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421.
Zhao Ruixing 《Acta Meteorologica Sinica》1991,5(4):473-481
In the stratified atmosphere in which the moment nondivergent approximation was applied,introducingthe nonlinear term because of the nonhomogcneous spatial distribution of density and assuming the solutionto be of the form of progressive wave,we obtain a two-order nonlinear system.By means of this system,allresults which were derived by Liu et al.(1984)were obtained.Moreover,it can be proved that there existedperiodic solution in the nonlinear systems when there existed periodic solution in the one-order approxima-tion system,and some mathematic problems arising from series expansion were avoided.In this paper,aseries of approximate solutions of nonlinear system is also discussed. 相似文献
422.
Forward modelling of the crustal structure of the eastern Honshu Island, Japan, was made based on the group velocities ofPL-waves in the period range of 20–30 s. The observed values of group velocity were obtained by appling the multiple filter technique to the seismograms for earthquakes with the epicentral distance ranging from 500 to 1000 km. The theoretical values were calculated using Oliver and Major's method to find the best fit dispersion curve in the least-squares sense. The obtained structural model has considerably high crustal velocities compared to other previous models. It was shown that thePL-wave group velocity in the period range of interest was most sensitive to seismic velocities of the center of the crust. Numerical experiments confirmed the applicability of the approximation methods employed to obtain both observed and theoretical group velocities. 相似文献
423.
The subseismic approximation in core dynamics 总被引:1,自引:0,他引:1
424.
425.
四阶矩准正态分布和三阶矩剪切近似的验证 总被引:1,自引:0,他引:1
本文利用近地面层大气湍流量的观测资料对四阶矩的准正态分布假定和三阶矩的剪切近似进行了实验验证。结果表明,四阶矩能够较好地符合准正态分布假定;三阶矩不仅完全满足剪切近似,甚至还可以对剪切程度进一步加强,并且得到了一系列剪切近似的加强修正系数。 相似文献
426.
Based on the two-stream approximation a broad-band parameterization scheme for solar radiative flux calculationis presented.The whole solar spectral region from 0.2 to 3.58 μm is divided into three broad spectral intervals.The effec-tive broad-band optical depths and single scattering albedos in the atmosphere in each spectral interval can be obtainedusing parameterized formulae from known atmospheric parameters.The overlapping scattering and/or absorption ef-fects of two atmospheric constituents are considered properly.In the consideration of radiative effect of clouds in theatmosphere the single scattering albedos and backscattering parameters of clouds in each broad spectral interval are giv-en preliminarily and the cloud optical depths are determined according to the cloud liquid water content. 相似文献
427.
声波方程逆散射反演的近似方法 总被引:7,自引:0,他引:7
我们在文献[1]里研究了介质参考波速沿某个方向线性变化时的三维声散射理论,导出了声波方程逆散射反演问题解的解析表达式.考虑到应用时的实际条件,本文根据上述反演方法导出2.5维模型的声波方程逆散射反演的波速扰动计算公式,给出该方法在“高频”近似条件下的波速扰动反演计算公式,从而使我们提出的“参考波速线性变化时的声波方程逆散射反演”理论更接近实际应用条件.本文给出的这些反演公式仍然具有原方法的优点,即不但可以使Born近似的假定在大多数情况下能得以满足,而且可以利用快速Fourier变换来快速实现介质波速扰动的反演成象. 相似文献
428.
429.
Kjell Kjenstad 《International journal of geographical information science》2013,27(9):1413-1437
This article describes how to construct a wide range of geometry objects (called GeographicGeometry objects) in the coordinate system of an ellipsoid such as the Geographic coordinate system. Each construction process is formulated analytically and algorithmically using a combination of a set of fairly well-known mathematical methods such as ellipsoid geodesic construction functions, spherical trigonometry and iterative refinement methods. Each such geometry object may efficiently be converted to a corresponding Cartesian geometry object in any map projection coordinate system using an approximation algorithm. This property makes them particularly useful as a coordinate-system-independent geometry representation. A geographic geometry object is normally topologically equivalent to its Cartesian geometry counterpart except for some discontinuity and singularity cases. 相似文献
430.