共查询到18条相似文献,搜索用时 142 毫秒
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从包含完整Coriolis力的Boussinesq近似的斜压大气运动方程组出发,利用半地转近似导出β效应和地球旋转水平分量fH=2Ωcosφ共同作用下的大气非线性Rossby波动所满足的KdV方程,求得了椭圆余弦波解和孤立波解.结果分析表明,若扰动与纬度有关,Coriolis参数分量fH将影响波动传播的频率特征,并加强水平散度对斜压Rossby波的作用;如果扰动与纬度无关,则 Coriolis 参数分量fH的影响消失. 相似文献
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L. D. Oliver G. Christakos 《Stochastic Environmental Research and Risk Assessment (SERRA)》1995,9(4):269-296
We present a diagrammatic method for solving stochastic 1-D and 2-D steady-state flow equations in bounded domains. The diagrammatic method results in explicit solutions for the moments of the hydraulic head. This avoids certain numerical constraints encountered in realization-based methods. The diagrammatic technique also allows for the consideration of finite domains or large fluctuations, and is not restricted by distributional assumptions. The results of the method for 1-D and 2-D finite domains are compared with those obtained through a realization-based approach. Mean and variance of head are well reproduced for all log-conductivity variances inputted, including those larger than one. The diagrammatic results also compare favorably to hydraulic head moments derived by standard analytic methods requiring a linearized form of the flow equation. 相似文献
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We present a diagrammatic method for solving stochastic 1-D and 2-D steady-state flow equations in bounded domains. The diagrammatic method results in explicit solutions for the moments of the hydraulic head. This avoids certain numerical constraints encountered in realization-based methods. The diagrammatic technique also allows for the consideration of finite domains or large fluctuations, and is not restricted by distributional assumptions. The results of the method for 1-D and 2-D finite domains are compared with those obtained through a realization-based approach. Mean and variance of head are well reproduced for all log-conductivity variances inputted, including those larger than one. The diagrammatic results also compare favorably to hydraulic head moments derived by standard analytic methods requiring a linearized form of the flow equation. 相似文献
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由所建立的三维qP波相速度表示式出发,导出并解析求解各向异性介质中的频散方程,得到三维各向异性介质中的相移算子,进而将以相移算子为基础的对称非平稳相移方法推广到各向异性介质,发展了一个三维各向异性介质的深度偏移方法. 文中使用的各向异性介质的速度模型与现行的各向异性构造的速度估计方法一致,将各向同性、弱各向异性及强各向异性统一在一个模型中. 所建立的各向异性介质对称非平稳相移波场延拓算子可以同时适应速度及各向异性参数横向变化;文中给出的算例虽然是针对二维VTI介质的,但所提出的算法同样适用于三维TI介质. 相似文献
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Modeling Full Seismogram Envelopes Using Radiative Transfer Theory with Born Scattering Coefficients
The equation of radiative transfer is used to model the transport of seismic energy in 2-D and 3-D acoustic random media.
Monte-Carlo solutions of this equation using non-isotropic Born scattering coefficients are compared to three analytical solutions:
Markov approximation, radiative transfer theory with isotropic scattering coefficients, and diffusion approximation. Additionally,
we compare to finite differences solutions of the full wave equation in 2-D. We find a good correspondence of radiative transfer
theory to Markov approximation for the case of multiple forward scattering. The comparison to radiative transfer theory with
isotropic scattering coefficients, a model frequently used in data analysis, demonstrates that in the case of forward scattering
the isotropic scattering model is not better than a diffusion approach. To compare radiative transfer theory with non-isotropic
scattering coefficients to finite differences solutions of the full wave equation, the finite source duration and the bandpass
filter process as well as the normalization of absolute amplitudes are explicitely taken into account. We find a good coincidence
of both theories for scattering parameters, which are realistic for usual Earth crust. The theory correctly describes the
unscattered direct wavefront, the envelope broadening caused by multiple forward scattering, as well as the late coda caused
by multiple wide angle scattering. For strong scattering, which can be expected for very heterogeneous media such as strato
volcanoes, the solutions of radiative transfer differ from the more complete solutions of the full wave equation. 相似文献
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A variationally coupled BEM–FEM is developed which can be used to analyse dynamic response, including free-surface sloshing motion, of 3-D rectangular liquid storage tanks subjected to horizontal ground excitation. The tank structure is modelled by the finite element method and the fluid region by the indirect boundary element method. By minimizing a single Lagrange function defined for the entire system, the governing equation with symmetric coefficient matrices is obtained. To verify the newly developed method, the analysis results are compared with the shaking-table test data of a 3-D rectangular tank model and with the solutions by the direct BEM–FEM. Analytical studies are conducted on the dynamic behaviour of 3-D rectangular tanks using the method developed. In particular, the characteristics of the sloshing response, the effect of the rigidity of adjacent walls on the dynamic response of the tanks and the orthogonal effects are investigated. © 1998 John Wiley & Sons, Ltd. 相似文献