Stability of earth dam contaminated by chemical transport     

Taebong Ahn  Chandra S. Desai 《国际地质力学数值与分析法杂志》1999,23(15):1893-1908

When chemicals are introduced into the oil, they affect soil properties such as hydraulic conductivity and stress–strain behavior. In this study, several chloride concentrations are varied from 0 to 20 per cent to analyse the effect of chemicals on soil properties. A series of laboratory triaxial tests are performed on the cylindrical specimens of sand–bentonite mixture with different sodium chloride contents (5, 10, 15 per cent) by Nannapaneni. Deformation (elastic modulus, E) and strength (cohesion, c′, and angle of friction, ϕ′) parameters are obtained from the triaxial tests as functions of confining pressure and sodium chloride concentrations, and variations of parameters are incorporated into stability analysis. The stress–strain–strength behaviour based on the above strength parameters is introduced in a finite element procedure with a modified residual flow procedure (RFP). By integrating a slope stability procedure in the finite element method, the stability with time of earth dam contaminated by sodium chloride is examined. It is found that increasing sodium chloride concentration for the soil considered increases stability. However, the procedure is general and can allow stability analysis under the influence of other chemical which may lead to decrease in stability. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Statistical approach to triple systems in three-dimensional motion     

Ranjeet Kumar  Navin Chandra  Surekha Tomar 《Astrophysics and Space Science》2018,363(7):147

This paper considers disruption of triple close approaches with low initial velocities and equal masses in the framework of statistical escape theory in a three-dimensional space. The statistical escape theory is based on the assumption that the phase trajectory of a triple system is quasi-ergodic. This system is described by allowing for both energy and angular momentum conservation in the phase space. In this paper, “possibility of escape” is derived with the formation of a binary on the basis of relative distances of the participating bodies. The complete statistical solutions (i.e. the semi-major axis \(a\), the distributions of eccentricity \(e\) of the binary, binary energy \({E}_{{b}}\), escape energy \({E}_{{s}}\) of escaper, and its escape velocity \({v}_{{s}}\)) of the system are derived from the allowable phase space volumes and are in good agreement with the numerical results in the range of perturbing velocities \({v}_{{i}}\)(\(10^{ - 1} \le {v}_{{i}} \le 10^{ - 10}\)) and directions of \({v}_{{i}}(0 \le \alpha _{{i}},\beta _{{i}},\gamma _{{i}} \le \pi )\), \({i} = 1,2,3\). In this paper, the double limit process has been applied to approximate the escape probability. Through this process, it is observed that the perturbing velocity \({v}_{{i}} \to 0^{ +} \), as the product of the semi-major axis \(a\) of the final binary and the square of the escape velocity \({v}_{{s}}\) approach 2/3, i.e. \({a} {v}_{{s}}^{2} \to 2 / 3\), whatever direction of \(\mathbf{v}_{{i}}\) may be.  相似文献   

Intra-day variability of three Seyfert galaxies measured with XMM-Newton     

Ashutosh Tripathi  Paul Joseph Wiita  Alok Chandra Gupta  Min-Feng Gu  Mai Liao 《天文和天体物理学研究(英文版)》2019,(8)

We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest( 30 ks) observations made for NGC 4051, MCG-06–30–15 and NGC 4151 by XMM-Newton between 2000 and 2015. The nuclei were quite active during essentially all of these observations and the overall X-ray fluxes(0.3–10 keV) varied by an order of magnitude. Most of the observations do appear to show characteristic timescales, estimated through their auto-correlation functions, ranging between ~2.9 ks and ~45.3 ks. The hard(2–10 keV) and soft(0.3–2.0 keV) bands are very well correlated but consideration of their hardness ratios shows that the sources typically soften during flares. We also provide new estimates of the central black hole masses for these three AGNs that support the hypothesis that Narrow Line Seyfert 1 galaxies have relatively small central black holes.  相似文献   

Coconut‐Shell‐Derived Carbon/Carbon Nanotube Composite for Fluoride Adsorption from Aqueous Solution     

Ramya Araga  Suresh Kali  Chandra S. Sharma 《洁净——土壤、空气、水》2019,47(5)

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The GH branch of PKP from deep-focus earthquakes     

Ramesh Chandra Agrawal 《Geophysical Journal International》1978,53(3):459-465

summary . Approximately 1000 PKP observations in the range 110° < Δ < 170° have been statistically studied to examine the existence of Bolt's GH branch of the PKP travel-time curve. Data give firm evidence for the existence of this branch from 130 to 153° but the possibility of its extending further cannot be ruled out. Observations for this branch fit the form:
Where a =(1150.3254±0.5328)s, b = (16.4907±0.3803)s, c = (−0.1316±0.0630)s.
Times for this branch are always greater by 2 s than the corresponding Gogna times from Pacific earthquakes.  相似文献   

