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91.
This paper deals with kinetics and equilibrium studies on the adsorption of arsenic species from simulated groundwater containing arsenic (As(III)/As(V), 1:1), Fe, and Mn in concentrations of 0.188, 2.8, and 0.6 mg/L, respectively, by Ca2+ impregnated granular activated charcoal (GAC‐Ca). Effects of agitation period and initial arsenic concentration on the removal of arsenic species have also been described. Although, most of the arsenic species are adsorbed within 10 h of agitation, equilibrium reaches after ~24 h. Amongst various kinetic models investigated, the pseudo second order model is more adequate to explain the adsorption kinetics and film diffusion is found to be the rate controlling step for the adsorption of arsenic species on GAC‐Ca. Freundlich isotherm is adequate to explain the adsorption equilibrium. However, empirical polynomial isotherm gives more accurate prediction on equilibrium specific uptakes of arsenic species. Maximum specific uptake (qmax) for the adsorption of As(T) as obtained from Langmuir isotherm is 135 µg/g. 相似文献
92.
A. Joshi P. Kumar M. Mohanty A. R. Bansal V. P. Dimri R. K. Chadha 《Pure and Applied Geophysics》2012,169(10):1821-1845
This paper presents the results of a modified two-step inversion algorithm approach to find S wave quality factor Q β(f) given by Joshi (Bull Seis Soc Am 96:2165–2180, 2006). Seismic moment is calculated from the source displacement spectra of the S wave using both horizontal components. Average value of seismic moment computed from two horizontal components recorded at several stations is used as an input to the first part of inversion together with the spectra of S phase in the acceleration record. Several values of the corner frequency have been selected iteratively and are used as inputs to the inversion algorithm. Solution corresponding to minimum root mean square error (RMSE) is used for obtaining the final estimate of Q β(f) relation. The estimates of seismic moment, corner frequency and Q β(f) from the first part of inversion are further used for obtaining the residual of theoretical and observed source spectra which are treated as site amplification terms. The acceleration record corrected for the site amplification term is used for determination of seismic moment from source spectra by using Q β(f) obtained from first part of inversion. Corrected acceleration record and new estimate of seismic moment are used as inputs to the second part of the inversion scheme which is similar to the first part except for use of input data. The final outcome from this part of inversion is a new Q β(f) relation together with known values of seismic moment and corner frequency of each input. The process of two-step inversion is repeated for this new estimate of seismic moment and goes on until minimum RMSE is obtained which gives final estimate of Q β(f) at each station and corner frequency of input events. The Pithoragarh district in the state of Uttarakhand in India lies in the border region of India and Nepal and is part of the seismically active Kumaon Himalaya zone. A network of eight strong motion recorders has been installed in this region since March, 2006. In this study we have analyzed data from 18 local events recorded between March, 2006 and October, 2010 at various stations. These events have been located using HYPO71 and data has been used to obtain frequency-dependent shear-wave attenuation. The Q β(f) at each station is calculated by using both the north-south (NS) and east-west (EW) components of acceleration records as inputs to the developed inversion algorithm. The average Q β(f) values obtained from Q β(f) values at different stations from both NS and EW components have been used to compute a regional average relationship for the Pithoragarh region of Kumaon Himalaya of form Q β(f)?=?(29?±?1.2)f (1.1 ± 0.06). 相似文献
93.
U. C. Mohanty A. Routray Krishna K. Osuri S. Kiran Prasad 《Pure and Applied Geophysics》2012,169(3):381-399
An attempt is made to evaluate the impact of the three dimensional variational (3DVAR) data assimilation within the Weather
Research Forecasting (WRF) modeling system to simulate two heavy rainfall events which occured on 26–27 July 2005 and 27–30
July 2006. During the 26–27 July 2005 event, the unprecedented localized intense rainfall 90–100 cm was recorded over the
northeast parts of Mumbai city; however, southern parts received only 10 cm. Model simulation with the data assimilation experiment
is reasonably well predicted for the rainfall intensity (800 mm) in 24 h and with accurate location over Mumbai agreeing with
observation. Divergence, vorticity, vertical velocity and moisture parameters are evaluated during the various stages of the
event. It is noticed that maximum convergence and vorticity during the mature stage; at the same time the vertical velocity
also follows a similar trend during the period in the assimilation experiment. Vorticity budget terms over the location of
heavy rainfall revealed that the contribution of the positive tilting term produced positive vorticity which triggered the
convection and negative contribution to vorticity from the tilting term to precede the dissipation of the system. Model simulations
from the second rain event, the off-shore trough at sea level along the west coast of India, is well represented after assimilation
of observations during day-1 and day-2 as compared to the control simulations; the orientation of the off-shore trough is
well matched with that of the observed. The intensity and spatial distribution of the rainfall has considerably improved in
the assimilation simulation. The statistical skill scores also revealed that the precipitation forecast during the period
has appreciably improved due to assimilation of observations. The results of this study indicate a positive impact of the
3DVAR assimilation on the simulation of heavy rainfall events. 相似文献
94.
