Journal Articles
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Item A simple, convenient and accurate gravimetric method for the determination of silver is presented. 4-Amino-3-methyl-5-mercapto-1,2,4-triazole precipitates silver quantitatively from ammoniacal tartrate medium. The complex is weighed as AgC3H5N4S after drying at 120-30°. Separation of silver from a large number of cations is described. Application of the method for quantitative analysis of alloys and complexes of silver is reported. The average relative error for the range 20-70 mg of silver is ± 0.25% and the relative standard deviation at the 40-mg level is 0.2%. © 1978.(4-Amino-3-methyl-5-mercapto-1,2,4-triazole as a gravimetric reagent for determination of silver in silver compounds, alloys and complexes) Gadag, R.V.; Gajendragad, M.R.1978Item In this paper E-stable methods of O(h4), O(h8) and O(h12) are derived for the direct numerical integration of initial value problems of second order differential equations with exponentially decreasing solutions. Numerical results are presented for both linear and nonlinear problems. © 1985 BIT Foundations.(Kluwer Academic Publishers, E-stable methods for exponentially decreasing solutions of second order initial value problems) Ananthakrishnaiah, U.1985Item Separately excited dc motors fed by sequentially operated multistage converters are commonly used in mainline traction. The drive performance can be greatly improved by operating the fully controlled converters with controlled flywheeling. The analysis and performance of a dc drive fed by two-stage sequentially operated fully controlled converters with controlled flywheeling are described. The modes of operation of the converter system are identified, and a method for calculating performance, taking these modes of operation into account, is presented. The nomograms and an analytical method of calculating them are presented for computing the optimum value of filter inductance. The performance of the drive with controlled flywheeling is compared with performance using normal control. The modes of operation and certain aspects of drive performance are verified experimentally.(TWO-STAGE SEQUENTIALLY OPERATED REGENERATIVE CONVERTERS WITH CONTROLLED FLYWHEELING.) Bhat, Subbanna P.; Dubey, Gopal K.1985Item Chemical amplification method for the determination of atmospheric sulphur dioxide(1997) Malingappa, M.; Balasubramanian, N.A sensitive spectrophotometric method is described for the determination of trace levels of sulphur dioxide in ambient air after fixing the gas in triethanolamine (TEA) or triethanolaminemannitol absorbing solutions. The method is based on the reaction of sulphur dioxide with iodine to form iodide and after the extraction of unreacted iodine, the iodide was oxidized to iodate by bromine. The generated iodate is utilized to oxidize hydroxylamine to nitrite which produces an azo dye in the presence of p-nitroaniline and N-(l-naphthyl)ethylenediamine dihydrochloride (NEDA) in acid medium with maximum absorption at 545 nm. The system obeys Beer's law over the concentration range 0-5 μg of sulphur dioxide in a final volume of 25 ml. The relative standard deviation is 2.5% at 4 μg of sulphur dioxide (n = 10). The interference of other gaseous species were suitably overcome by the proper reaction conditions. The developed method was applied to determine low levels of sulphur dioxide generated using permeation devices and ambient levels of sulphur dioxide in the vicinity of a sulphuric acid plant.Item Casting/mould interfacial heat transfer during solidification in graphite, steel and graphite lined steel moulds(Maney Publishing maney@maney.co.uk, 2003) Prabhu, K.; Mounesh, H.; Suresh, K.M.; Ashish, A.A.Heat flow between the casting and the mould during solidification of three commercially pure metals, in graphite, steel and graphite lined steel moulds, was assessed using an inverse modelling technique. The analysis yielded the interfacial heat flux (q), heat transfer coefficient (h) and the surface temperatures of the casting and the mould during solidification of the casting. The peak heat flux was incorporated as a dimensionless number and modeled as a function of the thermal diffusivities of the casting and the mould materials. Heat flux transients were normalised with respect to the peak heat flux and modeled as a function of time. The heat flux model proposed was used to estimate the heat flux transients during solidification in graphite lined copper composite moulds.Item Transmission and storage of medical images with patient information(Elsevier Ltd, 2003) Acharya, A.U.; Subbanna Bhat, S.; Kumar, M.S.; Min, L.C.Digital watermarking is a technique of hiding specific identification data for copyright authentication. This technique is adapted here for interleaving patient information with medical images, to reduce storage and transmission overheads. The text data is encrypted before interleaving with images to ensure greater security. The graphical signals are interleaved with