Faculty Publications
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Item Towards an ontology-based approach for specifying and securing Web services(2006) Maamar, Z.; Narendra, N.C.; Sattanathan, S.With the increasing popularity of Web services and increasing complexity of satisfying needs of users, there has been a renewed interest in Web services composition. Composition addresses the case of a user request that cannot be satisfied by any available Web service, whereas a composite service obtained by integrating Web services might be used. Because Web services originate from different providers, their composition faces the obstacle of the context heterogeneity of Web services. An unawareness or poor consideration of this heterogeneity during Web services composition and execution result in a lack of the quality and relevancy of information that permits tracking the composition, monitoring the execution, and handling exceptions. This paper presents an ontology-based approach for context reconciliation. The approach also focuses on the security breaches that threaten the integrity of the context of Web services, and proposes appropriate means to achieve this integrity. © 2005 Elsevier B.V. All rights reserved.Item Computer aided slope stability analysis(2006) Sastry, V.R.; Ram Chandar, K.; Santosh, M.Primary purpose of slope stability analysis in most of the engineering applications is to provide safe and economic design of slopes that prevent failure. The analysis technique chosen depends on both site conditions and potential mode of failure which depends upon the rock mass characteristics. Various slope stability analysis techniques include physical, numerical and analytical methods. Physical modeling is a time consuming process and a costly affair, while analytical method involves past experiences, it is site specific and depends upon various parameters which are difficult to quantify. Numerical analysis with sophisticated softwares provides an accurate solution within short duration. This paper presents an in-house developed software package called "V-slope" to analyze and interpret the slope with options for suggesting suitable safety measures based on the nature of slope. Slip circle and tension crack techniques were considered for analysis. The slope profile for different factor of safety (FOS) values will be displayed on the screen for easy understanding. In case the FOS is lower than the required, the V-slope gives suggestive measures. In case of temporary slopes the only way by which slope failure can be prevented is by decreasing the slope angle and in such cases the program gives additional volume of material to be excavated and the likely additional cost incurred for various slope angle options. For permanent slopes, option is provided for designing the soil nails, i.e. number of bolts required, length, diameter and spacing of the bolts etc. Finally the V-slope is compared with a comprehensive commercial software package Slide and the results were found very much satisfactory.Item Characterization of sealing ring cavitation in centrifugal pumps with water and viscous oil(Begell House Inc., 2010) Nair, K.G.; Ashok Babu, T.P.A.This research paper presents characterization of sealing ring cavitation in centrifugal pumps with water and viscous oil. The paper discusses development of theoretical formulation for sealing ring cavitation and simulation using software model along with experimental validation. The pump performance test results and its standard clearance for the sealing ring are used to simulate the theoretical model. The study is extended for pumps with SAE-30 lubricating oil. The simulation results present the variation of downstream pressure with different sealing ring dimensions in pumps. The value of downstream pressure determines the possibility of occurrence of cavitation at the clearance. The theoretical formulation developed is validated by using a venturi cavitation test set up. Clearances equivalent to various sealing ring dimensions are made at the test section using different hemispherical models. Theoretical formulation for downstream pressure at the clearance of venturi test section is derived using the test set up details and pump specification. The clearance cavitation coefficients as per K. K. Shelneves equation are obtained from theory as well as from experimentation and compared. The phenomena of cavitation damages the sealing ring which results a fall in performance of the pump. However this research work lead to the prediction of sealing ring cavitation in centrifugal pumps handling water and oil enabling the replacement of sealing ring before affecting cavitation damage. © 2010 Begell House, Inc.Item Modeling and design of field programmable gate array based real time robust controller for active control of vibrating smart system(Academic Press, 2015) Parameswaran, A.P.; Ananthakrishnan, B.; Gangadharan, K.V.The current paper focuses on accurate mathematical modeling of a vibrating piezoelectric laminate cantilever beam theoretically as well as experimentally so as to obtain the best replication of the system dynamics on the software platform for simulation studies. The developed models were tested for accuracy in time as well as frequency domain by employing the sweep sine test. The focus of the study is on the flexural modes of vibrations of the cantilever beam. Here, modeling is focused on the first vibratory mode as it has been observed that the effects of felt vibrations would be maximum in terms of system stability and its operational efficiency when the excitation frequency matches with the first natural frequency of the system (fn1). This was validated by appropriate non-parametric modeling of the smart system by subjecting it to the Impact Hammer test. Development of accurate system models play an important role in designing and testing various control algorithms for reliable active vibration control (AVC). In the final stage, a real time active vibration robust controller was designed using a proportional derivative sliding mode control (PDSMC) technique and deployed on a Field Programmable Gate Array (FPGA) platform. The efficiency of the developed real time controller was proved in time as well as frequency domains by subjecting the closed loop system to harmonic excitations at first natural frequency as well as sweep sine test focussing on the first vibratory mode with the conclusion that the developed controller will function satisfactorily at higher modes of vibrations. © 2015 Elsevier Ltd.Item An adaptive reactive power perturbation based hybrid islanding detection method for distributed generation systems(Acta Press journals@actapress.com, 2016) Krishnan, G.; Gaonkar, D.N.The intentional islanding operation of distributed generation (DG) systems can bring many benefits to the DG owner, distribution network operators and customers. One of the requirements for intentional islanding operation is the successful detection of the grid events which can lead to islanding