A NUMERICAL METHOD TO COMPUTE THE RESISTIVITY TRANSFORM FROM WENNER SOUNDING DATA*     

RAKESH KUMAR  M. V. RAMANAIAH CHOWDARY 《Geophysical Prospecting》1982,30(6):898-909

A numerical technique to compute the resistivity transform directly from the observed Wenner sounding data has been developed. In principle, the procedure is based on a decomposition method and consists of two steps: the first step determines a function that approximates the apparent resistivity data and the second step transforms this function into the corresponding kernel by an analytical operation. The proposed method is tested on some theoretical master curves. A high degree of precision is achieved with very little computer time. The applicability is shown on two field examples.  相似文献   

The central and eastern Arabian Sea as a perennial source of atmospheric carbon dioxide   总被引：3，自引：0，他引：3  

V. V. S. S. SARMA  M. DILEEP KUMAR  M. D. GEORGE 《Tellus. Series B, Chemical and physical meteorology》1998,50(2):179-184

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Daily rainfall statistics of TRMM and CMORPH: A case for trans-boundary Gandak River basin     

BRIJESH KUMAR  KANHU CHARAN PATRA  VENKAT LAKSHMI 《Journal of Earth System Science》2016,125(5):919-934

Satellite precipitation products offer an opportunity to evaluate extreme events (flood and drought) for areas where rainfall data are not available or rain gauge stations are sparse. In this study, daily precipitation amount and frequency of TRMM 3B42V.7 and CMORPH products have been validated against daily rain gauge precipitation for the monsoon months (June–September or JJAS) from 2005–2010 in the trans-boundary Gandak River basin. The analysis shows that the both TRMM and CMORPH can detect rain and no-rain events, but they fail to capture the intensity of rainfall.  相似文献   

Characteristics of severe thunderstorms studied with the aid of VLF atmospherics over North–East India     

A GUHA  TRISANU BANIK  BARIN KUMAR DE  RAKESH ROY  ABHIJIT CHOUDHURY 《Journal of Earth System Science》2013,122(4):1013-1021

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Late Quaternary fine silt deposits of Jammu,NW Himalaya: Genesis and climatic significance     

RAJINDER K GANJOO  VINOD KUMAR 《Journal of Earth System Science》2012,121(1):165-182

The fine silt deposits of Jammu (J & K State, India) stretch all along the Siwalik foothills from Jammu to the Potwar Plateau in Pakistan. The post-Siwalik deposits, first discussed by de Terra and Paterson (1939), are attributed to wind action. The deposits termed as ‘Potwar loessic silt’ comprising sandy silt are essentially of late Quaternary age (75–18 ka) and are re-looked herein from the point of view of genesis and climatic significance. The sorting, skewness and kurtosis parameters of fine silts of Jammu suggest fluvial environment of the deposits wherein the water budget fluctuated. The weak pedogenesis of fine silts at certain intervals corroborate to periods of less or no sedimentation. The bivariant plot studies further suggest fluvial environment of deposition for the fine silt at Jammu, with regular fluctuations in the budget of river water that was perhaps in consonance with oscillations in the climate of the region.  相似文献   

Low protein variability and genetic similarity between populations of the polar bear (Ursus maritimus)     

THOR LARSEN  HÅKAN TEGELSTRÖM  R. KUMAR JUNEJA  MITCHELL K. TAYLOR 《Polar research》1983,1(1):97-106

Blood samples from a total of 460 polar bears ( Ursus maritimus ) from various Arctic regions, but excluding the USSR, were collected during the period 1967-1981 to study electrophoretic variation in different proteins. Two hundred and one samples from Alaska, 48 from the Canadian Arctic, 89 from Svalbard, and 21 from Northeast Greenland were collected during the period 1967-1973 and were analysed by vertical polyacrylamide gel electrophoresis to study transferrin and hemoglobin polymorphism. Thirty-one samples collected in 1974 were analysed by starch gel electrophoresis for 14 enzyme systems in serum and red blood cells. Seventy samples collected from Alaska, the Barents Sea, and Canada in 1980-81 were studied by starch gel electrophoresis, and further analysed for protein variation by thin-layer isoelectric focusing, horizontal polyacrylamide gel electrophoresis, and two-dimensional electrophoresis. In all, about 75 loci were analysed for variation. The degree of protein and enzyme variation in the polar bear was observed to be relatively low. Starch gel electrophoresis revealed variation of an unidentified serum protein. The distribution of this protein indicates a closer connection between bears in Alaska and Canada compared to those in Greenland and Svalbard, but the differences were not significant. As in many large mammals, the information from protein variation in polar bears has limited use for management purposes. We could not find any simple system usable for identification of discrete populations. On the basis of protein variation as sole criterion, the populations investigated could not be separated. Possible explanations for the uniformity of blood proteins can be exchange of bears between geographical areas and/or a high selective pressure in polar bears.  相似文献   

