Faculty Publications

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Publications by NITK Faculty

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Subject: search.filters.subject.Comparative analysis

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Now showing 1 - 7 of 7
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    Comparative analysis of steady state heat transfer in a TBC and functionally graded air cooled gas turbine blade
    (2010) Coomar, N.; Kadoli, R.
    Internal cooling passages and thermal barrier coatings (TBCs) are presently used to control metal temperatures in gas turbine blades. Functionally graded materials (FGMs), which are typically mixtures of ceramic and metal, have been proposed for use in turbine blades because they possess smooth property gradients thereby rendering them more durable under thermal loads. In the present work, a functionally graded model of an air-cooled turbine blade with airfoil geometry conforming to the NACA0012 is developed which is then used in a finite element algorithm to obtain a non-linear steady state solution to the heat equation for the blade under convection and radiation boundary conditions. The effects of external gas temperature, coolant temperature, surface emissivity changes and different average ceramic/metal content of the blade on the temperature distributions are examined. Simulations are also carried out to compare cooling effectiveness of functionally graded blades with that of blades having TBC. The results highlight the effect of including radiation in the simulation and also indicate that external gas temperature influences the blade heat transfer more strongly. It is also seen that graded blades with about 70% ceramic content can deliver better cooling effectiveness than conventional blades with TBC. © 2010 Indian Academy of Sciences.
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    Energy efficient routing protocols for wireless sensor networks: A survey
    (2011) Shivaprakasha, K.S.; Kulkarni, M.
    Wireless Sensor Networks (WSNs) have become one of the emerging trends of the modern communication systems. They find their applications in various fields like habitat monitoring, home automation, environment monitoring, battle field environment etc. WSNs are different from Mobile Adhoc Networks in the perspective of energy awareness, adaptive communication patterns and the routing algorithms. As the sensor devices are powered by batteries, which cannot be recharged often, the power awareness is one of the major requirements in WSNs. Many energy aware routing protocols have been proposed in the literature. In this survey, an attempt has been made to summarize the various energy aware routing protocols available in the literature and also a comparative analysis of these has been made considering various network parameters like the delay, routing overhead, QoS, type of routing protocol etc. © 2011 Praise Worthy Prize S.r.l. - All rights reserved.
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    Influence of temperature on MWCNT bundle, SWCNT bundle and copper interconnects for nanoscaled technology nodes
    (Springer New York LLC journals@springer-sbm.com, 2015) Sandha, K.; Raj, B.
    This paper presents the comparative analysis of temperature dependent performance of Multi-walled carbon nanotubes (MWCNT), Single-walled carbon nanotube (SWCNT) and copper interconnects for nanoscaled technology nodes. The temperature dependent impedance circuit model is proposed for MWCNT bundle interconnects. The proposed model for MWCNT bundle shows the various electron–phonon scattering mechanisms dependency as a function of temperature. The performance in terms of propagation delay, power dissipation and power delay product for MWCNT bundle interconnects is simulated on the basis of temperature dependent electrical parameters for global interconnects at three different technology nodes viz. 32, 22 and 16 nm for temperature range 200 to 450 K. A similar analysis is performed for SWCNT bundle and copper interconnects and results are compared with the MWCNT bundle interconnects. The comparative results revealed that the performance of MWCNT bundle interconnects is better than the performance of SWCNT bundle and copper interconnects at different temperature ranging from 200 to 450 K for 32, 22 and 16 nm technology nodes at global interconnects. © 2015, Springer Science+Business Media New York.
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    Fuzzy logic approach for reactive power coordination in grid connected wind farms to improve steady state voltage stability
    (Institution of Engineering and Technology journals@theiet.org, 2017) Moger, T.; Dhadbanjan, T.
    This study presents a fuzzy logic approach for reactive power coordination in grid connected wind farms with different types of wind generator units to improve steady state voltage stability of power systems. The load bus voltage deviation is minimised by changing the reactive power controllers according to their sensitivity using fuzzy set theory. The proposed approach uses only few controllers of high sensitivity to achieve the desired objectives. The 297-bus and 417-bus equivalent grid connected wind systems are considered to present the simulation results. To prove the effectiveness of the proposed approach, a comparative analysis is carried out with the conventional linear programming based reactive power optimisation technique. Results demonstrated that the proposed approach is more effective in improving the system performance as compared with the conventional existing technique. © 2016 The Institution of Engineering and Technology.
