Removal of hazardous hexavalent chromium from aqueous solution using divinylbenzene copolymer resin     

S. Bajpai  A. Dey  M. K. Jha  S. K. Gupta  A. Gupta 《International Journal of Environmental Science and Technology》2012,9(4):683-690

This paper presents the removal of hazardous hexavalent chromium from liquid waste streams using divinylbenzene copolymer resin Amberlite IRA 96. Important sorption parameters such as contact time, pH, resin dosage and initial metal concentration were studied at 30?°C. The kinetic study was conducted using pseudo-first and pseudo-second-order kinetics at 30?°C. The sorption process was found to be pH dependent. Maximum removal was obtained at pH 2 under optimized conditions. The sorption process was rapid and 99?% of the removal was achieved in first 30?min. The equilibrium data were fitted to both Langmuir and Freundlich models. The better regression coefficient (R ²) in Freundlich model suggests the multilayer sorption process. The value of Gibbs free energy for sorption process was found to be ?12.394?kJmol^?1. The negative value indicated the spontaneity of the sorption process. Scanning electron microscope and energy dispersive X-ray spectroscopy studies were conducted to find the role of surface morphology during sorption process. The Fourier transform infrared study was conducted to identify the functional groups responsible for interaction between the resin and chromium. Desorption and regeneration studies were also carried out.  相似文献   

Activities of Ahmedabad Chapter of the Indian Society of Remote Sensing     

V. K. Jha 《Journal of the Indian Society of Remote Sensing》1990,18(4):i-i

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Correction     

V. K. Jha 《Journal of the Indian Society of Remote Sensing》1991,19(1):xiii-xiii

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Air Pollution Studies and Management Efforts in Nepal     

P.K. Jha  H.D. Lekhak 《Pure and Applied Geophysics》2003,160(1-2):341-348

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Evaluating persistence and identifying trends and abrupt changes in monthly and annual rainfalls of a semi-arid region in Western India     

Deepesh?MachiwalEmail author  Madan?Kumar?Jha 《Theoretical and Applied Climatology》2017,128(3-4):689-708

In this study, 43-year (1965–2007) monthly and annual rainfall time series of ten rainfall stations in a semi-arid region of western India are analyzed by adopting three tests for testing normality and by applying autoregressive technique for exploring persistence. Gradual trends are identified by three tests, and their magnitudes are assessed by the Sen’s slope estimator. Also, abrupt changes are detected by using four tests and they are further confirmed by two tests. Box-whisker plots revealed that the rainfalls of June and September are right skewed for all the stations. The annual rainfalls of Bhinder, Dhariawad, and Gogunda stations are found considerably right skewed. The normality tests indicated that the rainfall of July does not deviate from the normal distribution at all the stations. However, the annual rainfall is found non-normal at five stations. The monthly rainfalls of June, July, and August have persistence respectively at three (Mavli, Salumber, and Sarada), two (Kherwara and Sarada), and one (Mavli) stations, whereas the annual rainfall has persistence at Girwa and Mavli stations. Significantly increasing trend is detected at Mavli in the rainfall of July and in the annual rainfall (p value?>?0.05), while the negative trend in August rainfall at Dhariawad is found significant (p value?>?0.10). This study revealed that the presence of serial correlation does not affect the performance of the Mann-Kendall test. Mean values of trend magnitudes for the rainfalls of June, July, August, and September are 0.3, 0.8, ?0.4, and 0.4 mm year^?1, respectively, and the overall mean value for the annual rainfall is 0.9 mm year^?1. It is found that the standard normal homogeneity test and the Pettitt test are biased towards the end of the series to locate a change point. Conversely, the Bayesian test has a tendency to look for a change point in the beginning of time series. Confirmed abrupt changes in the rainfall time series are found in the year 2003 (Bhinder) in June; years 1974 (Mavli) and 1989 (Dhariawad and Salumber) in July; years 1972 (Sarada), 1990 (Dhariawad), and 2003 (Mavli) in August; years 1977 (Dhariawad), 1991 (Sarada), and 2004 (Kotra) in September; and in the year 1972 (Mavli and Sarada stations) in the annual series. It is emphasized that the significantly increasing trend of rainfall may have linkages with climate change and/or variability. Finally, this study recommends use of multiple statistical tests for analyzing hydrologic time series in order to ensure reliable decisions.  相似文献   

