Evolution of narrow-band spectrum of two random Stokes wavetrains in deep water     

Halder  Sourav  Dhar  Asoke Kumar 《Ocean Dynamics》2023,73(6):317-331

Ocean Dynamics - Fourth-order nonlinear evolution equation (NLEE), which is an excellent starting point for the analysis of nonlinear deep water surface waves, are used here to investigate the...  相似文献   

Aquifer modelling of the Ganga–Mahawa sub‐basin,a part of the Central Ganga Plain,Uttar Pradesh,India     

M. E. H. Ala Eldin  M. Sami Ahmed  V. V. S. Gurunadha Rao  R. L. Dhar 《水文研究》2000,14(2):297-315

The Ganga–Mahawa sub‐basin, which has an area of 1280 km² forms the western part of the Central Ganga Plain in the Moradabad and Badaun districts of western Uttar Pradesh, India. The Bundelkhand granite forms the basement complex, overlain unconformably by the upper Vindhyan sequence, which is further overlain by the Neogene (Middle and Upper) Siwaliks and finally by Quaternary alluvium. Four geomorphological units, the Varanasi older alluvial plain, Aligarh older alluvial plain, terrace zones and the Ganga recent floodplain, abandoned channels, channel scars and meander scars represent various landforms. The hydrogeological cross‐sections indicate the occurrence of a single aquifer down to 120 m. Some influent seepage from the River Ganga could be seen around Gangeswari, but the rest of the River Ganga is effluent. Groundwater‐flow modelling was carried out to assess the degree of Ganga river and aquifer interaction. The River Ganga marks the western boundary; boundaries to the northeast and southeast are set as fixed heads to simulate lateral inflow into and outflow from the sub‐basin respectively. The eastern boundary is simulated as a no‐flow condition. The Mahawa and Badmar rivers are considered to be effluent. The area modelled is covered by a grid of 34 rows×46 columns with three layers, viz., an unconfined aquifer, an aquitard which is underlain by a semi‐confined to confined aquifer. The permeability distribution was inferred from morphometric analysis and pumping tests. Natural recharge due to monsoon rainfall forms the main input. The River Ganga stage data at Ahar, Naora and Ramghat has been used for assigning surface water levels and river bed elevations in the model. Abstraction from all existing deep and shallow tube wells has been assigned as output at various cells. A steady state flow simulation was carried out and calibrated against the June 1986 water level; subsequent transient conditions were calibrated up to May 1995. The computed groundwater balance was comparable to that estimated from field investigations. The aquifer modelling study has attempted to integrate all available information and provided a tool that could be used for predictive simulation. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Drainage Performance of Different Sizes Tire Chips used Alone and Mixed with Natural Aggregates as Leachate Drainage Layer Material     

M. K. Kaushik  Arvind Kumar  Ajay Bansal 《Geotechnical and Geological Engineering》2016,34(1):167-191

Results of compressibility and hydraulic conductivity testing performed under different levels of average vertical stress were used to determine the appropriate tire chips size (in particular aspect ratio) and tire chip—gravel random state mix combination. Proper sidewall treatment was provided to reduce side wall friction up to minimum level and constant head conditions were maintained with appropriate design flow rate. Results showed that tire chips (length 25 mm, aspect ratio 1) mixed with 40 mm gravel in the random state in mixing ratio of 3:1 (ds:dg) was observed to undergo minimum strain, maximum hydraulic conductivity and hence free drainage even under high vertical stress levels. By selecting tire chips of appropriate aspect ratio and optimum mix combination for the construction of drainage layer of MSW landfill leachate collection system lower strain response, higher hydraulic conductivity values and relatively free drainage even under anticipated higher vertical stress levels may be achieved.  相似文献   

Optimal operation of reservoirs for downstream water quality control using linked simulation optimization     

