Vertical uplift resistance of close-spaced shallow rectangular group anchor plates embedded in sand     

R. Ganesh 《Marine Georesources & Geotechnology》2020,38(9):1070-1081

Abstract

This study describes an analytical solution for determining the ultimate vertical uplift resistance of a group of two and multiple number of close-spaced shallow rectangular anchor plates embedded horizontally in sand. The analysis was performed by using an upper bound theorem of limit analysis with the employment of the kinematically admissible three-dimensional (3D) rigid wedge collapse mechanisms. Results are obtained in terms of dimensionless uplift factors F_γ and F_q due to the components of soil self-weight and surcharge pressure acting on the ground surface for a wide range of parameters. It was found that the magnitude of uplift factors decreases substantially with a decrease in the clear spacing between the anchors, soil friction angle, and embedment ratio, and an increase in the aspect ratio of anchors. Further, it was noticed that when the clear spacing between the anchors is greater than or equal to the certain critical value, the interaction effect of anchors vanishes and the magnitude of uplift factors associated with a group of anchors becomes equal to that of single isolated anchors. The present solutions are found to compare reasonably well with those theoretical, numerical, and experimental results available in the literature.  相似文献   

Reply to comment on “Effect of surface wave inversion non-uniqueness on 1D seismic ground response analysis”     

Narayan Roy  Ravi Sankar Jakka  H. R. Wason 《Natural Hazards》2015,75(1):983-989

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An improved model for the formation times of dark matter haloes     

Carlo Giocoli  Jorge Moreno  Ravi K. Sheth  Giuseppe Tormen 《Monthly notices of the Royal Astronomical Society》2007,376(3):977-983

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The three-point correlation function of luminous red galaxies in the Sloan Digital Sky Survey     

Gauri V. Kulkarni  Robert C. Nichol  Ravi K. Sheth  Hee-Jong Seo  Daniel J. Eisenstein  Alexander Gray 《Monthly notices of the Royal Astronomical Society》2007,378(3):1196-1206

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Strong clustering of underdense regions and the environmental dependence of clustering from Gaussian initial conditions     

Ummi Abbas  Ravi K. Sheth 《Monthly notices of the Royal Astronomical Society》2007,378(2):641-648

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Near-nucleus photometry of comets using archived NEAT data     

Michael D. Hicks  Raymond J. Bambery  Priya Kollipara 《Icarus》2007,188(2):457-467

Though optimized to discover and track fast moving Near-Earth Objects (NEOs), the Near-Earth Asteroid Tracking (NEAT) survey dataset can be mined to obtain information on the comet population observed serendipitously during the asteroid survey. We have completed analysis of over 400 CCD images of comets obtained during the autonomous operations of two 1.2-m telescopes: the first on the summit of Haleakala on the Hawaiian island of Maui and the second on Palomar Mountain in southern California. Photometric calibrations of each frame were derived using background catalog stars and the near-nucleus comet photometry measured. We measured dust production and normalized magnitudes for the coma and nucleus in order to explore cometary activity and comet size-frequency distributions. Our data over an approximately two-year time frame (2001 August-2003 February) include 52 comets: 12 periodic, 19 numbered, and 21 non-periodic, obtained over a wide range of viewing geometries and helio/geocentric distances. Nuclear magnitudes were estimated for a subset of comets observed. We found that for low-activity comets (Afρ<100 cm) our model gave reasonable estimates for nuclear size and magnitude. The slope of the cumulative luminosity function of our sample of low-activity comets was 0.33 ± 0.04, consistent with the slope we measured for the Jupiter-family cometary nuclei collected by Fernández et al. [Fernández, J.A., Tancredi, G., Rickman, H., Licandro, J., 1999. Astron. Astrophys. 392, 327-340] of 0.38 ± 0.02. Our slopes of the cumulative size distribution α=1.50±0.08 agree well with the slopes measured by Whitman et al. [Whitman, K., Morbidelli, A., Jedicke, R., 2006. Icarus 183, 101-114], Meech et al. [Meech, K.J., Hainaut, O.R., Marsden, B.G., 2004. Icarus 170, 463-491], Lowry et al. [Lowry, S.C., Fitzsimmons, A., Collander-Brown, S., 2003. Astron. Astrophys. 397, 329-343], and Weissman and Lowry [Weissman, P.R., Lowry, S.C., 2003. Lunar Planet. Sci. 34. Abstract 34].  相似文献   

The probability distribution function of the Lyman α transmitted flux from a sample of Sloan Digital Sky Survey quasars     

Vincent Desjacques  Adi Nusser  Ravi K. Sheth 《Monthly notices of the Royal Astronomical Society》2007,374(1):206-219

We present a measurement of the probability distribution function (PDF) of the transmitted flux in the Lyman α (Lyα) forest from a sample of 3492 quasars included in the Sloan Digital Sky Survey data release 3 (SDSS DR3). Our intention is to investigate the sensitivity of the Lyα flux PDF as measured from low-resolution and low signal-to-noise ratio data to a number of systematic errors such as uncertainties in the mean flux, continuum and noise estimate. The quasar continuum is described by the superposition of a power law and emission lines. We perform a power-law continuum fitting on a spectrum-by-spectrum basis, and obtain an average continuum slope of  α_ν= 0.59 ± 0.36  in the redshift range  2.5 < z < 3.5  . We take into account that the variation in the continuum indices increases the mean flux by 3 and 7 per cent at   z = 3  and 2.4, respectively, as compared to the values inferred with a single (mean) continuum slope. We compare our measurements to the PDF obtained with mock lognormal spectra, whose statistical properties have been constrained to match the observed Lyα flux PDF and power spectrum of high-resolution data. Using our power-law continuum fitting and the SDSS pipeline noise estimate yields a poor agreement between the observed and mock PDFs. Allowing for a break in the continuum slope and, more importantly, for residual scatter in the continuum level substantially improves the agreement. A decrease of ∼10–15 per cent in the mean quasar continuum with a typical rms variance at the 20 per cent level can account for the data, provided that the noise excess correction is no larger than ≲10 per cent.  相似文献   

On the interaction of mesoscale eddies and a tropical cyclone in the Bay of Bengal     

Prakash  Kumar Ravi  Nigam  Tanuja  Pant  Vimlesh  Chandra  Navin 《Natural Hazards》2021,106(3):1981-2001

Natural Hazards - Oceanic eddies span over a wide range of sizes and affect the thermodynamic properties of water column. By modifying the thermal structure of the upper ocean, these eddies...  相似文献   

Blast Vibration and Fragmentation Control at Heavily Jointed Limestone Mine     

Paswan  Ranjit K.  Roy  M. P.  Shankar  Ravi  Singh  P. K. 《Geotechnical and Geological Engineering》2021,39(5):3469-3485

Geotechnical and Geological Engineering - The presence of structural inhomogeneity in a rock mass in the form of joints, fractures, bedding planes is a very common phenomenon. These discontinuities...  相似文献   

Halo abundances in the f_nl model     

Tsz Yan Lam  Ravi K. Sheth 《Monthly notices of the Royal Astronomical Society》2009,398(4):2143-2151

We show how the excursion set moving barrier model for halo abundances may be generalized to the local non-Gaussian f _nl model. Our estimate assumes that the distribution of step sizes depends on f _nl, but that they are otherwise uncorrelated. Our analysis is consistent with previous results for the case of a constant barrier, and highlights some implicit assumptions. It also clarifies the basis of an approximate analytic solution to the moving barrier problem in the Gaussian case, and shows how it might be improved.  相似文献