Neural networks for wave forecasting   总被引：1，自引：0，他引：1  

M. C. Deo  A. Jha  A. S. Chaphekar  K. Ravikant 《Ocean Engineering》2001,28(7)

The physical process of generation of waves by wind is extremely complex, uncertain and not yet fully understood. Despite a variety of deterministic models presented to predict the heights and periods of waves from the characteristics of the generating wind, a large scope still exists to improve on the existing models or to provide alternatives to them. This paper explores the possibility of employing the relatively recent technique of neural networks for this purpose. A simple 3-layered feed forward type of network is developed to obtain the output of significant wave heights and average wave periods from the input of generating wind speeds. The network is trained with different algorithms and using three sets of data. The results show that an appropriately trained network could provide satisfactory results in open wider areas, in deep water and also when the sampling and prediction interval is large, such as a week. A proper choice of training patterns is found to be crucial in achieving adequate training.  相似文献   

Origin of Rumjatar table-land,Nepal Himalayas     

V. K. Jha  A. K. Roy 《Journal of the Indian Society of Remote Sensing》1983,11(1):71-74

The Rumjatar Table-land with an area of 2.5 sq km and general southerly slope of 4′ is a unique feature amidst 2500 sq km of rugged Himalayan terrain of the Midland region of Napal, which has been studied through aerial photographs aud toposheets, with field checks. Though it exhibits some characteristics of a peneplain, it is in fact a “fock-fan” developed through denudation processes acting on weak rocks in a valley. The rock fan has now assumed the form of an upland through downcutting by the bounding streams on the sides, and concurrent uplift of the Himalayas. It is topped by soil cover.  相似文献   

Aerial remote sensing as an aid to engineering geologic investigation—A case study from Srinagar Hydel Project,Garhwal, U.P.     

V K Jha 《Journal of the Indian Society of Remote Sensing》1992,20(4):199-205

Aerial remote sensing coupled with selective field check was carried out to assess the feasibility of the Srinagar dam site, related construction works, location of Srinagar Thrust and to evaluate terrain factors that may have adverse influence on the life of the structure. The lithology of the area comprises mainly of quartzites, phyllites, basic rocks and limestones which trend WNW-ESE. The Srinagar Thrust following the regional trend passes through the centre of the area. The investigation has established the location and extension of Srinagar Thrust and other faults, and presently dormant state of Srinagar Thrust. It also links the major Kaliasaur landslide with a fault. There is a possibility that the slide would contribute a substantial amount of silt into the reservoir.  相似文献   

Flood estimation in Mahanadi river system,India using partial duration series     

Nibedita Guru  Ramakar Jha 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(2):135-145

Flood frequency analysis is a pre-requisite for setting up and safeguarding of many hydraulic structures, such as dams, barrages, check-dams, culverts and urban drainage systems. In the flood frequency analysis, partial duration series (PDS) may be considered when dealing with values exceeding certain limits causing floods. In fact, the PDS is capable of getting more information about extreme events than the annual maximum series (AMS). Additionally, an assumption that, the magnitude of the extreme events of a PDS is best described by a generalized Pareto (GP) distribution. The present work investigates the at-site flood frequency analysis to find the average number of peaks (λ) for modelling the PDS on the basis of the PDS/GP assumption and variability in the GP parameters coupled with the quantile estimation with an increase in the value of average number of peaks (λ) each year in the Mahanadi river system, Odisha, India. Also, to verify the PDS/GP assumption we tested seven different frequency distributions (Exponential, Gumbel, logistics, generalized extreme value (GEV), Lognormal (LN), generalized logistics (GL) and Pearson Type 3). Extensive daily discharge data collected from 23 gauging sites were used for the analysis. The results indicate precision and stability of GP distribution parameters for λ?=?4 for almost all the discharge sites. The peak flood estimated for various return periods in the Mahanadi river system using GP distribution is endowed with high correlation statistics for this λ value.  相似文献   

Exploring hydrogeology and groundwater dynamics in a lateritic terrain of West Bengal,India, under limited data conditions     

Deepesh Machiwal  Madan K. Jha 《Environmental Earth Sciences》2016,75(9):831

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