1. Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/1/5
Browse
59 results
Search Results
Item Asbestos mining - campaign against its utilisation in western world(1989) Venkat Reddy D.[No abstract available]Item TWO-STAGE SEQUENTIALLY OPERATED REGENERATIVE CONVERTERS WITH CONTROLLED FLYWHEELING.(1985) Bhat, Subbanna, P.; Dubey, Gopal, K.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.Item Topological energy-function analysis of stability of power systems(1987) Padiyar, K.R.; Sastry, H.S.Y.In this paper the direct stability evaluation of power systems, with voltage-dependent loads, using topological energy function is given with applications. This is based on the philosophy of a structure-preserving model for power systems. The loads are modelled as arbitrary functions of respectively bus voltages. A classical model is assumed for generators and system equations are formed using centre of angle (COA) reference. A topological energy function is developed and applied for the stability evaluation using the potential-energy boundary surface (PEBS) method. Examples of a 4-machine and a 7-machine system are considered for illustration. The critical clearing time (Tcr) is obtained both by digital simulation and by the direct method for various load characteristics and for different fault locations. � 1987.Item Transportation of granite statues(1989) Basavarajaiah, B.S.This paper deals with the problems faced during the transportation of two large granite monolith statues weighing 180 t and 120 t respectively through the narrow and winding country-roads on the western plains of the state of Karnataka. A brief resume of the problems faced during this operation and how these were overcome successfully have been presented.Item Wood burning cook stoves(1989) Nijaguna, B.T.; Uppin, S.B.The major domestic energy needs of people in the under-developed and developing countries are met by burning wood in cook stoves. The quest for energy conservation and its efficient use has motivated researchers the world over to look for improvements in wood burning cook stoves. Even a marginal increase in efficiency can contribute considerably to a total saving in energy consumption and therefore conservation. Analysis of cooking using wood shows that better energy efficiency can be achieved by complete and controlled combustion of wood, maximum energy transfer to food cooked and reducing the energy losses. The various component design features that contribute to better utilisation of wood energy are discussed. These can be of use in emerging designs, or in the modifications to the existing designs. In addition to dealing with the sizing factors, the rating or performance testing of wood stoves is detailed, thus providing a basis for comparison of different stoves. Operational guidelines that contribute to increased efficiency during cooking are provided.Item WAVE FORCE COEFFICIENTS ON SUBMARINE PIPELINES - AN OVERVIEW.(1984) Pranesh, M.R.; Somanatha, G.S.The use of submarine pipelines for economical and safe transportation of hydrocarbons is inevitable. As the applicability of pipelines are extended to other purposes, pipeline mileage is increasing alarmingly and into more hostile environment. Since wave force on submarine pipelines is identified to be a major force estimation of wave forces is of vital importance for design purposes. In this paper, an attempt has been made to identify possible reasons for discrepancies in the results of hydrodynamic coefficients. Various experimental results of wave forces on pipelines in newly constructed 2 m wide wave flume are also compared with the results available in literature. Based on the analysis, hydrodynamic coefficients to be used in the design are suggested.Item THREE-PHASE REGENERATIVE CONVERTER WITH CONTROLLED FLYWHEELING.(1985) Bhat, Subbanna, P.; Dubey, Gopal, K.The low-speed performance of a dc drive can be improved by operating the three-phase fully controlled bridge converter with controlled flywheeling. The analysis and performance of the drive with controlled flywheeling is 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. Nomograms and an analytical method of calculating them are presented for computing the optimum value of the filter inductance. The performance of the drive with controlled flywheeling is compared with performance using conventional control. The modes of operation and certain aspects of drive performance are verified experimentally.Item Texture dependent stress corrosion failure of commercial titanium sheets in bromine-methanol solution(1980) Sudhaker, Nayak, H.V.; Vasu, K.I.; Prasad, Y.V.R.K.The stress corrosion cracking (SCC) characteristics of ?-titanium sheets in a bromine-methanol solution have been studied in the annealed and cold-rolled conditions using longitudinal and transverse specimens. The times to failure for annealed longitudinal specimens were longer than those for similarly tested transverse specimens. The cold-rolled specimens developed resistance to SCC, but failed by cleavage when notched, unlike the intergranular separation in annealed titanium. The apparent activation energy was found to be texture dependent and was in the range 30 to 51 kJ mol-1 for annealed titanium, and 15kJ mol-1 for cold-rolled titanium. The dependence of SCC behaviour on the texture is related to the changes in the crack initiation times. These are caused by changes in the passivation and repassivation characteristics of the particular thickness plane. The thickness planes are identified with the help of X-ray pole figures obtained on annealed and cold-rolled material. On the basis of the activation energy and the electrochemical measurements, the mechanism of SCC in annealed titanium is identified to be the one involving stress-aided anodic dissolution. On the other hand, the results on the cold-rolled titanium are in support of the hydrogen embrittlement mechanism consisting of hydride precipitation. The cleavage planes identified from the texture data match with the reported habit planes for hydride formation. 1980 Chapman and Hall Ltd.Item Systems analysis of tank irrigation: II. delayed start and water deficit(1989) Prasad, R.; Mayya, S.G.Tank irrigation systems in the semiarid regions of India are discussed in this paper. To optimize the grain yield of rice, it is essential to start the agricultural operations in the second week of July so that favorable climatic conditions will prevail during flowering and yield formation stages. Because of low inflow during the initial few weeks of the crop season, often farmers are forced to delay planting until sufficient sowing rain and inflow have occurred or to adopt deficit irrigation during this period. The delayed start affects the grain yield, but will lead to an improved irrigation efficiency. A delayed start of agricultural operations with increased irrigation efficiency leads to the energy resources becoming critical during the peak requirement week, particularly those of female labor and animal power. This necessitates augmenting these resources during weeks of their peak use, either by reorganizing the traditional methods of cultivation or by importing from outside the system. ASCE.Item Systems analysis of tank irrigation: I. crop staggering(1989) Mayya, S.G.; Prasad, R.The irrigation potential of a tank system, thousands of which are found in South India, depends upon a number of factors other than water availability. These factors are mainly influenced by the agricultural technology adopted, food practices of people and livestock, the interdependence of land-human-livestock components of life, and socioeconomic practices prevailing in rural areas. The system needs to pertain not only to grain yield but also to fodder production. In semiarid regions of India, uneven distribution and insufficient rainfall during the initial crop season develops water stress in plants. Relatively higher irrigation efficiency, which is possible to attain in tank systems, leads to an increase in the energy resources required for various agricultural operations. An attempt is made in this paper to investigate the effect of these factors on the optimal use of irrigation potential of a minor irrigation tank system. The method involves developing a linear programming (LP) model to optimize the net profit from the system and to determine the optimal cropping pattern under the influence of various parameters, e.g., animal power, labor, fodder production, the resources of farmers, and the nutritional energy requirement of the system, in addition to water availability. The crucial nature of these factors as well as the irrigation efficiency is analyzed. The solution reveals the effectiveness of prevailing agricultural practices consistent with the availability of water resources in the initial crop season. ASCE.