In this paper, we study LRS Bianchi type II cosmological model with a nonzero time-dependent cosmological constant Λ for disordered
radiation in the framework of Barber’s second self creation theory of gravitation. The physical and geometrical aspects of
the model with singularities are also discussed. 相似文献
An assessment of cyclone risk and vulnerability at the village level has evolved, which is an important component of the information system for local level development action plans for preparedness and mitigation. Here, a case study for the Nellore district along the east coast of India is considered. Using maximum probable surges along the coast, total water level (TWL) due to the combined effect of surge, tide, and wind wave is computed for the most vulnerable coastal villages of the Nellore district due to any tropical cyclones. The computations suggest that the TWL along the Nellore coast varies from 2 m in the south to 4 m in the north. 相似文献
The seasonal variation of particulate matter and its relationship with meteorological parameters were measured at five different residential sites in Delhi. Sampling was carried out for one year including all three seasons (summer, monsoon, and winter). The yearly average concentration of particulate matter (PM2.5) was 135.16 ± 41.34 µg/m3. The highest average values were observed in winter (208.44 ± 43.67 µg/m3) and the lowest during monsoon season (80.29 ± 39.47 µg/m3). The annual average concentration of PM2.5 was found to be the highest at the Mukherjee Nagar site (242.16 µg/m3 ) during the winter and lowest at (Jawaharlal Nehru University) JNU (35.65 µg/m3) during the monsoon season. The strongest correlation between PM mass and a meteorological parameter was a strong negative correlation with temperature (R2=0.55). All other parameters were weakly correlated (R2<0.2) with PM mass.
An investigation was undertaken regarding the adsorption of different heavy metal ions from aqueous solutions using ??-diketone-functionalized styrene divinylbenzene resin under different experimental conditions such as initial concentration of metal ions, contact time, pH, and chelating capacity. The functionalization of resin was carried out by the condensation reaction of sodium salt of ??-diketones (pentane-1,3-dione) and chloromethylated styrene?Cdivinylbenzene resin in dichloromethane. Functionalized resin beads were characterized by Fourier transform infrared spectroscopy. The batch method was employed using different metal ions solution from 5 to 15?mg/L at different contact times. The adsorption kinetics was tested for the pseudo-first order, pseudo-second order reaction at different experimental conditions. The rate constant of adsorption kinetic models were also calculated and good correlation coefficient (R2?>?0.9941) was obtained for pseudo-second order kinetic model. The maximum adsorption value obtain for lead (0.725728?mg/g), chromium (0.9199?mg/g), nickel (0.4974?mg/g), cobalt (0.6196?mg/g) and cadmium (0.6519?mg/g) at equilibrium condition, which shows that ??-diketone-functionalized styrene divinylbenzene resin is an effective adsorbent for toxic metal ions. 相似文献
In recent years, there has been lot of emphasis on the study of urban land use/ land cover changes to discover the growth
pattern due to rapid urbanisation. This study presents spatial metrics and gradient analysis approach for quantifying and
capturing changes in urban landscape using LISS III imagery of 1999, 2001 and 2004 of Gurgaon, India. A combination of spatial
metrics i.e. percentage of landscape, mean patch size, number of patches, landscape shape index and largest patch index, available
in Fragstats ver. 3.3, have been used to quantify the patterns of urban growth in different directions in terms of size, shape
and complexity of development. The local built-up areas were quantified by the “moving window” technique. A gradient analysis
has been carried out through sampling from a reference point to 8 km in 16 directions with a window size of 500 mts. Results
of this study demonstrate the potential of spatial metrics and gradient modelling to quantify the impact of regional factors
on the growth pattern of Gurgaon city. 相似文献
Presently available simplified analytical methods and semi-empirical methods for the analysis of buried pipelines subjected to fault motion are suitable only for the strike-slip and the normal-slip type fault motions, and cannot be used for the reverse fault crossing case. A simple finite element model, which uses beam elements for the pipeline and discrete nonlinear springs for the soil, has been proposed to analyse buried pipeline subjected to reverse fault motion. The material nonlinearities associated with pipe-material and soil, and geometric nonlinearity associated with large deformations were incorporated in the analysis. Complex reverse fault motion was simulated using suitable constraints between pipe-nodes and ground ends of the soil spring. Results of the parametric study suggest that the pipeline's capacity to accommodate reverse fault offset can be increased significantly by choosing a near-parallel orientation in plan with respect to the fault line. Further improvement in the response of the pipeline is possible by adopting loose backfill, smooth and hard surface coating, and shallow burial depth in the fault crossing region. For normal or near normal orientations, pipeline is expected to fail due to beam buckling at very small fault offsets. 相似文献
