Faculty Publications
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Publications by NITK Faculty
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Item Hardware Acceleration of Optically Labeled Human Genome Sequencing using a Novel Algorithm(Institute of Electrical and Electronics Engineers Inc., 2018) Mulani, K.S.; Kumar, H.; Gaurav, M.K.; Sumam David, S.Recently, reconstruction of the entire DNA sequence from optically labeled genomes has been explored. In this paper, we present details of a novel algorithm for this genome assembly. We elucidate the design methodology and results for a multi-core CPU (1.98x speedup) and FPGA (7.022x speedup) implementation to accelerate the computations. © 2018 IEEE.Item Experimental and Analytical Evaluation of an Acceleration-Based Semiactive Control Strategy for Automotive Suspension Systems with Magneto-Rheological Damper(SAE International, 2023) Jamadar, M.E.H.; Devikiran, P.; Kumar, H.; Joladarshi, S.Most of the control strategies presented to date are based on either the velocities or displacement of the vehicle body and the wheel which are derived by filtering and converting the data from the accelerometer. This increases the computational load and therefore directly affects the performance of the semiactive suspension system. This study presents a control strategy purely based on the acceleration for semiactive control of vehicle suspension with a magneto-rheological MR damper. The effectiveness of the acceleration-based skyhook (ASH) control strategy is compared with the existing velocity-based skyhook (VSH) control strategy based on the vibration response of a single-degree-of-freedom (SDOF) system. The effectiveness of ASH is evaluated experimentally, and the reaction time is evaluated analytically. The experimental results revealed that the ASH reduces the peak displacement and peak acceleration of the mass under the free vibration test and also improves the settling time as compared to VSH. The amplitude of the displacement and acceleration was also found to be reduced under the forced vibration test with maximum improvement observed during high-frequency excitation. The reaction time of ASH was also found to be considerably lower than VSH. Therefore, it was learned that the proposed ASH performed better under high-frequency excitation than under lower-frequency excitation. Moreover, the lower reaction time of the ASH could improve the overall performance of the semiactive suspension system. © 2023 SAE International.Item Closed-Loop Vector Formulation in Euler’s Complex Numbers for Multi-Loop Planar Mechanisms With N-bars: A Novel Modeling Approach and Algorithm(Defense Scientific Information and Documentation Centre, 2023) Rahul, V.M.; Bhaktha, B.S.; Gangadharan, K.V.This paper presents a novel iterative algorithm incorporated in a user-friendly GUI for modeling the kinematics of multiple looped N-bar closed-loop mechanisms. Past research works have used custom coding or expensive commercial software to analyze the mechanisms of specific applications. The proposed algorithm focuses on kinematics and offers a quick, easy-to-use, cost-effective solution to analyze a wide range of generic mechanisms, reducing the need for custom coding and lowering computational costs. The algorithm employs algebraic equations, such as solving complex closed-loop vector equations using the Euler form of complex numbers, to simulate and derive the unknowns necessary to characterise any generic closed-loop mechanism. The Python code implemented in the algorithm adapts to various scenarios by utilising available information on the position, velocity, and acceleration variables of the mechanisms. The simulation tool can display real-time color contour plots (RGB color scale) for linear and angular velocities and accelerations, simulate mechanisms with multiple loops and switch configurations, and find inverse mechanisms. The approach for solving multiple loop problems and the algorithm utilized to solve the configurations, methods, equations used and GUI features implementation are all described in this study. The case study considered for a four-bar mechanism indicates a strong agreement between the results obtained from the proposed kinematics-based simulator and ANSYS software. These results demonstrate the simulator’s effectiveness in providing low-cost and user-friendly simulation results for various generic mechanisms involving multiple interconnected loops. © 2023, DESIDOC.Item MULTIDIMENSIONAL INVESTIGATION OF THERMAL BEHAVIOR OF HIGH-POWER ELECTRIC VEHICLE MOTOR DURING ON-ROAD DRIVING CONDITIONS THROUGH ELECTROMAGNETIC, THERMAL, AND DRIVE CYCLE ANALYSIS(Begell House Inc., 2024) Chauhan, V.K.S.; Koorata, P.K.This study addresses the critical need to understand the thermal behavior of electric motors in real-world driving conditions, which is crucial for the global transition to electric vehicles (EVs) and for achieving sustainable energy goals. The real-world driving conditions include acceleration and deceleration, resulting in speed variations, and existing research often limits its scope to constant speed conditions, potentially providing misleading results. As existing research predominantly confines itself to constant speed conditions, our study fills this gap by investigating