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Showing papers by "National Institute of Technology, Karnataka published in 2009"


Journal ArticleDOI
TL;DR: In this article, an implicit pressure-based finite volume method is used for time-accurate computation of incompressible flow using second order accurate convective flux discretisation schemes, which is validated against measurement data for mean surface pressure, skin friction coefficients, the size and strength of the recirculating wake for the steady flow regime and also for the Strouhal frequency of vortex shedding and the mean and RMS amplitude of the fluctuating aerodynamic coefficients for the unsteady periodic flow regime.

326 citations


Journal ArticleDOI
TL;DR: A new class of quinoline derivatives containing 1,2,4-triazole moiety were synthesized from derivatives of 4-hydroxy-8-(trifluoromethyl)quinoline-3-carbohydrazide 4 through multi-step reactions using microwave-induced technique, which has reduced the reaction time drastically as well as improved the yield when compared to conventional heating.

230 citations


Journal ArticleDOI
TL;DR: In the present investigation, a series of new Schiff and Mannich bases synthesized by the aminomethylation of 4-(3-substituted-1H-pyrazol-3-yl)methyleneamino-4H-1,2,4-triazole- 3-thiols were found to exhibit significant antimicrobial activity.

209 citations


Journal ArticleDOI
TL;DR: The pseudo-second-order model was found to explain the kinetics of Cu(2+) adsorption most effectively and is found to be the optimum conditions for the maximum uptake of copper ions in batch mode.

168 citations


Journal ArticleDOI
TL;DR: A new approach is presented for the enhancement of color images using the fuzzy logic technique and is found to be better than the genetic algorithm (GA)-based and entropy-based approaches.
Abstract: A new approach is presented for the enhancement of color images using the fuzzy logic technique. An objective measure called exposure has been defined to provide an estimate of the underexposed and overexposed regions in the image. This measure serves as the dividing line between the underexposed and overexposed regions of the image. The hue, saturation, and intensity (HSV) color space is employed for the process of enhancement, where the hue component is preserved to keep the original color composition intact. A parametric sigmoid function is used for the enhancement of the luminance component of the underexposed image. A power-law operator is used to improve the overexposed region of the image, and the saturation component of HSV is changed through another power-law operator to recover the lost information in the overexposed region. Objective measures like fuzzy contrast and contrast and visual factors are defined to make the operators adaptive to the image characteristics. Entropy and the visual factors are involved in the objective function, which is optimized using the bacterial foraging algorithm to learn the parameters. Gaussian and triangular membership functions (MFs) are chosen for the underexposed and overexposed regions of the image, respectively. Separate MFs and operators for the two regions make the approach universal to all types of contrast degradations. This approach is applicable to a degraded image of mixed type. On comparison, this approach is found to be better than the genetic algorithm (GA)-based and entropy-based approaches.

168 citations


Journal ArticleDOI
TL;DR: In this article, a study has been carried out with a view to calculate the coastal vulnerability index (CVI) to know the high and low vulnerable areas and area of inundation due to future accelerated sea level rise (SLR), and land loss due to coastal erosion.

136 citations


Journal ArticleDOI
TL;DR: In this article, the effect of surface roughness on spreading of vegetable oils on stainless steel substrates was investigated and the results showed that low viscosity liquids exhibit improved wetting characteristics during spreading on rough surfaces.

96 citations


Journal ArticleDOI
TL;DR: In this article, an extensive laboratory testing program was carried out to determine the properties of clean and contaminated lateritic soils using laboratory prepared municipal solid waste leachate was used in this study.

76 citations


Journal ArticleDOI
TL;DR: The newly synthesized compounds have been characterized by FTIR, (1)H NMR, (13)C NMR and mass spectral data, followed by elemental analysis, and exhibited promising results.

