Influence of Drying Temperature on Three Soils Physical Properties     

B. M. Sunil  A. V. Deepa 《Geotechnical and Geological Engineering》2016,34(3):777-788

Changes in plasticity characteristics of three soils upon drying are examined in this paper. These changes are attributed to aggregation of particles. The key characteristic evaluated was the impact of drying temperature on the index properties, compaction characteristics and California bearing ratio. The study found the effect of drying strongly depended on soil type, mineralogy or presence of cementing agents. The observed changes are found to be permanent and the implications are that these changes may affect the field performance of test soils.  相似文献   

Geochemical assessment of groundwater quality in vicinity of Bhalswa landfill,Delhi, India,using graphical and multivariate statistical methods   总被引：1，自引：0，他引：1  

Sunil Kumar Srivastava  A. L. Ramanathan 《Environmental Geology》2008,53(7):1509-1528

A geochemical assessment of groundwater quality and possible contamination in the vicinity of the Bhalswa landfill site was carried out by using a hydrochemical approach with graphical and multivariate statistical methods with the objective of identifying the occurrence of various geochemical processes and understanding the impact of landfill leachates on groundwater quality. Results indicate that nitrate, fluoride and heavy-metal pollution are in an alarming state with respect to the use of groundwater for drinking purposes. Various graphical plots and statistical analyses have been applied to the chemical data based on the ionic constituents, water types, and hydrochemical facies to infer the impact of the landfill on groundwater quality. The statistical analysis and spatial and temporal variations indicate the leaching of contaminants from the landfill to the groundwater aquifer system. The concentrations of heavy metals in the landfill leachates are as follows: Fe (22 mg/l), Mn (~20 mg/l), Cu (~10 mg/l), Pb (~2 mg/l), Ni (0.25 mg/l), Zn (~10 mg/l), Cd (~0.2 mg/l), Cl⁻ (~4,000 mg/l), SO₄²⁻ (~3,320 mg/l), PO₄³⁻ (~4 mg/l), NO₃⁻ (30 mg/l) and fluoride (~50 mg/l); all were much higher than the standards. The study reveals that the landfill is in a depleted phase and is affecting groundwater quality in its vicinity and the surrounding area due to leaching of contaminants.  相似文献   

Managing urban water supplies in developing countries - Climate change and water scarcity scenarios     

Kala Vairavamoorthy  Sunil D. Gorantiwar 《Physics and Chemistry of the Earth》2008,33(5):330-339

Urban areas of developing countries are facing increasing water scarcity and it is possible that this problem may be further aggravated due to rapid changes in the hydro-environment at different scales, like those of climate and land-cover. Due to water scarcity and limitations to the development of new water resources, it is prudent to shift from the traditional ‘supply based management’ to a ‘demand management’ paradigm. Demand management focuses on measures that make better and more efficient use of limited supplies, often at a level significantly below standard service levels. This paper particularly focuses on the intermittent water supplies in the cities of developing countries. Intermittent water supplies need to be adopted due to water scarcity and if not planned properly, results in inequities in water deliveries to consumers and poor levels of service. It is therefore important to recognise these realities when designing and operating such networks.The standard tools available for design of water supply systems often assume a continuous, unlimited supply and the supplied water amount is limited only be the demand, making them unsuitable for designing intermittent supplies that are governed by severely limited water availability. This paper presents details of new guidelines developed for the design and control of intermittent water distribution systems in developing countries. These include a modified network analysis simulation coupled with an optimal design tool. The guidelines are driven by a modified set of design objectives to be met at least cost. These objectives are equity in supply and people driven levels of service (PDLS) expressed in terms of four design parameters namely, duration of the supply; timings of the supply; pressure at the outlet (or flow-rate at outlet); and others such as the type of connection required and the locations of connections (in particular for standpipes). All the four parameters are calculated using methods and techniques that recognise the relationship between outflow at a water connection and the pressure experienced at that connection. The paper presents a case study where it is demonstrated that the new guidelines can provide an equitable and acceptable level of service throughout the design horizon of the project.  相似文献   

Green Electronics through Legislation and Lead Free Soldering     

Sunil Herat 《洁净——土壤、空气、水》2008,36(2):145-151

Management of used electrical and electronic equipment (EEE) is becoming a major issue as each year around 20 to 50 million tonnes of electronic waste (e‐waste) is generated worldwide. EEE contains over 1000 materials of which lead (Pb) has been one of the targets of the regulators forcing manufacturers to adopt lead free products. Industry has come up with several lead free solders with preference given to alloys containing tin, silver, and copper but there is no ,drop‐in' substitute to leaded solder. Issues with lead free solders such as temperature, intermetallics, tin whisker, tin pest, and reliability are yet to be resolved. The paper investigated the contribution of lead free soldering to green electronics in a holistic way. Global lead free movement has reached a point of no return. However, it is necessary to make sure that life span of EEE is not shortened thereby resulting in an unforeseen increase in e‐waste or problem shifting does not occur by shifting a problem from one life cycle to another or from one category/media to another.  相似文献   