temperature variations during on-road driving scenarios, utilizing the SAE J227 drive cycle as a benchmark. Based on recent studies, we consider the design parameters of an appropriate EV motor and subject the developed model to thermal and fluid flow analyses. The impact of confinement on motor temperature rise is also explored for potential temperature reduction, contributing up to 4 percent temperature reduction. The drive cycle–based study indicated that running the motor at a constant speed yields a considerably lower temperature rise (ΔT < 74°C) than actual driving conditions. In contrast, temperatures in actual driving scenarios could exceed 136°C within similar durations. This study looks into the actual heating challenges faced by electric motors used in EVs by integrating analyses from electrical, thermal, and transportation engineering. © 2024 by Begell House, Inc. www.begellhouse.com.Item Seismic stability evaluation of rubble mound breakwater: Shake table tests and numerical analyses(Elsevier Ltd, 2024) Akarsh, P.K.; Chaudhary, B.; Sajan, M.; Kumar, S.; Sah, B.Rubble mound (RM) breakwaters are coastal structures constructed to provide tranquil condition around the port areas. After past earthquakes such as the 2004 Indian Ocean earthquake and the 2011 Great East Japan earthquake, it was found that stability of breakwater not only depends on the wave action but seismic motions also play an important role for this. Very limited studies are available for the stability evaluation of RM Breakwater under earthquake motions by conducting physical model tests. To the end, an attempt has been made in the study to evaluate the stability of RM breakwater subjected to earthquake loadings. A series of shaking table tests conducted to evaluate the seismic behaviour of the RM breakwater. A prototype RM breakwater is modelled on two layers of seabed foundation soil. Different amplitudes of sinusoidal seismic motions (foreshocks and main shock) are provided at the base of the model. Later, the breakwater stability was evaluated for real earthquake motions. Various parameters such as settlement, horizontal displacement, acceleration-time histories and excess pore water pressure were measured during the tests. Deformation pattern was also studied by photos and videos captured during the tests. During the mainshock, the crown wall settled by 111 % more comparable to second foreshock; and the structure laterally displaced by more than 200 % comparable with first foreshock. The peak acceleration of input wave amplified while it was travelling from bottom to the crest of breakwater. The excess pore water pressure was maximum beneath the rubble mound, in loose sand and it was five times more during the mainshock compared to first foreshock. Due to loss in bearing capacity of foundation soil, the breakwater collapsed. Also, the effects like rolling down of armor units, densification and slumping of core material, shear deformation of breakwater body were observed during the main shock. Thus, the breakwater failed during the mainshock. Numerical analyses were also executed for both sinusoidal and real earthquake motions to make clear the mechanism of the breakwater behaviour subjected to the earthquake loadings. © 2024 Elsevier LtdItem Experimental investigation and optimization of performance, emission, and vibro-acoustic parameters of SI engine fueled with n-propanol and gasoline blends using ANN-GA coupled with NSGA3-modified TOPSIS hybrid approach(Elsevier Ltd, 2024) Kirankumar, K.R.; Kumar, G.N.; Kamath, N.; Gangadharan, K.V.In the present study, performance, emission, and vibro-acoustic studies were conducted on a spark ignition (SI) engine fueled with gasoline and an n-propanol blend at variable compression ratio (CR), speed, and propanol blend fraction (PBF). Experimental data were used to model an artificial neural network (ANN) trained with a genetic algorithm (GA). ANN predictive responses were employed to establish regression relationships between brake power (BP), brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), oxides of nitrogen (NOx), carbon monoxide (CO), hydrocarbon (HC), resultant vibration acceleration (RVA), and sound pressure level (SPL) with operating parameters using response surface methodology (RSM). These models served as objective functions in the non-dominated sorting genetic algorithm-3 (NSGA3), a multi-objective optimization (MOO) technique, to optimize responses and obtain non-dominated solutions. These solutions were filtered using a modified technique for order preference by similarity to the ideal solution (TOPSIS) to obtain a compromised optimal solution. ANN-GA model outcomes showed high accuracy, with coefficient of determination (R2) and root mean square error (RMSE) values ranging from 0.979 to 0.993 and 0.0381 to 0.0643, respectively. NSGA3 coupled with modified TOPSIS identified optimal operating conditions at 1271.77 RPM, a CR of 11.96, and a PBF of 33.26 %. © 2024 Elsevier LtdItem Numerical investigation of a novel flow damping device for mitigating liquid sloshing under bi-directional excitation(Springer Science and Business Media B.V., 2024) Jogi, P.; Jayalekshmi, B.R.Sloshing in liquid storage tanks (LSTs) poses a significant challenge, especially during the seismic events