Conference Papers
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Item Inverse modeling of heat transfer with application to solidification and quenching(2002) Prabhu, K.N.; Ashish, A.A.The inverse modeling of heat transfer involves the estimation of boundary conditions from the knowledge of thermal history inside a heat conducting body. Inverse analysis is extremely useful in modeling of contact heat transfer at interfaces of engineering surface during materials processing. In the present work, the one-dimensional transient heat conduction equation was inversely modeled in both cartesian as well as cylindrical coordinates. The model is capable of estimating heat flux transients, chill surface temperature, and total heat flow from the source to the sink for an input of thermal history inside the sink. The methodology was adopted to solve boundary heat transfer problems inversely during solidification and quenching. The response of the inverse solution to measured sensor data was studied by carrying out numerical experiments involving the use of varying grid size and time steps, future temperatures, and regularization techniques.Item Identification of voice disorders using speech samples(2003) Nayak, J.; Subbanna Bhat, P.This paper attempts to identify pathological disorders of larynx using Wavelet Analysis. Speech samples carry symptoms of disorder in the place of their origin. The speech signal is subjected to wavelet analysis, and the coefficients are used to identify disorders such as Vocal Fold Paralysis. Multilayer Artificial Neural Network is used for classification of normal and affected signals.Item The independent components of characters are 'strokes'(IEEE Computer Society help@computer.org, 1999) Srinivasan, S.H.; Ramakrishnan, K.R.; Bhagavathy, S.What are the natural features of handwritten characters and how to arrive at them automatically? We apply independent components analysis on handwritten characters. Independent components analysis extracts the underlying statistically independent signals from a mixture of them. We expect strokes to be the independent components of handwritten characters. Our findings show that stroke-like features emerge as a result of the analysis confirming the above intuition. This finding is significant since it gives automatic procedures for extracting stroke-like features from multilingual character data sets. We use these features for handwritten digit recognition using a very simple classifier. The classifier is chosen to be simple so that the quality of the input feature set can be evaluated. The recognition results indicate that the features arrived at by independent component analysis are useful. © 1999 IEEE.Item Simulation study of Borda's profile & parallel plane electrode to assess electric field uniformity(Institute of Electrical and Electronics Engineers Inc., 2003) Punekar, G.S.; Thejovathi, G.; Kishor, N.K.The electrode gaps which results in to uniform electric fields are the most widely used gap configurations in assessing dielectric strength. In the present study simulation results of two electrode gap configurations namely, parallel plane profile and Borda's profile are reported. The charge simulation method (CSM) is used to compute electric fields with errors in simulation being less than 0.04% (in potential). In order to assess the uniformity in electric field in the gap, numerical experiments are conducted by varying parameters like gap spacing, overall radius. Computed electric fields on the surface of the electrode help in comparing non-uniformity in electric fields for the two electrode configurations. Simulation results indicate that for the same overall dimension of the electrode and the gap spacing, parallel plane electrode gives lower non-uniformity factor when compared to the Borda's profile is that the maximum field on the electrode occurs at the edge of the electrode, which is away from the region of interest. Where as the maximum field in case of a plane electrode occurs at the edge of the linear portion of plane profile. Also looking at the field distribution along the gap axis indicates that Borda's profile yields more uniform fields. © 2003 Society of EMC Engineers.Item Performance and emission studies on the effect of injection timing and diesel replacement on a 4-S LPG-Diesel Dual-Fuel Engine(SAE International, 2003) Sudhir, C.V.; Desai, V.; Kumar, S.Y.; Mohanan, P.Reducing the emissions and fuel consumption are no longer future goals; instead they are the demands of the day. People are concerned about rising fuel costs and effects of emissions on the environment. Diesel engines are the major contributors to the increased levels of pollutants. In the present work an attempt is made for effective utilization of diesel engine with reduced fuel consumption, smoke density and NOx emissions. This is achieved by some minor modifications in diesel engine so as to run it as LPG-Diesel Dual-fuel engine with LPG (Liquefied Petroleum Gas) (70% Butane + 30% Propane) induction at air intake. The important aspect of LPG-Diesel dual-fuel engine is that, it shows significant reduction in smoke density, NOx emission and improved brake thermal efficiency with reduced energy consumption. An existing 4-S, single cylinder, naturally aspirated, water-cooled, direct injection, C.I. engine test rig was used for the experimental