Radiating fluid spheres in general relativity     

B. C. Tewari 《Astrophysics and Space Science》1988,149(2):233-239

In this paper Einstein's field equations for spherically-symmetric radiating fluid distributions are discussed and some new exact regular solutions are obtained.  相似文献   

Exotic thrust mass of the Padar area in Kashmir     

A.P. Tewari 《Tectonophysics》1981,73(4):285-294

To the south of the Great Himalaya Range in Kashmir, a group of metasedimentary rocks with altered ultrabasic rocks occur physically over the migmatitic complex, as a klippe. The best exposure of it is met with in the Kudi nala, west of Sumjam, where lensoid outcrops of basic and ultramafic rocks, comprising actinolite—tremolite rock intruded by garnetiferous amphibolite occur within the marble, calc-gneiss and graphitic schist-gneiss. These rocks occur at an altitude of 5000–5500 m and the underlying rocks comprise gneiss, migmatite, schist, etc.The klippe of the metasedimentaries with the basic and ultrabasic suite of rocks, shows a synclinal disposition with a sheared northern contact. The southern contact of this klippe is also sheared and a tectonic “melange” zone is exposed in certain outcrops. This unusual geological set up, along with the absence of a deep-seated fault in the area of investigation, had led the author to believe that this suite of metasedimentaries has no stratigraphic relation with the underlying rocks which they override. These are very much akin to some of the rock suites of the Indus ophiolitic zone outcropping far in the north, particularly those of the Suru valley (Kargil tehsil) and they appear to have been transported during post-Cretaceous times as a thrust mass. This is the first record of an exotic thrust nappe in the Kashmir Himalaya to the south of the Great Himalaya Range.  相似文献   

Deleterious Effects of Arsenic on the Nucleic Acids and Protein Metabolism in the Liver of Heteropneustes fossilis (BL.) — a Freshwater Teleost     

J. Pd. Shukla  U. N. Dwivedi  P. Tewari  M. Prasad 《洁净——土壤、空气、水》1985,13(5):611-614

The present paper deals with the toxic effects if any of the two concentrations of Arsenic(III)-oxide on the nucleic acids and protein metabolism in the liver of H. fossilis after exposure for 20 and 30 days. Causes for significant alterations have been discussed.  相似文献   

Satellite radiance assimilation using a 3DVAR assimilation system for hurricane Sandy forecasts     

Tanvir Islam  Prashant K. Srivastava  Dinesh Kumar  George P. Petropoulos  Qiang Dai  Lu Zhuo 《Natural Hazards》2016,81(2):845-867

  相似文献   

Early Triassic palynomorphs from Kuraloi Block,Belphar area,Ib-River coalfield,Mahanadi basin,Odisha     

S. Suresh Kumar Pillai  K. L. Meena  Rajni Tewari  Arun Joshi 《Journal of the Geological Society of India》2016,88(6):693-704

A rich assemblage of palynomorphs including miospores and megaspores has been recorded from the bore core no. IBKAN-2 drilled at a depth of 17.80m in Kuraloi Block-A, south-west part of the Ib-River Coalfield, Jharsuguda district, Odisha. The miofloral assemblage recovered shows prominence of cingulate, zonate, taeniate, non-striate and non saccate palynotaxa which indicate an early Triassic age and is comparable with the palynoassemblages of the same age known from the Damodar basin, India. The megaspore assemblage includes eight genera and fifteen species namely, Banksisporites karanpuraensis, B. indicus, B. utkalensis, Banksisporites sp., Barakarella pantii, Barakarella sp., Biharisporites spinosus, Biharisporites sp., Erlansonisporites triassicus, Erlansonisporites cf. erlansonii, Erlansonisporites sp. Jhariatriletes sp., Singhisporites sp., Ramispinatispora sp. and Talchirella trivedii. Records of megaspores are sparse in the early Triassic of Gondwana basins of India. The present study records the first occurrence of miospores and megaspores from the early Triassic of Mahanadi basin besides substantiating the earlier data.  相似文献   

Chrome-diopside Megacryst-bearing Lamprophyre from the Late Cretaceous Mundwara Alkaline Complex,NW India: Petrological and Geodynamic Implications     

Abhinay Sharma  Deepak Kumar  Samarendra Sahoo  Dinesh Pandit  N. V. Chalapathi Rao 《Journal of the Geological Society of India》2018,91(4):395-399