the image. Two types of error control-coding techniques are proposed to enhance reliability of transmission and storage of medical images interleaved with patient information. Transmission and storage scenarios are simulated with and without error control coding and a qualitative as well as quantitative interpretation of the reliability enhancement resulting from the use of various commonly used error control codes such as repetitive, and (7,4) Hamming code is provided. © 2003 Elsevier Science Ltd. All rights reserved.Item Noise analysis of heavy earth moving machinery deployed in opencast mines and development of suitable maintenance guidelines for its attenuation - Part 2(Multi-Science Publishing Co. Ltd, 2004) Vardhan, H.; Rao, Y.V.; Karmakar, N.C.The noise analysis of heavy earth moving machinery deployed in opencast mines and development of suitable maintenance guidelines for its attenuation were discussed. The impact of periodic maintenance on the noise characteristics of machines was studied. The maintenance schedule for which maximum fluctuation in the noise level occured was analyzed. The noise control of heavy earth moving equipment used in opencast was also elaborated.Item Assessment of heavy earth-moving machinery noise vis-à-vis routine maintenance(2006) Vardhan, H.; Karmakar, N.C.; Rao, Y.V.Exposure to noise from various types of equipment/machinery has been identified as a critical health hazard for personnel working in the Indian mining industry. Heavy Earth Moving Machinery (HEMM) used in mines has been identified as a major source of noise, and several earlier investigators have proposed various types of retrofit measures on these machines to reduce noise. The present work was taken up with the objective of evaluating the noise generation characteristics of HEMM as influenced by periodic maintenance. Detailed noise measurements were carried out in a large open pit coal mine located in India. The effect of maintenance on noise production was assessed for ten dumpers and three dozers by measuring the A-weighted one-third-octave band sound pressure levels after the machines had been subjected to maintenance at the end of 300 hours, 500 hours, 750 hours and 1000 hours of use. Measurements were also carried out to assess the effect of maintaining specific HEMM systems noise characteristics at 1000 hours. Assessment of sound pressure levels at each periodic maintenance revealed major sound level reductions with 1000 hours maintenance. The data also identified the major noise generating systems in HEMM as air systems, exhaust systems, cooling systems and fuel systems. © 2006 Institute of Noise Control Engineering.Item Noise problem and its control for heavy earth moving machinery deployed in opencast mines - A critical review(2006) Vardhan, H.; Rao, Y.V.; Karmakar, N.C.Worldwide, increasingly stringent regulations are coming into force, limiting the exposure of workers to industrial noise. Industrial noise and its consequences, is thus growing importance to employers, local and central government officials, trade unions, occupational hygienists and physicians and insurers. India is not an exception far this. The mining industry in India is facing serious problem of noise due to increasing demand of minerals for which large capacity machines are being deployed producing high noise levels. The present paper thoroughly reviews the noise problem and its control for heavy earth moving machinery's deployed in opencast mines both in India and worldwide. The various noise control approaches for heavy earth moving machinery's deployed in opencast mines are also discussed.Item Studies on nonlinear optical parameters of bis-chalcone derivatives doped polymer(Elsevier BV, 2006) Shettigar, S.; Chandrasekharan, K.; Umesh, G.; Sarojini, B.K.; Narayana, B.Two bis-chalcone derivatives, 1,5-[di(4-methoxyphenyl)]penta-1,4-dien-3-one and 1,5-[di(4-chlorophenyl)]penta-1,4-dien-3-one were synthesized. Their SHG conversion efficiencies are reported to be 6.0 and 5.0 times that of urea and hyper polarizabilities are 9.9×10-30 and 10.2×10-30 esu, respectively. The third-order nonlinear optical properties in PMMA matrix were studied by Z-scan technique using 7 ns laser pulses at 532 nm. The nonlinear refractive index ?, nonlinear absorption coefficient ?, magnitude of effective third order susceptibility ?