Faculty Publications

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    Morphometric evidences for neotectonism in the Mulki River basin of coastal Karnataka, India
    (2011) Radhakrishnan, K.; Lokesh, K.N.
    Mulki River basin, a rectilinear midland river draining the coastal Dakshina Kannada districts of Karnataka located in the Mulki-Pulikat Lake axis in south Indian Peninsula shield has been analysed for various morphometric characteristics to understand the tectonic conditions of the basin along with supporting evidences of geomorphology, geology and structural features using Remote Sensing and GIS technology. The regional neotectonism suggested by earlier workers evidenced through geomorphologic features and geology of the area has been established through morphometric analysis. Even though Mulki, a 6 th order river basin obeys the Horton's laws of stream order it disobeys the Horton's law of stream length, indicating the regional uplift due to neotectonic activities. Fluctuating stream length ratio of successive stream orders in the basin again stress upliftment and a late youth stage development of geomorphic features reflected in slope and topographic conditions. The range of varying bifurcation ratios and the low Form Factor along with Circularity and Elongation Ratios strongly suggest a geologically and structurally controlled drainage system with elongated basin shape and high relief pointing towards neotectonism. A very low relief ratio of 0.008342, with entrenched meandering plain and a steep structural ridge within the basin indicates a rejuvenation of the basin with regional uplift. A very coarse graded drainage texture of 7.84 with low stream frequency of 2.5 and a drainage density of 1.877km/km 2 suggest that the area is having highly resistant permeable subsoil in a low relief terrain indicative of neogene tectonic activities. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
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    An Alternative Method to Estimate Fundamental Period of Layered Soil Deposit
    (Springer India sanjiv.goswami@springer.co.in, 2015) Vijayendra, K.V.; Nayak, S.; Prasad, S.K.
    There are several approximate methods available for the estimation of fundamental period of layered soil deposits. Approximate methods based on weighted average of shear wave velocities of the layered soil profile are most widely employed in practice. On the other hand, methods which are more accurate are tedious and iterative in procedure; hence they are unpopular for quick estimation of fundamental period of soil deposits. A new method for computing the fundamental period of multilayered soil deposit is proposed in the present study. In this method, layered shear wave velocity profile is replaced with an equivalent linearly varying profile. Subsequently, based on analytical solution for fundamental period of the deposit with linearly varying shear wave velocity profile, an equation to estimate the fundamental period of the actual layered soil deposit is proposed. The efficiency of the proposed method and other available methods is relatively verified by comparing their results with values computed from recorded earthquake accelerograms of instrumented geotechnical downhole arrays. This comparative study, establishes accuracy and consistency of the proposed method vis-à-vis exact methods. © 2014, Indian Geotechnical Society.
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    A radial basis function method for fractional Darboux problems
    (Elsevier Ltd, 2018) Godavarma, C.; Prashanthi, P.; Vijesh, V.A.
    In this paper, a radial basis function (RBF) collocation known as Kansa's method has been extended to solve fractional Darboux problems. The fractional derivatives are described in the Caputo sense. Integration of radial functions that appears due to fractional derivatives have been dealt using Gauss–Jacobi quadrature method. The equation has been linearized using successive approximation. A few test problems have been solved and compared with available solutions. The effect of RBF shape parameter on accuracy and convergence has also been discussed. © 2017 Elsevier Ltd
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    11.39 fJ/conversion-step 780 kS/s 8 bit switched capacitor-based area and energyefficient successive approximation register ADC in 90 nm complementary metal-oxide- semiconductor
    (Institution of Engineering and Technology journals@theiet.org, 2018) Narasimaiah, J.D.; Laxminidhi, T.; Bhat, M.S.
    In this study, a design technique for low-energy consumption and area-efficient successive approximation register analogue-to-digital converter (ADC) is presented. Digital-to-analogue conversion equivalent voltage is acquired utilising passive sharing of charge between two unit capacitors and integration of the shared charge onto an input sample-and-hold capacitor, via a switched capacitor integrator circuit. The architecture is less parasitic sensitive and low noise, yielding an area and energyefficient ADC. To demonstrate the efficacy of the proposed technique, a ±350 mV 8 bit 0.78 MS/s ADC is designed in a 90 nm complementary metal-oxide-semiconductor process. The ADC core has a small area footprint of 0.00145 mm2 and has a figure-of-merit of 11.39 fJ/conv-step. © 2018, The Institution of Engineering and Technology.
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    A compact 4-to-8-bit nonbinary SAR ADC based on 2 bits per cycle DAC architecture
    (Springer, 2019) Bhat, K.G.; Laxminidhi, T.; Bhat, M.S.
    A compact programmable-resolution successive approximation register (SAR) analog to digital converter (ADC) for biosignal acquisition system is presented. The ADC features a programmable 4-to-8-bit DAC that makes the ADC programmable with 2 bits evaluated in each clock cycle. At low resolution with relaxed noise and linearity requirements, use of an increased clock speed improves energy efficiency. A single DAC architecture is used to generate references for 2 bits per cycle evaluation for all resolutions. Nonbinary switched capacitor circuits, least sensitive to parasitics, are proposed for the use in DAC for reference generation. The choice of architecture and circuit design are presented with mathematical analysis. The post-layout simulation of designed ADC in 90 nm CMOS process has 1.2 MS/s sampling rate at 8-bit mode with a power consumption of 185 ?W achieving an ENOB of 7.6. The active area of designed ADC is 0.06 mm2. The DAC resolution scaling and the use of variable sampling rate maximize efficiency at lower resolutions. Therefore, figure of merit (FOM) is degraded only by a factor of 4.7 for resolution scaling from 8 to 4 bits. This is a significant improvement over 16× degradation expected from 8-bit to 4-bit resolution scaling by truncating the bits. © 2019, Indian Academy of Sciences.