Faculty Publications
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Item Multicut-high dimensional model representation for reliability bounds estimation(Springer International Publishing, 2015) Balu, A.S.; Rao, B.N.The structural reliability analysis in presence of mixed uncertain variables demands more computation as the entire configuration of fuzzy variables needs to be explored. The existence of multiple design points plays an important role in the accuracy of results as the optimization algorithms may converge to a local design point by neglecting the main contribution from the global design point. Therefore, in this chapter, a method for estimating the reliability bounds of structural systems involving multiple design points in presence of mixed uncertain variables is presented. The proposed method involves weight function to identify multiple design points, multicut-high dimensional model representation for the limit state function approximation, transformation technique to obtain the contribution of the fuzzy variables and fast Fourier transform for solving the convolution integral. © Springer International Publishing Switzerland 2015Item Confidence bounds on failure probability using MHDMR(Springer India, 2015) Balu, A.S.; Rao, B.N.The structural reliability analysis in presence of mixed uncertain variables demands more computation as the entire configuration of fuzzy variables needs to be explored. Moreover the existence of multiple design points plays an important role in the accuracy of results as the optimization algorithms may converge to a local design point by neglecting the main contribution from the global design point. Therefore, in this paper a novel uncertain analysis method for estimating the failure probability bounds of structural systems involving multiple design points in presence of mixed uncertain variables is presented. The proposed method involves weight function to identify multiple design points, multicut-high dimensional model representation technique for the limit state function approximation, transformation technique to obtain the contribution of the fuzzy variables to the convolution integral and fast Fourier transform for solving the convolution integral. In the proposed method, efforts are required in evaluating conditional responses at a selected input determined by sample points, as compared to full scale simulation methods. Therefore, the proposed technique estimates the failure probability accurately with significantly less computational effort compared to the direct Monte Carlo simulation. The methodology developed is applicable for structural reliability analysis involving any number of fuzzy and random variables with any kind of distribution. The accuracy and efficiency of the proposed method is demonstrated through two examples. © Springer India 2015.Item Fuzzy structural analysis using surrogate models(IGI Global, 2016) Balu, A.S.; Rao, B.N.The exponential growth of computational power during the last few decades has enabled the finite element analysis of many real-life engineering systems which are too complex to be analytically solved in a closed form. In the traditional deterministic finite element analysis, system parameters such as mass, geometry and material properties are assumed to be known precisely and defined exactly. However, in practice most of the data used in the solution process of many practical engineering systems are either collected from experiments or acquired as empirical data from the past, which are usually ill defined, imprecise and uncertain in nature. This work presents a practical approach based on High Dimensional Model Representation (HDMR) for analyzing the response of structures with fuzzy parameters. The proposed methodology involves integrated finite element modelling, HDMR based surrogate model, and explicit fuzzy analysis procedures. © 2017 by IGI Global. All rights reserved.Item Cross-layer IDS for rushing attack in wireless mesh networks(2012) Karri, K.; Santhi Thilagam, P.; Rao, B.N.Wireless Mesh Networks (WMNs) are a promising technology to provide the wireless internet connectivity. WMNs are becoming a popular choice for wireless internet service providers to offer internet connectivity as it allows a fast, easy and inexpensive network deployment. However, security in WMNs is still in its infancy. Security and privacy has been a major concern in WMNs. WMNs are susceptible to broad variety of attacks due to its open medium, dynamic topology and lack of physical security. WMNs are more vulnerable in Network layer. Several attacks are possible in the network layer. Some of the attacks have possible solutions but there is no solution for to detect Rushing attack which leads to the Denial of Service. In this paper, the authors proposed Cross- Layer Intrusion Detection System (CLIDS) for Rushing attack. We evaluated the performance of our technique using network simulator 2. Simulation results show that CLIDS has less false positive and false negative rates than single layer intrusion detection system. Copyright © 2012 ACM.Item Efficient assessment of structural reliability in presence of random and fuzzy uncertainties(American Society of Mechanical Engineers (ASME), 2014) Balu, A.S.; Rao, B.N.This paper presents an efficient uncertainty analysis for estimating the possibility distribution of structural reliability in presence of mixed uncertain variables. The proposed method involves high dimensional model representation for the limit state function approximation, transformation technique to obtain the contribution of the fuzzy variables to the convolution integral and fast Fourier transform for solving the convolution integral. In this methodology, efforts are required in evaluating conditional responses at a selected input determined by sample points, as compared to full scale simulation methods, thus the computational efficiency is accomplished. The proposed method is applicable for structural reliability estimation involving any number of fuzzy and random variables with any kind of distribution. Copyright © 2014 by ASME.