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Dash A.K.,Institute of Technical Education and Research | Parhi D.R.K.,National Institute of Technology Rourkela
International Journal of Computational Materials Science and Surface Engineering | Year: 2011

The influence of cracks on the dynamic behaviour of a cracked cantilever beam with rectangular cross section is discussed in this work. Analytical and experimental investigations are carried out to find the relation between the change in natural frequencies and mode shapes for the cracked and un-cracked beam. Finite element analysis is being performed on the cracked structure to measure the vibration signatures, which is subsequently used in the design of smart system based on fuzzy logic for prediction of crack depths and locations following inverse problem approach. The fuzzy system is developed with relative natural frequencies and mode shapes as input parameters based on the triangular membership functions to calculate the deviation in the vibration parameters for the cracked dynamic structure. Results from experimental analysis are very close to the results predicted by the theoretical, finite element and fuzzy analysis. Copyright © 2011 Inderscience Enterprises Ltd. Source

Parhi D.R.,National Institute of Technology Rourkela | Dash A.K.,Institute of Technical Education and Research
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2011

This article analyses the dynamic behaviour of a beam structure containing multiple transverse cracks using neural network controller. The first three natural frequencies and mode shapes have been calculated using theoretical, finite-element, and experimental analysis for the cracked andun-cracked beam.Comparisons of the results among theoretical, finite-element, and experimental analysis have also been presented. The calculated vibration signatures were used to train the feed-forward multi-layered neural network controller with back-propagation technique for the prediction of cracks. Relative crack locations and relative crack depths are the output of the neural controller. Results obtained from the various analyses are validated using the developed experimental set-up. Results from neural controller have been presented for comparison with the output from theoretical, finite-element, and experimental analysis. From the evaluation of the performance of the neural network controller it is observed that the developed method can be used as a crack diagnostic tool in the domain of dynamically vibrating structures. © Authors 2011. Source

Singh A.V.,Indian Institute of Technology Delhi | Chandra S.,Indian Institute of Technology Delhi | Bose G.,Institute of Technical Education and Research
Thin Solid Films | Year: 2011

Aluminum nitride (AlN) films were deposited on a variety of substrates (glass, Si, oxidized Si, Al-SiO2-Si, Cr-SiO2-Si, and Au-Cr-SiO2-Si) by radio frequency (RF) magnetron sputtering using an AlN target. The films were deposited without external substrate heating. The effect of RF power, ambient gas (Ar and Ar-N2) and sputtering pressure on deposition rate and crystallinity were investigated. The structure and morphology of the films were studied by X-ray diffraction, scanning electron microscopy and atomic force microscopy techniques. These investigations revealed that the AlN films prepared in mixed gas ambient (Ar-N2) were highly c-axis oriented with moderate surface roughness on all the substrate. A strong IR absorption band was observed around 670 cm- 1 which confirms the presence of Al-N bond in the film. The dc resistivity of the films was measured to be in the range of 1011 to 1012 Ω-cm at moderate electric fields. The application of these films in piezoelectric based micro-electro-mechanical systems is discussed. © 2011 Elsevier B.V. All rights reserved. Source

Singh M.R.,National Institute of Technology Rourkela | Mahapatra S.S.,National Institute of Technology Rourkela | Mishra R.,Institute of Technical Education and Research
International Journal of Services and Operations Management | Year: 2015

This paper addresses a robust schedule for a flexible job shop scheduling problem with random machine breakdown. A multi objective framework based on quantum particle swarm optimisation (QPSO) is proposed to generate the predictive schedules that can simultaneously optimise the makespan and the robust measures. The results indicate that the proposed QPSO algorithm is quite effective in reducing makespan in the event that uncertainty is encountered in terms of stochastic machine breakdown. An exhaustive experimental study is conducted to study the effect of different proposed robustness measures on the generated schedules using benchmark problems. © 2015 Inderscience Enterprises Ltd. Source

Somani A.,University of Minnesota | Somani A.,Dynapower Company LLC | Gupta R.K.,General Electric | Mohapatra K.K.,University of Minnesota | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2013

Electric drives with open-end winding ac machines offer certain advantages over drives with star-or delta-connected machines. Such drives have been recently considered for some applications such as electric vehicles. Circulating currents have been experimentally observed in such open-end winding ac drives. These currents have the effect of increasing conduction losses in the stator winding resistance of the ac machine. Two major causes for these currents have been identified as device voltage drops in power semiconductor devices and dead time used for shoot-through current protection. These effects are analyzed, and a mathematical description for predicting their severity is provided. Experimental results are presented that support the theory. The theory developed should be useful for devising solutions for this problem such as the design of common-mode filters. Two methods of suppressing the circulating currents are also outlined, and their experimental results are presented. © 1982-2012 IEEE. Source

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