Faculty Publications
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Publications by NITK Faculty
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Item Design of an automated dispenser unit(IEEE Computer Society help@computer.org, 2014) Anoop Raghav, S.; Ajith, S.R.; Pramod, P.; Ramu, G.; Bhargav, S.D.B.; Sajeesh Kumar, M.P.; Bhat, N.; Ananthasuresh, G.K.This paper presents our work on developing an automated micropositioner and a low cost disposable dispenser module having a disposable dispenser core. The dispenser core is made up of Polydimethylsiloxane (PDMS). Once the user specifies the dispensing location in the Graphical User Interface (GUI), the movement of the micropositioner is automatic. The design, fabrication and characterization results of the dispenser module are also presented. The dispensing experiments are performed with Di-Ethanol Amine as the working reagent. The minimum dispensed volume achieved is about 4 nL. © 2014 IEEE.Item Handheld electrochemical workstation for serum albumin measurement(Institute of Electrical and Electronics Engineers Inc., 2016) Hebbar, S.; Kumar, V.; Bhat, M.S.; Bhat, N.This paper presents a novel handheld electrochemical workstation for serum albumin measurement. The system consists of a multi-path potentiostat module which performs electrochemical measurements on disposable test strip. The strip provides a port for applying blood sample. The test strip consists of 3 electrochemical cells for redundancy and parallel testing. The 3 sets of 3 electrodes (Working, Reference and Counter electrodes) are screen printed on a Polyethylene Terephthalate (PET) substrate. The system provides the unique capability of performing Cyclic Voltammetry and Chrono Amperometry measurements in three parallel paths. The system is very generic and flexible, with user defined inputs for voltage, sweep rate and time through 5 inch capacitive touch screen. The experimental results can be stored on micro SD card and the data is accessible with USB or Bluetooth interface. This paper reports an extensive characterization of system through several tests conducted on standard redox solution. The system is then validated for human serum albumin measurement, using clinical samples. This is the first ever point of care handheld diagnostic device in the world for human serum albumin measurement. © 2016 IEEE.Item Smart handheld platform for electrochemical bio sensors(Institute of Electrical and Electronics Engineers Inc., 2017) Hebbar, S.; Kumar, V.; Bhat, M.S.; Bhat, N.In this paper we present a smart handheld system for point of care biosensors. The system consists of a novel multi-path potentiostat module which performs electrochemical measurements on disposable test strip. The strip provides a port for applying bio-sample such as blood or urine. The analyte port on the disposable strip is designed with 3 sets of 3 electrodes (Working, Reference and Counter electrodes) screen printed on a Polyethylene Terephthlate (PET) substrate. The system provides the unique capability of performing Cyclic Voltametry and Chrono Amperometry measurements in three parallel paths, facilitating simultaneous measurement of three bio-analytes. The system is very generic and flexible, with user defined inputs for voltage, sweep rate and time through 5 inch capacitive touch screen. The experimental results can be stored on micro SD card and the data is accessible with USB or Bluetooth interface. © 2016 IEEE.Item 3d nano capacitors using electrodeposited nickel nanowires in porous anodic alumina template(Springer Science and Business Media, LLC, 2019) Viegas, A.E.; Dutta, S.; Rekha, S.; Bobji, M.S.; Raghavan, S.; Bhat, N.We report the fabrication and characterization of a new design of 3D nano Capacitors using Alumina nanopores as the dielectric material. Nickel nanowires grown inside the nanopores act as high surface area electrodes. These wires are combined together in the form interdigitated capacitor structure, to achieve very high capacitance density. © Springer Nature Switzerland AG 2019.Item Evaluation of ARIMA, Facebook Prophet and a boosting algorithm framework for monthly precipitation prediction of a semi-arid district of north Karnataka, India(Institute of Electrical and Electronics Engineers Inc., 2022) Chowdari, K.K.; Deb Barma, S.D.; Bhat, N.; Girisha, R.; Gouda, K.C.This study evaluates ARIMA, Facebook Prophet and a new boosting algorithm framework known as ThymeBoost for time series prediction of monthly precipitation of Belagavi district (semi-arid) in Karnataka. The dataset was divided into three periods (1901-2002, 1951- 2002, and 1971 - 2002). The first 70% of the data for each period was applied for training while the rest for testing. Also, the datasets were used in two different forms for both training and testing. In the first set, raw data was used as it is, and the second set of data was used after