73 citations


Journal ArticleDOI
TL;DR: In this article, the third-order nonlinear optical properties of chalcone derivative doped PMMA films were analyzed using nanosecond Z-scan at 532 nm and the observed nonlinear parameters were comparable with stilbazolieum derivatives for photonics and biophotonics applications.

69 citations


Journal ArticleDOI
TL;DR: In this paper, a study on Taguchi's optimization methodology, which is applied to optimize cutting parameters in turning of age hardened Al6061-15% vol. SiC 25 µm particle size metal matrix composites with Cubic boron nitride inserts (CBN KB-90 grade using steam as cutting fluid, is presented.
Abstract: This paper presents the study on Taguchi's optimization methodology, which is applied to optimize cutting parameters in turning of age hardened Al6061-15% vol. SiC 25 µm particle size metal matrix composites with Cubic boron nitride inserts (CBN) KB-90 grade using steam as cutting fluid. Analysis of variance (ANOVA) is used to study the effect of process parameters on the machining process. This procedure eliminates the need for repeated experiments, time and conserves the material by the conventional procedure. The turning parameters evaluated are speed, feed, depth of cut, nozzle diameter and steam pressure. A series of experiments are conducted using PSG A141 lathe (2.2 KW) to relate the cutting parameters on surface roughness, tool wear, cutting force, feed force, and thrust force. The measured results were collected and analyzed with the help of the commercial software package MINITAB15. As well, an orthogonal array, signal-to-noise ratio is employed to analyze the influence of these parameters. The method could be useful in predicting surface roughness, tool wear, cutting force, feed force and thrust force as a function of cutting parameters. From the analysis using Taguchi's method, results indicate that among the all-significant parameters, steam pressure is the most significant parameter.

Journal ArticleDOI
TL;DR: The anticonvulsant activity of the title compounds was established after intraperitoneal administration in three seizure models, which include maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and 6 Hz screens and their neurotoxicity was also evaluated.

Journal ArticleDOI
TL;DR: In this article, an attempt has been made to experimentally investigate the estimation of rock properties like compressive strength and abrasivity using sound levels produced during drilling using small portable pneumatic drilling equipment used in hard rock drilling.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the third-order nonlinear optical properties of two polythiophene composite films investigated using the Z-scan technique and found that the composite films exhibit self-defocusing nonlinearity.
Abstract: We report here the studies on third-order nonlinear optical properties of two novel polythiophene composite films investigated using the Z-scan technique. The measurements were carried out using a Q-switched, frequency doubled Nd:YAG laser producing 7 nanosecond laser pulses at 532 nm. Z-scan results reveal that the composite films exhibit self-defocusing nonlinearity. The real and imaginary parts of the third-order nonlinear optical susceptibility were of the order 10−12 esu. The effective excited-state absorption cross section was found to be larger than the ground state absorption cross section, indicating that the operating nonlinear mechanism is reverse saturable absorption (RSA). The polythiophene composite films also exhibit good optical power limiting of the nanosecond laser pulses. The nonlinear optical parameters are found to increase on increasing the strength of the electron-donor group, indicating the dependence of χ (3) on the electron-donor/acceptor units of polythiophenes.

Journal ArticleDOI
TL;DR: In this article, the strength deformation behavior of circular steel tubes filled with different grades of concrete under flexure was examined, and the effects of steel tube thickness, the cross sectional area of concrete, strength of in-filled concrete and the confinement of concrete on moment capacity and curvature of CFTs were examined.

Journal ArticleDOI
TL;DR: In this paper, a polymer blend electrolyte based on poly vinyl alcohol and poly styrene sulphonic acid has been studied as an electrolyte for supercapcitors, and a carbon-carbon supercapacitor has been fabricated using this electrolyte and its electrochemical characteristics and performance have been studied.
Abstract: A new polymer blend electrolyte based on poly vinyl alcohol and poly styrene sulphonic acid has been studied as an electrolyte for supercapcitors. A carbon–carbon supercapacitor has been fabricated using this electrolyte and its electrochemical characteristics and performance have been studied. The conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. The real and imaginary parts of the electrical modulus of samples show a long tail feature, which can be attributed to high capacitance of the material. The super capacitor showed a fairly good specific capacitance of 40 F g - 1 and a time constant of 5 s.

