1,721,791 research outputs found
A generalized processor sharing approach to flow control in integrated services networks
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1992.Includes bibliographical references (leaves 161-163).by Abhay Kumar J. Parekh.Ph.D
Minimizing the number of clusters in mobile packet radio networks
No full textThesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERINGBibliography: leaves 82-83.by Abhay Kumar Parekh.M.S
Hydrogeochemical investigation and groundwater quality assessment of Pratapgarh district, Uttar Pradesh
No full textGIS based evaluation of fluoride contamination and assessment of fluoride exposure dose in groundwater of a district in Uttar Pradesh, India
No full textScattering of radio frequency waves by cylindrical density filaments in tokamak plasmas
No full textIn tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments are routinely observed in the scrape-off layer. Radio frequency (RF) electromagnetic waves, excited by antenna structures placed near the wall of a tokamak, have to propagate through the scrape-off layer before reaching the core of the plasma. While the effect of fluctuations on the properties of RF waves has not been quantified experimentally, it is of interest to carry out a theoretical study to determine if fluctuations can affect the propagation characteristics of RF waves. Usually, the difference between the plasma density inside the filament and the background plasma density is sizable, the ratio of the density difference to the background density being of order one. Generally, this precludes the use of geometrical optics in determining the effect of fluctuations, since the relevant ratio has to be much less than one, typically, of the order of 10% or less. In this paper, a full-wave, analytical model is developed for the scattering of a RF plane wave by a cylindrical plasma filament. It is assumed that the plasma inside and outside the filament is cold and uniform and that the major axis of the filament is aligned along the toroidal magnetic field. The ratio of the density inside the filament to the density of the background plasma is not restricted. The theoretical framework applies to the scattering of any cold plasma wave. In order to satisfy the boundary conditions at the interface between the filament and the background plasma, the electromagnetic fields inside and outside the filament need to have the same k[subscript ∥], the wave vector parallel to the ambient magnetic field, as the incident plane wave. Consequently, in contrast to the scattering of a RF wave by a spherical blob [Ram et al., Phys. Plasmas 20, 056110-1–056110-10 (2013)], the scattering by a field-aligned filament does not broaden the k∥ spectrum. However, the filament induces side-scattering leading to surface waves and can also couple some power to the cold plasma wave different from the incident wave. The changes induced by a filament in the propagation of electron cyclotron waves and lower hybrid waves are illustrated by numerical results displaying the properties of the Poynting vector. The Poynting flux in the wake of the filament, and directed towards the core of the plasma, develops a spatial structure due to diffraction and shadowing. Thus, the fluctuations affect the uniformity of power flow into the plasma.United States. Department of Energy (Grant DE-FG02-91ER-54109)United States. Department of Energy (Grant DE-FG02-99ER-54525-NSTX)United States. Department of Energy (Grant DE-FC02-01ER54648
Evaluation of metal contamination and risk assessment to human health in a coal mine region of India: A case study of the North Karanpura coalfield
No full textAssessment of Mine Water Quality Using Heavy Metal Pollution Index in a Coal Mining Area of Damodar River Basin, India
No full textAssessment of Hydrogeochemical Processes and Mine Water Suitability for Domestic, Irrigation, and Industrial Purposes in East Bokaro Coalfield, India
No full textHydrogeochemical characterization and groundwater quality assessment in a coal mining area, India
No full textThe present study determines major and trace element chemistry of groundwater in the West Bokaro coalfield to assess the hydrogeochemical processes and groundwater quality for drinking and irrigation uses. For this urpose, 33 groundwater samples from different mining areas of the West Bokaro coalfield were collected and analysed for pH, electrical conductivity (EC), total dissolved solid (TDS), dissolved silica (SiO2), major cations (Ca2+, Mg2+, Na+, K+), anions (F−, Cl−, HCO3−, SO42− and NO3−) and trace metals (Mn, Cu, Pb,Zn, Ni, Co, As, Se, Al, Cd, Cr, Ba and Fe). The analytical results show the slightly acidic to alkaline nature of groundwater and dominance of HCO3− and SO42− in anionic and Ca2+ and Na+ in cationic abundance. High SO42− concentrations are attributed to the oxidative weathering of pyrite and gypsum dissolution. Supersaturation condition with respect to dolomite and calcite for most samples may result from the dissolution of gypsum after the water is saturated with respect to the carbonate minerals. The data plot on the Gibbs and Piper diagrams revealed that the groundwater chemistry is mainly controlled by rock weathering with secondary contribution from anthropogenic sources. In a majority of the groundwater samples, alkaline earth metals exceed alkalies and strong acids dominate over weak acid. Ca-Mg-HCO3, Ca-Mg-SO4-Cl and Ca-Mg-SO4 were the dominant hydrogeochemical facies. A comparison of groundwater quality parameters in relation to specified limits for drinking water shows that the concentrations of TDS, SO42−, NO3−, total hardness (TH), Fe and Ni are exceeding the desirable limits in many groundwater samples. Quality assessment for irrigation uses reveal that the groundwater is of good to suitable category. Higher salinity and magnesium hazard values at some sites restrict the suitability of groundwater for irrigation purposes
Evaluation of hydrogeochemical processes and groundwater quality in the Jhansi district of Bundelkhand region, India
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