normalizing the time series using the min-max concept (between 0 and 1). However, the normalized data were de-normalized for each period for performance metrics estimation. ThymeBoost is the best model for the first period of raw data and the second period of normalized data. In contrast, Prophet outperforms all other models for the normalized data in terms of all four measures. For the second period of raw data, no model emerged as the best model in terms of all performance metrics. Therefore, all three models performed similarly for the third period of raw and normalized data. © 2022 IEEE.Item Photoresponse of atomically thin MoS2 layers and their planar heterojunctions(Royal Society of Chemistry, 2016) Kallatt, S.; Umesh, G.; Bhat, N.; Majumdar, K.MoS2 monolayers exhibit excellent light absorption and large thermoelectric power, which are, however, accompanied by a very strong exciton binding energy-resulting in complex photoresponse characteristics. We study the electrical response to scanning photo-excitation on MoS2 monolayer (1L) and bilayer (2L) devices, and also on monolayer/bilayer (1L/2L) planar heterojunction and monolayer/few-layer/multi-layer (1L/FL/ML) planar double heterojunction devices to unveil the intrinsic mechanisms responsible for photocurrent generation in these materials and junctions. A strong photoresponse modulation is obtained by scanning the position of the laser spot, as a consequence of controlling the relative dominance of a number of layer dependent properties, including (i) the photoelectric effect (PE), (ii) the photothermoelectric effect (PTE), (iii) the excitonic effect, (iv) hot photo-electron injection from metal, and (v) carrier recombination. The monolayer and bilayer devices show a peak photoresponse when the laser is focused at the source junction, while the peak position shifts to the monolayer/few-layer junction in the heterostructure devices. The photoresponse is found to be dependent on the incoming light polarization when the source junction is illuminated, although the polarization sensitivity drastically reduces at the monolayer/few-layer heterojunction. Finally, we investigate the laser position dependent transient response of the photocurrent to reveal that trapping of carriers in SiO2 at the source junction is a critical factor to determine the transient response in 2D photodetectors, and also show that, by a systematic device design, such trapping can be avoided in the heterojunction devices, resulting in a fast transient response. The insights obtained will play an important role in designing a fast 2D TMD based photodetector and related optoelectronic and thermoelectric devices. © 2016 The Royal Society of Chemistry.Item Optimization of Platinum dioxide properties by plasma oxidation of sputtered PtOx(Elsevier B.V., 2019) Basu, N.; N.s, S.; Mamidala, S.R.; Shenoy, A.; Bhat, N.We have previously used reactively sputtered Platinum oxide thin film as DNA sensing element. In this work, we subject the reactively sputtered Platinum oxide thin films to an additional RIE step for 3, 6 and 9 min and carry out a detailed comparative study of the material and electrical properties of these films. XRD and XPS analysis revealed that when the reactively sputtered Platinum oxide film was subjected to RIE step for longer periods of time, it became progressively ?-PtO2 in nature. Activation energies of 0.24 eV, 0.26 eV, 0.29 eV and 0.31 eV were obtained for the as deposited film and the films subjected to RIE step for 3, 6 and 9 min respectively. The Hall mobility of the as deposited Platinum oxide film was found to be 32.15 cm2V?1s?1 at room temperature. However, when the as deposited film was subjected to RIE step for 9 min the mobility value rises to as high as 136.13 cm2V?1s?1 at room temperature. © 2019 Acta Materialia Inc.Item Surface modification of multi-directional forged biodegradable Mg-Zn alloy by ball burnishing process: Modeling and analysis using deep neural network(Elsevier Ltd, 2021) Ramesh, S.; Anne, G.; Bhat, N.; Aithal, G.; Shivananda Nayaka, H.; Arya, S.This research investigates the feasibility of improving surface integrity of the Mg-2%Zn alloy via a novel combined process of multidirectional forging (MDF) with ball burnishing technique. Mg-2%Zn alloy was subjected to multidirectional forging up to 5 passes at 280 °C and same sample is ball burnished with depth of press of 0.3 mm, feed of 300 mm/min and force of 250 N for 1 pass. Microstructure (optical and transmission electron microscope), phases (X ray diffraction), roughness (atomic force microscope) and mechanical properties (microhardness and tensile) were analyzed for cast, MDF processed and MDF + ball burnished samples. The study also defines a new reliability simulation framework to predict the roughness and hardness of the MDF + ball burnished samples using Deep Neural Network (DNN) approach. For the analysis, depth