Journal ArticleDOI
TL;DR: In this article, five mononuclear nickel(II) complexes were synthesized and characterized by means of elemental analysis, electronic, IR, 1H, 13C and 31P NMR spectroscopy.

Journal ArticleDOI
TL;DR: In this paper, a new way of characterizing solid-liquid suspensions and liquid phase mixing using nonintrusive wall pressure fluctuation measurements has been developed, and the results and discussion presented here will have useful implications.
Abstract: Stirred tanks are widely used in chemical process industries for catalytic reactions, dissolution of solids, crystallization, and so on. In designing and optimizing such processes, suspension quality of slurry is an important parameter. Suspension quality depends upon complex interactions of impeller generated flow, turbulence, and solid loading. Most of the earlier work on solid suspension focuses on identifying critical impeller speed for just suspension of solids (Njs). In this study, apart from Njs, aspects like cloud height and liquid phase mixing in solid−liquid suspensions were also studied. A new way of characterizing solid−liquid suspensions and liquid phase mixing using nonintrusive wall pressure fluctuation measurements has been developed. Systematic experimental data on Njs, cloud height, power consumption, mixing time, and circulation time over a range of solid volume fraction and impeller speeds have been presented here. The results and discussion presented here will have useful implications...

Journal ArticleDOI
TL;DR: In this paper, a corrosion inhibitor for mild steel in HCl and H2SO4 solutions using weight loss method, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization method was presented.

Journal ArticleDOI
TL;DR: A computer-based intelligent system for the identification of clinically significant maculopathy, non-clinically significant Maculopathy and normal fundus eye images using feed-forward architecture in an artificial neural network classifier for classification of different stages.
Abstract: Diabetes mellitus is a major cause of visual impairment and blindness. Twenty years after the onset of diabetes, almost all patients with type 1 diabetes and over 60% of patients with type 2 diabetes will have some degree of retinopathy. Prolonged diabetes retinopathy leads to maculopathy, which impairs the normal vision depending on the severity of damage of the macula. This paper presents a computer-based intelligent system for the identification of clinically significant maculopathy, non-clinically significant maculopathy and normal fundus eye images. Features are extracted from these raw fundus images which are then fed to the classifier. Our protocol uses feed-forward architecture in an artificial neural network classifier for classification of different stages. Three different kinds of eye disease conditions were tested in 350 subjects. We demonstrated a sensitivity of more than 95% for these classifiers with a specificity of 100%, and results are very promising. Our systems are ready to run clinically on large amounts of datasets.

Journal ArticleDOI
TL;DR: In this article, the corrosion behavior of composition modulated alloy (CMA) electrodeposits of Zn-Co was evaluated as a function of the switched cathode current densities and the number of layers.
Abstract: Composition modulated alloy (CMA) electrodeposits of Zn–Co were produced from acid chloride baths by the single-bath technique. Their corrosion behavior was evaluated as a function of the switched cathode current densities and the number of layers. The process was optimized with respect to the highest corrosion resistance. Enhanced corrosion resistance was obtained when the outer layer was slightly richer with cobalt. At the optimum switched current densities 40/55 mA cm−2, a coating with 600 layers showed ~6 times higher corrosion resistance than monolithic Zn–Co electrodeposit having the same thickness. The CMA coating exhibited red rust only after 1,130 h in a salt-spray test. The increased corrosion resistance of the multilayer alloys was related to their inherent barrier properties, as revealed by Electrochemical Impedance Spectroscopy. The corrosion resistance was explained in terms of n-type semiconductor films at the interface as supported by Mott–Schottky plots.