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    Impact of Different PQ Models of Wind Turbine Generating Units (WTGUs) on System Voltage Performance
    (Walter de Gruyter GmbH info@degruyter.com, 2017) Moger, T.; Dhadbanjan, T.
    This paper presents the voltage performance analysis of the system with various types of wind turbine generating units (WTGUs). A detailed voltage performance analysis is carried out by considering the different PQ models used for computing the reactive power output of the WTGUs (fixed/semi-variable speed and variable speed WTGUs). The different PQ models of fixed/semi-variable speed WTGUs incorporated for the studies are voltage dependent model, voltage independent model, power factor based model, and PX model. In addition, the variable speed WTGUs are also considered in different fixed power factor mode of operation. Based on these models, a comparative analysis is presented. A modified 27-bus equivalent distribution test system with dispersed wind generation is considered for the studies. Further, the case studies have been carried out by considering the various wind power output levels of WTGUs to examine its impact on system voltage performance. From the comparative analysis, the power factor based model can be the best choice over the other models (which are based on voltages) for the system studies with fixed/semi-variable speed WTGUs. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.
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    Batch verification of Digital Signatures: Approaches and challenges
    (Elsevier Ltd, 2017) Kittur, A.S.; Pais, A.R.
    Digital Signatures can be considered analogous to an ordinary handwritten signature for signing messages in the Digital world. Digital signature must be unique and exclusive for each signer. Multiple Digital Signatures signed by either single or multiple signers can be verified at once through Batch Verification. There are two main issues with respect to Batch Verification of Digital Signatures; first is the security problem and the second is the computational speed. Due to e-commerce proliferation, quick verification of Digital Signatures through specific hardware or efficient software becomes critical. Internet companies, banks, and other such organizations use Batch verification to accelerate verification of large number of Digital Signatures. Many Batch Verification techniques have been proposed for various Digital Signature algorithms. But most of them lack the security requirements such as signature authenticity, integrity, and non-repudiation. Hence there is a need for the study of batch verification of Digital Signatures. The main contributions of our survey include: (a) Identifying and categorizing various Batch verification techniques for RSA, DSS, and ECDSA(includes schemes based on Bilinear Pairing) (b) Providing a comparative analysis of these Batch Verification techniques (c) Identifying various research challenges in the area of Batch verification of signatures. © 2017 Elsevier Ltd
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    Influence of Support Vector Regression (SVR) on Cryogenic Face Milling
    (Hindawi Limited, 2021) Karthik, R.M.C.; Malghan, R.L.; Kara, F.; Shettigar, A.; Rao, S.S.; Herbert, M.A.
    The paper aims to investigate the processing execution of SS316 in manageable machining cooling ways such as dry, wet, and cryogenic (LN2-liquid nitrogen). Furthermore, "one parametric approach"was utilized to study the influence and carry out the comparative analysis of LN2over dry and LN2over wet machining conditions. Response surface methodology (RSM) is incorporated to build a relationship model among the considered independent variables (spindle speed: (S, rpm), feed rate (F, mm/min), and depth of cut (doc) (D, mm)) and the dependent variable (surface roughness (Ra)). Since there is the involvement of more than one independent variable, the generation of regression equation is "multiple linear regression."Based on the attained coefficient value of the independent variable, the respective impact on surface roughness is identified. The results of comparative analysis of LN2over dry and LN2over wet machining states revealed that LN2 machining yielded better surface finish with up to 64.9%, 54.9% over dry and wet machining, respectively, indicating the benefits of LN2 for achieving better Ra. The benchmark function of the proposed mode hybrid-bias (BNN-SVR) algorithm showcases the propensity to emerge out of the local minimum and coincide with the optimal target value. The performance of the (BNN-SVR) is a prevalent new ability to fetch the partially trained weights from the BNN model into the SVR model, thus leading to the conversion of static learning capability to dynamic capability. The performances of the adopted prediction approaches are compared through a range of attained error deviation, i.e., (RA: 3.95%-8.43%), (BNN: 2.36%-5.88%), (SVR: 1.04%-3.61%), respectively. Hybrid-bias (BNN-SVR) is the best suitable prediction model as it provides significant evidence by attaining less error in predicting Ra. However, SVR surpasses BNN and RSM approaches because of the convergence factor and narrow margin error. © 2021 Rao M. C. Karthik et al.