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Nagpur, India

Visvesvaraya National Institute of Technology Nagpur , also referred to as NIT Nagpur, formerly Regional College of Engineering, Nagpur and Visvesvaraya Regional College of Engineering , is an engineering institute in Nagpur, Maharashtra, in central India. The institute has been ranked among the best fifteen engineering colleges in India. The institute was established in June 1960 and later named in honor of engineer, planner and statesman, Sir Mokshagundam Visvesvaraya. It is one of the National Institutes of Technology and in 2007 was conferred the status of Institute of National Importance. Wikipedia.

Roul P.,Visvesvaraya National Institute of Technology
Communications in Theoretical Physics | Year: 2013

The purpose of the paper is to present analytical and numerical solutions of a degenerate parabolic equation with time-fractional derivatives arising in the spatial diffusion of biological populations. The homotopy - perturbation method is employed for solving this class of equations, and the time-fractional derivatives are described in the sense of Caputo. Comparisons are made with those derived by Adomian's decomposition method, revealing that the homotopy perturbation method is more accurate and convenient than the Adomian's decomposition method. Furthermore, the results reveal that the approximate solution continuously depends on the time-fractional derivative and the proposed method incorporating the Caputo derivatives is a powerful and efficient technique for solving the fractional differential equations without requiring linearization or restrictive assumptions. The basis ideas presented in the paper can be further applied to solve other similar fractional partial differential equations. © 2013 Chinese Physical Society and IOP Publishing Ltd. Source

Chatterjee A.,Visvesvaraya National Institute of Technology
International Journal of Mechanical Sciences | Year: 2010

Use of Volterra series in nonlinear system identification is well established now. The series represents response of a nonlinear system in a functional series form consisting of convolution integrals involving higher-order impulse response functions known as Volterra kernels. Multi-dimensional Fourier transforms of these Volterra kernels give the higher-order frequency response functions (FRFs). The measurement of these FRFs under harmonic excitation and their relationship with the first-order FRFs provide a basis for estimation of the nonlinear parameters. However, most of the methods employ single-tone excitation, which provide limited FRF measurement in a single experiment. In the present study, a novel procedure based on multi-tone excitation is presented for a typical Duffing oscillator and it is demonstrated that accurate estimation of both nonlinear and linear parameters is possible with fewer number of experiments. © 2010 Elsevier Ltd. All rights reserved. Source

Chatterjee A.,Visvesvaraya National Institute of Technology
Journal of Sound and Vibration | Year: 2010

Vibration measurements offer an effective, inexpensive and fast means of non-destructive testing of structures and various engineering components. There are mainly two approaches to crack detection through vibration testing; open crack model with emphasis on changes in modal parameters and secondly, the breathing crack model focusing on nonlinear response characteristics. The open crack model based on linear response characteristics can identify the crack only at an advanced stage. Researchers have shown that a structure with a breathing crack behaves more like a nonlinear system, similar to that of a bilinear oscillator and the nonlinear response characteristics can very well be investigated to identify the presence of the crack. In the present study, the bilinear restoring force is approximated by a polynomial series and a nonlinear dynamic model of the cracked structure is developed using higher order frequency response functions. The effect of crack severity on the response harmonic amplitudes are investigated and a new procedure is suggested whereby the crack severity can be estimated through measurement of the first and second harmonic amplitudes. © 2010 Elsevier Ltd. All rights reserved. Source

Chatterjee A.,Visvesvaraya National Institute of Technology
International Journal of Non-Linear Mechanics | Year: 2010

Identification of non-linear systems is mainly limited to polynomial form non-linearities. Among the non-polynomial forms, bilinear oscillator constitutes an important class of non-linear systems and it has been used for modeling of various physical systems, particularly for structural elements with a breathing crack. An identification procedure is presented here for the class of bilinear oscillator, using higher order FRFs derived from Volterra series under harmonic excitation. The procedure addresses the problem of both; identification of the non-linearity structure as well as estimation of the bilinear parameter, which can be correlated to the crack severity and structural degradation. The procedure is illustrated with numerical simulation and the estimation results indicate that even a weakly bilinear state introduced by a small crack size can be accurately identified and measured. © 2009 Elsevier Ltd. Source

Suryawanshi H.M.,Visvesvaraya National Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2010

In this paper, an approach to reduce common-mode voltage (CMV) at the output of multilevel inverter using 3-D space-vector modulation (SVM) is proposed. The 3-D SVM is superset of the traditional 2-D SVM, and thus, it inherits all the merits of traditional 2-D. A simple technique for the selection of switching states to constitute the reference vector is proposed here. The computational cost of the proposed technique is independent of voltage levels of inverter. This technique is easy to implement online in digital controller. The tradeoff between quality of output voltage and CMV is achieved in this paper. This paper realizes the implementation of 3-D SVM to reduce the CMV using a five-level diode-clamped inverter for a three-phase induction motor. Experimental and simulation results demonstrate the feasibility of the proposed technique. © 2010 IEEE. Source

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