共查询到20条相似文献,搜索用时 125 毫秒
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光折变聚合物中的小振幅空间光孤子 总被引:1,自引:1,他引:0
给出了稳态条件下光折变聚合物中的小振幅空间孤子的演化方程,得到了方程的暗、亮孤子解析解,并且给出了小振幅聚合孤子的宽度表达式结果表明,光折变聚合物中存在着双曲正切形式的小振幅暗空间孤子和双曲正割形式的小振幅亮空间孤子,小振幅聚合孤子的宽度与外加电场成反比关系. 相似文献
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初始振幅和波形对量子光孤子的影响 总被引:1,自引:1,他引:0
在线性近似条件下,量子化了非线性薛定锷方程,用后向传播法数值求解了初始振幅和波形对光孤子压缩比的影响。数值结果表明,增大初始振幅在初始一定距离范围内能减小压缩比,接近理想光孤子的脉冲波压缩效果最好。 相似文献
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运用约化摄动法研究了非均匀尘埃等离子体中孤子的传播情况. 在低阶近似下, 对于小的、但有限振幅的长波振动, 当分界面不连续变化时,孤子在不连续点的反射波与透射波均可由 KdV 方程来描述, 并给出了低阶近似情况下, 对于小的、但有限振幅的长波振动, 当入射波为单孤子时, 反射孤子与透射孤子的个数及其大小;当分界面是有限长度并连续变化时,对于小的、但有限振幅的长波振动, 尘埃声孤波由KdV型方程来描述,并由此给出了准孤子振幅、传播速度等参量在传播过程中的变化.
关键词:
尘埃等离子体
孤子
KdV方程
约化摄动法 相似文献
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The aim of this paper is to investigate the effects of the presence of a transverse crack in a rotating shaft under uncertain physical parameters in order to obtain some indications that might be useful in detecting the presence of a crack in rotating system. The random dynamic response of the cracked rotor is evaluated by expanding the changing stiffness of the crack (i.e. the breathing mechanism) as a random truncated Fourier series. To avoid the use of the Monte Carlo simulations (MCS), an alternative procedure that is based on a combination of the Harmonic Balance Method and the Stochastic Finite Element Method (SFEM) using the Polynomial Chaos Expansion (PCE) is proposed. So the response of the Fourier components of the cracked rotor is expanded in the polynomial chaoses. The random dynamic response obtained by applying this procedure is compared with that evaluated through numerical integration based on the Harmonic Balance Method and the Monte Carlo simulations. 相似文献
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Kazuhiko Ishikawa Hitomi Yamano Ki-ichiro Kagawa Katsuhiko Asada Koichi Iwata Masahiro Ueda 《Optics and Lasers in Engineering》2004,41(1):19-29
An optical method for directly measuring the thickness of a thin transparent film has been proposed by means of multi-wave laser interference at many incident angles, and confirmed experimentally by means of equipment made on an experimental basis. Two methods are available: one can be used when an index of refraction of the film, a wavelength λ, and two successive angles of incidence at which the sinusoidal light intensity has minimum values, are known (Method I), and another can be used without an index of film refraction when three successive angles of incidence and a wavelength are known (Method II). The smallest measurable thickness is 1.43λ for Method I, and 2.5λ for Method II. The largest measurable thickness is about 100λ for both methods. The measurement error by means of numerical calculation is Δh/h−1.01×10−2, and that obtained experimentally with an angular resolution of incident light of 0.3° is Δh/h7×10−2 for Method I. The refractive index can also be measured by means of Method II. 相似文献
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抛物型方程一类自由边界问题的微分求积区域分裂法 总被引:3,自引:0,他引:3
在微分求积法的基础上,结合区域分裂法的优点提出了一种新的数值计算方法——微分求积区域分裂法.数值试验表明,该方法在求解抛物型方程一类初值带有弱奇性的自由边界问题时十分灵活有效. 相似文献
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Inga M. Arkhipova Angelo Luongo Alexander P. Seyranian 《Journal of sound and vibration》2012,331(2):457-469
The phenomenon of stabilization by parametric excitation of an unstable, elastically restrained double inverted pendulum under its own weight is addressed. The solution is pursued by the Multiple Scale Method, as a perturbation of a critical Hamiltonian system, possessing a zero- and a real frequency. Several asymptotic expansions are carried out, which are able to capture the long-term behavior of the system, for generic (non-resonant) values of the excitation frequency, and some special (resonant) values of excitation-to-natural frequency ratio. It is shown that a proper ordering of the control parameters must be performed, and proper use of integer or fractional power expansions must be made, according to the resonance under study. In particular, a non-standard application of the Multiple Scale Method is illustrated for the 1:1 resonant case, requiring fractional powers and accounting for the ‘arbitrary constants’, generally omitted in regular cases. A comprehensive scenario of the stabilization regions is given in which lower-bound as well as upper-bound curves are evaluated, thus integrating results that recently appeared in the literature. 相似文献
