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JAYATI GHOSH 《Geographical review》2002,92(1):114-126
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Dipole sounding resistivity measurements over layered earth can be interpreted directly by adapting the procedure given by Koefoed (1968) for Schlumberger system. To carry out the first step of the interpretation leading to the determination of the raised kernel function, partial resistivity functions for the dipole method are derived and given in the form of standard curves. The second step involving the derivation of layering parameters from the kernel being independent of the electrode configurations remains unaltered. The applicability and limitations of the method are discussed. 相似文献
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The North–East Corridor(NEC) Testbed project is the 3rd of three NIST(National Institute of Standards and Technology) greenhouse gas emissions testbeds designed to advance greenhouse gas measurements capabilities. A design approach for a dense observing network combined with atmospheric inversion methodologies is described. The Advanced Research Weather Research and Forecasting Model with the Stochastic Time-Inverted Lagrangian Transport model were used to derive the sensitivity of hypothetical observations to surface greenhouse gas emissions(footprints). Unlike other network design algorithms, an iterative selection algorithm, based on a k-means clustering method, was applied to minimize the similarities between the temporal response of each site and maximize sensitivity to the urban emissions contribution. Once a network was selected, a synthetic inversion Bayesian Kalman filter was used to evaluate observing system performance. We present the performances of various measurement network configurations consisting of differing numbers of towers and tower locations. Results show that an overly spatially compact network has decreased spatial coverage, as the spatial information added per site is then suboptimal as to cover the largest possible area, whilst networks dispersed too broadly lose capabilities of constraining flux uncertainties. In addition, we explore the possibility of using a very high density network of lower cost and performance sensors characterized by larger uncertainties and temporal drift. Analysis convergence is faster with a large number of observing locations, reducing the response time of the filter. Larger uncertainties in the observations implies lower values of uncertainty reduction. On the other hand, the drift is a bias in nature, which is added to the observations and,therefore, biasing the retrieved fluxes. 相似文献
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NILANJAN DASGUPTA TARITWAN PAL JOYDEEP SEN TAMOGHNO GHOSH 《Journal of Earth System Science》2011,120(4):617-626
The study involves the characterization of pegmatoidal granite, southeast of Beawar, Ajmer district, Rajasthan. Earlier researchers
had described this granite as part of the BGC, basement to the Bhim Group of the Delhi Super Group rocks. However, the present
study indicates that it is younger than the rocks of Bhim Group of South Delhi Fold Belt, into which it is intrusive. The
intrusion is structurally controlled and the outcrop pattern is phacolithic. The granite had intruded post-D2 deformation of the Delhi orogeny along the axial planes of D2 folds. The intrusion has also resulted in the formation of a contact aureole about the calc gneisses. 相似文献
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Mohamed W. ALI-BIK Suranjan GHOSH N. PRABHAKAR Said H. Abd El RAHIM Hilmy E. MOUSSA 《《地质学报》英文版》2022,96(5):1545-1565
The Sa''al Metamorphic Complex (SMC; southern Sinai) encompasses the oldest arc rocks in the Arabian–Nubian Shield, comprising two non-consanguineous metavolcanic successions (the Agramiya Group and the Post-Ra''ayan Formation) separated by the metasediments of the Ra''ayan Formation. It experienced three distinct deformational events (D1–D3) and two low-medium grade regional metamorphic events (M1–M2). The Agramiya Group and the Ra''ayan Formation experienced all tectonometamorphic events (D1–D3 and M1–M2), whereas the Post-Ra''ayan volcanic rocks were only affected by the D3 and M2 events. D1 is an extensional event and is connected to the late Rodinia break-up (~Tonian; 900–870 Ma). The M1 metamorphism variably affected the older Agramiya Group, the rhyolitic tuffs experiencing lower to upper greenschist facies conditions and the basic and intermediate volcanic rocks undergoing amphibolite facies metamorphism. The Ra''ayan Formation metasediments experienced upper greenschist to amphibolite facies metamorphism. The upper greenschist facies M2 affected the youngest Post-Ra''ayan volcanic rocks and other stratigraphic successions. The compressive D2 and D3 events were coeval with the accretion of dismembered terranes in the assembly of Gondwana. D2 can be linked to the Tonian–Cryogenian arc-arc assembly (~880–760 Ma; in Elat and Sinai), whereas D3 and the accompanying M2 is constrained to 622–600 Ma (Ediacaran). 相似文献
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D. P. GHOSH 《Geophysical Prospecting》1971,19(2):192-217
Koefoed has given practical procedures of obtaining the layer parameters directly from the apparent resistivity sounding measurements by using the raised kernel function H(λ) as the intermediate step. However, it is felt that the first step of his method—namely the derivation of the H curve from the apparent resistivity curve—is relatively lengthy. In this paper a method is proposed of determining the resistivity transform T(λ), a function directly related to H(λ), from the resistivity field curve. It is shown that the apparent resistivity and the resistivity transform functions are linearily related to each other such that the principle of linear electric filter theory could be applied to obtain the latter from the former. Separate sets of filter coefficients have been worked out for the Schlumberger and the Wenner form of field procedures. The practical process of deriving the T curve simply amounts to running a weighted average of the sampled apparent resistivity field data with the pre-determined coefficients. The whole process could be graphically performed within an quarter of an hour with an accuracy of about 2%. 相似文献
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Computation of the grain-size distribution of the suspended load above a sand bed must take into consideration: (1) sorting processes from the bed to the bed layer and (2) sorting between the bed layer and suspension. Grain-size distributions of the bed layers above sand beds of three different types have been computed in this work, both by the Einstein and the Gessler methods. Using these as references, suspended load distributions have been obtained in each case by the Rouse suspension equation. A new formula has also been developed in partial modification of Hunt's method for direct computation of bed load and suspended load from a bed's grain-size distribution and flow parameters. Comparison of the computed data with actual observations in laboratory flumes show that no one method is particularly superior to the others, but the present method is advantageous because it affords direct computation of the suspended load from a bed's grain-size distribution, without going through an intermediate stage (bed load). The possible sources of error in each of the methods have been discussed. 相似文献