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Item Comparative study on kevlar/carbon epoxy face sheets with rubber core sandwich composite for low velocity impact response: FE approach(Elsevier Ltd, 2021) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.Recent trend has shifted towards replacing the conventional materials by fiber reinforced polymer composites for various structural applications since the fiber reinforced polymer composites exhibit high strength, lighter weight and low cost. This paper work concentrates on analysing the low velocity impact response of two types of sandwich composites namely kevlar epoxy with rubber core (KE-R-KE) and carbon epoxy with rubber core (CE-R-CE) in terms of energy absorption and damage mitigation. Modelling and analysis is carried out by making use of commercially available explicit finite element (FE) software. Results reveal that kevlar based sandwich composite outstands the carbon based composite both in terms of energy absorption by 37.7% and the energy absorption ratio of KE-R-KE is 1.36 times more compared to CE-R-CE sandwich composite. The damage study reveals that both the proposed sandwich composites exhibit similar damage mechanism dominated by matrix cracking followed by fiber breakage and delamination. The presence of rubber as core material helps in mitigating the damage to the bottom facesheet. © 2021 Elsevier Ltd. All rights reserved.Item Natural and anthropogenic factors controlling the dissolved organic carbon concentrations and fluxes in a large tropical river, India(2006) Balakrishna, K.; Kumar, I.A.; Srinikethan, G.; Mugeraya, G.Carbon studies in tropical rivers have gained significance since it was realized that a significant chunk of anthropogenic CO2 emitted into the atmosphere returns to the biosphere, that is eventually transported by the river and locked up in coastal sediments for a few thousand years. Carbon studies are also significant because dissolved organic carbon (DOC) is known to complex the toxic trace metals in the river and carry them in the dissolved form. For the first time, this work has made an attempt to study the variations in DOC concentrations in space and time for a period of 19 months, and estimate their fluxes in the largest peninsular Indian river, the Godavari at Rajahmundry. Anthropogenic influence on DOC concentrations possibly from the number of bathing ghats along the banks and domestic sewage discharge into the river are evident during the pre-monsoon of 2004 and 2005. The rise in DOC concentrations at the onset of monsoon could be due to the contributions from flood plains and soils from the river catchment. Spatial variations highlighted that the DOC concentrations in the river are affected more by the anthropogenic discharges in the downstream than in the upstream. The discharge weighted DOC concentrations in the Godavari river is 3-12 times lower than Ganga-Brahmaputra, Indus and major Chinese rivers. The total carbon fluxes from the Godavari into the Bay of Bengal is insignificant (0.5%) compared to the total carbon discharges by major rivers of the world into oceans. © Springer Science+Business Media, Inc. 2006.Item Studies on the removal of Pb(II) from wastewater by activated carbon developed from Tamarind wood activated with sulphuric acid(2008) Singh, C.K.; Sahu, J.N.; Mahalik, K.K.; Mohanty, C.R.; Mohan, B.R.; Meikap, B.C.The low-cost activated carbon were prepared from Tamarind wood material by chemical activation with sulphuric acid for the adsorption of Pb(II) from dilute aqueous solution. The activated carbon developed shows substantial capacity to adsorb Pb(II) from dilute aqueous solutions. The parameters studied include physical and chemical properties of adsorbent, pH, adsorbent dose, contact time and initial concentrations. The kinetic data were best fitted to the Lagergren pseudo-first-order and pseudo-second order models. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The maximum removal of lead(II) was obtained 97.95% (experimental) and 134.22 mg/g (from Langmuir isotherm model) at initial concentration 40 mg/l, adsorbent dose 3 g/l and pH 6.5. This high uptake showed Tamarind wood activated carbon as among the best adsorbents for Pb(II). © 2007 Elsevier B.V. All rights reserved.Item Optimization of culture medium for novel cell-associated tannase production from bacillus massiliensis using response surface methodology(2012) Belur, P.D.; Goud, R.; Goudar, D.C.Naturally immobilized tannase (tannin acyl hydrolase, E.C. 3.1.1.20) has many advantages, as it avoids the expensive and laborious operation of isolation, purification, and immobilization, plus it is highly stable in adverse pH and temperature. However, in the case of cell-associated enzymes, since the enzyme is associated with the biomass, separation