Static deformation of a uniform half-space due to a long dip-slip fault     

Sunita Rani  Sarva Jit Singh 《Geophysical Journal International》1992,109(2):469-476

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Evaluation of the Comparative Toxicity of Thiotox,Dichlorvos and Carbofuran to Two Fresh Water Teleosts Ophiocephalus punctatus and Mystus Vittatus     

S. R. Verma  Sarita Rani  S. K. Bansal  R. C. Dalela 《洁净——土壤、空气、水》1981,9(2):119-129

The present study was undertaken to evaluate the comparative toxicity of Thiotox (Endosulfan) (an organochlorine), Dichlorvos (DDVP) (an organophosphorus) and Carbofuran (a carbamate) so as to determine the TL 50 values, acute toxicity ranges, relative toxicities, relative susceptibility, safe concentrations, regression equations, heterogeneity factor and 95% confidence limits for the period of 24, 48, 72 and 96 h, taking two fresh water teleosts, Mystus vittatus and Ophiocephalus punctatus as test animals. From the relative toxicity of these pesticides it is evident that thiotox was the most toxic and dichlorvos the least toxic one, while the toxicity of carbofuran was in between these two extremes for both the fishes. On the basis of relative susceptibility, Mystus vittatus was found to be more susceptible than Ophiocephalus punctatus for thiotox, dichlorvos and carbofuran, respectively. The safe concentrations were computed for all the three pesticides taking different application factors, so as to avoid the long term water pollution by these pesticides.  相似文献   

Quasi-static deformation of a poroelastic half-space with anisotropic permeability by two-dimensional surface loads     

Sarva Jit Singh  Sunita Rani  Raman Kumar 《Geophysical Journal International》2007,170(3):1311-1327

An analytical solution is obtained of the fully coupled diffusion–deformation system of equations governing the quasi-static plane strain deformation of a poroelastic half-space with anisotropic permeability and compressible constituents. The stresses and the pore pressure are taken as the basic state variables. Displacements are obtained by integrating the coupled constitutive relations. The problem of surface loads is discussed in detail. Explicit analytical solutions are derived for normal line loading, shear line loading and normal strip loading. The permeability anisotropy is found to have a significant effect on the quasi-static deformation of the half-space. However, in the drained and undrained limits, the anisotropy has no effect. The stresses in the drained and undrained states are independent of the poroelastic parameters. Numerical computation of the pore pressure indicates that ignoring permeability anisotropy may lead to an overestimation of the pore pressure at points vertically below the point of normal loading. Further, anisotropy in permeability may lead to a dilution in the theoretical prediction of the Mandel–Cryer Effect.  相似文献   

Assessing coastal landscape vulnerability using geospatial techniques along Vizianagaram–Srikakulam coast of Andhra Pradesh,India     

Meenu Rani  Sufia Rehman  Haroon Sajjad  B. S. Chaudhary  Jyoti Sharma  Sandeep Bhardwaj  Pavan Kumar 《Natural Hazards》2018,94(2):711-725

Vizianagaram–Srikakulam coastal shoreline consisting of beaches, mangrove swamps, tidal channel and mudflats is one of the vulnerable coasts in Andhra Pradesh, India. Five site-specific parameters, namely rate of geomorphology, coastal elevation, coastal slope, shoreline change and mean significant wave height, were chosen for constructing coastal vulnerability index and assessing coastal landscape vulnerability. The findings revealed a shift of 2.5 km in shoreline towards the land surface because of constant erosion and that of 1.82 km towards the sea due to accretion during 1997–2017. The rate of high erosion was found in zones IV and V, and high accretion was found in zones II and III. Coastal vulnerability index analysis revealed constant erosion along shoreline and sea level rise in the study area. Most of the coast in zone V has recorded very high vulnerability due to erosion, high slope, significant wave height and sea level rise. Erosion and accretion, significant wave height, sea level rise and slope are attributed to high vulnerability in zones III and IV. Zone II recorded moderate vulnerability. Relatively lower slope, mean sea wave height and sea level rise have made this zone moderately vulnerable. Very low vulnerability was found in zone I, and low vulnerability was recorded in zone II. Accretion, low slope and low sea level rise were found to be causative factors of lower vulnerability. Thus, zones III, IV and V should be accorded higher priorities for coastal management. The findings can be helpful in coastal land planning and management and preparing emergency plans of the coastal ecosystems.  相似文献   

Coastal vulnerability assessment studies over India: a review   总被引：2，自引：2，他引：0  

N. N. V. Sudha Rani  A. N. V. Satyanarayana  Prasad Kumar Bhaskaran 《Natural Hazards》2015,77(1):405-428

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Dynamical instability of cylindrical symmetric collapsing star in generalized teleparallel gravity     