Journal ArticleDOI
TL;DR: In this article, an investigation was carried out to examine the influence of austempering temperature on microstructural parameters and the wear behaviour of ductile iron, and the results showed that the wear rate was dependent on the yield strength, austenite content and its carbon content.
Abstract: An investigation was carried out to examine the influence of austempering temperature on microstructural parameters and the wear behaviour of austempered ductile iron. Ductile iron was austenitised at 900 °C for 30 min and austempered for 2 h at 260, 280, 300, 320, 350, 380 and 400 °C. Resulting microstructures were characterised through optical microscopy and X-ray diffraction. Wear test was carried out using a pin-on-disc machine with sliding speed of 289 m min−1. Coarse ausferrite microstructure exhibited higher wear rate than fine ausferrite microstructure. At high austempering temperature large amounts of austenite was instrumental in improving the wear resistance through formation of deformation induced martensite. Study of the wear surface under scanning electron microscope showed that, under dry sliding condition, wear occurred mainly due to adhesion and delamination. Wear rate was found to be dependent on the yield strength, austenite content and its carbon content.

Journal ArticleDOI
TL;DR: In this article, the adsorption of phenol on granular activated carbon (GAC) from nutrient medium suitable for roorganisms’ growth and also the subsequent biodegradation were studied using two parameter Langmuir and Freundlich isotherm models.
Abstract: This paper presents the adsorption of phenol on granular activated carbon (GAC) from nutrient medium suitable for roorganisms’ growth and also the subsequent biodegradation. Two parameter Langmuir and Freundlich adsorption isotherm models were studied using large range of phenol concentration (50-1000 mg/L). In low range of phenol concentration (50-300 mg/L), correlation coefficient, normalized deviation “g% and separation factor were 0.9989, 2.18% and 0.38- 0.78 respectively, while for higher concentration range (400-1000 mg/L), the corresponding values were 0.9719, 1.9% and 0.45- 0.67. Freundlich isotherm gave correlation coefficient of 0.9984, 1/n. value of 0.7269 and normalized deviation of 4.55%. Comparison based on R2, adjusted R2, normalized deviation and root mean square deviation (RMSD) showed that the Redke-Prausnitz isotherm model gives better prediction compared to other models. Adsorption of phenol follows pseudo second order kinetics with correlation coefficient closer to one. Biodegradation study using immobilized cells of Nocardia hydrocarbonoxydans on GAC showed that, biodegradation begins well before GAC reaches the saturation period.

Journal ArticleDOI
TL;DR: In this article, the binodal curve was fitted to an empirical equation relating the concentrations of PEG 6000 and triammonium citrate, and the coefficients were estimated for the respective temperatures.
Abstract: Liquid−liquid equilibrium for an aqueous two-phase system containing poly(ethylene glycol) 6000 + triammonium citrate + water was studied at five different temperatures, (25, 30, 35, 40, and 45) °C. The binodal curve was fitted to an empirical equation relating the concentrations of PEG 6000 and triammonium citrate, and the coefficients were estimated for the respective temperatures. The effective excluded volume values were obtained from the binodal data. Tie line compositions were estimated and correlated using Othmer−Tobias and Bancroft equations, and the parameters are reported.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the results of physical model studies conducted in a monochromatic wave flume, to evaluate the wave transmission characteristics of a submerged plate breakwater.

Journal ArticleDOI
11 Aug 2009-Vacuum
TL;DR: In this paper, the effect of substrate temperature on the structural, optical and electrical properties of vacuum-deposition zinc telluride (ZnTe) thin films was investigated.

Journal ArticleDOI
TL;DR: In this paper, the effect of various binders on the performance and durability of porous friction course (PFC) mixes was investigated for three different aggregate gradations at two predetermined binder contents.