of the pure biomass is necessary. However, tannic acid, a known inducer of tannase, forms insoluble complexes with media proteins, making it difficult to separate pure biomass. Therefore, this study optimizes the production of cell-associated tannase using a "protein-tannin complex" free media. An exploratory study was first conducted in shake-flasks to select the inducer, carbon source, and nitrogen sources. As a result it was found that gallic acid induces tannase synthesis, a tryptose broth gives higher biomass, and lactose supplementation is beneficial. The medium was then optimized using response surface methodology based on the full factorial central composite design in a 3 l bioreactor. A 2 3 factorial design augmented by 7 axial points (? = 1.682) and 2 replicates at the center point was implemented in 17 experiments. A mathematical model was also developed to show the effect of each medium component and their interactions on the production of cell-associated tannase. The validity of the proposed model was verified, and the optimized medium was shown to produce maximum cell-associated tannase activity of 9.65 U/l, which is 93.8% higher than the activity in the basal medium, after 12 h at pH 5.0, 30°C. The optimum medium consists of 38 g/l lactose, 50 g/l tryptose, and 2.8 g/l gallic acid. © The Korean Society for Microbiology and Biotexhnology.Item Behavior of Alloying Elements during Electro-Slag Remelting of Ultrahigh Strength Steel(2012) Bandyopadhyay, T.R.; Rao, P.K; Prabhu, N.The paper deals with the behavior of principal constituents of an ultrahigh strength steels during ESR. The multiple analyses show no significant variation in the concentrations of silicon, manganese, vanadium, molybdenum, sulphur and phosphorus while concentrations of carbon, chromium, aluminium and titanium in the ESR ingot are found to be within the range of ± 0.01, ± 0.12, ± 0.008 and ± 0.01% respectively. Silicon and manganese show a loss of 0- 55 and 2-13% respectively whereas the degree of desulphurization is in the range of 0 (in Ar shield) to 52 (in air). The lower carbon and chromium content of the electrode than the aimed value can be corrected by adding ferrochromium in-situ during ESR. The recovery of carbon from FeCr was nearly 100% in most of the melts while the recovery of chromium varied over a fairly wide range. The distributions of carbon and chromium are also uniform along the height and width of ESR ingots. The recovery of the inoculant titanium was relatively low at the bottom of the ingot and it increases with height and reached a constant value above 100-150 mm height. For the same addition of titanium, its recovery decreases during ESR with argon shielding. © Metallurgical and Mining Industry.Item LiClO4-doped plasticized chitosan and poly(ethylene glycol) blend as biodegradable polymer electrolyte for supercapacitors(Institute for Ionics, 2013) Sudhakar, Y.N.; Muthu, M.; Bhat, D.K.Biodegradable polymer electrolyte comprising the blend of chitosan (CS) and poly(ethylene glycol) (PEG) plasticized with ethylene carbonate and propylene carbonate, as host polymer, and lithium perchlorate (LiClO4), as a dopant, was prepared by solution casting technique. The ionic conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. The variation of conductivity and dielectric properties has been investigated as a function of polymer blend ratio, plasticizer content and LiClO4 concentration at temperature range of 298-343 K. The DSC thermograms show two broad peaks for CS/PEG blend and increased with increase in the LiClO4 content. The maximum conductivity has been found to be 1. 1 × 10-4 S cm-1 at room temperature for 70:30 (CS/PEG) concentration. The electric modulus of the electrolyte film exhibits a long tail feature indicative of good capacitance. The activation energy of all samples was calculated using the Arrhenius plot, and it has been found to be 0. 12 to 0. 38 eV. A carbon-carbon supercapacitor has been fabricated using this electrolyte, and its electrochemical characteristics and performance have been studied. The supercapacitor showed a fairly good specific capacitance of 47 F g-1. © 2012 Springer-Verlag.Item Methodological and parametric studies of machinability of carbon and alloy steels(2013) Lalbondre, R.; Krishna, P.; Mohan Kumar, G.C.The carbon and alloy steels form an increasingly diverse variety and range of steels in manufacturing industries. The assessment of the machinability of an engineering material becomes a matter of prime activity to improve productivity. The machinability of carbon and alloy steels is affected by many factors, such as the composition, microstructure, and strength level of the steel; the feeds, speeds, and depth of cut; and the choice of cutting fluid, cutting tool material and its