The occurrence of a rare mantle-derived chrome-diopside megacryst (～8 mm), containing inclusions of olivine, in a lamprophyre dyke from the late Cretaceous polychronous (～100 – 68 Ma) Mundwara alkaline complex of NW India is reported. The olivine inclusions are forsteritic (Fo: 85.23) in composition, and their NiO (0.09 wt%) and CaO (0.13 wt%) contents imply derivation from a peridotitic mantle source. The composition of the chrome diopside (Cr₂O₃: 0.93 wt ) (Wo_45.27 En_48.47 Fs_5.07 and Ac_1.18) megacryst is comparable to that occurring in the garnet peridotite xenoliths found in diamondiferous kimberlites from Archaean cratons. Single pyroxene thermobarometry revealed that this chrome diopside megacryst was derived from a depth range of ～100 km, which is relatively much deeper than that of the chrome-diopside megacrysts (～40–50 km) reported in spinellherzolite xenoliths from the alkali basalts of Deccan age (ca. 66–67 Ma) from the Kutch, NW India. This study highlights that pre- Deccan lithosphere, below the Mundwara alkaline complex, was at least ～100 km thick and, likely, similar in composition to that of the cratonic lithosphere.  相似文献   

Evaluation of the Effect of Fault on the Stability of Underground Workings of Coal Mine through DEM and Statistical Analysis     

Arka Jyoti Das  Prabhat Kumar Mandal  Satya Prakash Sahu  Angad Kushwaha  Rana Bhattacharjee  Subhashish Tewari 《Journal of the Geological Society of India》2018,92(6):732-742

The rock mass around an excavation is generally traversed by different geological discontinuities such as faults, folds, slips, joints, etc. Fault is one of the major geological discontinuities which creates lot of difficulties during underground winning of coal. Entire stress regime and ground conditions in the formation are altered in and around the faults. Faults also impose detrimental effects by introducing impurities, including clay and various forms of mineral matter into the coal seams; opening of pathways for the influx of water and gas into the underground workings; displacing the coal seams upward/downwards making the coal seams difficult or sometimes impractical to mine. Appropriate evaluation of the effect of the fault on the stability of the underground workings is a requisite for safe design of the underground mining structures. In this paper, a study has been carried out to assess the effect of the fault on the stability of underground coal mines by numerical simulation with distinct element method (DEM). On the calibrated DEM model, parametric study has been performed by varying the selected parameters, the dip and the friction angles of the fault. The analysis of variance (ANOVA) shows that both the factors have statistically significant effect on the strength of the coal pillar. Similarly, the displacement of the immediate roof and the height of the disturbed strata are evaluated by the DEM modelling and statistical analysis when the fault passes through the middle of the gallery. The results of ANOVA for both cases indicate that the both factors have significant effect on the displacement of the immediate roof and the height of the disturbed strata. It is obtained from the study that the low angle fault causes high instability in the immediate roof. The paper has been supplemented with the field observations where instability in underground roadways of a coal mine in India is caused by the fault. It was observed in VK-7 incline mine of Singareni Collieries Company Limited, India that there was sudden failure of immediate roof of a roadway where a low angle fault crosses the middle of the roadway. The findings of the paper help to understand the behaviour of the coal pillar and the surrounding rock mass in the presence of the fault. The study would also help to take appropriate decisions about the unstable regions of the working safeguarding safety in underground coal mines.  相似文献   

Petrology and Sr-Nd isotope systematics of the Ahobil kimberlite (Pipe-16) from the Wajrakarur field,Eastern Dharwar craton,southern India     

Abhinay Sharma  Alok Kumar  Praveer Pankaj  Dinesh Pandit  Ramananda Chakrabarti  N.V. Chalapathi Rao 《地学前缘(英文版)》2019,10(3):1167-1186

