(SoE) School of Engineering

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

This paper enhances the recently proposed twin SVM Jayadeva et al. [Jayadeva, Khemchandani, R., Chandra, S., 2007. Twin support vector machines for pattern classification. IEEE Trans. Pattern Anal. Machine Intell. 29 (5), 905-910] using smoothing techniques to smooth twin SVM for binary classification. We attempt to solve the primal quadratic programming problems of twin SVM by converting them into smooth unconstrained minimization problems. The smooth reformulations are solved using the well-known Newton-Armijo algorithm. The effectiveness of the enhanced method is demonstrated by experimental results on available benchmark datasets. © 2008 Elsevier B.V. All rights reserved.

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Electrical Engineering

Pattern Recognition Letters

Application of smoothing technique on twin support vector machines

This paper describes design and implementation of a control philosophy for simultaneous stabilization and performance improvement of an electromagnetic levitation system. An electromagnetic levitation system is an inherently unstable and strongly nonlinear system. To determine the overall closed loop stability for such a system, cascade lead-lag compensation has mostly been reported [1,2]. However, a single lead controller can not satisfy both stability and performance for such unstable systems [3]. Performance enhancement to satisfy the conflicting requirements of fast response with almost zero overshoot and zero steady state error has been successfully achieved by using a two loop controller configuration. The lead controller in the inner loop is designed to ensure stability while the outer loop PI controller is designed for performance enhancement. This approach decouples the twin requirements of stabilization (by the inner loop) and performance achievement (by the outer PI loop). The outermost PI controller has been designed using the 'Approximate Model Matching' technique [4]. The proposed control strategy has been implemented and the experimentation has been demonstrated successfully. Different experimental results have been included for verification.

Asian Journal of Control

Novel method of controller design for simultaneous stabilization and performance improvement of an electromagnetic levitation system

In this paper, we use the approach of adaptive critic design (ACD) for control, specifically, the action-dependent heuristic dynamic programming (ADHDP) method. A least squares support vector machine (SVM) regressor has been used for generating the control actions, while an SVM-based tree-type neural network (NN) is used as the critic. After a failure occurs, the critic and action are retrained in tandem using the failure data. Failure data is binary classification data, where the number of failure states are very few as compared to the number of no-failure states. The difficulty of conventional multilayer feedforward NNs in learning this type of classification data has been overcome by using the SVM-based tree-type NN, which due to its feature to add neurons to learn misclassified data, has the capability to learn any binary classification data without a priori choice of the number of neurons or the structure of the network. The capability of the trained controller to handle unforeseen situations is demonstrated. © 2007 IEEE.

IEEE Transactions on Neural Networks

SVM-based tree-type neural networks as a critic in adaptive critic designs for control

Seismic response of liquid storage tank can be strongly influenced by the presence of submerged components. This modification of the dynamic characteristics of the liquid tank systems with internal components can be very useful for improving their seismic behavior. In this paper, a pressure-based finite element technique has been developed to analyze the slosh dynamics of a partially filled rigid container with bottom-mounted submerged components. The fluid is assumed homogeneous, isotropic, inviscid, and to exhibit only limited compressibility. The problem is linearized assuming the frequency of the exciting oscillation not in the immediate neighborhood of the natural slosh frequency, so that the slope of the free surface is small. The linearized problem is spatially discretized using the Galerkin weighted residual method. Earthquake excitations are used as the prescribed boundary condition. The solution is advanced in time using Newmark's constant average acceleration method. The developed code has been used to investigate the effect of a bottom-mounted rectangular component on the slosh dynamics of a liquid-filled rigid container. Numerical results obtained are compared with the existing solutions to validate the code. The parametric study of the tank-fluid system shows the importance of height, width and location of the submerged structural components. © 2007 Elsevier Ltd. All rights reserved.

Mechanical Engineering

Journal of Sound and Vibration

Slosh dynamics of liquid-filled containers with submerged components using pressure-based finite element method

In this paper an overview of power amplifier for multi-magnet based DC electromagnetic levitation system has been presented. The general requirement of power amplifier for levitation system has been described. The proposed multi-magnet based single axis levitation scheme has been described in brief. Different possible switched mode power circuits for the multi-magnet based electromagnetic levitation system have been discussed and a comparative study has been made of the different topologies of power amplifiers based on their structure and practical results that derived from the proposed experimental set-up. In the actual work design, fabrication and testing of multimagnet based electromagnetic levitation scheme has been made as a complete project. But in this paper the emphasis is given on the power amplifier portion due to limitation of space. © 2007 IEEE.

Proceedings of the International Conference on Power Electronics and Drive Systems

A study of different possible switched modi chopper circuits for multi-magnet based DC electromagnetic levitation system

Given a set of points S in any dimension, we describe a deterministic algorithm for finding a T ⊂ S, | T | = O (1 / ε) such that the centroid of T approximates the centroid of S within a factor 1 + ε for any fixed ε > 0. We achieve this in linear time by an efficient derandomization of the algorithm in [M. Inaba, N. Katoh, H. Imai, Applications of weighted Voronoi diagrams and randomization to variance-based k-clustering (extended abstract), in: Proceedings of the Tenth Annual Symposium on Computational Geometry, 1994, pp. 332-339]. © 2007 Elsevier B.V. All rights reserved.

Information Processing Letters

A linear time deterministic algorithm to find a small subset that approximates the centroid

This paper presents improved algorithms for the following problem: given an unweighted directed graph G (V, E) and a sequence of on-line shortest-path/reachability queries interspersed with edge-deletions, develop a data-structure that can answer each query in optimal time, and can be updated efficiently after each edge-deletion. The central idea underlying our algorithms is a scheme for implicitly storing all-pairs reachability/shortest-path information, and an efficient way to maintain this information. Our algorithms are randomized and have one-sided inverse polynomial error for query. © 2004 Elsevier Inc. All rights reserved.

Fulltext

Journal of Algorithms

Improved decremental algorithms for maintaining transitive closure and all-pairs shortest paths

We present for the first time, analysis of irreversible snapback caused due to the regenerative n-p-n turn-on in a DENMOS through a critical understanding of 'thermal runaway' under ESD conditions. The estimated It2 value from transient simulations has been correlated with the quasi-steady TLP data. A new regenerative bipolar turn-on induced failure model has been proposed and corroborated with experimental observations and failure analysis. We have also investigated the current crowding mechanism to understand the improvement in It2 value under gate and substrate biasing. © 2007 IEEE.