Electrical Engineering

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International Journal of Neural Systems

Erratum: Neuro-fuzzy decision trees (International Journal of Neural Systems (2006) 16:1 (63-78))

A measure to evaluate functional dependency of crisp system output on crisp system input(s) proposed by Pawlak in the context of rough set theory, has been extended to the fuzzy input-output case by using fuzzy-rough hybrids. We have shown that the proposed measure covers Pawlak's measure as a limiting case.

Pattern Recognition Letters

On the extension of functional dependency degree from crisp to fuzzy partitions

This letter provides the theory and mathematical analysis in support of a recently proposed frequency modulated thermal wave imaging for nondestructive subsurface defect detection in solids. The authors illustrate how the technique simultaneously combines the advantages of both conventional pulse based thermography as well as modulated lock-in thermography. A specimen is heated for launching thermal waves into the sample, not at a single frequency (lock-in) or at all frequencies (pulse), but in a desired range of frequencies. While peak power requirement is reduced, phase images obtained retain known advantages. Experimental results from a carbon fiber reinforced plastic sample are presented in support. © 2006 American Institute of Physics.

Applied Physics Letters

Theory of frequency modulated thermal wave imaging for nondestructive subsurface defect detection

A little explored relationship between the structural and electrical properties of radio frequency sputtered AlN films is studied as a function of nitrogen concentration. It is found that the grain growth mechanism is responsible for an improvement of structural properties and a degradation of electrical properties. © 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Scripta Materialia

Influence of nitrogen concentration on grain growth, structural and electrical properties of sputtered aluminum nitride films

In this paper, we investigate the potential of Support Vector Machines (SVMs) for power quality data mining in electrical power systems. Modified wavelet transform, known as S-transform, has been used to extract unique features of the various power quality disturbances. Feature vectors from S-transform analysis are used to train the SVM classifier. Various multi-class SVM algorithms have been applied on the power quality data under study and the Directed Acyclic Graph (DAGSVM) algorithm is found to be performing well. A comparison between the DAGSVM method and the one based on Artificial Neural Network demonstrates the efficiency of the SVM method in classifying PQ disturbances. © 2006 IEEE.

Proceedings - Third International Conference onInformation Technology: New Generations, ITNG 2006

Knowledge discovery in power quality data using Support Vector Machine and S-transform

Fuzzy decision trees are powerful, top-down, hierarchical search methodology to extract human interpretable classification rules. However, they are often criticized to result in poor learning accuracy. In this paper, we propose Neuro-Fuzzy Decision Trees (N-FDTs); a fuzzy decision tree structure with neural like parameter adaptation strategy. In the forward cycle, we construct fuzzy decision trees using any of the standard induction algorithms like fuzzy ID3. In the feedback cycle, parameters of fuzzy decision trees have been adapted using stochastic gradient descent algorithm by traversing back from leaf to root nodes. With this strategy, during the parameter adaptation stage, we keep the hierarchical structure of fuzzy decision trees intact. The proposed approach of applying backpropagation algorithm directly on the structure of fuzzy decision trees improves its learning accuracy without compromising the comprehensibility (interpretability). The proposed methodology has been validated using computational experiments on real-world datasets. © World Scientific Publishing Company.

Neuro-Fuzzy decision trees

Effects of MgO deposition on SiSi O2 system and charge carrier trapping and recombination in SiSi O2 MgO structures are studied using second-harmonic generation (SHG). An ultrafast 800 nm laser was used both for multi-photon induced electron injection through the Si O2 into a potential well in the MgO, and for monitoring the time-dependent SHG signal, which is sensitive to the electric field at the SiSi O2 interface. Our results indicate that the MgO deposition introduces new trap states, and electrons trapped in the MgO transport more readily through the Si O2 than those in traps on the surface of Si O2. We attribute this to differences in trap energy levels and/or differences in process damage-induced defect densities in the Si O2. © 2006 American Institute of Physics.

Studies of charge carrier trapping and recombination processes in Si/SiO 2/MgO structures using second-harmonic generation

This paper describes design and implementation of a single axis dc attraction type electromagnetic suspension system where an electromagnet of 2.6 kg mass is levitated over a large gap under a fixed ferromagnetic guide-way. The electromagnet exhibits nonlinear force-current-distance characteristics, and if controllers are to be designed by using linear analysis, the air-gap is restricted to a small region around the chosen nominal operating point. In this work, an attempt has been made to increase the operating range of an electromagnetic suspension system by using the concept of piecewise linear control where the nonlinear force-current-airgap relationships of the magnetic suspension system have been successively linearized at several operating points with a suitable controller designed for each operating point. A novel analog switching scheme has been designed and implemented to automatically switch to the relevant controller depending on the actual air-gap. © 2006 ISA - The Instrumentation, Systems, and Automation Society.

ISA Transactions

Large gap control in electromagnetic levitation

The present work reports on the little explored correlation of electrical properties in conjunction with morphology of RF sputtered aluminum nitride (AlN) films at different substrate temperatures (100 °C -400 °C). Electrical properties, especially insulator charge density (Qin) and interface state density (Dit) were studied by using Al/AlN/Si (MIS) as a test vehicle. X-ray diffraction, FTIR spectroscopy, AFM and SEM techniques were studied for crystal orientation, bond formation, surface roughness and grain size of AlN film, respectively. Relatively highly c-axis (0 0 2) oriented films were found in between 200 °C and 300 °C with FTIR absorption peak at 682 cm-1. Decrease in Qin from 7.9 × 1011 cm-2 to 1.0 × 1011 cm-2 found to be associated with increase in surface roughness and grain size, with temperature. There is no significant change in interface state density with deposition temperature. It is found that better crystallinity results in a good dielectric constant. © 2005 Elsevier B.V. All rights reserved.

Current Applied Physics

Correlation of electrical and morphological properties of sputtered aluminum nitride films with deposition temperature

An attempt to correlate deposition-induced effects and the morphological properties with the electrical properties of the aluminum nitride (AlN) films have been made. The AlN film was sputter deposited on silicon while increasing the pressure in steps from 2×10-3 to 8×10-3 mbar. An X-ray diffractogram revealed that the intensity of (0 0 2) orientation increased till 6×10-3 mbar pressure, but it changed to (1 0 0) orientation of the AlN film at 8×10-3 mbar. The FTIR spectra of the absorption band of the films were observed around 682 cm-1 and became prominent at 6×10-3 mbar. A decrease in the grain size was seen by SEM images at 8×10-3 mbar. The AFM measurements revealed that the surface roughness varied from 1.56 to 3.24 nm with pressure. It was found that the insulator charge density (Qin) increased from 1.4×1011 cm-2 to 1.3×1012 cm-2 with increase in pressure. On the other hand, the interface state density (Dit) was found minimum (7.3×1011 eV-1 cm-2) at 6×10-3 mbar. It is found that presence of the Qin and Dit are primarily governed by the sputtering pressure of the AlN film. © 2006 Elsevier Ltd. All rights reserved.