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991.
992.
WINSURF模板库的设置及其在瑞雷波频散曲线提取中的应用 总被引:1,自引:0,他引:1
WINSURF模板库是物化探数据处理的一种强有力工具,以其在瑞雷波频散曲线提取中的应用为例,阐述了WINSURF模板库设置的基本方法和技巧,并给出了实例模板库。应用结果表明,WINSURF模板库稳定性好、通用性强,可直接作为工具来使用,从而大大缩短了程序开发周期,避免了重复编程和资源浪费,提高了科研和工作效率。 相似文献
993.
A Model for Deepwater Oil/Gas Blowouts 总被引:1,自引:0,他引:1
When gas is released in deepwater, the high pressure and low temperature can convert the gases into hydrates, which are buoyant. As these hydrates travel upwards they will encounter regions of lower pressure and can decompose into free gas. The presence or absence of hydrates has a significant impact on the behaviour of the jet/plume due to the alteration of the buoyancy. The free gas may dissolve in water. This paper describes a computer model developed to simulate the behaviour of oil and gas released from deepwater locations in the ocean. The model integrates the hydrodynamics and thermodynamics of the jet/plume with kinetics and thermodynamics of hydrate formation/decomposition. Model formulation and comparison of results with laboratory data for hydrates is presented. Scenario simulations show the behaviour of oil/gas under different deepwater conditions. 相似文献
994.
The influence of vegetation on longitudinal dispersion was studied in a laboratory flume for three flow velocities and three plant population densities. Rhodamine was injected continuously upstream of the dowel array and sampled at two positions downstream. The dispersion coefficient was estimated by fitting the concentration time series at the final downstream station. Enhanced turbulence as well as diminished vertical shear resulted in a lower dispersion coefficient when the plants were present. In addition, recirculation zones behind each stem trapped and delayed a fraction of the mass, enhancing the longitudinal dispersion and creating significant frontal delay. 相似文献
995.
During the Mw = 7.4 Izmit earthquake of 17 August 1999, the Yeilyurt district of Istanbul underwent damage despite the epicentral distance of 90 km. At Avclar (20 km west of Yeilyurt), the ground motion was even stronger and has caused heavy damage and fatalities. We investigate whether the observed ground motions can be explained by theoretical site amplifications calculated from one-dimensional (1-D) shear-wave velocity models. For this purpose, microtremors recorded with sensor-arrays set up at two sites were analyzed to obtain phase velocity dispersion curves using both the conventional and the Capon frequency–wavenumber (f–k) methods. At the Yeilyurt site, the conventional f–k method offered reliable phase velocity estimations whereas the Capon method showed scatter in the estimations. At the Avclar site, on the other hand, the Capon method provided a higher resolution than the conventional method and hence, allowed estimation of wavelengths up to seven times the array size. At the Yeilyurt site, the shallow shear-wave velocity profile that is correlated with the lithology obtained from boreholes yields a ground motion amplification factor of about 3 at the frequency of 1 Hz. At the Avclar site, the phase velocity dispersion curve is comparable with the one previously obtained using the spatial autocorrelation method. The site amplification factors calculated from the 1-D shear-wave velocity model are around 2–3 at the frequencies of 0.4, 1.2 and 2.3 Hz, which are about 2–3 times smaller than the amplifications obtained from reference-site techniques using weak/strong motion records of earthquakes. We suggest that the discrepancy may be caused by a 2- or 3-D effect introduced by surface and/or bedrock topography not accounted for by the horizontally stratified model considered here. 相似文献
996.
The average layered structure of the intracratonic Paraná Basin, SE Brazil, is investigated with surface-wave group velocities
from a small regional earthquake recorded by two broadband stations. Rayleigh and Love waves in the period range 1–4.2 s are
used to infer average properties down to about 4 km. Genetic algorithm techniques are used to find the best fitting 1-D S-wave
model. The inverted 1-D models show fair correlation with the average properties of the propagation paths as expected from
geology and borehole information. However, different S-wave velocity models are obtained for the different inversion parameterizations.
