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41.
The impact of vertical resolution on the evolution and movement of tropical cyclones was studied using NCAR MM5 model with a horizontal resolution of 9 km. Four numerical experiments were performed with different vertical resolutions, that is, with 23 vertical levels as control experiment, and 36 vertical levels with high resolution in the lower troposphere, 33 vertical levels with high resolution in the upper troposphere and 46 vertical levels with increased vertical resolution throughout the troposphere as relative to base experiment. The results indicate that increased vertical resolution in the lower troposphere produces efficient intensification and better structure in terms of eye and eyewall. Increased vertical resolution at lower levels improves the prediction of vertical shear of horizontal wind. Experiments with high resolution in the lower troposphere and high resolution throughout the troposphere simulate better track up to 72 hours. 相似文献
42.
Sunil K. Jha 《洁净——土壤、空气、水》2012,40(12):1392-1400
The geochemical characteristics and the spatial distribution of the fluoride were studied in the soils of Indo‐Gangetic plains using multivariate analysis. The fluoride (F) distribution in soil profiles and surface soil (0–15 cm) samples were studied. It was found that total fluoride (TF) in the profiles ranged from 248 to 786 mg kg?1 with a mean of 515.1 mg kg?1 whereas CaCl2 extractable soluble fluoride (FCa) was found to be in the range of 1.68 to 99.1 mg F kg?1 soil. On the other hand, in surface soils, the TF and FCa ranged from 118 to 436 mg kg?1 with a mean of 251.2 mg kg?1 and 1.01 to 5.05 mg kg?1 with a mean of 2.12 mg kg?1, respectively, in the study area. The principal component analysis revealed that the natural weathering of fluoride bearing rock and minerals, various ion‐exchange and dissolution processes in the soil, alkalinity, sodium adsorption ratio, calcium (Ca), magnesium (Mg), and clay contents of the soil are responsible for high fluoride occurrence in the area. The fluoride contamination index developed by using these factors could explain more than 76% variance of F contamination due to FCa in soils. The interpolated kriged map of FCa in surface soil indicated a distinct loop of 1.0–2.0, 2.0–3.0, 3.0–4.0, and >4.0 mg kg?1. 相似文献
43.
A landslide susceptibility zonation (LSZ) map helps to understand the spatial distribution of slope failure probability in
an area and hence it is useful for effective landslide hazard mitigation measures. Such maps can be generated using qualitative
or quantitative approaches. The present study is an attempt to utilise a multivariate statistical method called binary logistic
regression (BLR) analysis for LSZ mapping in part of the Garhwal Lesser Himalaya, India, lying close to the Main Boundary
Thrust (MBT). This method gives the freedom to use categorical and continuous predictor variables together in a regression
analysis. Geographic Information System has been used for preparing the database on causal factors of slope instability and
landslide locations as well as for carrying out the spatial modelling of landslide susceptibility. A forward stepwise logistic
regression analysis using maximum likelihood estimation method has been used in the regression. The constant and the coefficients
of the predictor variables retained by the regression model have been used to calculate the probability of slope failure for
the entire study area. The predictive logistic regression model has been validated by receiver operating characteristic curve
analysis, which has given 91.7% accuracy for the developed BLR model. 相似文献
44.
Biraja Kumar Sahu Mehmuna Begum M.K. Khadanga Dilip Kr Jha N.V. Vinithkumar R. Kirubagaran 《Marine pollution bulletin》2013,66(1-2):246-251
Port Blair is the capital city of Andaman & Nicobar Islands, the union territory of India. More than 50% of the population of these islands lives around Port Blair Bay. Therefore the anthropogenic effects in the bay water were studied for monitoring purpose from seven stations. Physico-chemical parameters of seawater were analyzed in samples collected once in every 3 months for 2 years from seven sampling stations located in Port Blair Bay, South Andaman Island to evaluate the spatial and tidal variation. Cluster analysis and factor analysis were applied to the experimental data in an attempt to understand the sources of variation of physico-chemical parameters. In cluster analysis, the stations Junglighat Bay and Phoenix Bay having high anthropogenic influence formed a separate group. The factors obtained from factor analysis indicated that the parameters responsible for physico-chemical variations are mainly related to land run-off, sewage outfall and tidal flow. 相似文献
45.
46.
Surendra Kumar Jha J. P. Shrivastava C. L. Bhairam 《Journal of the Geological Society of India》2012,79(2):117-134
Clays associated with the Precambrian unconformity-related (sensu lato) uranium mineralization that occur along fractures of Rohini carbonate, Bandai sandstone and clay-organic rich black carbonaceous
Gorakalan shale of the Sonrai Formation from Bijawar Group is significant. Nature and structural complexity of these clays
have been studied to understand depositional mechanism and palaeoenvironmental conditions responsible for the restricted enrichment
of uranium in the Sonrai basin. Clays (<2 μm fraction) separated from indurate sedimentary rocks by disaggregation, chemical
treatment and centrifugation were examined using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Presence
of tv-1M type illite is inferred from the Rohini and Bandai Members of the Sonrai Formation, indicative of high fluid/rock
interaction and super-saturation state of the fluids available in proximity with the uranium mineralization. It is observed
that the Sonrai Formation is characterized by kaolinite > chlorite > illite > smectite mineral assemblages, whereas, Solda
Formation contains kaolinite > illite > chlorite clays. It has been found that the former mineral assemblage resulted from
the alteration process is associated with the uranium mineralization and follow progressive reaction series, indicating palaeoenvironmental
(cycles of tropical humid to semi-arid/arid) changes prevailed during maturation of the Sonrai basin. The hydrothermal activity
possibly associated with Kurrat volcanics is accountable for the clay mineral alterations. 相似文献
47.
