共查询到20条相似文献,搜索用时 15 毫秒
1.
A hierarchy of dynamic plate equations is derived for a fully anisotropic elastic plate. Using power series expansions in the thickness coordinate for the displacement components, recursion relations are obtained among the expansion functions. Adopting these in the boundary conditions on the plate surfaces and along the edges, a set of dynamic equations with pertinent edge boundary conditions are derived on implicit form. These can be truncated to any order and are believed to be asymptotically correct. For the special case of an orthotropic plate, explicit plate equations are presented and compared analytically and numerically to other approximate theories given in the literature. These results show that the present theory capture the plate behavior accurately concerning dispersion curves, eigenfrequencies as well as stress and displacement distributions. 相似文献
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L. Nickelson A. Bubnelis S. Asmontas 《Applied Physics A: Materials Science & Processing》2012,109(4):877-881
Here, we present the phase constant dependencies of propagating eigenmodes of an open cylindrical anisotropic metamaterial waveguide when the metamaterial permittivity and permeability tensor components may accept values close or equal to zero. Dispersion characteristics of rod and hollow-core waveguides with the radii 0.5, 2.5, and 5 mm at the left-handed polarization of the microwave are shown here. There are unusual shapes of eigenmode dispersion characteristics and anomalous sectors of the characteristics at certain frequencies. The first eigenmode of the rod waveguide with the lowest cutoff frequency is a particularly important mode because it is a single one in the frequency range 1.0?C1.9 GHz, and some small variations on the frequency produce large changes in the phase constant. We can observe packages of dispersion characteristic branches when their cutoff frequencies closed to the metamaterial electric and magnetic plasma frequencies between 1.9 and 3.5 GHz. There are only three modes in the hollow core anisotropic metamaterial waveguide at the frequency range 1.4?C2.8 GHz. 相似文献
3.
In this paper, non-axisymmetric guided wave propagation in circular cylindrical, anisotropic structures is studied in a frequency range up to 1 MHz. The investigations are carried out with carbon fibre reinforced tubes. The aim is the experimental determination of their effective linear elastic material properties in a non-destructive way. Therefore, an analytical model of the dispersion equation is fitted to the experimentally detected dispersion curves by systematically adjusting the desired material properties. A total least square scheme accompanied by an outlier detection criterion is used for this optimization task. Since the raw data of the measured dispersion curves contain a lot of noise, these outliers have to be detected and excluded, to achieve accurate results. Good agreement is found between the measured curves and the analytically calculated curves based on the estimated parameters. This fact indicates a high accuracy of the determined material properties. 相似文献
4.
《Ultrasonics》2005,43(2):123-132
In this paper, non-axisymmetric guided wave propagation in circular cylindrical, anisotropic structures is studied in a frequency range up to 1 MHz. The investigations are carried out with carbon fibre reinforced tubes. The aim is the experimental determination of their effective linear elastic material properties in a non-destructive way. Therefore, an analytical model of the dispersion equation is fitted to the experimentally detected dispersion curves by systematically adjusting the desired material properties. A total least square scheme accompanied by an outlier detection criterion is used for this optimization task. Since the raw data of the measured dispersion curves contain a lot of noise, these outliers have to be detected and excluded, to achieve accurate results. Good agreement is found between the measured curves and the analytically calculated curves based on the estimated parameters. This fact indicates a high accuracy of the determined material properties. 相似文献
5.
A novel concept for a liquid-core lightguide in cylindrical symmetry is presented. For a concrete 17 cm long device using water as a core and the transparent fluorinated polymer Teflon as a cladding layer, the coupling efficiency and guiding properties are investigated theoretically and compared with experimental results. The guide is found to exhibit low losses. A possible application of this type of guide is investigated by replacing the optical cell of a standard UV/VIS spectrometer by the cylindrical liquid-core waveguide. An increasing sensitivity for especially low concentrations of a polluting dye by a factor of about 15 is observed. Concentrations as low as a few parts per billion of the pollutant can be detected with a good signal-to-noise ratio. 相似文献
6.
We use the framework of a general quasiclassical theory of superconductivity which allows for arbitrary gap and Fermi surface
anisotropy and for impurity scattering in Born approximation. We derive general Ginzburg-Landau integro-differential equations,
which comprise all previous limiting cases considered in the literature. From these equations more specialized Ginzburg-Landau
equations may easily be derived. 相似文献
7.