purpose. With proper instrumentation the tests were conducted under various LPG flow rates, loads, and injection timings. The influence of the diesel replacement by LPG on smoke density, brake specific energy consumption and brake thermal efficiency was studied. The optimal diesel replacement pertaining to the maximum allowable LPG flow limits could be assessed with these experiments. The influence of the injection timing variation on the engine performance and smoke density was analyzed form the experimental results. It was observed that beyond half load operation of the dual-fuel engine, thermal efficiency increased with diesel replacement, and at full load up to 4% improvement was observed compared to full diesel operation. There was drastic reduction in NOx emissions (up to40- 60 %) for the entire load range, except near full load where NOx increased (by38%) beyond full diesel value at normal injection timing. At full load reduction in smoke density up to 40% to 60% was observed compared to full diesel operation. At advance injection timing of 30°btdc the performance of the dual fuel engine was better with lower smoke density, while the NOx emission was found to be higher. Copyright © 2003 SAE International.Item SOLAR INSOLATION AT SURATHKAL - WEST COAST OF INDIA.(Pergamon Press, 1986) Nijaguna, B.T.[No abstract available]Item Intelligent approach for efficient operation of electrical distribution automation systems(2003) Manjunatha Sharma, K.; Sreedhar, P.N.The distribution systems play a vital role in making efficient service in terms of power quality, reliability, and economy. The distribution network reconfiguration can be used for planning as well as real time control. This paper presents an efficient approach for network reconfiguration approach based on artificial neural networks. A package "DISTFLOW" is developed adopting the proposed technique. The off-line simulation results and daily load curve data are used for training of the neural network. Further the distribution system operation is optimized by selecting optimum compensation level computed by Genetic Algorithms (G.A). The proposed integrated approach is applied to 140 bus practical system of Surathkal city subdivision, of the power utility Mangalore electricity supply company (MESCOM).Item ELECTRO-CHEMICAL BEHAVIOUR OF COATED REINFORCEMENT IN CEMENT CONCRETE.(1987) Patil, B.T.; Gajendragad, M.R.; Ramchandran, T.; Ranganna, G.; Sudhaker Nayak, H.V.Concrete constructions exposed to marine environments eventually suffer from corrosion of embedded steel rods, in its advanced state, this corrosion can crack the concrete and weaken the structure. The behaviour of paint coated reinforcements in cement concrete containing different amounts of chloride through an electrode polarization technique. Coated steel rods perform better as far as corrosion of rebar is concerned.Item Estimation of evolutionary spectrum based on STFT and modified group delay(2003) Narasimhan, S.V.; Pavanalatha, S.This paper proposes a new estimator for Evolutionary Spectrum (ES) based on short time Fourier transform (STFT) and modified group delay (MGD). Here, the STFT enables crossterm suppression and the MGD preserves the frequency resolution of the rectangular window. It is applicable to deterministic and random signals generated by time varying systems. The proposed method provides signal to noise ratio enhancement due to the use of MGD. The results indicate that for linear chirp signals and for time varying random process, its frequency resolution is close to that of WVD and better than Evolutionary periodogram (EP) and STFT. Further, its noise immunity is better than those of EP and STFT.Item Computation of lightning induced voltages on telecommunication subscriber lines(Institute of Electrical and Electronics Engineers Inc., 2002) Kannu, P.D.; Thomas, M.J.The electric and magnetic fields produced by a lightning stroke in the vicinity of a telecommunication line can illuminate the line and it can acquire induced overvoltages which may be detrimental to the equipments connected to the telecommunication line. The magnitude and waveshape of the electromagnetic fields produced by lightning as well as the induced voltage on telecommunication line are influenced by the finite conductivity of the ground. In this paper, the induced transient voltages on an overhead telecommunication subscriber line due to a nearby lightning stroke to the ground are computed. From the results it is seen that the induced voltage is bipolar for all the observation points except at the line midpoint for the lightning striking point location chosen in this study. It is also observed that the finite ground conductivity decreases the magnitude of the induced voltage at the line terminations where as it increases the induced voltage as the line mid point is approached. The results obtained in this study will be useful in evolving a suitable lightning protection scheme for the rural telephone exchanges which are interconnected using overhead lines instead of underground cables as in the case of urban exchanges. At the same time these rural telephone exchanges have become more vulnerable to transient overvoltages as they are being converted into digital ones with their susceptibility levels for transient overvoltages being much lower than the old electromechanical exchanges. © 2001 Convenor.