Neerja Jha Pauline Sabina K. Rajni Tewari N. C. Mehrotra 《Journal of the Geological Society of India》2011,77(2):137-148
42 genera of palynomorphs have been reported from the qualitative and quantitative analysis of the palynoflora from both open
cast mine and bore holes viz., Ballarpur open cast mine, Durgapur open cast mine and Bore hole CMWNM-57 on barrier between
Kawadi/Majri open cast and Hindustan Lalpeth Colliery from the Wardha valley coalfield of Wardha basin. Two palynoassemblages
have been recorded i.e., an Upper Karharbari palynoassemblage comprising dominance of radial monosaccate genus Parasaccites and subdominance of nonstriate disaccate genus Scheuringipollenites and a Lower Barakar palynoassemblage consisting of dominance of Scheuringipollenites and subdominance of striate disaccates chiefly Faunipollenites, suggesting an Early Permian age (Late Sakmarian to Early Artinskian) to the sediments. It is further authenticated by the
occurrence of palynotaxa viz., Crucisaccites, Caheniasaccites, Indotriradites and Tiwariasporis. Upper Karharbari Formation has been demarcated for the first time in lithologically designated Barakar Formations in Ballarpur,
Durgapur, Majri and Hindustan Lalpeth Colliery while the sample 57/2 of bore hole CMWNM from Kawadi area may belong to the
Kamthi Formation on the basis of pinkish yellowish coarse grained to medium grained sandstone. An attempt has been made to
correlate these palynoassemblages with other Lower Gondwana basins of Early Permian affinity. 相似文献
48.
Groundwater-level prediction using multiple linear regression and artificial neural network techniques: a comparative assessment 总被引:4,自引:3,他引:1
The potential of multiple linear regression (MLR) and artificial neural network (ANN) techniques in predicting transient water levels over a groundwater basin were compared. MLR and ANN modeling was carried out at 17 sites in Japan, considering all significant inputs: rainfall, ambient temperature, river stage, 11 seasonal dummy variables, and influential lags of rainfall, ambient temperature, river stage and groundwater level. Seventeen site-specific ANN models were developed, using multi-layer feed-forward neural networks trained with Levenberg-Marquardt backpropagation algorithms. The performance of the models was evaluated using statistical and graphical indicators. Comparison of the goodness-of-fit statistics of the MLR models with those of the ANN models indicated that there is better agreement between the ANN-predicted groundwater levels and the observed groundwater levels at all the sites, compared to the MLR. This finding was supported by the graphical indicators and the residual analysis. Thus, it is concluded that the ANN technique is superior to the MLR technique in predicting spatio-temporal distribution of groundwater levels in a basin. However, considering the practical advantages of the MLR technique, it is recommended as an alternative and cost-effective groundwater modeling tool. 相似文献
49.
A reconnaissance survey was conducted to examine the physicochemical properties of the potable water of Northern parts of the State of Mizoram, India, as well as the adjoining southern parts of the State of Assam, India. Groundwater samples were taken from those sources of water which were used as potable water source in the area. All the samples were analyzed for ionic concentrations of potassium (K+), sodium (Na+), calcium (Ca2+), magnesium (Mg2+), chlorine (Cl?), sulfate (SO 4 2? ), manganese (Mn), iron (Fe), and arsenic (As). Parameters such as pH, electrical conductivity, total dissolved solids, and total hardness were also measured in situ using digital instruments. The aim of the present work is to study the various physicochemical parameters following the recommendations of World Health Organization in order to test whether these sources are safe enough to be used as potable water resources. Furthermore, present work will throw light on the probable causes of presence of arsenic in Silchar City of southern Assam and total absence of it in neighboring state of Mizoram. 相似文献
50.
We present a well behaved class of charged analogue of M.C. Durgapal (J. Phys. A, Math. Gen. 15:2637, 1982) solution. This solution describes charged fluid balls with positively finite central pressure, positively finite central density; their ratio is less than one and causality condition is obeyed at the centre. The outmarch of pressure, density, pressure-density ratio and the adiabatic speed of sound is monotonically decreasing, however, the electric intensity is monotonically increasing in nature. This solution gives us wide range of parameter for every positive value of n for which the solution is well behaved hence, suitable for modeling of super dense stars. Keeping in view of well behaved nature of this solution, one new class of solution is being studied extensively. Moreover, this class of solution gives us wide range of constant K (0≤K≤2.2) for which the solution is well behaved hence, suitable for modeling of super dense stars like strange quark stars, neutron stars and pulsars. For this class of solution the mass of a star is maximized with all degree of suitability, compatible with quark stars, neutron stars and pulsars. By assuming the surface density ρ b =2×1014 g/cm3 (like, Brecher and Capocaso, Nature 259:377, 1976), corresponding to K=0 with X=0..235, the resulting well behaved model has the mass M=4.03M Θ , radius r b =19.53 km and moment of inertia I=1.213×1046 g?cm2; for K=1.5 with X=0.235, the resulting well behaved model has the mass M=4.43M Θ , radius r b =18.04 km and moment of inertia I=1.136×1046 g?cm2; for K=2.2 with X=0.235, the resulting well behaved model has the mass M=4.56M Θ , radius r b =17.30 km and moment of inertia I=1.076×1046 g?cm2. These values of masses and moment of inertia are found to be consistent with the crab pulsars. 相似文献