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991.
Summary. Asymptotic ray theory (ART) fails in transition regions near critically reflected, bottom glancing or caustic-forming rays in a vertically inhomogeneous layered earth. These deficiencies are repaired here by replacing the transitional ray fields with guided modes plus truncation remainders. Exact ray-mode equivalences and their high-frequency asymptotic approximations are formulated, and their validity and efficiency are verified by numerical comparisons for SH motion in a two-layer earth model comprised of an inhomogeneous sediment above an homogeneous semi-infinite bedrock. 相似文献
992.
Anomalies of some tidal waves of UT1 总被引:1,自引:0,他引:1
Summary. The M f and M m waves of UT1 have been analysed from the BIH data during the period 1967.0 to 1984.0 in order to derive the Love number k .
These analyses performed during successive intervals of this period show some anomalies in the values of the Love number k derived from the Mf wave. Large variations with time of the amplitude and the phase appear for this wave while the values derived from the M m wave present a good stability during the whole period.
The spectrum of the UT1-residuals (as obtained by removing the theoretical zonal tidal UT1 terms) shows the existence of a perturbation wave near the Mf period. This wave lies in the range 13.5–13.9 day according to the analysed interval; it could be related with the perturbation wave noticed by some authors near the M f gravimetric wave. 相似文献
These analyses performed during successive intervals of this period show some anomalies in the values of the Love number k derived from the M
The spectrum of the UT1-residuals (as obtained by removing the theoretical zonal tidal UT1 terms) shows the existence of a perturbation wave near the M
993.
B. A. Hobbs 《Geophysical Journal International》1982,68(1):253-264
Summary. A method is described for finding a resistivity model that fits given magnetotelluric data in the one-dimensional case. The procedure is automatic and objective in that no a priori model structure is imposed. Starting with a uniform half space derived directly from the data, the procedure gradually transforms the half space to one with a continuous and smooth resistivity distribution whose response fits the measured data. The method is illustrated by application to two magnetotelluric data sets. 相似文献
994.
This work examines the use of an annually updated metropolitan data system as a tool for evaluating benign racial location policies during the first year of the Section 8 Existing Rent Supplement program. Case-study evidence shows that the rent supplement program (with benign locational policies) is ineffective in reducing the isolation faced by minority groups, and that the information used to monitor compliance of the program with benign locational policies lags badly behind the true state of affairs. As a result, new areas of racial concentration have been encouraged and augmented. 相似文献
995.
This article is an English translation of the work cited in 46: 3092. The authors review the conclusions of Pivovarov (see 44: Title 3118) concerning the nature of the urbanization process and optimal city size in the USSR. The relationship between urbanization and the characteristics of a given socioeconomic system is examined, and the possibility of determining optimal size for cities of different functional types is evaluated 相似文献
996.
997.
Brooks B. Ellwood 《Geophysical Journal International》1979,57(2):431-443
Summary. Anisotropy of magnetic susceptibility measurements have been performed on 154 specimens taken from 25 different seams in the South Wales Coal Field, up to 24 samples per seam. The magnetic fabric determined is represented, in general, by oblate spheroids with minimum ( K c ) AMS axes usually clustered at a near-vertical, or occasionally, near-horizontal pole which is normal to the magnetic foliation plane defined by great circle distributions of maximum ( K a ) and intermediate ( K b ) axes. The results suggest that the coalification process and variations in rank within the coal field are due to the combined effects of vertical compression and compaction resulting from variations in overburden pressure, and to horizontal compression, due to variations in tectonic thrusting during the Variscan Orogeny. Analysis of the AMS of closely spaced samples across a single anthracite seam shows no systematic variability in magnetic properties within the seam. 相似文献
998.
Summary. The contributions from the oceanic and ionospheric dynamos, Lo and LI respectively, to the geomagnetic lunar daily variation, L , at Alibag, a coastal station in the Indian equatorial region, are calculated from the L harmonics derived from a 41–yr long series of observations. The analysis in the calendar months shows a steady and significant ocean dynamo contribution in the vertical component, Z, in all the months except April. Examination, by an analysis of the data year by year, of the association of Lo and LI with varying solar and magnetic activities reveals, surprisingly, a stable correlation between the magnetic activity index A P and the oceanic part in the horizontal and vertical components but not in declination, which probably indicates the influence of induced currents, along the latitudes, on L o . 相似文献
999.
Mark B. Boslough Thomas J. Ahrens Arthur C. Mitchell 《Geophysical Journal International》1986,84(3):475-489
Summary. Temperatures of CaAl2 Si2 O8 (anorthite glass) shocked to pressures between 48 and 117 GPa have been measured in the range from 2500 to 5600 K, using optical pyrometry techniques. The pressure dependence of the shock temperatures deviates significantly from predictions based on a single high-pressure phase. Either a variable specific heat, or the existence of three phase transitions, at pressures of about 55, 85 and 100 GPa and with transition energies of about 0.5 MJ kg−1 each (∼ 1.5 MJ kg−1 total) can explain the shock-temperature data. The proposed phase transition at 100 GPa can possibly be identified with the stishovite melting transition. Theoretical models of the time dependence of the thermal radiation from the shocked anorthite based on the geometry of the experiment and the absorptive properties of the shocked material yield good agreement with observations, indicating that it is not necessary to invoke intrinsic time dependences to explain the data in many cases. Observed time dependences were used to calculate absorption coefficients of the shocked material of from about 2 mm−1 to greater than 24 mm−1 – an increasing function of shock pressure. The assumption that the shocked material radiates as a black body is supported by the theoretical model, and by the close agreement between measured and calculated black body spectral radiance as a function of wavelength. 相似文献
1000.