Snow cover depletion curve (SDC) is one of the important variables in snow hydrological applications, and these curves are very much required for snowmelt runoff modeling in a snowfed catchment. Remote sensing is an important source of snow cover area which is used for preparation of SDC. Snow cover maps produced by Moderate Resolution Imaging Spectroradiometer (MODIS) satellites are one of the best source of satellite-based snow cover area at a regular interval. Therefore, in this study, snow cover maps have been prepared for the years 2000?C2005 using MODIS data. The study area chosen viz. Beas basin up to Pandoh dam falls in western Himalayan region. For snowmelt runoff modeling, catchment is divided into number of elevation zones and SDC is required for each zone. When sufficient satellite data are not available due to cloud cover or due to some other reasons, then SDC can to be generated using temperature data. Under changed climate conditions also, modified SDC is required. Therefore, to have SDC under such situations, a relationship between snow cover area and cumulative mean temperature has been developed for each zone of the catchment. This procedure of having snow cover maps has two main purposes. First, it could potentially be used to generate snow cover maps when cloud-free satellite data are not available. Second, it can be used to generate snow-covered area in a new climate to see the impact of climate change on snowmelt runoff studies. 相似文献
We investigate the spatial and temporal variations of the high-degree mode frequencies calculated over localized regions of the Sun during the extended minimum phase between solar cycles 23 and 24. The frequency shifts measured relative to the spatial average over the solar disk indicate that the correlation between the frequency shift and magnetic field strength during the low-activity phase is weak. The disk-averaged frequency shifts computed relative to a minimal activity period also reveal a moderate correlation with different activity indices, with a maximum linear correlation of about 72?%. From the investigation of the frequency shifts at different latitudinal bands, we do not find a consensus period for the onset of solar cycle 24. The frequency shifts corresponding to most of the latitudes in the northern hemisphere and 30° south of the equator indicate the minimum epoch to be February 2008, which is earlier than inferred from solar activity indices. 相似文献
Two-dimensional finite element method was used for evaluating the effect of orthogonal compression on precursor faults. The tendency of reactivation of precursor faults as thrust or normal was analyzed involving the positions and angles of precursor faults with the stresses, strains and displacements. Twelve cases were taken up with different combinations of precursor fault angles (high, >45° and low, <45°) and fault positions for analysis. Different positions and angles of precursor faults are correlated with stresses, strains, and displacements and are discussed in detail. It is hoped that this would help in understanding the past and the present geodynamics of the earth’s crust. 相似文献
Inductively coupled plasma-mass spectrometry is well suited for the precise, accurate and rapid determination of rare earth elements in most geological samples. However, determination of rare earth elements in certain mantle-derived materials, without applying preconcentration techniques, remains problematical due to low natural concentrations (generally < 1 ng g−1). Consequently, USGS reference materials DTS-1 (a dunite) and PCC-1 (a partially serpentinized harzburgite) have only suggested rather than recommended values for the rare earth elements in reference material compilations. We compared results obtained using two ICP-MS instruments: a U-5000AT ultrasonic nebuliser coupled to a PQ2+ quadrupole ICP-MS and an ELEMENT sector field ICP-MS equipped with a MCN-6000 microconcentric desolvating nebuliser, with the suggested literature values for these two reference materials. Precision and accuracy of analytical methods employed by both instruments were demonstrated by excellent relative standard deviations (< 2%) and inter-laboratory agreement (< 5%) for numerous analyses of BHVO-1 and BIR-1, which are well established with rare earth elements contents at the μg g−1 level. Repeat analyses of DTS-1 and PCC-1 at each laboratory indicate that each method is generally precise to better than 5% at sub-g g−1 levels. Furthermore, values from both instruments generally agree to within 10%. Our DTS-1 and PCC-1 values agree reasonably well with selected data reported in the literature (except for Ce and Sm in DTS-1) but exhibit poorer agreement with reported compilation values. With the demonstrated level of precision and accuracy, we contend that these new values for DTS-1 and PCC-1, generated by two different instruments, are the best estimates of the true whole-rock composition of these samples reported to date. 相似文献