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C. Bourlier 《Waves in Random and Complex Media》2018,28(4):724-742
In a previous paper, by combining three techniques, i.e. Subdomain Decomposition Iterative Method (SDIM), Adaptive Cross Approximation (ACA), and Forward–Backward Spectral Acceleration (FBSA), from the Method of Moments (MoM), a high-efficiency calculation of the propagation and scattering in ducting maritime environments has been proposed. In this paper, this algorithm is updated by adding a perfectly conducting object above the sea surface, assumed to be highly conducting, which makes the environment very complex. Then, to quantify the effect of the object on the total scattered field, the coherent and incoherent powers, with and without object, are simulated by considering a surface of 800,000 unknowns (length of 6 km and a frequency of 5 GHz). 相似文献
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《Waves in Random and Complex Media》2013,23(3):218-225
Abstract Plasmonic wave propagation in a chain waveguide created by a triangular array of silver nanoshell cylinder was investigated using finite element method and Finite Difference Time Domain Method. It is observed that the trimer nanoshell cylinder array provides better field propagation compared to single-chain and pair-chain nanoshell cylinder arrays. Results show that the resonant wavelength of the structure is highly sensitive to the permittivity of either the core or the surrounding medium. It is also observed that as the core thickness of the waveguide is increased surface plasmon resonance shows a red shift. 相似文献
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Weikai Su Wei Hong ZhengHau Zhu YunYi Wang 《International Journal of Infrared and Millimeter Waves》1992,13(12):1925-1941
In this paper, the scattering parameters of a waveguide cross junction loaded with a metallic post in the center are analyzed for the first time by using the Method of Lines. The homogeneous boundary condition of the third kind and curved boundary are introduced in the formulation. Numerical results are in good agreement with the experimental data. The scattering parameters at Ka-band and W-band of the cross junctions loaded with metallic posts of different radii are presented. It is shown from the numerical results that loaded with metallic posts is an effective means for adjusting the network parameters of the waveguide cross junction to satisfy some special requirements in the design of millimeter wave components. 相似文献
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It is attempted to model a displacive phase transformation by Continuous Displacement Cluster Variation Method. The main focus of the present study is placed on distorted to non-distorted phase transformation in the two-dimensional square lattice. The entropy is formulated within the single-site approximation (point approximation), while the pair-wise atomic interaction energies are combined to stabilize a distorted phase at low temperatures. The distorted to non-distorted phase transformation in the present study is of the second order, and the calculated distribution of atoms suggests that the transformation is of the displacive type in the classification. 相似文献
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Method for laser pulse shaping by a discrete transmission line has been improvedand simplified.Some calculations are given about deformation of the shaped pulse,passingthrough a laser amplifier.The required profile of electrical pulse can be deduced from the newcalculation when the amplified driving pulse profile is defined.The noise effect is estimated. 相似文献
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Arpita Srivastava 《Optics & Laser Technology》2011,43(7):1208-1211
This paper uses the Beam Propagation Method to investigate numerically the switching behavior of a Nonlinear Mach-Zehnder Interferometer (NMZI). A saturating-type nonlinearity has been considered for the present investigations. It is shown that the input versus output characteristics change drastically when a Kerr type nonlinear medium is replaced by a saturating type nonlinear medium. In contrast to an NMZI with Kerr nonlinearity, where only quantitative behavior changes with NMZI length, quantitative as well as qualitative behaviors change in the case of a saturating nonlinearity. We propose an all-optical stabilizer and MZI with stable “ON” and “OFF” states on the basis of our investigation. 相似文献