Faculty Publications
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Item Silicon Photonic Microring Resonator for High-Sensitivity Temperature Sensing(Institute of Electrical and Electronics Engineers Inc., 2025) Chowdari, N.K.; Singh, M.The rapid advancements in silicon photonics has enabled the development of novel optical devices tailored for high-precision sensing applications. Among these, plasmonic microring resonators are promising devices because of their compactness, high sensitivity, and ability to interact with surface plasmons, which enhances their sensing capabilities. This paper focuses on the design and simulation of a plasmonic microring resonator for temperature sensing applications. The numerical study of plasmonic micro-ring resonator is performed with COMSOL Multiphysics software. The device operates based on the thermo-optic effect, where temperature variations induce changes in the refractive index of the resonator material, leading to measurable shifts in the resonant wavelength. This resulted in a maximum device sensitivity(SD) of 463.23 nm/RIU, and maximum temperature sensitivity(ST) of 90.01 pm/K. This work contributes to the advancement of silicon photonic sensing technology, offering a robust and scalable solution for applications in biomedical diagnostics, environmental monitoring, and industrial sensing. © 2025 IEEE.Item The effect of subsurface barrier on the motion of the sea water - fresh water interface in coastal equifers is analysed for sudden drawdown conditions. A Galerkin finite element model is used for this purpose to carry out the parametric studies on the effect of location, width and hydraulic conductivity of the barrier. The results indicated marked variations in the interface profile as compared to no barrier condition. The width and hydraulic conductivity play a decisive role in delaying the interface response for any drawdown situations. Among the various barrier locations considered, the barrier at Lo was found to be most effective in checking the intrusion.(Effect of subsurface barrier on salt water intrusion) Mahesha, A.; Babu, M.2001Item Parametric studies were carried out to analyse the effect on sea water intrusion of freshwater recharge through a finite width strip parallel to the coast. A vertically integrated one-dimensional finite element model was used for this purpose. The studies included the analysis of the effect of location, width, intensity and the period of recharge on sea water-freshwater interface motion. Relationships were established between the interface motion and the recharge parameters applicable to wide ranging practical cases. From the studies, the ideal location for recharge was identified to achieve the maximum repulsion of intrusion. The width of recharge also affects the interface motion and the widths greater than 2% of the initial intrusion length were effective in controlling the intrusion. The results indicated that the reduction of intrusion up to 30% could be achieved through strip recharge. © 2001 Taylor & Francis Group, LLC.(Effect of strip recharge on sea water intrusion into aquifers; Effet d’une bande de recharge sur l’intrusion d’eau de mer dans les aquifères) Mahesha, A.2001Item Effect of permeability of subsurface barrier on salt water intrusion in coastal aquifers(2006) Mahesha, A.; Lakshmikant, K.Semi-pervious, subsurface barriers are considered to be one of the viable solution for the control of saltwater intrusion in coastal aquifers. Investigations are carried out in this work to assess the performance of the barrier with different permeabilities using a finite element model. The advancement of saltwater - freshwater interface and the water table profiles are monitored for fresh water withdrawals at inland locations under the scenarios of wide ranging hydraulic conductivities of the barrier. The results indicated that barrier is able to check the advancement of the intrusion significantly with the hydraulic conductivity being less than certain limit. The performance of the barrier is also compared with no barrier conditions. Marked variations in the interface and water table profiles are observed as compared to no barrier condition. The performance of the barrier was not found to be satisfactory beyond certain limit of permeability.Item Simulation of varada aquifer system for sustainable groundwater development(2008) Ramesh, H.; Mahesha, A.Groundwater flow modeling has been used extensively worldwide with varying degrees of success. The ability to predict the groundwater flow is critical in planning and implementing groundwater development projects under increasing demand for fresh water resources. This paper presents the simulation of the aquifer system for planning the groundwater development of Varada basin, Karnataka, India using the Galerkin finite-element method. The government of Karnataka State, India is implementing the World Bank assisted project, "Jal Nirmal" for a sustainable development of the region, thereby ensuring a safe supply of drinking water to the northern districts of the state. Varada basin is one of the beneficiaries of the project in Haveri district. Field tests carried out in the study area indicate that the region is predominantly a confined aquifer with transmissivity and storage coefficients ranging from 5.787×10-6m2/s (0.500 m2/day) to 4.213×10-3m2/s (3.640×102m2/day) and 0.011-0.001× 10-2, respectively. This study mainly emphasizes the spatial and temporal variability of groundwater potential under different developmental scenarios. The model predictions were reasonably good with correlation coefficients ranging from 0.78 to 0.91 with the root mean square error of about 0.46-0.78 during calibration and validation. The stated accuracies are based on comparisons between measured and calculated heads. The outcome of the study would be a useful input for the conjunctive use of surface water and groundwater planning for the sustainable development of the region. © 2008 ASCE.Item Conceptual model for the safe withdrawal of freshwater from coastal aquifers(2009) Mahesha, A.The effect of