Abdul Jawad  Davood Momeni  Shamaila Rani  Ratbay Myrzakulov 《Astrophysics and Space Science》2016,361(4):141

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Geochemical and thermodynamic aspects of sorption of strontium on kaolinite dominated clay samples at Kalpakkam     

R. Deepthi Rani  P. Sasidhar 《Environmental Earth Sciences》2012,65(4):1265-1274

The mobility of strontium in subsurface is largely influenced by sorption on to clay minerals. In the present study, kaolinite clay samples collected from the Kalpakkam nuclear plant site were employed to understand the sorption characteristics of strontium by batch method. The effect of several parameters such as time, strontium ion concentration, pH, temperature and ionic strength was investigated. The kinetic studies suggested pseudo-second-order mechanism. The experimental sorption data was fitted to Langmuir adsorption model for obtaining the sorption capacity of the sorbent. The maximum sorption capacity was 5.77 mg/g at 298 K and was found to increase with an increase in temperature. It was observed that the distribution coefficient (K _d) of strontium on clay increased as the pH of the solution increased. The distribution coefficient was found to decrease with an increase in concentration of Na⁺ and Ca²⁺ ions. This variation of K _d suggests that cation exchange is the predominant sorption process. It was also observed that sorption process is endothermic. The thermodynamic parameters such as ∆G ⁰, ∆H ⁰ and ∆S ⁰ were calculated. The negative values obtained for ∆G ⁰ indicated that the sorption of strontium on clay was spontaneous at all studied concentrations. ∆G ⁰ becomes more negative with an increase in temperature, suggests that the sorption process is more favorable at higher temperatures.  相似文献   

Near hydrothermal alteration of obsidian glass: Implications for long term performance assessments     

Nishi Rani  J. P. Shrivastava  R. K. Bajpai 《Journal of the Geological Society of India》2012,79(4):376-382

Obsidian glass alteration experiments under near hydrothermal conditions were performed to study mechanism and conditions of formation of altered minerals. X-ray diffraction patterns and cell dimensions of the specimens treated at 150, 200 and 300°C (pH = 8.03) revealed appearance of three main minerals — illite (9.5–10 Å), chlorite (7.04 Å) and halloysite (10.25Å). Further increase in the pH favours matrix dissolution with the formation of secondary altered layers. SEM-EDS study show that the alteration causes smoothing of the grain surfaces. These surfaces exhibits etch pits and series of depressions, formed by the process of dissolution. SEM — Back Scattered Electron images of obsidian specimens show thin laminae of smectite, with foliated bulky rims and cellular honeycomb texture, formed by precipitation from the solution as well as by direct transformation of glass during alteration. This mechanism is resulting from the alteration of alkalis by ionic inter-diffusion with H₃O⁺ and H⁺ and inward diffusion of H₂O, leading to free diffusion of silica into solution and then to a local rearrangement of the glass framework. Thus, a direct transformation of glass into clay minerals is the major reaction mechanism as evidenced by the mechanism of glass dissolution and subsequent mineral precipitation.  相似文献   

Generalized teleparallel gravity via some scalar field dark energy models     

M. Sharif  Shamaila Rani 《Astrophysics and Space Science》2013,345(1):217-223

We consider generalized teleparallel gravity in the flat FRW universe with a viable power-law f(T) model. We construct its equation of state and deceleration parameters which give accelerated expansion of the universe in quintessence era for the obtained scale factor. Further, we develop correspondence of f(T) model with scalar field models such as, quintessence, tachyon, K-essence and dilaton. The dynamics of scalar field as well as scalar potential of these models indicate the expansion of the universe with acceleration in the f(T) gravity scenario.  相似文献   

A set of linked optimization models for an inter-basin water transfer     

D. Rani  D.K. Srivastava  T.R. Gulati 《水文科学杂志》2013,58(2):371-392

ABSTRACT

A set of linked optimization models was used to evaluate planning and operation of the proposed Pamba-Achankovil-Vaippar (PAV) water transfer project in India. The shortage of water for irrigation in the Vaippar basin has led to the need for water import. The project consists of three reservoirs. The models were applied at three levels. At Level-1, the projections of water requirement for irrigation in the Vaippar basin at Reservoir-1 were estimated using an LP model. Level-2 was operated at three sub-levels: the first was the determination of the export requirements from the Pamba basin (Reservoir-2) to the Achankovil basin (Reservoir-1); the second was determining the capability of Reservoir-2 to export and sizing of the three reservoirs to meet the above targets was the third sub-level. Integrated reservoir operation and canal irrigation water distribution were done at Level-3. DP models were employed at levels-2 and 3. The linked LP, DP and simulation models were found effective for planning water transfers.  相似文献