Faculty Publications
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Item Analytical solutions using a higher order refined computational model with 12 degrees of freedom for the free vibration analysis of antisymmetric angle-ply plates(2008) Swaminathan, K.; Patil, S.S.Analytical formulations and solutions to the natural frequency analysis of simply supported antisymmetric angle-ply composite and sandwich plates hitherto not reported in the literature based on a higher order refined computational model with 12 degrees of freedom already reported in the literature are presented. The theoretical model presented herein incorporates laminate deformations which account for the effects of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate thus modelling the warping of transverse cross sections more accurately and eliminating the need for shear correction coefficients. In addition, another higher order computational model with five degrees of freedom already available in the literature is also considered for comparison. The equations of motion are obtained using Hamilton's principle. Solutions are obtained in closed-form using Navier's technique by solving the eigenvalue equation. Plates with varying slenderness ratios, number of layers, degrees of anisotropy, edge ratios and thickness of core to thickness of face sheet ratios are considered for analysis. Numerical results with real properties using above two computational models are presented and compared for the free vibration analysis of multilayer antisymmetric angle-ply composite and sandwich plates, which will serve as a benchmark for future investigations. © 2007 Elsevier Ltd. All rights reserved.Item Stability of horizontal oil well - A Jointed Rock model approach(2011) Anantharamu, A.; Singh, T.N.; Venkat Reddy, D.Advancement in technology has paved different ways for the extraction of oil. Drilling of wells, production and injection of fluids results in the alteration of pre-existing stress field in a reservoir. The current study is undertaken to analyze the stability of horizontal oil wells with the change in radius of the well, Poisson's ratio, saturation density, permeability and also to find stress distribution around horizontal oil wells drilled in different reservoir conditions, stress distribution before and after production and also to assess the effect of stress distribution on the stability. The knowledge of stress distribution and its redistribution with change in reservoir conditions can help in selecting well locations and orientations for maximum sweep in reservoirs. Displacement of the particles gives the direction of fracture propagation. As the particle size increases, fracture propagation increases. The stability analysis has been done using Jointed Rock method of Numerical Modeling. Numerical models are mathematical models that use numerical time-stepping procedure to obtain the models behavior over time. The results of the model are shown to agree qualitatively with field observations. The extent of stress distribution is dependent on radius of the well, pore pressure in the reservoir, fracture density of the reservoir and drilling direction. Horizontal wells drilled in highly fractured reservoirs will be less stable. In case of anisotropy, since the stability is very less we must reduce the radius of the well in order to increase the FOS and hence the stability. © 2011 CAFET-INNOVA TECHNICAL SOCIETY.Item Characterization of PtIV-containing polyoxometalates by high-resolution solid-state 195Pt and 51V NMR spectroscopy(Royal Society of Chemistry, 2016) Dugar, S.; Izarova, N.V.; Mal, S.S.; Fu, R.; Joo, H.-C.; Lee, U.; Dalal, N.S.; Pope, M.T.; Jameson, G.B.; Kortz, U.We report on the feasibility of applying high-resolution solid-state 195Pt MAS NMR spectroscopy for several PtIV-containing polyoxotungstates, and of 195Pt as well as 51V for a PtIV-containing polyoxovanadate. This method is particularly useful for polyanions which are unstable in solution and/or poorly soluble, as well as for systems exhibiting crystallographic disorder of Pt and W sites. We also report solution 195Pt and 183W NMR spectra of hexatungstoplatinate(iv) [H3PtW6O24]5- for the first time. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2016.Item Fully automatic segmentation of phalanges from hand radiographs for bone age assessment(Taylor and Francis Ltd., 2019) Simu, S.; Lal, S.; Fadte, K.; Harlapur, A.Segmentation of bones from hand radiograph is an important step in automated bone age assessment (ABAA) system. Main challenges in the segmentation of bones are the intensity inhomogeneity caused by the irregular distribution of X-rays and the overlapping pixel intensities between the bone and soft tissue. Hence, there is a need to develop a robust segmentation technique to tackle the problems associated with the hand radiographs. This paper proposes a fully automatic technique for segmentation of phalanges from left-hand radiograph for bone age assessment. The proposed technique is divided into five stages which are pre-processing, extraction of Phalangeal region of interest, edge preservation, segmentation of phalanges and post-processing. Quantitative and qualitative results of proposed segmentation technique are evaluated and compared with other state-of-the-art segmentation methods. Qualitative results of proposed segmentation technique are also validated by different medical experts. The segmentation accuracy achieved by proposed segmentation technique is 94%. The proposed technique can be used for development of fully ABAA of a person for better accuracy. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.Item Predictions for the Cosmic Microwave Background from an Anisotropic Quantum Bounce(American Physical Society revtex@aps.org, 2020) Agullo, I.; Olmedo, J.; Sreenath, V.We introduce an extension of the standard inflationary paradigm on which the big bang singularity is replaced by an anisotropic bounce. Unlike in the big bang model, cosmological perturbations find an adiabatic regime in the past. We show that this scenario accounts for the observed quadrupolar modulation in the temperature anisotropies of the cosmic microwave background, and we make predictions for the polarization angular correlation functions E-E, B-B, and E-B, together with temperature-polarization correlations T-B and T-E, that can be used to test our ideas. We base our calculations on the bounce predicted by loop quantum cosmology, but our techniques and conclusions apply to other bouncing models as well. © 2020 American Physical Society.