1. Journal Articles
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Item Aqueous corrosion behaviour of ductile iron and ductile iron containing 1 wt. pct. chromium(1997) Surendranathan A.O.; Hebbar, K.R.; Sudhaker Nayak, H.V.Ductile irons with graphite in spheroidal form enjoy the processing characteristics of grey iron and mechanical properties of steel. This paper describes the corrosion behaviour of ductile iron containing 1 wt. % chromium in sea water, dilute sulphuric acid and dilute sodium hydroxide solutions and compares with that of unalloyed ductile iron. Study is made in as-cast, annealed and cold worked (upto 28% reduction in thickness) conditions at three different temperatures. Since the alloying addition brings changes in the proportion of phases, the corrosion behaviour of the two materials studied were different, though alloying addition is small, indicating corrosion behaviour to be structure sensitive.Item Use of mining and seismological parameters as premonitors of rockbursts(1997) Srinivasan, C.; Arora, S.K.; Yaji, R.K.Comprising one of the deepest mines in the world, the gold mining region of the Kolar Gold Fields (KGF) in southern India is known to be confronted with the acute problem of rockbursts that pose a hazard to workmen and cause disruptions in the production schedule. In combination with mining parameters, seismological data of these rockbursts events systematically monitored over the years using a regional seismic network have been employed to examine and model premonitory characteristics of the events. Linear empirical relations are established relying on correlations seen between the seismic energy released due to a rockburst, total tonnage of ore mined out and total number of rockbursts, as well as seismic events in some shallow and deep workings currently active at KGF. The deterministic model, although not free from certain limitations at present, has been applied to predict rockburst activity with some success. � 1997 Elsevier Science Ltd.Item Wave attenuation characteristics of single row of perforated hollow piles in laboratory(1999) Subba, Rao; Rao, N.B.S.; Prasad, J.S.Laboratory investigation on perforated hollow piles in a single row was conducted in a two dimensional regular wave flume to study the performance of such an arrangement in dissipating wave energy. The influence of spacing between the piles, size of perforations, different percentage of perforations and water depth on wave attenuation has been investigated. It is found that water depth has insignificant effect on transmission coefficient (K(t)) at higher wave steepness. K(t) decreases as the relative clear spacing of piles (b/D) decreases and also it decreases as the incident wave steepness increases. At lower value of b/D, K(t) decreases with increase in percentage of perforations. For the same percentage of perforations, the pile groups with larger size of perforations transmit more wave energy than pile groups with smaller size of perforations. The perforated hollow pile breakwater is an alternative solution to protect the coast from erosion where the erosion is due to wave energy concentration or onshore offshore movement of sand.Item Variable-feedrate CNC interpolators for constant material removal rates along Pythagorean-hodograph curves(1998) Farouki, R.T.; Manjunathaiah, J.; Nicholas, D.; Yuan, G.-F.; Jee, S.An NC system that machines a curved shape at fixed depth of cut experiences time-varying cutting forces due to the 'curvature effect' - the material removal rate is higher than nominal in concave regions, and lower in convex regions. A curvature-dependent feedrate function that automatically compensates for this effect is formulated, and it is shown that, for Pythagorean-hodograph (PH) curves, the periodic real time computation of reference points in accordance with this function can be analytically reduced to a sequence of root-finding problems for simple monotone functions. Empirical results from an implementation of this variable-feedrate interpolators on an open-architecture CNC milling machine are presented and compared with results from fixed-feedrate interpolators. The curvature-compensated feedrate scheme has important potential applications in ensuring part accuracy and in optimizing part programs consistent with a prescribed accuracy. � 1998 Elsevier Science Ltd. All rights reserved.Item Solid substrate fermentation of coconut coir pith for cellulase production(1994) Muniswaran, P.K.A.; Charyulu, N.C.L.N.Coconut pith, available in abundance, especially in tropical countries, can be an excellent new substrate for the production of cellulase enzyme by solid substrate cultivation of Trichoderma viride