of the DG system. This paper presents the hybrid islanding detection method based on adaptive reactive power variation with a passive algorithm that relies on the transient response characteristics for facilitating islanding detection. The proposed method presented in this paper can overcome the problems in the reactive power variation based methods. Extensive studies are conducted for differentiating the transient characteristic features for islanded and non-islanded systems. In this study the adaptive reactive power sequence is modified to enhance the performance under sudden load changes. The proposed method proved to detect all probable islanding situations with minimum run-on time. The performance of the method is evaluated using simulation results obtained from MATLAB/SIMPOWERSYSTEMS software considering wind power based DG system.Item 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.Item Computational analysis of unsteady flow in turbine part of turbocharger(Springer Heidelberg, 2017) Rao, H.K.S.; Raviteja, S.; Kumar, G.N.Turbocharging technique is widely employed in internal combustion engines to improve the performance and to reduce the exhaust emissions. Flow analysis through the turbocharger has been a guiding method to optimize the turbocharger design. Usually, the turbocharger turbine is analyzed at steady states. But in practical scenario the turbine operates with unsteady flow due to the reciprocating motion of exhaust port and creates unsteady environment in the turbine. In order to increase turbine efficiencies and effective engine turbocharger matching, proper understanding of unsteady flow physics within the turbine is essential. Currently the turbine and compressors maps are obtained by using 1D code which includes extrapolation techniques. These methods neglect heat transfer and windage effects, hence resulting in lower aerodynamic efficiencies. Three dimensional analysis could lead to a better estimation of the flow field, helping the designer to build a high efficiency turbocharger. The present article concentrates on investigating unsteady flow field in the turbine part of a turbocharger. The necessary unsteady conditions at turbine inlet were obtained using commercially available one dimensional engine simulation software AVL Boost. A turbocharged twin cylinder CRDI diesel engine test rig was modelled within the workspace. The exhaust mass flow rate, pressure and temperature were recorded as a function of crank angle. These results were used as the boundary condition for the 3D analysis of the turbine. ANSYS CFX tools were used to solve the unsteady case. The turbine geometry was generated using ANSYS bladegen. The model selected for analysis is k-? turbulence Model. The pulsating performance, effect of secondary flows and entropy generation are discussed in the paper. © Springer India 2017.Item Life cycle energy analysis of a metro station building envelope through computer based simulation(Elsevier Ltd, 2018) Aneesh, N.R.; Shivaprasad, K.N.; Das, B.B.This study focuses on the energy auditing of a metro terminal station building envelope which is located at a major city in south India. Embodied energy was calculated using the unit embodied energy values and by quantifying major energy consuming material used for the construction of a metro terminal station building. e-Quest, the energy simulation software was used for modelling the terminal station building and thereby calculated the yearly consumption of operational energy. Terminal station building is modelled with a detailed description of the building in e-Quest, which is being analysed with lighting, equipment's, thermostat settings, hourly scheduling of occupants and climatic data as the inputs to the model. In assessing the life cycle energy of the terminal station building, recurring energy and transportation energy were also calculated. In addition, this study discusses the comparative analysis on operational energy consumption for the same metro station model for three different climatic regions across India. Further, the present study on life cycle energy is compared with the life cycle energies of different types of buildings obtained from the literature, for an understanding of the energy usage demand per year per capita, between a public utility building, a commercial building and different types of residential buildings. © 2018 Elsevier LtdItem Development of an industrial ferritic rolling process for IF grade steel(Taylor and Francis Ltd., 2020) Kumar, D.S.; Sambandam, M.; Bhat K, U.K.Interstitial free (IF) grade steels have high transformation temperatures and often results in non-uniform rolling and lower yields. In the present work, industrial ferritic rolling process is developed, where finish rolling is carried out below the Ar1 temperature for the IF grade steel. Offline simulation was carried out using a hot strip mill model (HSMM) software and full-scale ferritic rolling was carried out in a seven-stand hot strip mill under two different finishing and coiling temperatures and compared with austenitic rolling. Furnace drop-out temperature, mill speed and inter-stand cooling were controlled to achieve the desired low rolling temperatures. Both ferritic rolled coils had strained elongated grains and well-developed alpha (<110>//RD) and gamma (<111>//ND) textures. The lower finishing and coiling temperature processed coil shows higher microstructural and textural variation along with the thickness. This work established the optimum parameters for the industrial ferritic rolling process for IF grade steel. © 2020, © 2020 Institute of Materials, Minerals and Mining.Item Numerical Simulations of Fluid Flow and Heat Transfer through Aluminum and Copper Metal Foam Heat Exchanger–A Comparative Study(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) Kotresha, B.; Gnanasekaran, N.This article discusses about a numerical simulation of a metal foam heat exchanger system carried out by a commercial software. A metal foam layer is attached to the bottom of the heat exchanger to absorb heat from the exhaust hot gas leaving the system. Two types of metal foams with two different pores per inch (PPI) values are considered for heat transfer enhancement. Similarly, two different materials Aluminum and copper, that poses high thermal conductivity, metal foams are considered for the present numerical simulations. The heat exchanger system is simulated over a range of 6–30 m/s fluid velocity. The proposed simulations are compared with theoretical and experimental data available in the literature. The goal is to improve the thermal performance of the heat exchanger by decreasing the pressure drop and maximizing the heat transfer rate. Finally, it has been noticed that the velocity of the fluid decreases as PPI increases at the expense of its pressure drop. The copper metal foam gives a maximum increase of 4–10% heat transfer rate compared to aluminum metal foams for a fluid velocity of 30 m/s. © 2019, © 2019 Taylor & Francis Group, LLC.