and necessitating the implementation of effective mitigation strategies. This study proposes a novel technique by introducing a flow-damping device (FDD) made up of singly curved cylindrical plates connected to a cylindrical stem. The FDD is designed to be placed inside the LSTs to dissipate seismic energy, thereby reducing sloshing effects. Numerical analysis was conducted using the Arbitrary Lagrangian and Eulerian formulations in ABAQUS to assess the efficiency of various FDD configurations in reducing sloshing displacements in LSTs. The liquid storage tank with and without FDDs, were subjected to uni and bi-directional ground motion records of Imperial valley and Northridge earthquakes with a scaled peak ground acceleration. The study revealed that the FDD configuration consisting of eight plates evenly distributed around the stem with two plates oriented towards each other is the most effective FDD in reducing the seismic response parameters. When the FDD is connected to the tank base and placed centrally inside the tank at a distance of one-sixth of the tank’s length from both ends of the tank wall achieved a maximum reduction of 52.64% in sloshing displacements and 47.99% in impulsive hydrodynamic pressures. These results emphasize the substantial effectiveness of the proposed FDD design in reducing sloshing and hydrodynamic effects in LSTs during seismic events. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Deterministic Seismic Hazard Analysis of Sree Padmanabhaswamy Temple, Kerala State(Springer, 2025) Padmanabhan, M.P.H.; Siddhardha, R.; Kolathayar, S.; Hegde, R.; Beekanahalli Mokshanatha, B.M.Deterministic seismic hazard analysis (DSHA) is a technique employed to estimate potential hazards and ground shaking resulting from specific earthquake scenarios at a given location. In the present study, DSHA is conducted for the Sree Padmanabhaswamy Temple, situated in the southernmost district of Kerala, India. This seismic hazard study is crucial due to the temple’s proximity to seismic events such as the 1900 AD Coimbatore earthquake with a magnitude of 6.3 Mw and the 2000 Pala earthquake with a magnitude of 4.7 Mw. This study examines earthquake data within a 500 km radius surrounding the Sree Padmanabhaswamy Temple in Thiruvananthapuram District, Kerala, from 1819 to 2022 AD. The seismic zone of the temple site is III according to the Indian zonation map (IS 1893 (Part 1): 2016), relying on past earthquakes recorded throughout India. The collected earthquake data underwent a homogenization process to determine the moment magnitude (Mw), distinguishing foreshocks and aftershocks from the main shocks. A seismotectonic map was developed comprising of geological discontinuities and 316 earthquakes events with moment magnitudes between 3.0 and 6.3 Mw. The software tools employed for this work include MATLAB, QGIS and ZMAP. The Log-likelihood technique (LLH) was used to choose the ground motion prediction equations (GMPEs) for the location. The GMPEs were then given weights based on the computed values of the data support index (DSI). The study region was partitioned into a grid size of 0.05° × 0.05° (5 km × 5 km). Using MATLAB code, the peak ground acceleration (PGA) was estimated for the site and PGA was found in the center of each grid cell, taking into account all seismic sources within a 500 km radius. In addition, site-specific deterministic spectrum was also developed. The findings show that Sree Padmanabhaswamy Temple has low seismicity, which is defined by weak to moderate earthquakes that have sources close to the temple. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.Item Numerical study on reinforced vertical cuts integrated with RC buildings under the effects of ground motion(Institute of Engineering Mechanics (IEM), 2025) Amrita; Jayalekshmi, B.R.; Shivashankar, R.Soil nailing is an effective method used for stabilizing excavations and natural ground slopes. In situations with space constraints due to rapid urbanization, the available space near the soil-nailed vertical cuts can be utilized to construct multi-storied buildings. However, the presence of a building in proximity to the retained soil mass may alter the seismic response of a nailed structure. The building can be either constructed at a distance, connected or attached to the soil-nailed structure depending on the space availability. This study evaluates the behavior of such an integrated soil-nailed, wall-building system under seismic excitations by employing finite element analysis. The seismic response of a nailed wall supporting a vertical cut of a height of 6m under different connectivity conditions with an adjacent multi-story RC building is analyzed. Parametric studies are conducted with various heights of a building and under different frequency content of seismic excitations. The performance of the integrated system is evaluated regarding displacement and the acceleration response of the soil-nailed wall, as well as tensile force mobilized in nails. The innovative concept of integration between the two structures yields better seismic stability of the nailed structure, as well as for optimum use of land in space-constrained grounds with vertical cuts. © Institute of Engineering Mechanics, China Earthquake Administration 2025.