Faculty Publications
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Publications by NITK Faculty
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Item Generation of monodisperse aerosols through condensation nuclei control(WITPress marketing@witpress.com, 2007) Kadlimatti, H.M.; Gangamma, S.; Varghese, S.K.A device for the generation of monodisperse aerosols through condensation nuclei control has been designed and tested in the present study. A continuous flow, evaporation-condensation aerosol generator has been designed to produce monodisperse aerosols of low vapor pressure organic liquids, such as dioctyl phthalate (DOP), at flow rates over 2.5 1pm. Nebulised NaCl particles are passed through the particle number controller to reduce the number concentration close to 105/cc to suppress homogeneous condensation. The condensation nuclei with nitrogen as a carrier gas are passed through a bubbler containing DOP, producing a nuclei-vapor mixture. The mixture is condensed producing the aerosols of narrow size distribution. A heater section previous to the condenser section provides complete evaporation across the tube diameter, while the condenser walls in free convection create a low temperature gradient, both of which enhance aerosol monodispersity. The results show that controlling the nuclei number concentration as well as vapor source can produce aerosols with sufficient monodispersity. © 2007 WIT Press.Item Developing regression models for predicting pan evaporation from climatic data - A comparison of multiple least-squares, principal components, and partial least-squares approaches(2007) Kovoor, G.M.; Nandagiri, L.Regression models for predicting daily pan evaporation depths from climatic data were developed using three multivariate approaches: multiple least-squares regression (MLR), principal components regression (PCR), and partial least-squares (PLS) regression. The objective was to compare the prediction accuracies of regression models developed by these three approaches using historical climatic datasets of four Indian sites that are located in distinctly different climatic regimes. In all cases (three approaches applied to four climatic datasets), regression models were developed using a part of the data and subsequently validated with the remaining data. Results indicated that although performances of the regression models varied from one climate to another, more or less similar prediction accuracies were obtained by all three approaches, and it was difficult to identify the best approach based on performance statistics. However, the final forms of the regression models developed by the three approaches differed substantially from one another. In all cases, the models derived using PLS contained the smallest number of predictor variables; between two to three out of a possible maximum of six predictor variables. The MLR approach yielded models with three to six predictor variables, and PCR models included all six predictor variables. This implies that the PLS regression models are the most parsimonious in terms of input data required for estimating epan from climate variables, and yet yield predictions that are almost as accurate as the more data-intensive MLR and PCR models. © 2007 ASCE.Item Dual colorimetric receptor with logic gate operations: Anion induced solvatochromism(Royal Society of Chemistry, 2014) Kigga, M.; Swathi, N.; Manjunatha, J.R.; Das, U.K.; Nityananda Shetty, A.N.; Trivedi, D.R.A receptor R1 was designed and synthesised for colorimetric detection of F- ions as well as Cu2+ ions via intramolecular charge transfer mechanism. Upon addition of F- ions in dry DMSO, the color of the receptor R1 changed from pale yellow to blue. The receptor showed a unique property of solvatochromism by displaying different coloration with different solvents only in the presence of F- ions, which were applied to determine the percentage composition of binary solvent mixtures. The receptor R1 was able to detect Cu2+ ions colorimetrically where it exhibited a color change from pale yellow to orange-red. In addition, the receptor was subjected to molecular logic gate applications, wherein it showed 'ON-OFF' switching operations. © 2014 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Prediction of daily pan evaporation using support vector machines(CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2014) Pammar, L.; Deka, P.C.Water scarcity globally has lead to severe problems in water management. Understanding the rate of evaporation, from surface water resources is essential for precise management of the water balance. However, evaporation is difficult to measure experimentally due to its nature. Preparing reliable forecasts of evaporation has become an essential element towards efficient water management. The objective of this paper is to predict daily pan evaporation using different kernel functions of Support Vector Machines (SVM's) based regression approach for the meteorological data obtained for the region 'Lake Abaya' which