A benchmark study on problems related to CO2 storage in geologic formations   总被引：1，自引：0，他引：1  

Holger Class  Anozie Ebigbo  Rainer Helmig  Helge K. Dahle  Jan M. Nordbotten  Michael A. Celia  Pascal Audigane  Melanie Darcis  Jonathan Ennis-King  Yaqing Fan  Bernd Flemisch  Sarah E. Gasda  Min Jin  Stefanie Krug  Diane Labregere  Ali Naderi Beni  Rajesh J. Pawar  Adil Sbai  Sunil G. Thomas  Laurent Trenty  Lingli Wei 《Computational Geosciences》2009,13(4):409-434

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Enhanced velocity mixed finite element methods for modeling coupled flow and transport on non-matching multiblock grids     

Sunil G. Thomas  Mary F. Wheeler 《Computational Geosciences》2011,15(4):605-625

The enhanced velocity mixed finite element method, due to Wheeler et al. (Comput Geosci 6(3–4):315–332, 2002), is analyzed and extended to the problem of modeling slightly compressible flow coupled to the transport of chemical species through porous media, on non-matching multiblock grids. Applications include modeling bio-remediation of heavy oil spills and many other subsurface hazardous wastes, angiogenesis in transition of tumors from dormant to malignant states, transport of contaminants in ground water flow, and acid injection from well bores to increase permeability of surrounding rock. The analysis and numerical examples presented here demonstrate convergence and computational efficiency of this method.  相似文献   

Charged anisotropic models for quark stars     

Jefta M. Sunzu  Sunil D. Maharaj  Subharthi Ray 《Astrophysics and Space Science》2014,352(2):719-727

We perform a detailed physical analysis for a class of exact solutions for the Einstein–Maxwell equations. The linear equation of state consistent with quark stars has been incorporated in the model. The physical analysis of the exact solutions is performed by considering the charged anisotropic stars for the particular nonsingular exact model obtained by Maharaj, Sunzu and Ray. In performing such an analysis we regain masses obtained by previous researchers for isotropic and anisotropic matter. It is also indicated that other masses and radii may be generated which are in acceptable ranges consistent with observed values of stellar objects. A study of the mass-radius relation indicates the effect of the electromagnetic field and anisotropy on the mass of the relativistic star.  相似文献   

Reduction of PPP convergence period through pseudorange multipath and noise mitigation   总被引：1，自引：0，他引：1  

Garrett Seepersad  Sunil Bisnath 《GPS Solutions》2015,19(3):369-379

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Study on effect of surface roughness on overland flow from different geometric surfaces through numerical simulation          下载免费PDF全文

Sunil P. Maske  Manoj K. Jain 《水文研究》2014,28(4):2595-2616

Effect of variability in surface roughness on overland flow from different geometric surfaces is investigated using numerical solution of diffusion wave equation. Three geometric surfaces rectangular plane, converging and diverging plane at slopes 1 to 3% are used. Overland flow is generated by applying rainfall at constant intensity of 10 mm/h for period 30 min and 100 min. Three scenarios of spatial roughness conditions viz. roughness increasing in downstream direction, roughness decreasing in downstream direction and roughness distributed at random are considered. Effect of variability of roughness on overland flow in terms of depth, velocity of flow and discharge along the distance from upstream to downstream for different geometric surfaces are discussed in detail. Results from the study indicate that roughness distribution has significant effect on peak, time to peak and overall shape of the overland flow hydrograph. The peak occurs earlier for the scenario when roughness increases in downstream direction as compared to scenario when roughness is decreasing in downstream for all three geometric surfaces due to very low friction factor and more velocity at the top of the domain. The converging plane attains equilibrium state early as compared to rectangular and diverging plane. Different set of random values result in different time to peak and shape of hydrograph for rectangular and diverging plane. However, in case of converging plane, the shape of computed hydrographs remains almost similar for different sets of random roughness values indicating stronger influence of converging geometry than effect due to variation of roughness sequence on computed runoff hydrograph. Hierarchically, the influence of geometry on overland flow is stronger than the influence of slope and the influence of slope is stronger than the influence of roughness. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Study of electron energy and angular distributions and calculations of X-ray,EUV line flux and rise times     

Ranjna Bakaya  Sunil Peshin  R. R. Rausaria  P. N. Khosa 《Journal of Astrophysics and Astronomy》1987,8(3):263-270

Evolution of energy and angular distributions of electrons has been studied by combining small-angle analytical treatment with large-angle Monte Carlo calculations as a function of column density for initially monoenergetic and monodirectional electrons. The incident electron energies considered are 20, 30 and 60 keV at 0°, 30° and 60° angles of incidence. Using these distributions, time evolution of extreme ultraviolet (EUV) spectrum has been studied. The slopes of the curves calculated compare well with the experimentally observed curve.  相似文献