Journal ArticleDOI
TL;DR: In this article, the use of portable falling weight deflectometers (PFWDs) has gained popularity in recent years, mainly because of the inherent capability of PFWDs in obtaining quick estimates of the modulus of subgrade in addition to their simplicity in design and portability.
Abstract: The evaluation of subgrade strength plays a major role in pavement design. An understanding of subgrade properties enables the selection of road materials for sub-base and base courses. In developing countries like India, apart from the use of well-established traditional pavement evaluation techniques such as the California bearing ratio (CBR) test and the dynamic cone penetrometer (DCP) test, the use of non-destructive testing devices such as the portable falling weight deflectometers (PFWDs) has gained popularity in recent years. This is mainly because of the inherent capability of PFWDs in obtaining quick estimates of the modulus of subgrade in addition to their simplicity in design and portability. Thus, there exists a need to correlate the results obtained using PFWDs with those obtained using traditional approaches such as the CBR and the DCP for the benefit of road engineers. This work focuses on exploring the correlations between these approaches for lateritic soils in Dakshina Kannada district, ...

Journal ArticleDOI
TL;DR: Simulations show that an infinite dilution solution assumption to calculate the saturation equilibrium over droplet could induce errors in estimating particle growth, which is significant in the case of particles of size greater than 1 μm and at number concentrations higher than 105/cm3.
Abstract: In the nearly saturated human respiratory tract, the presence of water-soluble substances in the inhaled aerosols can cause change in the size distribution of the particles. This consequently alters the lung deposition profiles of the inhaled airborne particles. Similarly, the presence of high concentration of hygroscopic aerosols also affects the water vapor and temperature profiles in the respiratory tract. A model is presented to analyze these effects in human respiratory system. The model solves simultaneously the heat and mass transfer equations to determine the size evolution of respirable particles and gas-phase properties within human respiratory tract. First, the model predictions for nonhygroscopic aerosols are compared with experimental results. The model results are compared with experimental results of sodium chloride particles. The model reproduces the major features of the experimental data. The water vapor profile is significantly modified only when a high concentration of particles is present. The model is used to study the effect of equilibrium assumptions on particle deposition. Simulations show that an infinite dilution solution assumption to calculate the saturation equilibrium over droplet could induce errors in estimating particle growth. This error is significant in the case of particles of size greater than 1 mum and at number concentrations higher than 10(5)/cm(3).

Journal ArticleDOI
TL;DR: In this paper, the second-order Boltzmann equation method (LBM) with multiple relaxation time (MRT) model is applied to investigate lid-driven flow in a 3D, rectangular cavity, and compare the results with flow in an equivalent two-dimensional (2D) cavity.
Abstract: Purpose - The purpose of this paper is to apply lattice Boltzmann equation method (LBM) with multiple relaxation time (MRT) model, to investigate lid-driven flow in a three-dimensional (3D), rectangular cavity, and compare the results with flow in an equivalent two-dimensional (2D) cavity. Design/methodology/approach - The second-order MRT model is implemented in a 3D LBM code. The flow structure in cavities of different aspect ratios (0.25-4) and Reynolds numbers (0.01-1000) is investigated. The LBM simulation results are compared with those from numerical solution of Navier-Stokes (NS) equations and with available experimental data. Findings - The 3D simulations demonstrate that 2D models may predict the flow structure reasonably well at low Reynolds numbers, but significant differences with experimental data appear at high Reynolds numbers. Such discrepancy between 2D and 3D results are attributed to the effect of boundary layers near the side-walls in transverse direction (in 3D), due to which the vorticity in the core-region is weakened in general. Secondly, owing to the vortex stretching effect present in 3D flow, the vorticity in the transverse plane intensifies whereas that in the lateral plane decays, with increase in Reynolds number. However, on the symmetry-plane, the flow structure variation with respect to cavity aspect ratio is found to be qualitatively consistent with results of 2D simulations. Secondary flow vortices whose axis is in the direction of the lid-motion are observed; these are weak at low. Reynolds numbers, but become quite strong at high Reynolds numbers. Originality/value - The findings will be useful in the study of variety of enclosed fluid flows.