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11.
The technique of linear digital filtering as developed for the direct interpretation of Schlumberger and Wenner soundings (Ghosh 1971) has been applied here for the derivation of the resistivity transform function from the field dipole measurements as the first step in directly interpreting dipole data. Filter coefficients for this transformation have been worked out for the radial-polar, perpendicular and parallel (30°) arrays of dipole sounding. The procedure combines speed with accuracy. 相似文献
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The computation method described in this paper is based on the existence of a linear relationship between the mutual coupling ratio and the kernel function in the integral expression for it. Accordingly, the mutual coupling ratio can be determined by first computing sample values of the kernel function and then subjecting these to a digital linear filter. In the present paper the appropriate sampling distance is determined and the values of the digital filter coefficients are computed, both for electromagnetic sounding with horizontal coils and for electromagnetic sounding with perpendicular coils. 相似文献
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D GAYATRI VANI S RAMBABU M RAJASEKHAR G V RAMA B V APPARAO A K GHOSH 《Journal of Earth System Science》2011,120(4):755-771
The Indian northeast monsoon is inherently chaotic in nature as the rainfall realised in the peninsular India depends substantially
on the formation and movement of low-pressure systems in central and southwest Bay of Bengal and on the convective activity
which is mainly due to the moist north-easterlies from Bay of Bengal. The objective of this study is to analyse the performance
of the PSU-NCAR Mesoscale Model Version 5 (MM5), for northeast monsoon 2008 that includes tropical cyclones – Rashmi, Khai-Muk
and Nisha and convective events over Sriharikota region, the rocket launch centre. The impact of objective analysis system
using radiosonde observations, surface observations and Kalpana-1 satellite derived Atmospheric Motion Wind Vectors (AMV)
is also studied. The performance of the model is analysed by comparing the predicted parameters like mean sea level pressure
(MSLP), intensity, track and rainfall with the observations. The results show that the model simulations could capture MSLP
and intensity of all the cyclones reasonably well. The dependence of the movement of the system on the environmental flow
is clearly observed in all the three cases. The vector displacement error and percentage of improvement is calculated to study
the impact of objective data analysis on the movement and intensity of the cyclone. 相似文献
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We present here, an experimental set-up developed for the first time in India for the determination of mixing ratio and carbon isotopic ratio of air-CO2. The set-up includes traps for collection and extraction of CO2 from air samples using cryogenic procedures, followed by the measurement of CO2 mixing ratio using an MKS Baratron gauge and analysis of isotopic ratios using the dual inlet peripheral of a high sensitivity isotope ratio mass spectrometer (IRMS) MAT 253. The internal reproducibility (precision) for the δ 13C measurement is established based on repeat analyses of CO2±0.03‰. The set-up is calibrated with international carbonate and air-CO2 standards. An in-house air-CO2 mixture, ‘OASIS AIRMIX’ is prepared mixing CO2 from a high purity cylinder with O2 and N2 and an aliquot of this mixture is routinely analyzed together with the air samples. The external reproducibility for the measurement of the CO2 mixing ratio and carbon isotopic ratios are ±7 (n?=?169) $\upmu $ mol·mol???1 and ±0.05 (n?=?169) ‰ based on the mean of the difference between two aliquots of reference air mixture analyzed during daily operation carried out during November 2009–December 2011. The correction due to the isobaric interference of N2O on air-CO2 samples is determined separately by analyzing mixture of CO2 (of known isotopic composition) and N2O in varying proportions. A +0.2‰ correction in the δ 13C value for a N2O concentration of 329 ppb is determined. As an application, we present results from an experiment conducted during solar eclipse of 2010. The isotopic ratio in CO2 and the carbon dioxide mixing ratio in the air samples collected during the event are different from neighbouring samples, suggesting the role of atmospheric inversion in trapping the emitted CO2 from the urban atmosphere during the eclipse. 相似文献
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R. K. VERMA R. MAJUMDAR DEBABRATA GHOSH ASHISH GHOSH N. C. GUPTA 《Geophysical Prospecting》1976,24(1):19-30
Results of a gravity survey conducted over Raniganj coalfield, one of the Gondwana basins of Damodar Valley in north-eastern part of India, are presented. The gravity field was separated into regional and residual components. The residual Bouguer anomaly map shows that the coalfield is characterized by a gravity low of about—32 mGal associated with Gondwana sediments. The deepest part of basin is found to be located near Asansole (23° 40’N, 86° 55’E), where the maximum thickness of sediments is estimated to be about 1.3 miles (2.08 km). The faults along the northern as well as the southern boundaries are found to be normal. The Gondwana sediments appear to continue eastward beneath alluvium and laterite of Bengal basin as far as 87° 25’E. 相似文献
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The basic principles of the application of the linear system theory for smoothing noise-degraded d.c. geoelectrical sounding curves were recently established by Patella. A field Schlumberger sounding is presented to demonstrate first their application and validity. To achieve this purpose, firstly it is pointed out that the required smoothing or low-pass filtering can be considered as an intrinsic property of the transformation of original Schlumberger sounding curves into pole-pole (two-electrode) curves. Then we sketch a numerical algorithm to perform the transformation, opportunely modified from a known procedure for transforming dipole diagrams into Schlumberger ones. Finally we show a field example with the double aim of demonstrating (i) the high quality of the low-pass filtering, and (ii) the reliability of the transformed pole-pole curve as far as quantitative interpretation is concerned. 相似文献
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Vivesh V. KAPUR Kamlesh KUMAR Pranav J. PANDYA Amit K. GHOSH Arindam CHAKRABORTY Anupam SHARMA Gaurav CHAUHAN M. G. THAKKAR 《《地质学报》英文版》2022,96(6):1867-1883
The oldest Asian record of alpheid shrimps, assigned to genus Alpheus, based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin, western India reported herein, extends the fossil record of the family Alpheidae from Asia by ~22 million years. An early Miocene (Aquitanian) age is estimated based on the associated assemblage of calcareous nannofossils, Sphenolithus disbelemnos, Cyclicargolithus floridanus, and Reticulofenestra haqii. The co-occurring microbiota includes bony fish otolith remains, identified as “genus Gobiidarum”, isolated teeth of Dasyatis rays, Sphyrna sharks, and teleosts, ctenoid and placoid scales, ostracods, belonging to the genera Paractinocythereis, Alocopocythere, Ruggieria? Aglaiocypris, Bairdoppilata, and echinoid spines. Taken together, the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy, X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow (neritic) to coastal marine (intertidal) depositional paleoenvironment. 相似文献