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1.
Jerome Métral Laurent Charlet Sara Bureau Sukumar Basu Mallik Sudipta Chakraborty Kazi M Ahmed MW Rahman Zhongqi Cheng Alexander van Geen 《Geochemical transactions》2008,9(1):1
Background
The origin of the spatial variability of dissolved As concentrations in shallow aquifers of the Bengal Basin remains poorly understood. To address this, we compare here transects of simultaneously-collected groundwater and aquifer solids perpendicular to the banks of the Hooghly River in Chakdaha, India, and the Old Brahmaputra River in Araihazar, Bangladesh. 相似文献2.
C. Sukumar G. Gowthami R. Nitya V. Janaki Seralathan Kamala-Kannan K. Shanthi 《Environmental Earth Sciences》2014,72(3):839-847
Batch sorption system using co-immobilized (activated carbon and Bacillus subtilis) beads as adsorbent was investigated to remove Cr(VI) from aqueous solution. Fourier transform infrared spectroscopy analysis showed the functional groups of both bacteria and activated carbon in co-immobilized beads. Experiments were carried out as a function of contact time (5–300 min), initial metal concentration (50–200 mg L?1), pH (2–8), and adsorbent dose (0.2–1 g L?1). The maximum percentage of removal was found to be 99 %. Langmuir model showed satisfactory fit to the equilibrium adsorption data of co-immobilized beads. The kinetics of the adsorption followed pseudo-second-order rate expression, which demonstrates that chemisorption plays a significant role in the adsorption mechanism. The significant shift in the Fourier transform infrared spectroscopy peaks and a Cr peak in the scanning electron microscope–energy dispersive spectroscopy spectra further confirmed the adsorption. The results indicate that co-immobilized beads can be used as an effective adsorbent for the removal of Cr(VI) from the aqueous solution. 相似文献
3.
S. Sukumar 《Journal of Astrophysics and Astronomy》1987,8(4):281-294
The refraction of radio waves as they traverse through the terrestrial ionosphere and troposphere introduces a differential
phase path which results for a radio interferometer in variations of the visibility phase. Though refraction due to troposphere
is significant for synthesis radio telescopes operating at 1.0 GHz and above, ionospheric refraction is dominant at lower
frequencies. This problem is important in the case of Ooty Synthesis Radio Telescope (OSRT) operating at 326.5 MHz, due to
its proximity to the magnetic equator. This paper deals with the nature of phase variations suffered by OSRT due to refraction
and explains the methodology evolved to alleviate them. 相似文献
4.
A. Sukumar 《Journal of the Geological Society of India》2009,74(4):533-534
Discussion
Petrology of Mafic-Ultramafic Rocks Along North Purulia Shear Zone, West Bengal by Aditi Mandal and Arijit Ray. Jour. Geol. Soc. India, v.74, July, 2009; pp.108–118. 相似文献5.
6.
Thomas?Oommen Debasmita?MisraEmail author Anupma?Prakash Sukumar?Bandopadhyay Sathy?Naidu John?J.?Kelley 《Natural Resources Research》2011,20(1):11-24
Multiple Regressive Pattern Recognition Technique (MRPRT) is an adapted approach for improved geologic resource estimation.
We developed and tested this approach for the Platinum (Pt) bearing region near Goodnews Bay, Alaska, which presents an example
of a complex depositional environment. We applied geospatial and pattern recognition methods to assess the spatial distribution
of offshore Pt in the Goodnews Bay area from point data collected by various agencies. We used the coefficient of correlation
(r) and the Nash–Sutcliffe efficiency (E) to quantitatively assess the degree of accuracy of the estimated Pt distribution. We split the study area, based on trend
analysis, into two regions: inside the Bay and outside the Bay. We could not obtain appreciable estimates from the geospatial
and pattern recognition methods. Using MRPRT, we were able to improve r from 0.57 to 0.93 and the E from 28.31 to 92.91 inside the Bay. We achieved improvement in r from 0.55 to 0.61 and E from 28.46 to 34.52 outside the Bay. The reasons for a non-significant improvement outside the Bay have been discussed. The
results indicate that the proposed MRPRT has wide application potential in georesource estimation where input data is often
scarce. 相似文献
7.
Bibhash Nath Doris Stüben Sukumar Basu Mallik Debashis Chatterjee Laurent Charlet 《Applied Geochemistry》2008
The present study demonstrates the importance of hydrogeochemical characteristics (groundwater flow and recharge) of an aquifer in the release of As to groundwater. The study area (∼20 km2) is located in Chakdaha block, Nadia district, West Bengal, which hosts groundwaters of variable As content. The spatial distribution pattern of As is patchy with areas containing groundwater that is high in As (>200 μg L−1) found in close vicinity to low As (<50 μg L−1) groundwaters (within 100 m). The concentration of groundwater As is found to decrease with depth. In addition, the data shows that there is no conspicuous relationship between high groundwater As concentration and high groundwater abstraction, although the central cone of depression has enlarged over 2 a and is extending towards the SE of the study area. The river Hooghly, which forms the NW boundary of the study site, shows dual behaviour (effluent and influent during pre- and post-monsoon periods, respectively), complicating the site hydrogeology. The observed groundwater flow lines tend to be deflected away from the high As portion of the aquifer, indicating that groundwater movement is very sluggish in the As-rich area. This leads to a high residence time for this groundwater package, prolonging sediment–water interaction, and hence facilitating groundwater As release. 相似文献
8.
9.
A giant radio telescope for observing galactic and extragalactic radio sources at metre wavelengths is proposed. By locating a parabolic cylindrical antenna at a site close to the Equator such that its axis lies parallel to earth's axis, it is possible to construct a large collecting area economically. The proposed instrument will be very powerful for studying compact and diffuse features of radio sources, monitoring their variability, recombination and deuterium line work, studies of interplanetary medium and pulsar search.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983. 相似文献
10.
Faults are geological entities with thickness several orders of magnitude smaller than the grid blocks typically used to discretize geological formations. On using the extended finite element method (X-FEM), a structured mesh suffices and the faults can arbitrarily cut the elements in the mesh. Modeling branched and intersecting faults is a challenge, in particular when the faults work as internal fluid flow conduits that allow fluid flow in the faults as well as to enter/leave the faults. By appropriately selecting the enrichment function and the nodes to be enriched, we are able to capture the special characteristics of the solution in the vicinity of the fault. We compare different enrichment schemes for strong discontinuities and develop new continuous enrichment functions with discontinuous derivatives to model branched and intersecting weak discontinuities. Symmetric fluid flows within the regions embedded by branched, coplanar intersecting, and noncoplanar intersecting faults are considered to verify the effectiveness of the proposed enrichment scheme. For a complex fault consisting of branched and intersecting faults, the accuracy and efficiency of the X-FEM is compared with the FEM. We also demonstrate different slipping scenarios for branched and intersecting faults with the same friction coefficient. In addition, fault slipping triggered by an injection pressure and three-dimensional fluid flows are modeled to show the versatility of the proposed enrichment scheme for branched and intersecting weak discontinuities. 相似文献