(3) and the coupling factor ? have been investigated. The values obtained are of the order of 10-14 cm2/W, 1.2 cm/GW, 10-14 esu and 0.2, respectively, which are comparable with the values obtained in stilbazoleum like dyes. The experimental investigation also shows that they are very interesting optical limiting materials and their optical limiting behaviour is mainly due to two photon absorption phenomenon. © 2006 Elsevier Ltd. All rights reserved.Item Design of haul road lighting system. Part II: Design based on optimal cost considerations(2006) Karmakar, N.C.; Mangalpady, M.; Rao, Y.V.; Yaragatti, U.R.The proper selection of lighting installations is very important for the provision of cost-effective lighting systems without compromising light quality. In this study a computer program was developed to evolve a cost-effective lighting system for haul roads in surface mines. This program is beneficial in assessing the viability of various lighting installations in order to achieve cost-effective solutions. Using the program, illumination design was studied for an 800 m long stretch of haul road. Nine different types of light sources were considered at mounting heights of 12 m and 16 m. The study shows that at a 12 m mounting height, 100 W high-pressure sodium vapour (HPSV) lamps offer the most cost-effective design, followed by 250 W HPSV lamps. In the case of 16 m pole heights the annual lighting cost is minimum for 150 W HPSV lamps, followed by 250 W HPSV lamps. This work also shows that optimum design based on energy consumption need not be the same as design based on optimum cost considerations as cost parameters may vary widely with location.Item Strength behaviour of geogrid reinforced shedi soil subgrade and aggregate system(2006) Ravi Shankar, A.U.R.; Suresha, S.N.Shedi soil (Lithomargic clay), a yellowish-white silty soil underlying lateritic soil, is densely deposited along Konkan belt of India. The strength behaviour of Shedi soil under varying moisture content is major problem for road construction projects in this region. In the present investigation, the subgrade is stabilized with geogrid, keeping the geogrid at different positions from top of subgrade, to locate its optimum position. The plate load tests were also conducted at soaked and unsoaked conditions for unreinforeced, reinforced (with Geogrid) subgrade with aggregate base course. An equation has been established based on load-deflection values recorded for subgrade of un-reinforced and reinforced with geogrid at different levels. The deflection values obtained from equation and from the laboratory investigation were compared. In the case of reinforced subgrade with aggregate base course, the theoretical deflection values were computed based on Burmister's theory and compared with laboratory deflection values.Item Bending of sandwich plates with anti-symmetric angle-ply face sheets - Analytical evaluation of higher order refined computational models(2006) Swaminathan, K.; Patil, S.S.; Nataraja, M.S.; Mahabaleswara, K.S.The aim of the present study is to assess the accuracy of the few computational models based on various shear deformation theories in predicting the bending behaviour of sandwich plates with anti-symmetric angle-ply face sheets under static loading. Five two-dimensional models available in the literature are used for the present evaluation. The performance of the various models is evaluated on a simply supported laminated plate under sinusoidal loading. The equations of equilibrium are derived using the principle of minimum potential energy (PMPE). Analytical solution method using double Fourier series approach is used in conjunction with the admissible boundary conditions. The accuracy of each model is established by comparing the results of composite plates with the exact solutions already available in the literature. After establishing the correctness of the theoretical formulations and the solution method, benchmark results for transverse displacement, in-plane stresses, moment and shear stress resultants are presented for the multilayer sandwich plates. © 2006 Elsevier Ltd. All rights reserved.Item Stability of breakwater defenced by a seaward submerged reef(2006) Shirlal, K.G.; Rao, S.; Ganesh, V.; Rao, M.The stability of a uniformly sloped conventional rubble mound breakwater defenced by a seaward submerged reef is investigated using physical model studies. Regular waves of wide ranging heights and periods are used. Tests are carried out for different spacings between two rubble mound structures (X/d=2.5-13.33) and for different relative heights (h/d=0.625-0.833) and relative widths (B/d=0.25-1.33) of the reef. It is observed that a reef of width (B/d) of 0.6-0.75 constructed at a seaward distance (X/d) of 6.25-8.33 breaks all the incoming waves and dissipates energy and protects the breakwater optimally. © 2005 Elsevier Ltd. All rights reserved.Item Characterization of the MSW leachate at Mangalore dump yard, India(2006) Ravishankar, R.; Madhuri, B.; Mugeraya, G.In India, solid waste generation is about 1,00,000 MT per day, of which over 90% is land filled. Landfills are nothing but dump yards without top and bottom impermeable layers. All types of wastes viz., Hazardous, Industrial and even biomedical waste are dumped in these yards. Municipal agencies, responsible for handling wastes, are constructing engineered land fills wherever additional land is available as per MSW (Handling & Management) Rules 2000. The rule stipulates the same limits for leachate discharge as that of industrial wastes. But the characteristics of leachate are not available with the authorities to decide on the system of treatment process. As new landfills