Anirban Dhar  Bithin Datta 《水文研究》2008,22(6):842-853

A methodology is developed for optimal operation of reservoirs to control water quality requirements at downstream locations. The physicochemical processes involved are incorporated using a numerical simulation model. This simulation model is then linked externally with an optimization algorithm. This linked simulation–optimization‐based methodology is used to obtain optimal reservoir operation policy. An elitist genetic algorithm is used as the optimization algorithm. This elitist‐genetic‐algorithm‐based linked simulation–optimization model is capable of evolving short‐term optimal operation strategies for controlling water quality downstream of a reservoir. The performance of the methodology developed is evaluated for an illustrative example problem. Different plausible scenarios of management are considered. The operation policies obtained are tested by simulating the resulting pollutant concentrations downstream of the reservoir. These performance evaluations consider various scenarios of inflow, permissible concentration limits, and a number of management periods. These evaluations establish the potential applicability of the developed methodology for optimal control of water quality downstream of a reservoir. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Genetic implications of rare uraninite and pyrite in quartz-pebble conglomerates from Sundargarh district of Orissa,Eastern India     

Ajay Kumar  A. S. Venkatesh  P. V. Ramesh Babu  S. Nayak 《Journal of the Geological Society of India》2012,79(3):279-286

Petrographic and EPMA studies reveal the presence of discrete grains of uraninite and pyrite are being reported for the first time in quartz-pebble conglomerates from western margin of Bonai granite pluton, Sundargarh district, Orissa. Uraninite grains (2–3 μ in size) are subrounded to muffin shaped which show variation in UO₂ (63.86 to 71.73 wt %), ThO₂ (5.48 to 6.42 wt %) and RE₂O₃ (1.57 to 2.23 wt %). Pegmatitic source of uraninite is revealed by comparing UO₂, ThO₂, PbO, CaO content and ratios of UO₂/ThO₂ and CaO/ThO₂ in uraninites from pegmatite and other environments and areas. Subrounded to muffin shape of uraninite, their association with subrounded pyrite and heavies like zircon, tourmaline, chromite, monazite, magnetite and their comparable chemistry with well established quartzpebble conglomerates of India and world are indicative of their detrital origin. Pyrite, minor chalcopyrite and rare galena are observed as sulphide phases in conglomerate. Variable shapes of pyrite, their low Co (up to 0.16 wt %) and Ni contents (up to 0.09 wt %) and Co/Ni ratio less than 1.0 (mean= 0.63) favours sedimentary/diagenetic origin.  相似文献   

Infrared and electronic absorption spectra of formaldehyde in gas phase and astrophysical H<Subscript>2</Subscript>O ice     

Mahadevappa Naganathappa  Shivaji Waghmare  Ajay Chaudhari 《Astrophysics and Space Science》2011,332(2):249-256

This work reports theoretical infrared and electronic absorption spectra of formaldehyde and its ions in gas phase and H₂O ice at different levels of theory. The vibrational frequencies from this work at B3LYP/6-311++G^** level are in agreement with the experimental determinations. The gas phase dipole moment of neutral formaldehyde 2.4 D is in excellent agreement with the experimental value of 2.33 D. An influence of ice on vibrational frequencies of neutral formaldehyde molecule was obtained using Self Consistence Isodensity Polarizable Continuum Model (SCI-PCM) with dielectric constant 78.5. Significant shift in vibrational frequencies for neutral formaldehyde molecule when studied in H₂O ice and upon ionization is observed. All the vibrational modes in cation and anion of formaldehyde in gas phase are red shifted than the corresponding modes in neutral formaldehyde. Two vibrational modes are blue shifted and all other modes are red shifted for neutral formaldehyde in H₂O ice. Time dependent density functional theory (TDDFT) is used to study electronic absorption spectrum of neutral formaldehyde and its charged states. It is found that like neutral formaldehyde, its cation and anion also display strong σ→σ ^∗ electronic transitions in vacuum and far UV regions. This study should help in detecting formaldehyde molecule and its ions in gas phase and in H₂O ice in different astronomical environment.  相似文献   

River sinuosity in a humid tropical river basin,south west coast of India   总被引：2，自引：0，他引：2  

