(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

We report the effect of inert gas (argon and helium) along with different concentrations of oxygen on the structural and optical properties of the rf magnetron sputtered nanocrystalline tungsten oxide thin films. The crystal structure and surface morphology were studied by X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. We find that the atomic mass of the sputtering gas significantly affects the primary crystallite size as well as the surface morphology and texture. We were able to relate the higher oxidation of the tungsten atoms with low partial pressure of oxygen when films are deposited in helium instead of argon. It was also observed that the bandgap of the WO3 films increases with increase in the partial pressure of oxygen. © 2008 Elsevier B.V. All rights reserved.

World University root node

Electrical Engineering

Thin Solid Films

Effect of sputtering gas on structural and optical properties of nanocrystalline tungsten oxide films

The challenges associated with the OFDM system are addressed. OFDM transmits redundancy in terms of Cyclic Prefix (CP), which decreases the spectral efficiency of the system. A pulse shaping filter for the OFDM systems is proposed to remove the constraint of CP. Also, transmit and receive filters in OFDM system suffer from poor frequency response because of the use of rectangular window function. The non-rectangular window based prototype filters are proposed for the transmitter and receiver end. The comparison of performance of OFDM system and the suggested filter bank based multicarrier systems is provided in terms of BER and the stop band attenuation of the constituent filters.

IEEE Region 10 Annual International Conference, Proceedings/TENCON

Elimination of Cyclic Prefix of OFDM systems using filter bank based multicarrier systems

This paper deals with pressure-based finite element analysis of fluid-structure systems considering the coupled fluid and structural dynamics. The present method uses two-dimensional fluid elements and structural line elements for the numerical simulation of the problem. The equations of motion of the fluid, considered inviscid and compressible, are expressed in terms of the pressure variable alone. The solution of the coupled system is accomplished by solving the two systems separately with the interaction effects at the fluid-solid interface enforced by an iterative scheme. Non-divergent pressure and displacement are obtained simultaneously through iterations. The Galerkin weighted residual method-based FE formulation and the iterative solution procedure are explained in detail followed by some numerical examples. Numerical results are compared with the existing solutions to validate the code for sloshing with fluid-structure coupling. © 2008 Elsevier B.V. All rights reserved.

Mechanical Engineering

Finite Elements in Analysis and Design

2D simulation of fluid-structure interaction using finite element method

This paper develops an adaptive fuzzy controller for robot manipulators using a Markov game formulation. The Markov game framework offers a promising platform for robust control of robot manipulators in the presence of bounded external disturbances and unknown parameter variations. We propose fuzzy Markov games as an adaptation of fuzzy Q-learning (FQL) to a continuous-action variation of Markov games, wherein the reinforcement signal is used to tune online the conclusion part of a fuzzy Markov game controller. The proposed Markov game-adaptive fuzzy controller uses a simple fuzzy inference system (FIS), is computationally efficient, generates a swift control, and requires no exact dynamics of the robot system. To illustrate the superiority of Markov game-adaptive fuzzy control, we compare the performance of the controller against a) the Markov game-based robust neural controller, b) the reinforcement learning (RL)-adaptive fuzzy controller, c) the FQL controller, d) the H∞ theory-based robust neural game controller, and e) a standard RL-based robust neural controller, on two highly nonlinear robot arm control problems of i) a standard two-link rigid robot arm and ii) a 2-DOF SCARA robot manipulator. The proposed Markov game-adaptive fuzzy controller outperformed other controllers in terms of tracking errors and control torque requirements, over different desired trajectories. The results also demonstrate the viability of FISs for accelerating learning in Markov games and extending Markov game-based control to continuous state-action space problems. © 2007 IEEE.

IEEE Transactions on Fuzzy Systems

A markov game-adaptive fuzzy controller for robot manipulators

Power amplifier is one of the important elements of any attraction type levitation system. Due to the advancement in power electronics and control technology it is now possible to develop power amplifier which will have the properties like fast dynamics, large bandwidth, ability to carry large payload, energy efficient, high reliability and cost effective. Both linear and switching mode power amplifiers have been used in the field of DC electromagnetic suspension system. In this paper different possible switched mode power circuits for both single as well as 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, working principle and experimental results. In the actual work design, fabrication and testing of both single and multi-magnet based electromagnetic levitation scheme has been made as a complete project. But in this paper the main focus is on the power amplifier. © 2008 Inderscience Enterprises Ltd.