Extremely energetic 4B/X17.2 flare and associated phenomena     

Wahab Uddin  Ramesh Chandra  Syed Salman Ali 《Journal of Astrophysics and Astronomy》2006,27(2-3):267-276

We observed 4B/X17.2 flare in Hα from super-active region NOAA 10486 at ARIES, Nainital. This is one of the largest flares of current solar cycle 23, which occurred near the Sun’s center and produced extremely energetic emission almost at all wavelengths from γ-ray to radio-waves. The flare is associated with a bright/fast full-halo earth directed CME, strong type II, type III and type IV radio bursts, an intense proton event and GLE. This flare is well observed by SOHO, RHESSI and TRACE. Our Hα observations show the stretching/de-twisting and eruption of helically twisted S shaped (sigmoid) filament in the south-west direction of the active region with bright shock front followed by rapid increase in intensity and area of the gigantic flare. The flare shows almost similar evolution in Hα, EUV and UV. We measure the speed of Hα ribbon separation and the mean value is ∼ 70 km s^-1. This is used together with photospheric magnetic field to infer a magnetic reconnection rate at three HXR sources at the flare maximum. In this paper, we also discuss the energetics of active region filament, flare and associated CME.  相似文献   

The heating and cooling in certain active region loops     

Suresh Chandra 《Astrophysics and Space Science》1987,135(1):195-196

Narain and Kumar (1985) have mixed up various situations which are quite different from each other. In view of that, the conclusions drawn by them may not be reliable.  相似文献   

Tectonic segmentation of the Burmese-Indonesian arc     

Umesh Chandra 《Tectonophysics》1984,105(1-4)

Several lines of evidences, which include change in trend and offset in arcs, bathymetry and sedimentation, faulting in the region, change in composition and trend of the line of volcanoes, spatial distribution of earthquakes and change in dip of the Benioff zone, suggest a tectonic segmentation of the Burmese-Indonesian Arc. Two transverse boundary zones, viz., the North Andaman Boundary Zone and the Sunda Boundary Zone separating segments of the arc are identified. Larger than usual thickness of the oceanic crust beneath the Ninetyeast Ridge reduces the average density of the lithosphere carrying the ridge. The buoyancy effect caused by the reduced average density inhibits the subduction of an approximately triangular shaped lithosphere between the Burmese-Indonesian Arc and the Ninetyeast Ridge, which in turn causes tectonic segmentation along the arc. The model predicts and some available focal mechanism solutions confirm left lateral northeast faulting within the Sunda Boundary Zone.  相似文献   

Temperature dependence of CO2 solubility in high pressure quenched glasses of diopside composition     

Chandra S Rai  Shiv K Sharma  David W Muenow  Dean W Matson  Charles D Byers 《Geochimica et cosmochimica acta》1983,47(5):953-958

The temperature dependence of carbon dioxide solubility in glasses of diopside composition, quenched from 20 kbar, has been investigated using a combination of high-temperature mass spectrometry and Raman spectroscopy.CO₂-charged diopside glasses were synthesized in a piston-cylinder apparatus. Because of diffusion of hydrogen through the platinum capsules, significant amounts of H₂O, CH₄ and CO were detected along with CO: in the diopside glasses. All three carbon species show a bimodal release pattern in the mass pyrograms. The CO₂ solubility shows a linear and negative temperature dependence. We do not observe any maxima in the solubility curve as was reported previously (Mysen and virgo, 1980a).None of the additional bands observed in Raman spectra of CO₂-charged diopside glasses compared to those in the spectrum of diopside glass can be assigned to molecular CO₂. These bands are caused by CO^?2₃ ions and indicate that the physical solubility of molecular carbon dioxide is negligible. The bimodal release pattern observed for CO₂ in the mass pyrograms, is consistent with the Raman data which strongly suggests that CO^?2₃ ions are present in at least two distinct sites in the glass.  相似文献   

On unsteady flow of a viscous fluid between two parallel plates under variable surface charges     

Subhash Chandra Nandy 《Pure and Applied Geophysics》1970,83(1):56-61

Summary The equations of electricity and the equations of hydrodynamics have been used to solve the problem of unsteady flow of a viscous fluid under variable surface charges.  相似文献