subsurface barrier on the motion of the saltwater-freshwater interface in coastal aquifers is analyzed for wide ranging freshwater pumping scenarios. A Galerkin finite-element model considering sharp interface approach is used for this purpose. A semi-pervious subsurface barrier extending up to impervious bottom of the aquifer is considered at certain distance inland, parallel to the seacoast. The effect of barrier is analyzed in checking the advancement of the saltwater-freshwater interface under different scenarios of freshwater withdrawals at seaward and landward locations of the barrier and compared with nonbarrier conditions. The results indicated that barrier is able to check the advancement of the intrusion significantly and in certain cases, the progress is completely stalled for withdrawals on the landward side. Also, marked variations in the interface profile are observed as compared to no barrier condition, especially, for the seaward freshwater developments. From the model, nearest possible locations from the seacoast have been worked out for the safe withdrawal of freshwater where their effects are negligible on the saltwater advancement. © 2009 ASCE.Item Studies on Uniaxial compressive strength of laterite masonry prisms(2011) Unnikrishnan, S.; Narasimhan, M.C.; Venkataramana, K.Laterite is a well known conventional building material in Asian countries. In spite of its large popularity in construction, a systematic characterization of this material, as a building block, has not been seriously attempted so far. The strength and elastic properties of laterite masonry are influenced by the individual properties of the laterite blocks and the mortar. In the present study, characterization of the laterite block and the mortar and compressive strength of laterite masonry prisms have been investigated using detailed laboratory experiments and numerical analysis. The experimental results, related to the compressive strength and stress-strain characteristics of laterite and mortar and compressive strength of laterite masonry prisms are presented. Finite element analysis of laterite masonry prism has also been carried out. The studies have shown that the modulus of elasticity of laterite blocks tested is less than that of mortar used in making the laterite masonry. Further, the laterite masonry prisms have been observed to have failed by bond failure and subsequent splitting of laterite blocks. Also, increase in thickness of mortar joint gives rise to a decrease in laterite tensile stresses in mortar joint leading to higher prism strengths, if bond remains intact. © 2011 CAFET-INNOVA technical society. All right reserved.Item Full scale experiment and finite element modeling of support structures of substation equipment for evaluation of ground motion amplification(2012) Nandam, S.; Ramesh Babu, R.; Venkataramana, K.Post earthquake performance of porcelain insulators installed for high voltage substation equipment, in general, revealed their vulnerability to failure, not due to any quality deficiency, but due to failure of their supporting structures. Most of the equipment in standalone state, withstood to tests of induced vibrations conforming to International standards. The same tested equipment, when erected in position over its supporting structure failed to sustain earthquake ground accelerations, as the supporting structure adversely contributed to amplification of the ground seismic motions while traversing to the top of the structure or the base of the insulator. This paper critically examines salutary effects of damping of vibrations on a typical instrument- transformer, using a rubber based elastic damper, with particular reference to the connected porcelain insulators, in partial containment of amplification of earthquake acceleration or in minimizing attendant distress on them. The analytical study carried out is based on experimental studies conducted on the equipment using shake table and then correlating the results obtained using finite element analysis, on the full scale model to draw meaningful conclusions. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.Item Studies on the dynamic characteristics of monolithic RC wall panels(2013) Amitha, S.B.; Chethan, K.; Bhavanishankar, S.; Annapurna, B.P.; Venkataramana, K.; Ramesh Babu, R.Monolithically built RC wall panels permits for the industrialized construction of a group of integrated buildings using mechanized, rationalized and mass-production procedure. This is a unique, fast and economical technique. Most of the national and international codes comprise of a brief design procedure of this type of construction. Lot of research is being carried out worldwide about the effect of dynamic loads on these structures. In this paper, FE analysis is done on a designed typical monolithic RC wall panel structure for all zones as per Indian code and the results are compared with different international codal provisions and the formulae presented by Saheb & Desayi and Doh & Fragomeni. This paper consists of background, design and construction of monolithic RC wall panel, FE analysis and comparison of results. © 2013 CAFET-INNOVA TECHNICAL SOCIETY.Item Effects of prestressing the reinforcement on the behavior of reinforced granular beds overlying weak soil(Elsevier Ltd, 2014) Shivashankar, R.; Jayamohan, J.The effects of prestressing the reinforcement on the strength improvement and settlement reduction of a reinforced granular bed overlying weak soil are being investigated through a series of laboratory scale bearing capacity tests. The influences of parameters such as strength of underlying weak soil, thickness of granular bed, magnitude of prestressing force, direction of prestressing forces and number of layers of reinforcement are being examined. Finite element analyses are carried out using the FE program PLAXIS to study the effect of prestressing the reinforcement. Results obtained from finite element analyses are found to be in reasonably good agreement with the experimental results. © 2013 Elsevier Ltd.
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