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141.
Application of the weighted residual method to diffraction by 2-D canyons of arbitrary shape: I. Incident SH waves 总被引:1,自引:0,他引:1
A solution for the two-dimensional scattering and diffraction of plane SH waves by canyons of arbitrary shape in an elastic half space is presented. The wave field for arbitrary geometry in this paper is computed numerically by the method of weighted residues (moment method). The wave displacement field computed by the present residual method for the case of a semi-circular canyon was shown to agree analytically and numerically with that computed by the exact closed form series solution. The same observations about ground amplifications, their dependence on frequencies and orientations of the incident waves, can be stated here for canyons of arbitrary shape as previously made for circular canyons. 相似文献
142.
Overall Properties of A Material With Inclusions Or Cavities 总被引:1,自引:0,他引:1
J. A. Hudson 《Geophysical Journal International》1994,117(2):555-561
143.
采用了单柱离子色谱法测MnO2产品中无机离子杂质;提出了消除干扰的可行途径,将La(OH)3加入后能同时消除进样峰的干扰和溶剂峰的出现。选用1.75mmol/L邻苯二甲酸1.75mmol/L三羟甲基氨基甲烷为混合淋洗剂测定F^-,Cl^-,NO3^和SO^2-4,其标准加入回收率为95%-105%;RSD(n=7)为2.47%-8.08%。 相似文献
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This article summarizes work on multiple scattering based on models of media with randomly distributed scatterers. The scatterers are isotropic and statistically uniform. Measuring distance in terms of mean-free pathL
s and time in terms of the mean-free timesL
s/V, whereV is the velocity of scattered waves, we have more convenient dimensionless distance and time. It can be shown that after the dimensionless time equals 0.65 energy contributed from multiple scattering becomes predominant. Thus the later coda reflects the effect of multiple scattering rather than single scattering. Treating the seismic record, including starting and tail parts, as a whole, the diffusion theory predicts that at a dense distribution of scatterers and a small distance between source and receiver, codas reflect mainly intrinsicQ
i. Of course, this conclusion is coincident with the presumption of the diffusion theory,Q
s>Q
i. However, from a new integral equation of multiple scattering, which deals with the scattered waves and primary waves separately, the conclusion is similar but clearer. This article quotes the new expression for coda energy in two-dimensional space. It shows that if the receiver is close to the source, the coda decay reflects only intrinsicQ
i, then as the distance increases, effects of scatteringQ
s, are involved in the decay feature. The theoretical plots of coda decay show that it seems in most cases in the earthQ
i should not be smaller than one tenth ofQ
s.Project Sponsored by the Joint Earthquake Science Foundation of China. 相似文献