of press, feed and number of passes served as inputs for the DNN model. After configuring and training procedure of the model, the predicted roughness and microhardness of the MDF + ball burnished were compared with the results of experimental data. A large increase of microhardness was observed for MDF-5 + BB-1 (5 pass MDF processed Mg-2%Zn alloy + Ball burnished sample), found to be 98 Hv and surface roughness of 306 nm was achieved. According to the results, the obtained R-squared value is very close to the 99.5 percentage from the model for predicting roughness and hardness which is a promising result. Corrosion behavior of the AS-1, MDF-5 and MDF-5 + BB-1 was evaluated in Hank's balanced salt solution. Corrosion rate of the MDF-5 + BB-1 samples were found to be 0.87 mm/y which is 7 times better than that of AS-1 samples (6.10 mm/y). Grain refinement and residual stresses were higher in the MDF-5 + BB-1 sample, which helped significantly to enhance corrosion resistance. © 2021 The Society of Manufacturing EngineersItem EVALUATION OF ERA5 AND IMERG PRECIPITATION DATA FOR RISK ASSESSMENT OF WATER CYCLE VARIABLES OF A LARGE RIVER BASIN IN SOUTH ASIA USING SATELLITE DATA AND ARCHIMEDEAN COPULAS(Zibeline International Publishing Sdn. Bhd., 2022) Deb Barma, S.D.; Uttarwar, S.B.; Barane, P.; Bhat, N.; Mahesha, A.Precipitation as a major water cycle variable influences the occurrences and distribution of terrestrial water storage change (TWSC), evapotranspiration (ET), and river discharge (Q) of a large river basin. However, its relationship with the other water cycle variables using probabilistic dependence structure concept has not been addressed much. Furthermore, precipitation derived from gauge record is plagued by bias due to orography and under-catch. To fill these gaps, bivariate copula and precipitation derived from reanalysis and satellite data were used. In the present study, the basin-wide averages of the precipitation products APHRODITE, ERA5, and IMERG were used as predictors, whereas the areal mean of MOD16 evapotranspiration, GRACE TWSC, and gauge discharge were used as dependent variables (predictants) for the Brahmaputra basin. The bivariate Archimedean copulas were applied to all the pairs of precipitation-TWSC, precipitation-ET and precipitation-Q based on the optimal marginal distributions obtained. Using the best copula for each pair of the variables, the conditional probability was constructed to predict the predictants for different precipitation amounts (5th, 25th, 50th, 75th, and 95th percentiles). The focus of the analysis was on two scenarios of the predictants (i.e.,≤ 5th and ≥ 95th percentiles). The non-exceedance conditional distribution of TWSC, ET, and Q (all predictants ≤ 5th percentile) decreases with precipitation increase. However, the exceedance probability of the predictants (≥ 95th percentile) increases gradually with an increase in precipitation. The results revealed that both ERA5 and IMERG precipitation data could be used to derive probabilistic measures of the water cycle variables in the absence of gauge-based precipitation. © 2022 by the authors.Item Trends of seasonal and annual rainfall of semi-arid districts of Karnataka, India: application of innovative trend analysis approach(Springer, 2023) Chowdari, K.; Deb Barma, S.D.; Bhat, N.; Girisha, R.; Gouda, K.C.; Mahesha, A.Trend analysis of rainfall is often carried out in water resources management to understand its distribution over a given region. The cumulative seasonal and annual rainfall derived from monthly datasets spanning 102 years (1901–2002) for 11 districts of the semi-arid Karnataka, India, was used for the trend analysis. The two-step homogeneous test approach was carried out on all the time series. Then, lag-1 autocorrelation was conducted only on homogeneous time series. Only 78.18 % of the total time series data were detected as homogeneous, and 95.35% of time series data were found to have insignificant autocorrelation. Then, the Innovative Trend Analysis (ITA) method was applied to 43 homogeneous rainfall time series, as well as to 41 time series using the MK and SR tests, and to two time series using the mMK test. The MK and SR tests detected a significant trend in 14.63% of the time series, while the ITA method was able to detect a trend in 93.02% of the total time series data. The MK and SR tests revealed significant trends in winter and post-monsoon season precipitation for two districts, but only for one district in the case of summer and annual rainfall. No trend was identified for monsoon season precipitation. The mMK test showed a positive trend for the post-monsoon season in a district, while the ITA method revealed significant trends for all seasons in most districts. The sub-trend analysis revealed trends that traditional methods were unable to detect. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.