Since lateral heterogeneities are expected along the paths, several synthetic tests are performed with heterogeneous propagation
paths. For approximately homogenous path (i.e., little lateral variation), the main features of the average synthetic model
can be retrieved for different model parameterizations. For strong lateral variations, however, the average dispersion curve
can produce very different 1-D inverted models depending on the parameterization. Also, the 1-D inverted models may differ
significantly from the average properties of the inhomogeneous path, and wrong depths to interfaces may be inferred. For real
data inversions, it is then suggested that various different parameterizations should be tested. If the resulting models show
consistent features, this probably indicates homogeneity in the propagation path. But, if very different and unstable features
are obtained in the 1-D inversions, then strong lateral variation may be present in the propagation path, and the average
1-D model may not represent average properties along the path. 相似文献
997.
The generalized Rayleigh type surface waves are studied in a multilayered medium consisting of anisotropic poroelastic solid
layered stack beneath a fluid layer and overlying a heterogeneous elastic solid half-space. The heterogeneity, considered,
is of vertical type. The interface between solid layer and half-space is treated as an imperfect interface and suitable boundary
conditions are applied thereat. The technique of transfer matrix is used to obtain the dispersion equation in compact and
convenient form. Numerical results are obtained for particular models. The effects of anisotropy and heterogeneity on the
surface waves speed are discussed. 相似文献
998.
G. Gioia G. Lacorata E. P. Marques Filho A. Mazzino U. Rizza 《Boundary-Layer Meteorology》2004,113(2):187-199
Relative dispersion in a neutrally stratified planetary boundary layer (PBL) is investigated by means of large-eddy simulations (LES). Despite the small extension of the inertial range of scales in the simulated PBL, our Lagrangian statistics turn out to be compatible with the Richardson t3 law for the average of square particle separation, where t is time. This emerges from the application of non-standard methods of analysis through which a precise measure of the Richardson constant was also possible. Its value is estimated as C2 0.5, in close agreement with recent experiments and three-dimensional direct numerical simulations. 相似文献
999.
Aybige ?AkinciEmail author Jorge ?Mejia Alemayehu L.?Jemberie 《Pure and Applied Geophysics》2004,161(1):73-91
We have measured group delays of the spectral components of high-frequency P-waves along two portions of the North Anatolian Fault Zone (NAFZ) in Turkey and in a region of southern Germany. Assuming that the observed dispersion is associated with attenuation in the crust and that it can be described by a continuous relaxation model, we obtained Q and the high-frequency relaxation times for those waves for each of the three regions. Individual P-wave Q values exhibit large scatter, but mean values in the NAFZ increase from about 25 to 60 over the distance range 5–90 km. Mean Q values are somewhat higher in the eastern portion of the NAFZ than in the western portion for measurements made at distances between 10 and 30 km. P-wave Q values in Germany range between about 50 and 300 over the hypocentral distance range 20–130 km. In that region we separated the effects of Q for basement rock (2–10 km depth) from that of the overlying sediment (0–2 km depth) using a least-squares method. Q varies between 100 and 500 in the upper 8–10 km of basement, with mean values for most of the distance range being about 250. Q in the overlying sediments ranges between 6 and 10. Because of large scatter in the Q determinations we investigated possible effects that variations of the source-time function of the earthquakes and truncation of the waveform may have on Q determinations. All of our studies indicate that measurement errors are relatively large and suggest that useful application of the method requires many observations, and that the method will be most useful in regions where the number of oscillations following the initial P pulse is minimized. Even though there is large scatter in our Q determinations, the mean values that we obtained in Turkey are consistent with those found in earlier studies. Our conclusions that Q is significantly higher in the basement rock of Germany than in the basement rock of Turkey and that Q is lower in western Turkey than in eastern Turkey are also consistent with results of Q studies using Lg coda. 相似文献
1000.