Faculty Publications
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Item Analysis of Cyclic Variations and Combustion Behavior of Liquid Phase Hydrocarbons Under Uniform Axial and Radial Magnetic Fields(Springer Science and Business Media Deutschland GmbH, 2023) Oommen, L.P.; Kumar, G.N.The present study experimentally investigates the combustion characteristics of a multi-cylinder MPFI spark ignition engine fuelled by gasoline under uniform magnetic fields. Permanent magnets made of N38 grade NdFeB are used to magnetize the liquid phase hydrocarbons and the impact produced on combustion characteristics like in-cylinder pressure and net heat release rate are studied under different speeds and load conditions of the engine operation. Three different magnetic intensities (3200 G, 4800 G, and 6400 G) are employed in two different magnetization patterns (axial and radial) at an inbuilt ignition timing of 5 deg bTDC. Magnetic field assisted combustion is observed to enhance the performance characteristics of the engine, while simultaneously reducing the exhaust emissions to a significant level. A statistical analysis of cyclic fluctuations in magnetic field-assisted combustion is also made which shows a reduction in fluctuations (COV) with the application of each stage of ionization. The increase observed in peak pressures and heat release rates along throughout the combustion cycles with reduction in cyclic variations indicate that magnetic field-assisted combustion exhibits better combustion characteristics as compared to normal gasoline combustion. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Machine Learning Approach for Testing the Efficiency of Software Reliability Estimators of Weibull Class Models(Springer Science and Business Media Deutschland GmbH, 2025) Murulidhar, N.N.; Tantri, B.Usage of software in every field has resulted in the concern over its quality and durability. In this regard, there is a need to have a systematic way of assessing the reliability of the software. One such assessment is the estimation of software reliability. Numerous works have been done in estimating the reliability of the software by making use of software failure times. Most of the software failure times follow Weibull distribution. Herein, Weibull models are considered. Two well-known estimators, viz, the Maximum Likelihood Estimator and the Minimum Variance Unbiased Estimator have been obtained and combined to get Improved Estimator, which satisfies maximum number of statistical properties of a good estimator. In addition, the comparison of the three estimators is carried out by means of coefficient of variation, which considers both the mean and the standard deviation. The comparison is further enhanced by applying statistical tests to these estimators. Machine learning, being the most widely used technique in recent times, herein it is intended to use the R programming language, which is considered as a powerful machine learning language, to carry out statistical tests pertaining to these estimators. Few datasets have been considered and the estimates have been tested for comparison using Modified signed-likelihood ratio test for equality of coefficients of variations. The output results have been analyzed to test the significance of the differences between the coefficients of variation. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.Item Novel Software Reliability Estimate for Exponential Class Models(International Society of Science and Applied Technologies, 2022) Murulidhar, N.N.; Tantri, B.R.Increasing usage of software in every domain has raised concern over its quality and durability. Many indicators for measuring the quality and durability of the software exist. One such indicator is the software reliability, which is a measure of the life time of the software. Estimation of software reliability enables the users of the software to decide whether or not to accept the software. Knowing the probability distribution of the failure times of the software, the reliability of the software can be estimated. Herein, software reliability models having exponential failure times have been considered. The reliability has been estimated by considering the methods of Maximum Likelihood Estimation (MLE) and Minimum Variance Unbiased Estimation (MVUE). The two estimators are combined to obtain the Improved Estimator (IM). Few data sets have been considered and the estimates have been obtained using the said three methods. The three estimators are then compared using the coefficient of variation. It is observed that the Improved Estimator possesses the least value of coefficient of variation, thus indicating that the Improved Estimator is better as compared to the other two estimators and hence provides more accurate estimate of reliability. © 2022 International Society of Science and Applied TechnologiesItem Improved Estimator of Software Reliability for Weibull Class Models(International Society of Science and Applied Technologies, 2023) Murulidhar, N.N.; Tantri, B.R.Increase in the usage of software in every field has resulted in having concern over its quality and durability. Research in this area is still of importance and many researchers are still working towards the improvement in the reliability of the software products. Measures of quality in terms of reliability are vast and obtaining the estimate of reliability would provide more insight into the durability and hence in assessing the performance of the software. Software reliability models are widely used in this estimation process. Most of the failure data models fall into Weibull class models, in which, the failures times are assumed to be distributed as Weibull. Herein, such Weibull class software reliability models are considered. It is intended to combine two well-known estimators, viz, the Maximum Likelihood Estimator and the Minimum Variance Unbiased Estimator. Both estimators have their own pros and cons, in terms of the properties satisfied by them. Herein, it is intended to preserve the statistical properties satisfied by both the estimators by combining them to get an Improved Estimator, which satisfies maximum number of statistical properties of a good estimator. In addition, the comparison of the three estimators is carried out by means of coefficient of variation, which considers both the mean and the standard deviation. The comparison is further enhanced by considering the quartile coefficient of dispersion of the three estimators. Some bench mark failure data are considered to establish the efficiency of the improved estimator. © RQD 2023. All rights reserved.All right reserved.Item Analyzing the Heterogeneity in Public Transit Demand: Impact of Spatial and Temporal Attributes(Springer Science and Business Media Deutschland GmbH, 2025) Shanthappa, N.K.; Mulangi, R.H.; Venkateswari, N.P.The usage of personal vehicles is causing several issues like traffic congestion, greenhouse