射的普遍规律.并且就介质的运动方向与介质表面垂直或平行两种特殊情形进行了较为详细的分析。 相似文献
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本文用群论方法讨论了量子力学中三维各向同性谐振子的能级简并度与对称性的关系,经过运算给出了三维各向同性谐振子具有SU(3)对称性的结论. 相似文献
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On the feasibility of variable separation method based on Hamiltonian system for plane magnetoelectroelastic solids
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The eigenvalue problem of an infinite-dimensional Hamiltonian operator appearing in the isotropic plane magnetoelectroelastic solids is studied. First, all the eigenvalues and their eigenfunctions in a rectangular domain are solved directly. Then the completeness of the eigenfunction system is proved, which offers a theoretic guarantee of the feasibility of variable separation method based on a Hamiltonian system for isotropic plane magnetoelectroelastic solids. Finally, the general solution for the equation in the rectangular domain is obtained by using the symplectic Fourier expansion method. 相似文献
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《Molecular physics》2012,110(11-12):1269-1288
A generic equation of state (EoS) is developed for the hard cylindrical disc model to describe the isotropic phase of hard cut-sphere particles introducing a correction parameter to incorporate the negative contributions from higher-order virial coefficients. The isotropic–nematic–columnar phase diagram of hard cut-sphere fluids is investigated combining the new EoS with a scaled Onsager free energy for the nematic phase and an extended cell theory for columnar phase. By mapping the virial coefficients of an oblate spherocylinder on to those of the cylindrical disc (which are known algebraically), the new generic EoS is used to describe the isotropic and nematic phases of hard oblate spherocylinder particles. The predictions of the generic EoS are compared with available simulation data. 相似文献
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Propagation of S-polarized surface polaritons circumferentially around a locally cylindrical surface
The dispersion relation is derived and solved for s-polarized surface polaritons propagating circumferentially around a portion of a cylindrical interface between vacuum and an isotropic dielectric. In the case that the dielectric is convex toward the vacuum these modes are found to be radiative, and consequently are attenuated as they propagate on the cylindrical surface. When the dielectric is concave toward the vacuum the resulting surface polaritons are nonradiative and propagate unattenuated on the cylinder. Such modes do not exist in the case of a planar interface between a homogeneous isotropic dielectric and vacuum. 相似文献
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《Composite Interfaces》2013,20(2):93-119
A volume integral equation method is introduced for the solution of elastostatic problems in an unbounded isotropic elastic solid containing interacting multiple anisotropic elliptical inclusions subject to uniform remote tension or remote in-plane shear. This method is applied to two-dimensional problems involving long parallel elliptical cylindrical inclusions. A detailed analysis of the stress field at the interface between the matrix and the central elliptical inclusion is carried out for square and hexagonal packing of anisotropic inclusions. The effects of the number of anisotropic inclusions and various inclusion volume fractions on the stress field at the interface between the isotropic matrix and the central elliptical cylindrical inclusion are investigated in detail. The stress field at the interface between the isotropic matrix and the central elliptical inclusion is also compared with that between the isotropic matrix and the central circular inclusion. 相似文献
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Multilayered solid structures made of isotropic, transversely isotropic, or general anisotropic materials are frequently used in aerospace, mechanical, and civil structures. Ultrasonic fields developed in such structures by finite size transducers simulating actual experiments in laboratories or in the field have not been rigorously studied. Several attempts to compute the ultrasonic field inside solid media have been made based on approximate paraxial methods like the classical ray tracing and multi-Gaussian beam models. These approximate methods have several limitations. A new semianalytical method is adopted in this article to model elastic wave field in multilayered solid structures with planar or nonplanar interfaces generated by finite size transducers. A general formulation good for both isotropic and anisotropic solids is presented in this article. A variety of conditions have been incorporated in the formulation including irregularities at the interfaces. The method presented here requires frequency domain displacement and stress Green's functions. Due to the presence of different materials in the problem geometry various elastodynamic Green's functions for different materials are used in the formulation. Expressions of displacement and stress Green's functions for isotropic and anisotropic solids as well as for the fluid media are presented. Computed results are verified by checking the stress and displacement continuity conditions across the interface of two different solids of a bimetal plate and investigating if the results for a corrugated plate with very small corrugation match with the flat plate results. 相似文献
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Jin Shuo Mei Qun Wu Kuang Zhang 《Applied Physics A: Materials Science & Processing》2012,108(4):1001-1005
Based on the concept of complementary medium, a method which can make the conventional cylindrical cloak with axial symmetrical cloaked region to be not blind by filling the isotropic complementary in inner cloaked region is proposed. Firstly, the perfect electric conductor cylindrical shell was removed. Secondly, the symmetrical cloaked region was separated into two symmetrical regions along the symmetry axis and filled with isotropic complementary medium according to folding transformation. Full wave simulations are performed to confirm the effectiveness of the proposed method. The simulation results show that the converted cloak not only can exchange information with the outside, but also its presence cannot be detected. 相似文献
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N. M. Sakevich 《Russian Physics Journal》1967,10(8):30-32
Calorimetric methods are applied to p-azoxyanisole and cholesteryl caprinate. The heats of conversion to the solid state substantially exceed those for conversion to isotropic liquid. The latter result indicates that liquid crystals are closer to liquids than to solids. 相似文献
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A solution of a non-homogeneous orthotropic elastic cylindrical shell for axisymmetric plane strain dynamic thermoelastic problems is developed. Firstly, a new dependent variable is introduced to rewrite the governing equation, the boundary conditions as well as the initial conditions. Secondly, a special function is introduced to transform the inhomogeneous boundary conditions to the homogeneous ones. Then by virtue of the orthogonal expansion technique, the equation with respect to the time variable is derived, of which the solution can be obtained. The displacement solution is finally presented, which can degenerate in a rather straightforward way to the solution for a homogeneous orthotropic cylindrical shell and isotropic solid cylinder as well as that for a non-homogeneous isotropic cylindrical shell. Using the present method, integral transform can be avoided. It is fit for a cylindrical shell with arbitrary thickness subjected to arbitrary thermal loads. It is also very convenient to deal with dynamic thermoelastic problems for different boundary conditions. Besides, the numerical calculation involved is very easy to be performed. Several examples are presented. 相似文献
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Direct MC modelling of individual elastic and inelastic scattering events of electrons in solids is described. The examples cover transmission through thin solid layers as well as backscattering from flat surfaces of bulk solids. Divergent beams and isotropic emission of incident electrons with energies from 5 to 200 keV are treated.Presented at the Seminar on Secondary Electrons in Electron Spectroscopy, Microscopy, and Microanalysis, Chlum (The Czech Republic), 21–24 September, 1993. 相似文献