1. Faculty Publications

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End date: 1989Has files: Yes

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    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.
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    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.
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    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.
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    The effect of the thickness of the porous material on the parallel plate channel flow when the walls are provided with non-erodible porous lining
    (1976) Channabasappa, M.N.; Umapathy, K.G.; Nayak, I.V.
    Flow through a channel whose walls are lined with non-erodible porous material is investigated using Beavers and Joseph slip boundary condition. It is shown that the effect of porous lining is to increase the mass flow rate and to decrease the friction factor. 1976 Martinus Nijhoff Publishers.
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    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.
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    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.
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    State-Space Models Using Modified Cauer Continued Fraction
    (1982) Parthasarathy, R.; John, S.
    This letter presents a procedure for obtaining reducedader models in statespace formulation, using modifd Cauer continued fraction as the basis. The proposed procedure is amenable to programming on a digital computer. Copyright 1982 by The institute of Electrical and Electronic Engineeer, Inc.
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    Optimum shape design of rotating disks
    (1980) Bhavikatti, S.S.; Ramakrishnan, C.V.
    This paper deals with optimum shape design of the rotating disks by nonlinear programming method. The shape of the cross section is defined by 5th degree polynomial which is completely determined by the boundary conditions and four design variables. The stress analysis of the disk is carried out by finite element method using isoparametric elements. The optimization technique used is with improved movelimit method of sequential linear programming. Progress of optimization is investigated with three different objective functions. After preliminary studies a weighted objective function is selected for detailed investigation. Optimum shapes are obtained for different speeds and for different fit pressures from hub. The results are presented in non-dimensionalised form. 1980.
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    On Model Reduction by Modified Cauer Form
    (1983) Parthasarathy, R.; Jayasimha, K.N.; John, S.
    A simple algorithm for obtaining the continued fraction quotients in the modified Cauer form (MCF) from the given system matrices in companion form is presented. In the sequel, the triple of all lower order models in companion form is directly obtained. A matrix method of obtaining the time-moments and Markov parameters from the MCF quotients is also outlined. Finally, it is shown that system reduction by matching a set of MCF quotients is equivalent to system reduction by matching a set of time-moments and Markov parameters. Copyright 1983 by The Institute of Electrical and Electronics Engineers, Inc.
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    On exceptional values of entire and meromorphic functions
    (1974) Narayanan, K.A.
    Let f(z) be meromorphic function of finite nonzero order ?. Assuming certain growth estimates on f by comparing it with r?L(r) where L(r) is a slowly changing function we have obtained the bounds for the zeros of f(z) -g (z) where g (z) is a meromorphic function satisfying T (r, g)=o {T(r, f)} as r ? ?. These bounds are satisfied but for some exceptional functions. Examples are given to show that such exceptional functions exist. 1974 Indian Academy of Sciences.