Anthony D. Osborne 《Physics letters. A》1981,83(7):311-313
It is shown how to obtain separable solutions, which include travelling-wave solutions as a special case, of a large class of nonlinear wave equations, including the Korteweg-de Vries-Burgers equation and Fisher's equation. 相似文献
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A. D. Lapin 《Acoustical Physics》2006,52(5):618-621
The problem on the scattering of a zero-order axisymmetric mode by a ring of equally spaced identical monopole-dipole resonators positioned in the cross section of a wide circular pipe is considered. The solution to the problem is used to formulate the requirements for a set of resonators that provide a complete absorption of the zero-order mode in the pipe. 相似文献
10.
An extension of method of horizontal rays and vertical modes developed for underwater acoustics to the spatially inhomogeneous anisotropic electrodynamic problem is proposed.Leningrad State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 7, 790–797, July, 1991. 相似文献
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基于电磁模式的色散方程,研究了有损金属圆波导中电磁模式的传输问题.在考虑了损耗层厚度影响的情况下,得到了各模式传输常数的近似解析表达式,此式适用于截止频率附近.通过解析表达式和波导模式色散方程,对衰减常数和相位常数进行了大量数值计算,得到了它们随损耗层厚度、频率以及损耗层电导率的变化规律,两种方法所获得的结果有较好的一致性.研究表明,损耗强度和损耗层厚度的变化会改变波导中电磁模式的色散和简并特性,对于改善高功率回旋行波放大器中注波互作用带宽和模式竞争非常有益.
关键词:
有损圆波导
相位常数
衰减常数
色散方程 相似文献
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Lluí as Torner Concepci an Santos Juan P. Torres Dumitru Mihalache 《Fiber and Integrated Optics》1994,13(3):271-280
The existence of new hybrid waveguide modes of properly tailored integrated optical waveguides consisting of ultrathin films clad by positive birefringent media is pointed out. 相似文献
16.
研究中通过建立和求解填充各向异性超常媒质的矩形波导TE模式和TM模式的波动方程和场分布方程,讨论了各向异性超常媒质矩形波导的有效介电常数、有效磁导率、相位常数以及传输系数与所填充超常媒质本构参数之间的变化关系.研究发现,填充了各向异性超常媒质的矩形波导的导波特性在截止频率之上的频率区域,其导波特性由所填充超常媒质的横向本构参数决定,而与超常媒质的纵向本构参数无关.但是,在截止频率之下的频率区域,该矩形波导的导波特性则由所填充超常媒质的横向本构参数和纵向本构参数共同决定.研究中通过典型的计算实例对所得到的结
关键词:
各向异性
超常媒质
矩形波导
导波特性 相似文献
17.
V. V. Tyutekin 《Acoustical Physics》2008,54(4):445-448
Helical normal waves of a waveguide that has the form of a fluid-filled thin elastic shell are considered. A dispersion equation for this kind of wave is derived, and its solutions are presented for certain values of parameters characterizing the problem. 相似文献
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Tao Pan Guo-Ding Xu Tao-Cheng Zang Lei Gao 《Applied Physics A: Materials Science & Processing》2009,95(2):367-372
We have numerically studied the characteristics of a slab waveguide loaded with dispersive anisotropic metamaterials. For
two typical-structured metamaterials, we have analyzed the tensor expressions of frequency-dependent permittivity and permeability
and discussed influences of the resonant cell structures on waveguiding characteristics. Numerical results show that the slab
waveguide loaded with anisotropic metamaterials may, to some extent, behave as the slab waveguides of isotropic left-handed
metamaterials (LHMs) core and conventional right-handed materials core. To one’s interest, some unusual properties are revealed
in this paper, such as the coexistence of the fundamental guided mode and negative group velocity, and extraordinarily large
normal or anomalous group velocity dispersion. Our results may find some potential applications in both linear and nonlinear
optical technology. 相似文献
19.
Tingting Tang 《Optik》2013,124(24):6757-6759
We study the optical modes in a plasmonic waveguide with electrically anisotropic metamaterial and dielectric, including symmetric (anti-symmetric) photonic mode and symmetric (anti-symmetric) plasmonic mode. The dispersion curves for these modes are derived, and a graphical method is used to calculate the solution of symmetric photonic mode and anti-symmetric plasmonic mode. By simulation results the conditions of the existence for these modes are deduced in each case. 相似文献
20.
Based on the Debye series modified with respect to the method of horizontal beams and vertical modes, the asymptotics of eigenwaves of a smooth irregular anisotropic spherical anisotropic waveguide channel is constructed.State University, St. Petersburg. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 5, pp. 457–466, May, 1995. 相似文献