Faculty Publications

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Publications by NITK Faculty

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    Prediction of secondary dendrite arm spacing in squeeze casting using fuzzy logic based approaches
    (De Gruyter Open Ltd, 2015) Gowdru Chandrashekarappa, M.G.C.; Krishna, K.; Parappagoudar, M.B.
    The quality of the squeeze castings is significantly affected by secondary dendrite arm spacing, which is influenced by squeeze cast input parameters. The relationships of secondary dendrite arm spacing with the input parameters, namely time delay, pressure duration, squeeze pressure, pouring and die temperatures are complex in nature. The present research work focuses on the development of input-output relationships using fuzzy logic approach. In fuzzy logic approach, squeeze cast process variables are expressed as a function of input parameters and secondary dendrite arm spacing is expressed as an output parameter. It is important to note that two fuzzy logic based approaches have been developed for the said problem. The first approach deals with the manually constructed mamdani based fuzzy system and the second approach deals with automatic evolution of the Takagi and Sugeno's fuzzy system. It is important to note that the performance of the developed models is tested for both linear and non-linear type membership functions. In addition the developed models were compared with the ten test cases which are different from those of training data. The developed fuzzy systems eliminates the need of a number of trials in selection of most influential squeeze cast process parameters. This will reduce time and cost of trial experimentations. The results showed that, all the developed models can be effectively used for making prediction. Further, the present research work will help foundrymen to select parameters in squeeze casting to obtain the desired quality casting without much of time and resource consuming. © by M.B. Parappagoudarb 2015.
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    Securing web applications from injection and logic vulnerabilities: Approaches and challenges
    (Elsevier B.V., 2016) Deepa, G.; Santhi Thilagam, P.S.
    Context: Web applications are trusted by billions of users for performing day-to-day activities. Accessibility, availability and omnipresence of web applications have made them a prime target for attackers. A simple implementation flaw in the application could allow an attacker to steal sensitive information and perform adversary actions, and hence it is important to secure web applications from attacks. Defensive mechanisms for securing web applications from the flaws have received attention from both academia and industry. Objective: The objective of this literature review is to summarize the current state of the art for securing web applications from major flaws such as injection and logic flaws. Though different kinds of injection flaws exist, the scope is restricted to SQL Injection (SQLI) and Cross-site scripting (XSS), since they are rated as the top most threats by different security consortiums. Method: The relevant articles recently published are identified from well-known digital libraries, and a total of 86 primary studies are considered. A total of 17 articles related to SQLI, 35 related to XSS and 34 related to logic flaws are discussed. Results: The articles are categorized based on the phase of software development life cycle where the defense mechanism is put into place. Most of the articles focus on detecting the flaws and preventing the attacks against web applications. Conclusion: Even though various approaches are available for securing web applications from SQLI and XSS, they are still prevalent due to their impact and severity. Logic flaws are gaining attention of the researchers since they violate the business specifications of applications. There is no single solution to mitigate all the flaws. More research is needed in the area of fixing flaws in the source code of applications. © 2016 Elsevier B.V. All rights reserved.
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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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    DetLogic: A black-box approach for detecting logic vulnerabilities in web applications
    (Academic Press, 2018) Deepa, G.; Santhi Thilagam, P.S.; Praseed, A.; Pais, A.R.
    Web applications are subject to attacks by malicious users owing to the fact that the applications are implemented by software developers with insufficient knowledge about secure programming. The implementation flaws arising due to insecure coding practices allow attackers to exploit the application in order to perform adverse actions leading to undesirable consequences. These flaws can be categorized into injection and logic flaws. As large number of tools and solutions are available for addressing injection flaws, the focus of the attackers is shifting towards exploitation of logic flaws. The logic flaws allow attackers to compromise the application-specific functionality against the expectations of the stakeholders, and hence it is important to identify these flaws in order to avoid exploitation. Therefore, a prototype called DetLogic is developed for detecting different types of logic vulnerabilities such as parameter manipulation, access-control, and workflow bypass vulnerabilities in web applications. DetLogic employs black-box approach, and models the intended behavior of the application as an annotated finite state machine, which is subsequently used for deriving constraints related to input parameters, access-control, and workflows. The derived constraints are violated for simulating attack vectors to identify the vulnerabilities. DetLogic is evaluated against benchmark applications and is found to work effectively. © 2018 Elsevier Ltd
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    A Switched-Capacitor-Based Multilevel Inverter Topology with Reduced Components
    (Institute of Electrical and Electronics Engineers Inc., 2018) Sandeep, N.; Yaragatti, U.R.
    This letter presents an improved sensorless nine-level inverter topology with reduced number of components. It is formed by cascading a three-level T-Type neutral clamped point inverter with a floating capacitor (FC) fed two-level converter unit. Additionally, two line-frequency switches are appended across the dc-link. A simple logic-form equations-based pulse width modulator is designed which is in-charge of maintaining the FC voltage at its reference value without any aid of voltage and current sensor. Thus, the complexity in control of the proposed topology is very minimal. The working principle of the proposed inverter and formulation of logic-form equations is deliberated in detail. Furthermore, experimental results obtained from the developed prototype are presented to validate feasibility and operability of the proposed topology. Finally, a comprehensive comparison with some of the recently reported inverter topologies proving the merits of the proposed topology is included. © 1986-2012 IEEE.