Detailed mineralogical, bulk-rock geochemical and Sr-Nd isotopic data for the recently discovered Ahobil kimberlite(Pipe-16) from the Wajrakarur kimberlite field(WKF), Eastern Dharwar craton(EDC),southern India, are presented. Two generations of compositionally distinct olivine, Ti-poor phlogopite showing orangeitic evolutionary trends, spinel displaying magmatic trend-1, abundant perovskite, Tirich hydrogarnet, calcite and serpentine are the various mineral constituents. On the basis of(i) liquidus mineral composition,(ii) bulk-rock chemistry, and(iii) Sr-Nd isotopic composition, we show that Ahobil kimberlite shares several characteristic features of archetypal kimberlites than orangeites and lamproites. Geochemical modelling indicate Ahobil kimberlite magma derivation from small-degree melting of a carbonated peridotite source having higher Gd/Yb and lower La/Sm in contrast to those of orangeites from the Eastern Dharwar and Bastar cratons of Indian shield. The T_Dm Nd model age(～2.0 Ga) of the Ahobil kimberlite is(i) significantly older than those(1.5～1.3 Ga) reported for Wajrakarur and Narayanpet kimberlites of EDC,(ii) indistinguishable from those of the Mesoproterozoic EDC lamproites,and(iii) strikingly coincides with the timing of the amalgamation of the Columbia supercontinent. High bulk-rock Fe-Ti contents and wide variation in oxygen fugacity fO_2, as inferred from perovskite oxybarometry, suggest non-prospective nature of the Ahobil kimberlite for diamond.  相似文献   

Adsorption of Metal Ions onto the Chemically Modified Agricultural Waste     

Ponnusamy Senthil Kumar  Subramaniam Ramalingam  Ramasundaram Vijayakumar Abhinaya  Selvaraj Dinesh Kirupha  Arukkani Murugesan  Subramanian Sivanesan 《洁净——土壤、空气、水》2012,40(2):188-197

This paper discusses about the adsorption of metal ions such as Cu(II), Cd(II), Zn(II), and Ni(II) from aqueous solution by sulfuric acid treated cashew nut shell (STCNS). The adsorption process depends on the solution pH, adsorbent dose, contact time, initial metal ions concentration, and temperature. The adsorption kinetics was relatively fast and equilibrium was reached at 30 min. The adsorption equilibrium follows Langmuir adsorption isotherm model. The maximum adsorption capacity values of the modified cashew nut shell (CNS) for metal ions were 406.6 mg/g for Cu(II), 436.7 mg/g for Cd(II), 455.7 mg/g for Zn(II), and 456.3 mg/g for Ni(II). The thermodynamic study shows the adsorption of metal ions onto the STCNS was spontaneous and exothermic in nature. The kinetics of metal ions adsorption onto the STCNS followed a pseudo‐second‐order kinetic model. The external mass transfer controlled metal ions removal at the earlier stages and intraparticle diffusion at the later stages of adsorption. A Boyd kinetic plot confirms that the external mass transfer was the slowest step involved in the adsorption of metal ions onto the STCNS. A single‐stage batch adsorber was designed using the Langmuir adsorption isotherm equation.  相似文献   

Attenuation of P- and S-waves in the Chamoli Region, Himalaya, India     

Babita Sharma  S. S. Teotia  Dinesh Kumar  P. S. Raju 《Pure and Applied Geophysics》2009,166(12):1949-1966

The attenuation properties of the crust in the Chamoli region of Himalaya have been examined by estimating the frequency-dependent relationships of quality factors for P waves (Q_α) and for S waves (Q_β) in the frequency range 1.5–24 Hz. The extended coda normalization method has been applied on the waveforms of 25 aftershocks of the 1999 Chamoli earthquake (M 6.4) recorded at five stations. The average value of Q_α is found to be varied from 68 at 1.5 Hz to 588 at 24 Hz while it varies from 126 at 1.5 Hz to 868 at 24 Hz for Q_β. The estimated frequency-dependent relations for quality factors are Q_α = (44 ± 1)f^(0.82±.04) and Q_β = (87 ± 3)f^(0.71±.03). The rate of increase of Q(f) for P and S waves in the Chamoli region is comparable with the other regions of the world. The ratio Q_β/Q_α is greater than one in the region which along with the frequency dependence of quality factors indicates that scattering is an important factor contributing to the attenuation of body waves in the region. A comparison of attenuation relation for S wave estimated here (Q_β = 87f^0.71) with that of coda waves (Q_c = 30f^1.21) obtained by Mandal et al. (2001) for the same region shows that Q_c > Q_β for higher frequencies (>8 Hz) in the region. This indicates a possible high frequency coda enrichment which suggests that the scattering attenuation significantly influences the attenuation of S waves at frequencies >8 Hz. This observation may be further investigated using multiple scattering models. The attenuation relations for quality factors obtained here may be used for the estimation of source parameters and near-source simulation of earthquake ground motion of the earthquakes, which in turn are required for the assessment of seismic hazard in the region.  相似文献