is located in the Great Rift Valley, southern part of Ethiopia. The meteorological parameters considered for study includes daily details of mean-temperature (T), wind speed (W), sunshine hours (Sh), relative humidity (Rh), rainfall (P). Among the kernel functions used for study, the polynomial kernel function proved its credibility by showing improved performance in training and testing periods. The evidence for performance of polynomial kernel function was seen in terms of correlation coefficient (CC) obtained for training and testing is respectively 0.940, 0.956 which is acceptable. © 2014 CAFET-INNOVA TECHNICAL SOCIETY.Item Pharmaceutical Co-Crystal of Flufenamic Acid: Synthesis and Characterization of Two Novel Drug-Drug Co-Crystal(Elsevier B.V., 2017) Nechipadappu, S.K.; Tekuri, V.; Trivedi, D.R.Two novel pharmaceutical co-crystals of anti-inflammatory drug flufenamic acid (FFA) with 2-chloro-4-nitrobenzoic acid (CNB) and ethenzamide (ETZ) have been synthesized by solvent evaporation method as well as by solvent drop-assisted grinding method. The synthesized co-crystals were characterized thoroughly by various spectroscopic methods and crystal structures were determined by single-crystal x-ray diffraction technique. In FFA-CNB co-crystal, robust supramolecular acid-acid homosynthon was observed. FFA-ETZ co-crystal is formed via robust supramolecular acid-amide heterosynthon. In FTIR spectra, a significant shift in the carbonyl stretching frequency was observed for the co-crystals due to the presence of intermolecular hydrogen bond. 1H nuclear magnetic resonance study suggests the presence of hydrogen bond in the solution state of FFA-ETZ co-crystal; however, it was absent for FFA-CNB co-crystal. Solubility study in Millipore water revealed that the solubility of FFA is increased by 2-fold when it is in the form of FFA-CNB co-crystal and no increment in the solubility of FFA was observed in FFA-ETZ co-crystal. About 5-fold increment in the solubility of FFA was observed in both the co-crystals in 0.1 N HCl (pH 1) solution. The synthesized co-crystals were found to be non-hygroscopic at ?75% relative humidity and stable for a period of 6 months at ambient temperature (?25°C). © 2017 American Pharmacists Association®Item Daily pan evaporation modeling in climatically contrasting zones with hybridization of wavelet transform and support vector machines(Springer Verlag service@springer.de, 2017) Pammar, L.; Deka, P.C.The estimation of evaporation has been under surveillance, which is being carried out by many researchers toward applications in the fields related to hydrology and water resources management. Due to complexities associated with its estimation, research has employed several modes via direct and indirect methods to estimate. Accurate estimations are still the thrust area of research in these fields. The pan evaporation estimations with the help of data modeling techniques have provided better results in the recent past. The advancement in the field of data modeling has introduced several techniques which can best fit the data type and provide accurate estimations. The novel gamma test (GT) was used to decide the best input–output combination. Parameter optimization was carried out by grid search. The developed models gave better estimations of pan evaporation, but exhibited some limitations with nonlinearity, and sparse and noisy data. These limitations paved way for data pre-processing techniques such as wavelet transform. This study made an attempt to explore hybrid modeling using discrete wavelet transform (DWT) and support vector machines (SVR) for pan evaporation estimation. Two stations representing contrasting climatic zones namely ‘Bajpe’ and ‘Bangalore’ located in the state of Karnataka, India, are selected in this study. The meteorological datasets recorded at these stations are analyzed using gamma test and grid search to use the best input–output combinations for the models. The modeled pan evaporation estimations are very promising toward ever demanding accuracy expected in the associated fields. © 2017, The International Society of Paddy and Water Environment Engineering and Springer Japan.Item Computational investigation of air solid flow in a spray dryer for effluent treatment(Scientific Publishers, 2020) Singh, S.K.; Ali, B.In this work, the hydrodynamics and evaporation rate of the co-current spray dryer is numerically investigated through ANSYS Fluent (CFD). The performance of the spray dryer depends on the geometry, operating conditions, and underlying hydrodynamics in such systems. To predict the air-solid flow in a spray dryer, the Euler-Lagrangian CFD model is used to track the particles in the dryer. The continuous phase turbulence is predicted using RNG version of k-turbulence model. To quantify the flow pattern, a horizontal line is considered and spatial variation of velocity profiles are analyzed. The predicted air velocity variation was found to be maximum at the center of the core. Further, the airflow pattern