Oldest Asian Record of Snapping Shrimps (Malacostraca: Alpheidae) from the Kutch Basin, Western India and Associated Biota: Biostratigraphic, Paleoenvironmental and Paleoecological Significance     

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   

METAMODELLING APPROACH TO DESIGN THE ALLUVIAL CHANNELS AT INCIPIENT MOTION     

Achanta Ramakrishna RAO Bimlesh KUMAR Gopu SREENIVASULU 《国际泥沙研究》2007,22(3):218-227

The design of an alluvial channel for critical conditions requires information about four basic parameters, i.e., particle size d, water depth y, energy slope Sf and average velocity u. Most of the investigators use a standard or modified form of the critical Shields’ parameter to define the incipient motion of a particular grain size. Shields’ diagram describes an iterative process of determining the incipient motion parameters. To design a process that does not require iteration, one must know the resistance relationship. The absence of a universal resistance equation increases the difficulty of defining the model. Metamodelling techniques are widely used in engineering designs to simulate a complex system. This article describes a Metamodel, which employs the radial basis function (RBF) network to predict the average velocity u and energy slope Sf based on experimental data of incipient condition. With the help of the Metamodel generated by the RBF network, design curves have been presented to predict the u and Sf based on known values of the particle size and water depth. It has been found that this model improves the predictability of incipient motion.  相似文献   

Measurement of marine productivity using <Superscript>15</Superscript>N and <Superscript>13</Superscript>C tracers: Some methodological aspects     

NAVEEN GANDHI  SANJEEV KUMAR  S PRAKASH  R RAMESH  M S SHESHSHAYEE 《Journal of Earth System Science》2011,120(1):99-111

Various experiments involving the measurement of new, regenerated and total productivity using ¹⁵N and ¹³C tracers were carried out in the Bay of Bengal (BOB) and in the Arabian Sea. Results from ¹⁵N tracer experiments indicate that nitrate uptake can be underestimated by experiments with incubation time <4 hours. Indirect evidence suggests pico- and nano-phytoplankton, on their dominance over microphytoplankton, can also influence the f-ratios. Difference in energy requirement for assimilation of different nitrogen compounds decides the preferred nitrogen source during the early hours of incubation. Variation in light intensity during incubation also plays a significant role in the assimilation of nitrogen. Results from time course experiments with both ¹⁵N and ¹³C tracers suggest that photoinhibition appears significant in BOB and the Arabian Sea during noon. A significant correlation has been found in the productivity values obtained using ¹⁵N and ¹³C tracers.  相似文献   

Meso-scale atmospheric events promote phytoplankton blooms in the coastal Bay of Bengal   总被引：1，自引：0，他引：1  

K MANEESHA  V V S S SARMA  N P C REDDY  Y SADHURAM  T V RAMANA MURTY  V V SARMA  M DILEEP KUMAR 《Journal of Earth System Science》2011,120(4):773-782

The Bay of Bengal is considered to be a low productive region compared to the Arabian Sea based on conventional seasonal observations. Such seasonal observations are not representative of a calendar year since the conventional approach might miss episodic high productive events associated with extreme atmospheric processes. We examined here the influence of extreme atmospheric events, such as heavy rainfall and cyclone Sidr, on phytoplankton biomass in the western Bay of Bengal using both in situ time-series observations and satellite derived Chlorophyll a (Chl a) and sea surface temperature (SST). Supply of nutrients through the runoff driven by episodic heavy rainfall (234 mm) on 4–5 October 2007 caused an increase in Chl a concentration by four times than the previous in the coastal Bay was observed within two weeks. Similar increase in Chl a, by 3 to 10 times, was observed on the right side of the cyclone Sidr track in the central Bay of Bengal after the cyclone Sidr. These two episodic events caused phytoplankton blooms in the western Bay of Bengal which enhanced ~40% of fishery production during October–December 2007 compared to that in the same period in 2006.  相似文献