geometry. Thus the machinability is an intrinsic technological property which is complex to understand and difficult to determine. This paper discusses different methodology of determining the machinability and its rating/index. One of the methodologies, the face turning method in particular, shall be used to determine the machinability of carbon and alloy steel. Further it deals with identifying the appropriate cutting parameters to test the machinability in an effective, simple and easy way. The research work findings here provide useful economic machining solution of knowing, in advance, the machinability of steels to gain and maintain a competitive advantage. © 2013 CAFET-INNOVA TECHNICAL SOCIETY.Item Production of naringinase from a new soil isolate, Bacillus methylotrophicus: Isolation, optimization and scale-up studies(2014) Mukund, P.; Belur, P.D.; Saidutta, M.B.Five strains of naringin-degrading bacteria were isolated and found to be positive for extracellular naringinase activity. The one that showed highest activity in the selective medium was identified by 16S rRNA analysis as Bacillus methylotrophicus. The best combination of carbon-nitrogen source was determined by employing two-level full factorial analyses, comprising 24 experiments in shake flasks. Sucrose-yeast extract showed significant increase in naringinase activity (7.46 U/L) compared to the basal medium. Naringinase production was found to be inducible and naringin was found to be the best inducer among naringin, naringenin, hesperidin, and L-rhamnose. Inoculum size of 2% (v/v) and age of 48 hr favored naringinase and biomass production. Highest naringinase activity of 8 U/L was observed at the initial medium pH of 6. Response surface modeling was applied based on central composite design to determine the effects of three independent variables (sucrose, yeast extract, and naringin) and their mutual interactions. In total, 20 experiments were conducted and a statistical model was developed, which predicted naringinase production of 10.61 U/L. Subsequently, verification experiments were conducted and validity of the model was verified. Bioreactor studies conducted with the optimized medium showed an enzyme production of 12.05 U/L within 34 hr of fermentation. Copyright © Taylor & Francis Group, LLC.Item Reduction of carbon emission by enhancing energy efficiency of forced draft fans in thermal power plants(Acta Press journals@actapress.com, 2014) Mandi, R.P.; Yaragatti, R.Y.In this paper, various techno-economical feasible methods for reducing the carbon emission by enhancing the energy efficiency of forced draft (FD) fans in coal-fired thermal power plants based on the energy audit study conducted in 28 numbers of 210MW power plants in India are discussed. The best operating points for pressure gain, flow, pressure drop, equipment efficiency, power input and specific energy consumption are simulated by using MATLAB, and presented in this paper with case study to validate the results. Optimizing the pressure at FD fan discharge and maintaining the optimum secondary air pressure at windbox will enhance the combustion characteristics. Operational optimization and control of excess air will reduce the auxiliary power of FD fans. Optimum sizing of FD fans and motors will reduce the auxiliary power by 0.10% gross energy generation and reduce the CO2 emission by 1,600 t/year.Item Plant root nodule like nickel-oxide-multi-walled carbon nanotube composites for non-enzymatic glucose sensors(Royal Society of Chemistry, 2015) Prasad, R.; Gorjizadeh, N.; Rajarao, R.; Sahajwalla, V.; Badekai Ramachandra, B.R.Herein, in this work we synthesized plant root nodule like NiO-MWCNT nanocomposites by a simple, rapid and solvent-free method using nickel formate as a precursor. Using a first-principle simulation study the interactions and charge transfer behaviour of the NiO and MWCNT composite is investigated. The as-prepared NiO-MWCNT composite is employed to fabricate a modified non-enzymatic carbon paste electrode (CPE) for glucose sensing. From the electrochemical investigation, the fabricated sensor shows an excellent sensitivity of 6527 ?A mM-1 cm-2 with a detection limit of 19 ?M and a linear response over a range from 0.001 mM to 14 mM of glucose concentrations, at an applied potential of 0.5 V. Importantly the sensor also exhibits greater stability, selectivity and reproducibility. A first principle simulation study shows the differences in charge density and charge transfer behaviour from nanotubes to NiO nanoparticles, which in turn enhances the electro catalytic property of the NiO-MWCNT composite. Hence, these results indicate that the NiO-MWCNT composite is a potential material for non-enzymatic electrochemical glucose sensors. This journal is © The Royal Society of Chemistry.