is analyzed for various operating temperatures and feed properties. It was found that airflow pattern influences particle behavior with minimum deposition rates on each section of the wall when air temperature is 350 K. © 2020 Scientific Publishers. All rights reserved.Item Polymer-based immobilized Fe2O3–TiO2/PVP catalyst preparation method and the degradation of triclosan in treated greywater effluent by solar photocatalysis(Academic Press, 2021) Pragada, S.C.; Thalla, A.K.The present study involves a novel protocol to develop a ternary composite catalyst for an effective post-treatment technique for greywater. The ternary film of Fe2O3–TiO2/polyvinyl pyrrolidine (PVP) is coated on a glass tube using spray coating with annealing at 320 °C. The structure, thermal, microstructure, and surface properties of the coated film are characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Thermo Gravimetric Analysis (TGA). The scratch hardness of photocatalysts at different Fe2O3/TiO2 compositions is investigated based on the width measurement of scratch using FESEM analysis. Results show that at an optimum coating of 5% of Fe2O3/TiO2 composition catalytic film, the maximum scratch hardness (7.984 GPa) is obtained. Also, the photocatalyst has the highest cohesive bond strength and wearing resistance. The degradation of triclosan (TCS) in treated greywater, discharged from the anaerobic-aerobic treatment system, is investigated at a lab-scale using a solar photocatalytic reactor. The response surface analysis has been performed from the different sets of experimental trials for various optimal parameters. It is observed that the TCS degradation efficiency of 83.27% has resulted under optimum conditions. © 2021 Elsevier LtdItem Effect of fuel preheating on performance, emission and combustion characteristics of a diesel engine fuelled with Vateria indica methyl ester blends at various loads(Academic Press, 2022) Kodate, S.V.; Raju, P.S.; Yadav, A.K.; Kumar, G.N.The present study examines the preheated (95 °C) and unheated (35 °C) Vateria indica methyl ester (VIME) blends by studying the engine performance, combustion, and emission characteristics at various loads. A single-cylinder, TV1 Kirloskar direct injection diesel engine is used to carry out the tests. Biodiesel produced from Dhupa fat through the transesterification process is used as a renewable fuel in a diesel engine. In this work, diesel (B0), VIME (B100), and two binary blends (B30 and B50) are used. VIME has a higher viscosity, higher density, and lower calorific value than diesel, resulting in lesser brake thermal efficiency (BTE) and higher brake specific energy consumption (BSEC). Due to high viscosity of the biodiesel, preheating of fuel is done before injecting into cylinder. Preheating reduces the viscosity, and enhances the atomization and vaporization of fuel, resulting in improved engine performance. For a given blend of VIME biodiesel and diesel, the preheated blend has better BTE, decreased BSEC and lesser CO and HC emissions, with a slight increment in NOX emission compared to the unheated blend. The preheated B30 blend has a BTE value of 30.3% which is close to the BTE value of 30.1% of unheated diesel at 100% load condition. CO, HC, and soot emissions are decreased by 16.2%, 34.4%, and 16.5%, respectively, for preheated B100 fuel compared to unheated B100, at full load. © 2021 Elsevier LtdItem ZnSxSe1−x thin films: A study into its tunable energy band gap property using an experimental and theoretical approach(Elsevier Ltd, 2022) Ray, S.; Barman, B.; Darshan, C.; Tarafder, K.; Bangera, K.V.In recent times, ZnS and ZnSe thin films are drawing tremendous attention towards opto-electrical devices due to their optimal wide band gap energy. By alloying ZnS and ZnSe films to obtain ZnSxSe1−x thin films, the band gap of the ZnSxSe1−x film can be tuned to a value according to the device requirements. Herein, ZnSxSe1−x thin films were deposited on pre-cleaned glass substrates using a thermal evaporation system and the various properties of the obtained thin films were analyzed by altering the percentage of sulfur concentration in the films. The XRD analysis illustrated that the prepared films are polycrystalline in nature and oriented along cubic (1 1 1) plane. The deviation of (1 1 1) preferential peak position with composition ‘x’ along the absence of any secondary peaks confirms the formation of ternary ZnSxSe1−x thin films. DFT analysis verifies the formation of pristine ZnSxSe1−x alloy system. FESEM micrographs displayed that the ZnSxSe1−x thin films do not have any cracks or pinholes. EDAX analysis of the films revealed the existence of Zn, Se and S in an appropriate quantity. Optical analysis revealed the effective band gap tailoring of ZnSxSe1−x thin films. The band gap of the ZnSxSe1−x thin films increases from 2.59 eV to 3.38 eV as the composition ‘x’ varied from 0 to 1 and band composition was determined using the DOS plot obtained using VASP. © 2022 International Solar Energy Society