U. C. Mohanty Krishna K. Osuri A. Routray M. Mohapatra Sujata Pattanayak 《Marine Geodesy》2013,36(4):294-314
An attempt is made to delineate the relative performances and credentials of GFS, FNL, and NCMRWF global analyses/forecast products as initial and boundary conditions (IBCs) to the WRF-ARW model in the simulation of four Bay of Bengal tropical cyclones (TCs). The results suggest that FNL could simulate horizontal advection of vorticity maxima at 850 hPa; hence, the tracks are more realistic with least errors as compared to GFS and NCMRWF. The mean landfall errors for 24-, 48-, and 72-hour forecasts are 73, 41, and 72 km, respectively. The TC intensity is well captured by NCMRWF IBCs, as it could predict 850 hPa vorticity maxima. The 24-hour accumulated rainfall is well simulated with FNL, and equitable threat score is more than 0.2 up to 100 mm with minimum bias. 相似文献
95.
Comparative evaluation of performances of two versions of NCEP climate forecast system in predicting Indian summer monsoon rainfall 总被引:1,自引:0,他引:1
Nachiketa Acharya Makarand A. Kulkarni Uma C. Mohanty Ankita Singh 《Acta Geophysica》2014,62(1):199-219
The operational prediction of climatic variables in monthly-to-seasonal scales has been issued by National Centers for Environmental Prediction (NCEP) through Climate Forecast System model (CFSv1) since 2004. After incorporating significant changes, a new version of this model (CFSv2) was released in 2011. The present study is based on the comparative evaluation of performances of CFSv2 and CFSv1 for the southwest monsoon season (June-July-August-September, JJAS) over India with May initial condition during 1982–2009. It was observed that CFSv2 has improved over CFSv1 in simulating the observed monsoon rainfall climatology and inter annual variability. The movement of the cell of Walker circulation in years of excessive and deficient rainfall is better captured in CFSv2, as well. The observed teleconnection pattern between ISMR-sea surface temperature (SST) is also better captured in CFSv2. The overall results suggest that the changes incorporated in CFSv1 through the development of CFSv2 have resulted in an improved prediction of ISMR.21 相似文献
96.
Microtremor survey in Talchir, India to ascertain its basin characteristics in terms of predominant frequency by Nakamura's ratio technique 总被引:2,自引:0,他引:2
M. Yanger Walling William K. Mohanty Sankar K. Nath Supriyo Mitra Ajesh John 《Engineering Geology》2009,106(3-4):123-132
The Talchir Basin, one of India's oldest basins, has been a subject of interest because of its rich coal deposits. The maximum thickness of the basin is about 1500 m. Beyond the basin is the hard metamorphic rocks of Precambrian age. The ambient noise survey data have been analyzed for the Talchir Basin using Nakamura's technique of horizontal–vertical-spectral-ratio (HVSR) to ascertain the basin structure in terms of the predominant frequency. The predominant frequency varies from 0.25 Hz to 7.8 Hz but a major portion of the basin comes under the range of 0.3 Hz–2.4 Hz while on the metamorphic rocks it is as high as 7.8 Hz. The variation in predominant frequency shows a good correlation with the sediment thickness of the basin. The results have been compared with the previous studies by other researchers and it shows consistency with the northerly dip of the basin. The present study has also been compared with the results of the synthetic seismogram that was performed for the Talchir Basin. The predominant frequency obtained from HVSR technique complements well with the frequency at which the peak response spectra ratio is observed. The present study of the predominant frequency identifies quite well the characteristics of Talchir Basin and is in good agreement with the synthetic ground motion modeling of the region. 相似文献
97.
Farakka Barrage Project (FBP) constructed in 1975 on the river Ganga in West Bengal, India has largely altered hydro-geomorphic processes inducing a different kind of impetus in channel dynamics especially channel oscillation of the Bhagirathi river. Controlled hydro-geomorphological regime drastically altering natural regime has significantly influenced channel process with resultant change in channel geometry. Geospatial analysis using topographical maps of 1927, 1954 and 1974 along with satellite images of 1990, 2004, and 2014 clearly portrays rapidity in channel evolution in the post-Farakka period which is explicitly proved from four meander cut-offs after 1975. The meander geometry analysis of 66 loops of lower Bhagirathi river during 1927–2014 in terms of four basic parameters (radius of curvature, wavelength, amplitude, and channel length) and four indices (sinuosity index, radius–wavelength ratio, meander shape index and meander form index) depicts telltale pattern of channel straightening with increased number of wide and open loops after the construction of barrage. The average sinuosity of the loops has increased from 2.27 in 1927 to 2.35 in 1974 and dwindles to 1.80 in 2014. This distinct outcome induced by FBP is also found for other indices explained with special reference new hydraulic regime in post-Farakka period. 相似文献
98.
99.
In this paper, we have constructed mesonic stiff fluid cosmological models in five dimensional LRS Bianchi type-I and Bianchi
type-VI0 space times in general theory of relativity. Some physical and geometrical properties of the models are discussed. 相似文献
100.
In this paper, we constructed some five dimensional LRS Bianchi type-I string cosmological models based on Lyra geometry and studied some physical and geometrical properties of the models. 相似文献