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    Novel color normalization method for hematoxylin eosin stained histopathology images
    (Institute of Electrical and Electronics Engineers Inc., 2019) Roy, S.; Lal, S.; Kini, J.R.
    With the advent of computer-assisted diagnosis (CAD), the accuracy of cancer detection from histopathology images is significantly increased. However, color variation in the CAD system is inevitable due to the variability of stain concentration and manual tissue sectioning. The small variation in color may lead to the misclassification of cancer cells. Therefore, color normalization is a very much essential step prior to segmentation and classification in order to reduce the inter-variability of background color among a set of source images. In this paper, a novel color normalization method is proposed for Hematoxylin and Eosin stained histopathology images. Conventional Reinhard algorithm is modified in our proposed method by incorporating fuzzy logic. Moreover, mathematically, it is proved that our proposed method satisfies all three hypotheses of color normalization. Furthermore, several quality metrics are estimated locally for evaluating the performance of various color normalization methods. The experimental result reveals that our proposed method has outperformed all other benchmark methods. © 2019 IEEE.
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    A Fuzzy Logic Based Switching Methodology for a Cascaded H-Bridge Multi-Level Inverter
    (Institute of Electrical and Electronics Engineers Inc., 2019) Azeem, H.; Yellasiri, Y.; Jammala, V.; Shiva Naik, B.S.; Panda, A.K.
    In this letter, an unusual switching technique is implemented using a fuzzy logic approach. The proposed technique simplifies the conventional method by eliminating the traditional logic-gate design. The fuzzy logic pulse generator acts as a lookup table as well as a pulse generator. On the basis of the modulation index as input, controlled membership functions (MFs) and rules of the fuzzy logic controller open various possibilities of producing pulses directly. The proposed technique is evaluated on the cascaded multi-level inverter with symmetric and asymmetric operations using selective harmonic elimination pulsewidth modulation. MFs are designed on the basis of pre-calculated firing conditions for different modulation index values. Hardware verification is carried out to support the proposed switching technique. © 1986-2012 IEEE.
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    A High Performance Early Acknowledged Asynchronous Pipeline using Hybrid-logic Encoding
    (Elsevier B.V., 2020) Girija Sravani, K.; Rao, R.
    This paper details a novel asynchronous pipelining methodology that maximizes the throughput buffering capacity and robustness of gate-level pipelined systems. The data paths in the proposed pipeline style are encoded using hybrid logic encoding scheme, which incorporates simplicity of the single-rail encoding and robustness of the dual-rail encoding. The control path that provides the synchronization between pipeline stages is constructed based on the simple and high-speed early acknowledgment protocol. Further, the proposed pipeline accommodates isolate phase to achieve 100% storage capacity. Two test cases: A 4-bit,10-stage FIFO and a 16-bit adder, have been designed in 90 nm technology to validate the proposed pipeline style. The FIFO has been laid out in the UMC 180 nm process using the cadence tool suite. The post-layout results of FIFO show 12.5% better throughput than the high capacity single-rail pipeline. Simulation results of the adder also reveal that the proposed structure achieves the throughput of 3.44 Giga-items/sec, which is 44.18% higher than the APCDP (Asynchronous pipeline based on constructed critical path) and 11.9% higher than the high capacity single-rail pipelines. © 2019 Elsevier B.V.
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    Fuzzy and improved fuzzy-wavelet approach in modeling municipal residential water consumption estimation using climatic variables
    (Springer, 2020) Surendra, H.J.; Deka, P.C.
    This work highlights the importance of fuzzy-wavelet denoise and fuzzy-wavelet compress in modeling the municipal residential water consumption estimation. To begin, fuzzy logic is used with different rules, membership criteria and fuzzy set. Based on accuracy of the developed model, optimum number of rules and best membership function were selected. To improve the accuracy of the single fuzzy model, wavelets technique (denoise and compress approach) was coupled with fuzzy logic and results were compared to single fuzzy technique. To map the input and output functions, the present research work includes Mamdani fuzzy inference approach based on various climatic input variables like rainfall, maximum temperature, minimum temperature and relative humidity. The models were trained based on climatic data to a certain period, and corresponding estimated models were tested for the same period. Result highlights that models with denoise and compress approach have better accuracy compared to single fuzzy model. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
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    Study the dynamic behaviour of seven DOF of full car model with semi-active suspension system
    (Inderscience Publishers, 2021) Hemanth, H.; Shamanth, S.; Devaraj, D.; Kumar, H.; Gangadharan, K.V.
    This paper presents an investigation on the ride comfort and road-holding performance of a vehicle equipped with the semi-active suspension system. The full car semi-active suspension model with 7 degrees of freedom (7 DOF) system is adopted for the study and a fuzzy-logic control strategy is considered for minimising the effect of road disturbance on vehicle performance. The responses of a vehicle have been analysed under the Indian average random road profile (ISO8608) against the conventional passive suspension system. The performance of the semi-active suspension system is evaluated by heave, roll and pitch acceleration of the vehicle body around its centre of gravity. The performance of a vehicle with the semi-active suspension system has been compared with the response conventional passive suspension system. The result specifies that, the semi-active suspension system with a fuzzy-logic controller reduces around 43% of vibration amplitude at the resonance frequency of vehicle than the passive suspension system. © © 2021 Inderscience Enterprises Ltd.