NCIM 1051. The effect of type of pretreatment, type and level of nutrient medium, inoculum volume, average substrate particle size, and time of fermentation on cellulase enzyme production by T. viride in coconut pith solid culture was studied. The hydrogen peroxide-pretreated coconut pith was found to be a better substrate. Reese and Mandels' mineral solution mixed with coconut pith in the ratio of 10:1 (v/w; ml g-1) supported maximum cellulase activity. The effect of inoculum volume on enzyme production was only marginal. An average substrate particle size of 375 ?m resulted in better enzyme production. The highest filter paper activity and carboxymethylcellulase activities of 4.27 and 12.05 IU g-1, respectively, were obtained in 7 days of fermentation, and the maximum cellobiase activity that could be obtained was 1.8 IU g-1 in 8 days. 1994.Item Thermomechanical treatment of spinodal Cu-32Ni-2Cr alloy(1994) Bhat, R.Raghavendra; Rao, P.PrasadProgress in spinodal decomposition of a Cu-32Ni-2Cr alloy subjected to quench?age and quench?work?age treatments have been studied through hardness measurements as well as by X-ray diffraction techniques. It is found that recovery processes occur during early stages of aging which are interpreted in terms of the migration of matrix dislocations to interfaces. The kinetics of spinodal decomposition is found to be enhanced by prior deformation. Thermomechanical treatment results in a substantial increase in strength.Item The crystal structure of hydrated barium copper oxalate(1996) Kasthuri, V.B.; Rao, P.M.; Nethaji, M.BaCu(C2O4)2 6 H2O is triclinic, P1, with a = 6.5405(9), b = 9.202(3), c= 10.939(1) , ? = 8546(2), ? = 79.22(1), ? = 80.45(2), V = 636.99(1) 3, Z=2, D0, = 2.14, Dc = 2.465 g cm-3, R = 0.074. wR = 0.0746 for 2219 significant reflections |F0| = 6.0?F0. The barium has eleven coordinations and the coordination polyhedra is a capped antiprism. Six water oxygen atoms are coordinated whereas the other five are coming from the oxalate group. In the unit cell the molecules form a polymeric network. One lattice water molecule belongs to the coordinating water. The barium oxygen distances vary from 2.75 to 3.15 .Item Systems analysis of tank irrigation: I. Crop staggering(1991) Mayya, S.G.; Prasad, R.[No abstract available]Item Switched digital video access networks(1996) Bankapur, R.J.; Beuscher, H.J.; Runyon, J.P.; Sanku, A.C.R.; Sehgal, C.S.Telecommunications service providers are upgrading their network infrastructure to enhance telephony and to enable future video and data services. This discussion focuses on an access network that serves as a platform for transporting telephony and asynchronous transfer mode (ATM) data to the customer premises using fiber-in-the-loop (FITL) technology. The platform provides the building blocks that will enable service providers to furnish a wide variety of offerings, such as interactive and broadcast video, Internet access, and other high-bandwidth data communications. The platform is called the switched digital video (SDV) access network. This paper describes the SDV access network, and it also presents an example of how SDV network elements could be configured with other broadband network elements to provide an interactive video services network.Item Study of corrosion behaviour of ductile iron by electrochemical polarisation techniques(1998) Surendranathan, A.O.; Hebbar, K.R.; Sudhaker, Nayak, H.V.The use of electrochemical methods to characterize materials for their corrosion behaviour is well known. Both linear polarisation and Tafel extrapolation techniques are made use of to study the corrosion behaviour of ductile iron (DI) in natural sea water, 5 v/o H2SO4 and 5 w/o NaOH. Samples were tested in the as cast, annealed and cold worked conditions at 300 K, 325 K and 340 K. It was found that annealed material had the least corrosion rate. This is explained on the basis of the proportion of phases in the microstructure, the DI has on annealing. On annealing as cast DI, certain amount of cementite in the pearlite is converted into ferrite. Since a single phase material is always more corrosion resistant than a multiphase one, ferrite phase increases corrosion resistance. High degree of cold working is detrimental with respect to corrosion resistance as it increases the stored energy and dislocation density in the material thereby enhancing the kinetics of corrosion reactions. The activation energy for DI was found to be lowest in sulphuric acid medium and highest in sodium hydroxide medium. The corrosion rates for DI in H2SO4 medium were the highest while in NaOH they were the lowest irrespective of material condition and technique of rate measurement.