International Journal of Power Electronics

Some aspects of switching power amplifier used in electromagnetic levitation system

The experimental findings on the mechanical behavior of clays with dispersed microfabric are indicative of the need for comprehensive evaluation of the constitutive theories being widely used in practice. The clay deposits can be found having all the stages of microfabrics in their natural state and the dispersed microfabric is one of those. Despite the fact that the effects of microfabric can be radical sometimes, those are seldom given due consideration during the design process. Since the success of numerical modelling of a geotechnical structure is strongly dependent on the accuracy of the constitutive equations, the results produced by commonly used constitutive models can be highly misleading. The present paper is focused on identifying such issues which make the study of dispersed clays important and show the need for incorporating the influence of microfabric into constitutive formulations. Two of the most widely known models, Modified Cam-Clay (MCC) model (Roscoe and Burland, 1968) and the single hardening (SH) model (Lade, 1990), have been calibrated for the Kaolin clay with dispersed microfabric and the predicted response has been compared with the experimental observations. This comparative study has been used to provide an insight into the important issues which still need attention.

Civil Engineering

12th International Conference on Computer Methods and Advances in Geomechanics 2008

Issues in modeling the stress-strain behavior of Kaolin clay with dispersed microfabric

Materials Science and Technology: A Comprehensive Treatment

Effect of Multiphase Flow on Corrosion

Using fuzzy-rough hybrids, we have proposed a measure to quantify the functional dependency of decision attribute(s) on condition attribute(s) within fuzzy data. We have shown that the proposed measure of dependency degree is a generalization of the measure proposed by Pawlak for crisp data. In this paper, this new measure of dependency degree has been encapsulated into the decision tree generation mechanism to produce fuzzy-rough classification trees (FRCT); efficient, top-down, multi-class decision tree structures geared to solving classification problems from feature-based learning examples. The developed FRCT generation algorithm has been applied to 16 real-world benchmark datasets. It is experimentally compared with the five fuzzy decision tree generation algorithms reported so far, and the rough decomposition tree algorithm. Comparison has been made in terms of number of rules, average training time, and classification accuracy. Experimental results show that the proposed algorithm to generate FRCT outperforms existing fuzzy decision tree generation techniques and rough decomposition tree induction algorithm. © 2007 Springer-Verlag London Limited.

Pattern Analysis and Applications

FRCT: Fuzzy-rough classification trees

This paper proposes a novel control approach that incorporates a hybrid game strategy in Markov-game-based fuzzy control. Specifically, we aim at designing a "safe and universally consistent"controller that exhibits an ability to maintain performance against large disturbance and environment variations. The proposed hybrid control is a convex combination (based on experiential information) of "a variation of cautious fictitious play" approach and the "minimax" control approach implemented on a fuzzy Markov game platform. We show analytical convergence of Markov-game-based control in the presence of bounded external disturbances, and extend the analysis to show convergence of the proposed Markov-game-based hybrid control approach. Controller simulation and comparison against baseline Markov game fuzzy control and fuzzy Q-learning control on a highly nonlinear two-link robot brings out the superiority of the approach in handling severe environment and disturbance variations over different desired trajectories. This paper illustrates the possibility of obtaining "universal consistency," i.e., reasonable performance against severe environment and disturbance variations, by hybridizing "cautious fictitious play" with "minimax" approaches in Markov-game-based control. © 2008 IEEE.

Hybrid game strategy in fuzzy Markov-game-based control

This paper describe the design principle of a dc attraction type electromagnetic suspension system where a hollow steel cylinder of 658 g mass is levitated under a fixed I-core (solenoid type) electromagnet with a single degree-of-freedom. Electromagnet exhibits non-linear force against distance characteristics and hence, this controller has been designed by using linear small perturbation model of the magnet at the desired operating point. In all previously reported papers 1-3 the system design has been done by considering a suitable voltage source as the exciting input to the magnet coil. In the present work, over all system order reduction has been tried by taking a controlled current source as the excitation for the magnet coil. The resulting system is simpler and has second order transfer function. The present work also reports a very simple power electronic converter suitable for this scheme of levitation. The proposed circuit uses only one power switch in contrast to commonly used asymmetrical H-bridge type converter4. The present circuit, though less energy efficient compared to the asymmetrical bridge converter will be quite cost effective for low power applications. The prototype has been successfully tested and levitation demonstrated.