Electrical Engineering

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Shiv Nadar University

Identification of gene locations in a DNA sequence is one of the important problems in the area of genomics. Nucleotides in exons of a DNA sequence show f = 1/3 periodicity. The period-3 property in exons of eukaryotic gene sequences enables signal processing based time-domain and frequency-domain methods to predict these regions. Identification of the period-3 regions helps in predicting the gene locations within the billions long DNA sequence of eukaryotic cells. Existing non-parametric filtering techniques are less effective in detecting small exons. This paper presents a Harmonic Suppression filter and parametric Minimum Variance Spectrum estimation technique for gene prediction. We show that both the filtering techniques are able to detect smaller exon regions and adaptive MV filter minimizes the power in introns (non-coding regions) giving more suppression to the intron regions. Furthermore, 2-simplex mapping is used to reduce the computational complexity.

World University root node

(SoE) School of Engineering

IEEE Region 10 Annual International Conference, Proceedings/TENCON

Digital signal processing for gene prediction

In power systems the primary requirement is to find a rigorous approach to suppress the harmonics and ultimately extract the fundamental frequency component. The method presented enables the FIR filter design satisfying specific frequency characteristics with auxiliary constraints. The job of design is converted to an optimization problem with the constraint using standard mean square criterion. The strategy behind detection is to optimize the destined constraint function and to minimize the mean square error. The performance of the advised technique is compared with that of LMS and linear optimal filters. Experimental results both in ideal and noisy condition associated with the three methods are given.

Constrained filter-based fundamental frequency tracking in power systems

In this paper, QR-RLS based adaptive channel TEQ(Time Domain Equalizer) to make the OFDM systems robust for delay spreads exceeding the CP(cyclic prefix) is presented. The performance of the proposed method is compared with standard LMS and exponentially weighted RLS based TEQ, in terms of computational complexity and BER. QR decomposition using Givens transformation results in better computational complexity compared to standard RLS and QRD based on gram schmidt orthogonalization process. The simulation results show that this method gives better results as compared to the aforementioned methods. © 2008 IEEE.

Proceedings of ICSCN 2008 - International Conference on Signal Processing Communications and Networking

QR-RLS based adaptive channel TEQ for OFDM Wireless LAN

Electromagnetic levitation system (EMLS) is inherently unstable and strongly nonlinear in nature. A cascade lead compensation control scheme utilizing inner current loop and outer position loop has been designed and implemented for stabilization of a single magnet based single axis levitation system. The prototype has been successfully tested and stable levitation has been demonstrated at the desired operating gap. The dynamic performance of the controller has been studied experimentally by applying different disturbance inputs (square wave, sinusoidal etc.) with increasing magnitudes and frequencies. The effect of different basic parameters of the levitation system on the performance of the designed controller has also been observed. ©2008 IEEE.

PECon 2008 - 2008 IEEE 2nd International Power and Energy Conference

A practical study on the dynamic performance of a controller for an electromagnetic levitation system

We present a detailed understanding of filamentation, through rigorous mixed-mode 3D simulation in a nano-meter scale drainextended NMOS (DE-NMOS). Localization is first triggered in the 2D plane due to regenerative turn-on of the parasitic bipolar. 3D Simulations performed by adding width along the Z-axis (i.e., W) show a very prominent localization effect, which leads to electro-thermal runaway in the DE-NMOS and causes an irreversible damage. © 2008 IEEE.

IEEE International Reliability Physics Symposium Proceedings

3D device modeling of damage due to filamentation under an ESD event in nanometer scale drain extended NMOS (DE-NMOS)

Using a two-color laser technique, we have measured the temperature dependence of the second- and third-order optical nonlinear susceptibilities, χ (2) and χ (3), at the Si/ SiO2 interface. A laser beam at 540 nm directed normal to the surface was used to pump electrons from the silicon valence band to trap states on the SiO2 surface leaving the holes at or near the interface thus creating a capacitance electric field. A second beam of wavelength 800 nm incident at 45° on the same spot resulted in a second-harmonic signal whose intensity was related to the varying interfacial electric field. We find that the photoinduced electric field is temperature independent since the charge distributions remain unchanged after pumping and both χ (2) and χ (3) increase as the temperature increases. © 2008 The American Physical Society.

Physical Review B - Condensed Matter and Materials Physics

Temperature-dependent second- and third-order optical nonlinear susceptibilities at the Si/ SiO2 interface

A simple scheme that allows fast control of induction motor torque has been presented. It is different from the conventional direct torque control (DTC) scheme in the sense that it does not use the popular DTC switching table. Also, it does not require use of any online fast computing device like a microprocessor, personal computer (PC) or digital signal processor (DSP). The proposed scheme uses only commonly used discrete hardware components for its implementation. The experimental results obtained from the hardware realization of the proposed scheme are found to be in close agreement with the simulation results. © 2007 Elsevier Ltd. All rights reserved.

Energy Conversion and Management

Digital simulation and hardware implementation of a simple scheme for direct torque control of induction motor

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.

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.

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

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.