gas emissions, and massive energy consumption. These issues can be alleviated by implementing a public bus transport system. But the irregular frequency of buses and longer waiting times are diminishing the attractiveness of public bus transportation in India. To implement an affordable and efficient public transport system, it is necessary to understand the heterogeneity of public transit demand under different conditions. Limited scholarly exploration on the impact of spatial and temporal characteristics on the heterogeneity of public transit demand under Indian conditions. This paper aims to measure public transit demand heterogeneity using the coefficient of variation of transit demand, which is defined as a ratio of standard deviation to mean. Spatial, temporal, and weather characteristics are considered to analyze their influence on the heterogeneity of public transit demand. The statistical variability analysis is performed using Electronic Ticketing Machine (ETM) data, weather data, and bus network data. The results indicate that the combined impact of weather conditions and the built environment has a stronger influence on the variability in Public Transit Demand (PTD) than each factor individually. Based on the analyses, it is recommended to change the service type to improve the transport system's efficiency. This study suggests the importance of incorporating spatial, temporal, and weather characteristics. This study can help stakeholders to optimize public transport networks and schedule service frequency. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.Item Spectrophotometric determination of platinum(IV) in alloys, complexes, environmental, and pharmaceutical samples using 4-[N,N-(diethyl)amino] benzaldehyde thiosemicarbazone(2010) Naik, P.P.; Karthikeyan, J.; Nityananda Shetty, A.N.4-[N,N-(Diethyl)amino] benzaldehyde thiosemicarbazone (DEABT) is proposed as an analytical reagent for the spectrophotometric determination of platinum(IV). The DEABT forms 1:2 yellow complex with Pt(IV), which is sparingly soluble in water and completely soluble in water-ethanol-DMF medium. The Pt(IV)-DEABT complex shows maximum absorbance at 405 nm. Beer's law is valid up to 7.80 ?g cm-3, and optimum concentration range for the determination of platinum(IV) is 0.48-7.02 ?g cm-3. The molar absorptivity and Sandell's sensitivity of the method are found to be 1.755 × 104 dm3 mol-1 cm-1 and 0.0012 ?g cm-2, respectively. The relative error and coefficient of variation (n=6) for the method does not exceed ±0.43% and 0.35%, respectively. Since the method tolerates a number of metal ions commonly associated with platinum, it can be employed for the determination of platinum in environmental samples, pharmaceutical samples, alloys, catalysts, and complexes. The method is rapid as the Pt(IV)-DEABT complex is soluble in water-ethanol-DMF medium and not requiring any time consuming extraction method for the complex. © 2010 Springer Science+Business Media B.V.Item Despeckling low SNR, low contrast ultrasound images via anisotropic level set diffusion(Kluwer Academic Publishers, 2014) Bini, A.A.; Bhat, M.S.Speckle is a form of multiplicative and locally correlated noise which degrades the signal-to-noise ratio (SNR) and contrast resolution of ultrasound images. This paper presents a new anisotropic level set method for despeckling low SNR, low contrast ultrasound images. The coefficient of variation, a speckle-robust edge detector is embedded in the well known geodesic "snakes" model to smooth the image level sets, while preserving and sharpening edges of a speckled image. The method achieves much better speckle suppression and edge preservation compared to the traditional anisotropic diffusion based despeckling filters. In addition, the performance of the filter is less sensitive to the speckle scale of the image and edge contrast parameter, which makes it more suitable for the detection of low contrast features in an ultrasound image. We validate the method using both synthetic and real ultrasound images and quantify the performance improvement over other state-of-the-art algorithms in terms of speckle noise reduction and edge preservation indices. © 2012 Springer Science+Business Media, LLC.Item Cycle by cycle variations of LPG-gasoline dual fuel on a multi-cylinder MPFI gasoline engine(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Vighnesha, N.; Shankar, K.S.; Dinesha, P.; Mohanan, P.Combustion stability of a multipoint port fuel injection spark ignition engine working on liquefied petroleum gas (LPG)-gasoline dual fuel mode of operation was analysed. LPG-gasoline ratio was varied from 0 to 100% by controlling the injector signals at wide open throttle condition and 3000 RPM. Increasing LPG ratio will give higher peak pressure and higher indicated mean effective pressure (IMEP) because of the higher flame propagation speed of LPG. The experiment showed that maximum pressure will occur nearer to top dead centre when compared to gasoline. Fluctuation in maximum pressure is higher for LPG and is minimum for 50% LPG. Time return map showed that combustion instabilibity will be more for 100% LPG and is less for 50% LPG. Coefficient of variation of IMEP and maximum pressure for gasoline is higher than LPG. With 100% LPG, NOx emission is almost three times that of gasoline. Hence it can be concluded that 50% LPG will give the better combustion characteristics when compared to other fuel blends. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.Item Experimental studies on cyclic variations in a single cylinder diesel engine fuelled with raw biogas by dual mode of operation(Elsevier Ltd, 2020) Jagadish, C.; Gumtapure, V.In this research work, cycle-by-cycle variations of a single cylinder, diesel engine operated with raw biogas is investigated. The biogas used to run the engine is obtained from food waste and as the composition of 88.10%-CH4 + 11.895%-CO2. To study the combustion characteristics, the naturally aspirated diesel engine is converted into dual mode by inducting the biogas into the intake manifold for different proportions from BG20 to BG60 with a step of 10% is mixed with air (i.e. BG60-60% of biogas by mass) respectively. Combustion parameters are measured and recorded by the means of the data acquisition system (DAQ) for 100 combustion cycle. By determining the parameters such as standard deviation, coefficient of variation and return map, the cycle variability is analyzed. From the experimental result, it is observed that as the engine is operated at higher loads and as the biogas is increased from BG20 to BG60 the cyclic variations for maximum cylinder pressure (Pmax) and indicated mean effective pressure (IMEP) increases. Coefficient of variation of Pmax for BG20 and BG40 is lower by 2.3% and 11.98% as compared to diesel. From time return map, BG40 showed good combustion stability and lesser NOx emission compared to diesel. © 2020 Elsevier Ltd