B. Ajay Kumar  Girish Gopinath  M. S. Shylesh Chandran 《Arabian Journal of Geosciences》2014,7(5):1763-1772

The variability in ground water potential at different regions of the Meenachil River basin and the remarkable distribution of palaeodeposit of sand at its middle to lower reaches have led to interpret the sinuosity indexes of the main channel as well as the tributaries of the River for elucidating the relationship between mathematical expressions and filed observations. The measurement of digital elevation model-derived river sinuosity was carried out for 846 km² of the basin area of Meenachil River. The drainage networks of 10 major sub-watersheds and four mini-watersheds were delineated using remote sensing data—geocoded false colour composite of Indian Remote Sensing satellite (IRS)-1D (LISS III) data with a spatial resolution of 23.5 m—coupled with the Survey of India toposheets (1:50,000). The calculation of the sinuosity indexes were carried out using Arc GIS (8.3 version) software. Hydraulic sinuosity indexes, topographic sinuosity index and standard sinuosity index were calculated. The study depicts the remarkable correlation between theoretical data sets with field observations and the influence of tectonic control on river planforms. Three structurally controlled regions of Meenachil River basin were established using Remote Sensing and Geographical Information System.  相似文献   

Integrated biological control of water hyacinths, Eichhornia crassipes by a novel combination of grass carp, Ctenopharyngodon idella (Valenciennes, 1844), and the weevil, Neochetina spp.     

GOPALAKRISHNAN Ayyaru  RAJKUMAR Mayalagu  孙军  PARIDA Ajay  VENMATHI MARAN Balu Alagar 《中国海洋湖沼学报》2011,29(1)

The efficacy of grass carp Ctenopharyngodon idella (Cyprinidae) and weevils Neochetina spp. (Curculionidae) to control the aquatic weed, water hyacinth, is investigated in a square net cage (happas) setting at a farm in Cuddalore District, South India. This novel combination of insects and fish is found to be superior to individual treatments for controlling the weed growth within 110 d. The biomass of the weed, number of plants, percentage of flowered plants and chlorophyll contents were studied. The weed ...  相似文献   

Assessment of heavy metals in sediments near Hazira industrial zone at Tapti River estuary, Surat, India   总被引：3，自引：1，他引：2  

Bhavna A. Shah  Ajay V. Shah  Chirag B. Mistry  Alok J. Navik 《Environmental Earth Sciences》2013,69(7):2365-2376

Heavy metal accumulation due to industrial activities has become a very sensitive issue for the survival of the aquatic life. Therefore, distributions of several heavy metals have been studied in the surface sediments of Tapti–Hazira estuary, Surat, to assess the impact of anthropogenic and industrial activities near estuary. Totally 60 sediment samples were collected from four different sites at Tapti–Hazira estuary, Surat from January 2011 to May 2011 and examined for metal contents. The average heavy metal load in the study area are found to be 43.28–77.74 mg/kg for Pb, 48.26–72.40 mg/kg for Cr, 117.47–178.80 mg/kg for Zn, 71.13–107.82 mg/kg for Ni, 123.17–170.52 mg/kg for Cu, 0.74–1.25 mg/kg for Cd, 14.73–21.69 mg/kg for Co. Calculated enrichment factors (EF) reveal that enrichment of Pb and Cd is moderate at all sites, whereas other metals Cr, Ni, Zn, Co, and Cu show significant to very high enrichment. Geo-accumulation index (I _geo) results revealed that the study area is nil to moderately contaminated with respect to Cd, moderately to highly polluted with respect to Pb, Zn, and Cu and high to very highly polluted with respect to Co and Cr.  相似文献   

Spatial geochemical variation of major and trace elements in the marine sediments of Mumbai Harbor Bay     

Ajay Kumar  R. K. Singhal  Sabyasachi Rout  P. M. Ravi 《Environmental Earth Sciences》2013,70(7):3057-3066

The resulting concentration data sets of major (Na, K, Mg, Ca and Fe) and trace elements (Cu, Ni, Co and Mn) in bed and suspended sediments were used to evaluate the enrichment factor for anthropogenic influences and principal component analysis for identifying the origin of source contributions in the studied area. Normalization of metals to Fe indicated that high enrichment factors in the bed sediment were in the order of Co > Cu > Na > Ca > Ni except Mg, K and Mn while for suspended sediments, only Co has a high enrichment factor. High enrichment of Co and Cu reflected the contamination of sediments from anthropogenic sources. The high influence of Na and Ca in sediments may be caused for seawater salinization factor. A significant positive correlation among enrichment factors of various elements of interest suggests a common origin/identical behavior during transport in the sediment system.  相似文献