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1.
Tapendra Nath Maulik 《Pure and Applied Geophysics》1965,60(1):42-50
Summary Propagation of surface wave in heterogeneous media with various laws of variation of elastic properties have been discussed previously by several authors. There the laws of variations were taken on the considerations that the solutions might be had in terms of known functions. Here the approximate solutions for polynomial law of variations of elastic properties have been obtained. 相似文献
2.
We have sampled particles of native aluminium (Al°) in two sediment cores from the Central Indian Basin (CIB). The cores are geographically separated but are located at the base of two seamounts. The native Al° particles occurring as grains and spherules, have an average Al content of 95% and are associated with volcanogenic–hydrothermal material. Morphologically and compositionally, the specimens are similar to those reported from the East Pacific Rise. After ruling out several processes for the presence of the native Al°, we hypothesize that during progressive melting of magma, a basaltic magma is produced which has high contents of reductants such as methane and hydrogen, and a low oxygen fugacity. During the upward migration of such magma, reduction to metallic aluminium and the formation of native Al° particles takes place. 相似文献
3.
A unified ionospheric electron collision frequency model profile 〈νg〉 has been calculated in the height range 50–500 km. The computed profile accounts for the electron collisions with the neutral particles as well as the ions. Experimental values of momentum transfer cross-sections have been used for electron collisions with N2, O2 and Ar and theoretical values for N, O, He and H. It is observed that the electron-ion collisions 〈νei〉 dominate over the electron-neutral collisions 〈νen〉 above 170 km. However, 〈νe?N〉 is of the same order of magnitude as 〈νe?O〉 in the height range 170–210 km. Above 360 km 〈νe?O〉 becomes more important among the neutrals. The temporal, seasonal and solar epoch variations of 〈νei〉 are also shown. A typical electron collision frequency profile 〈νg〉 corresponding to the exospheric temperature of 1100 K has been compared with the available experimental results for D, E and F-regions obtained from different experimental techniques. This profile has been used to determine the electrical, thermal, heat flow and current flow conductivities, the mobility and the diffusivity of electrons. The results so obtained are found to be in good agreement with the earlier results. 相似文献
4.
5.
Conventional stratigraphic correlations are based on similarity of lithology, order of superposition, marker bed, unconformity, grade of metamorphism, fossil content and geochronology of the rock units. The Gondwana strata have been correlated referring to the above mentioned criteria. In the present work, the Talchir and Karharbari formations of two adjacent Gondwana basins separated by over 200 Km were examined with respect to their palaeocurrent directions. The study suggests that the palaeocurrent populations of different formations in both the basins are statistically dissimilar, this is because, both are stratigraphically distinct in order of superposition and thus are not correlatable. On the other hand, the palaeocurrent populations of the same formation in both the basins are statistically similar and stratigraphically correlatable. It is suggested that the similarity of palaeocurrent can be regarded as a criterion for stratigraphic correlation at least in local and regional scale. 相似文献
6.
Pankaj K. Mishra Sankar K. Nath Mrinal K. Sen Gregory E. Fasshauer 《Computational Geosciences》2018,22(5):1203-1218
Scattered data interpolation schemes using kriging and radial basis functions (RBFs) have the advantage of being meshless and dimensional independent; however, for the datasets having insufficient observations, RBFs have the advantage over geostatistical methods as the latter requires variogram study and statistical expertise. Moreover, RBFs can be used for scattered data interpolation with very good convergence, which makes them desirable for shape function interpolation in meshless methods for numerical solution of partial differential equations. For interpolation of large datasets, however, RBFs in their usual form, lead to solving an ill-conditioned system of equations, for which, a small error in the data can cause a significantly large error in the interpolated solution. In order to reduce this limitation, we propose a hybrid kernel by using the conventional Gaussian and a shape parameter independent cubic kernel. Global particle swarm optimization method has been used to analyze the optimal values of the shape parameter as well as the weight coefficients controlling the Gaussian and the cubic part in the hybridization. Through a series of numerical tests, we demonstrate that such hybridization stabilizes the interpolation scheme by yielding a far superior implementation compared to those obtained by using only the Gaussian or cubic kernels. The proposed kernel maintains the accuracy and stability at small shape parameter as well as relatively large degrees of freedom, which exhibit its potential for scattered data interpolation and intrigues its application in global as well as local meshless methods for numerical solution of PDEs. 相似文献
7.
This paper explores a development intervention, discourses involved and people's encounter at the interfaces during interaction and negotiation processes in everyday project life. It aims to get insight in the participatory intervention; how participatory is it and what is the intention behind the concept? This ethnography of an ongoing program in Kenya concludes that creation of participatory projects is a strategy of development practitioners to have high-rated evaluation of the project for donor funding but, in practice, the concept of participation is used by actors according to their interest and need. 相似文献
8.
The acute toxicity of nickel sulphate to Colisa fasciatus has been evaluated by static bioassay experiments. The LC 50 values of nickel for 24, 48, 72 and 96 h were computed to be 96.12, 60.18, 24.45 and 16.72 mg/1, respectively. Their 95 % confidence limits have also been investigated. 相似文献
9.
Self-similar MHD shock waves have been studied under the action of monochromatic radiation into a non-uniform stellar atmosphere with a constant intensity on unit area. It has been assumed that the radiation flux moves through the gas. Variation of flow variables have heen shown in tables for two different cases. 相似文献
10.
Rabindra Nath Das 《Astrophysics and Space Science》1979,63(1):155-170
The general equation for radiative transfer of line scattering intensity — including the effects of scattering, absorption and thermal emission — in the Milne-Eddington model is considered here. The scattering function is assumed to be quadratically anisotropic in the cosine of the scattering angle, and Planck's intensity function is assumed for thermal emission. The exact solutions for emergent intensity from the bounding face and the intensity at any optical depth are obtained by the method of the Laplace transform in combination with the Wiener-Hopf technique. 相似文献