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971.
972.
An attempt is made to reveal a geochemical compatibility with paleoenvironment to understand the genesis of bauxite deposits that are derived from two different parent rocks. For this purpose two in situ bauxite profiles, one developed over basalt and another over sandstone, have been taken. Gibbsite is the major mineral in all these bauxites with minor occurrences of goethite, hematite, anatase, kaolinite, etc. From the study it is evident that the paleoenvironment and geochemical processes are vital factors that could lead to the formation of bauxites. The significance of this is fully discussed. 相似文献
973.
Rock samples belonging to ten lithological types under different stages of weathering, were collected from different stratigraphical
horizons at Bhagalpur. Their densities and porosities were determined experimentally and the data obtained were fitted empirically
in a linear equation for each lithological type. The slopes of the curves, which were negative in each case, showed that the
increase in porosity for the same decrease in density were in the order, white sandstone > ferruginous sandstone > white claystone
> porphyritic gneiss > quartzite > pegmatite > amphibolite ≅ biotite gnejss > basalt ≅ dolerite. A new weathering potential
index based on the density-porosity data was proposed and the values for a specific stage of weathering for all the lithological
types studied fall within the same range. 相似文献
974.
Man has had to live with floods since the very inception of his existence. Fury of flood causes heavy damages to both life and property. Accurate flood inundation data is one of the essential requirements for effective management of flood problem. Remote Sensing methods are well suited for acquiring flood inundation data because of synoptic, repetitive coverage of the satellite data. This paper briefs on an attempt to map flood inundated areas in a part of Mahanadi river basin using remote sensing data. 相似文献
975.
The wave-induced nearshore circulation model suggested by Noda has been modified and applied for three small segments along
the coast of Goa. The present model incorporates the prevailing bottom topography and considers its variation along with the
radiation stress as the driving force for the circulation. We find that the flow pattern is strongly dependent on bottom topography.
While normal incidence of waves results in a cellular pattern of flow, meandering flows prevail for oblique incidence along
the coast. The shoreward flows are always located over shoals while the rip currents prevail over channels. The onshore/offshore
flows show magnitudes as high as 3·1 m/s, while those alongshore reach a maximum of 1·1 m/s. When compared with field observations
these values are slightly higher. 相似文献
976.
977.
HF doppler observations of the vertical drift velocity and group height of the 5.5 MHz plasma frequency level of the post-sunset
bottomside F-region obtained on a fewESF (equatorial spread-F) and non-ESF days at Trivandrum are presented. The results show that on the non-ESF days, the maximum group height attained is about 400 km and the maximum velocity is less than 30 m/sec. On theESF days, however, the corresponding values are found to be in the range of 400–650 km and 30–50 m/sec. TheESF onset is found to be significantly delayed relative to the velocity peak indicating that it is more closely linked to the
layer height than to the drift velocity. 相似文献
978.
Sensitivity of the radar scattering coefficient to the oceanic wind vector in the midangular range for frequencies from L-
to Ku- band is studied. This is based on computations of scattering coefficient via the two-scale scattering theory employing
a semi-empirical model for the ocean spectrum suggested by Fung and Lee and the slope distribution by Cox and Munk. Higher
frequency and incident angles of over 45 degrees seem to yield better wind sensitivity. 相似文献
979.
This paper points out certain discrepancies when the incoherent scatter radar observations at Jicamarca and the electron density models, (the Bent andiri) were compared. In all cases the bottomside semi-thickness of the observed profile was significantly greater than that of both Bent andiri models. The decay constants associated with the topside ionosphere for the observed profiles were generally greater than that of the two models, the difference being more pronounced in theiri model. The results call for a revision of the models so that they accurately represent the electron density distribution at the equator. 相似文献
980.
Continuation by integral equation methods: A note on surface integration over the double layer 总被引:1,自引:0,他引:1
Richard D. Ray 《Pure and Applied Geophysics》1984,122(5):725-730
Upward continuation from a non-level surface may be performed by an integral equation method as shown previously by Bhattacharyya and Chan. Integration over the double layer is often computed using a centroid rule quadrature formula, but under certain circumstances more accurate formulae are required. One such formula may be found using a geometric approach. The result is equivalent to an expression recently published by Hansen and Miyazaki. 相似文献