are being constructed it is very essential to have a data on the MSW leachate characteristics for deciding on the best treatment method. Therefore in this study the characteristics of the leachate generating from Mangalore MSW landfill was studied during July 2004 to November 2004. pH of the leachate is on the basic side with the value around 8.1±0.2. There is no much variation in the temperature as it was 27°C during July'04 and increased only by 2°C to 29.2°C. towards the end of the study period. Total solids initially decreased from 12800 mg/L to 10300 mg/L due to post monsoon season and as the rainwater dilution decreases, the value of solids increased to 14530 ppm. Total dissolved solids gradually increased from 6700ppm to 10,530 ppm, which is very high compared to standards (2100 ppm). BOD and COD values gradually increased from 200 to 1200 ppm and 2000 to 7200 ppm respectively. This gradual increase can be attributed to the decreased amount of infiltration. These values are much higher than the stipulated standards. Copyright © Enviromedia.Item Biodegradability of PMMA blends with some cellulose derivatives(2006) Bhat, D.K.; Muthu, M.S.High polymer blends of Polymethyl methacrylate (PMMA) with cellulose acetate (CA) and Cellulose acetate phthalate (CAP) of varying blend compositions have been prepared to study their biodegradation behavior and blend miscibility. Films of PMMA-CA, and PMMA-CAP blends have been prepared by solution casting using Acetone and Dimethyl formamide(DMF) as solvents respectively. Biodegradability of these blends has been studied by four different methods namely, soil burial test, enzymatic degradation, and degradation in phosphate buffer and activated sludge degradation followed by water absorption tests to support the degradation studies. Degradation analysis was done by weight loss method. The results of all the tests showed sufficient biodegradability of these blends. Degradability increased with the increase in CA and CAP content in the blend compositions. The miscibility of PMMA-CA and PMMA-CAP blends have been studied by solution viscometric and ultrasonic methods. The results obtained reveal that PMMA forms miscible blends with either CA or CAP in the entire composition range. Miscibility of the blends may be due to the formation of hydrogen bond between the carbonyl group of PMMA and the free hydroxyl group of CA and CAP. © Springer Science+Business Media, Inc. 2006.Item Heat transfer during quenching of modified and unmodified gravity die-cast A357 cylindrical bars(2006) Prabhu, K.; Hemanna, P.Heat transfer during quenching of chill-cast modified and unmodified A357 Al-Si alloy was examined using a computer-aided cooling curve analysis. Water at 60°C and a vegetable oil (palm oil) were used as quench media. The measured temperatures inside cylindrical probes of the A357 alloy were used as inputs in an inverse heat-conduction model to estimate heat flux transients at the probe/quenchant interface and the surface temperature of the probe in contact with the quench medium. It was observed that modified alloy probes yielded higher cooling rates and heat flux transients. The investigation clearly showed that the heat transfer during quenching depends on the casting history. The increase in the cooling rate and peak heat flux was attributed to the increase in the thermal conductivity of the material on modification melt treatment owing to the change in silicon morphology. Fine and fibrous silicon particles in modified A357 probes increase the conductance of the probe resulting in higher heat transfer rates. This was confirmed by measuring the electrical conductivity of modified samples, which were found to be higher than those of unmodified samples. The ultrasound velocity in the probes decreased on modification. ©ASM International.Item Designing cost-effective lighting system for surface mine projects(2006) Mangalpady, M.; Karmakar, N.C.; Rao, Y.V.The objective of lighting in mines is to provide good illumination, which improves the safe and efficient working environment. The artificial lighting is very much essential for the sustained production, to meet the ever-growing demand of the mineral industry. Haul roads within the pit are one of the critical areas in surface mines where lighting installations are not permanent due to regular movement of faces. Though the initial investment for the lighting is very less compared to total project cost, the annual cost is considerably high against the running cost of the project. The proper selection of lamps, reflectors, mountings etc., for particular type of work is very important for energy efficient lighting system, without compromising with the quality of light. A computer model has been developed to evolve a cost effective lighting system for surface mine projects. This model helps in assessing viability of various light sources, so as to achieve energy effective solutions. Properly designed lighting system can prove to be a very cost effective investment for the mine owner.