Time filter

Source Type

Barddhamān, India

Dandapathak M.,Hooghly Mohsin College | Sarkar S.,Burdwan Raj College | Sarkar B.C.,University of Burdwan

The dynamics of an optical phase locked loop (OPLL) with first order loop filter having inherent loop time delay is investigated. In the presence of delay, the system is modeled as a third order autonomous system. In the out of lock condition or during the process of locking, the dynamics of the system is highly nonlinear and different nonlinear phenomena, like limit cycle oscillation, period doubling, chaotic oscillations etc., may be observed with the variation of design parameters. Applying the techniques of the nonlinear dynamics, we have calculated the effects of the inherent loop time delay in determining the state of the loop. The analytical results predicting the parameter values for stable and unstable region of operation are obtained using the quasi-linear Routh-Hurwitz method. The parameter range required for the onset of chaotic oscillations is estimated by Melnikov's global perturbation method. The predicted results are in agreement with those obtained by numerical integration of system equations. © 2014 Elsevier GmbH. All rights reserved. Source

Sarkar B.C.,University of Burdwan | Sarkar S.,Burdwan Raj College | Guin A.K.,University of Burdwan | Koley C.,NIT Mizoram
International Journal of Bifurcation and Chaos

We have studied the performance of a Gunn oscillator (GO) based angle modulator-demodulator system in transmitting chaotic signals in the X-band microwave frequency channel. The principle of bias tuning of a GO is employed to implement the angle modulator used in the transmitter. The said GO is operated in a free running condition and then in a frequency synchronized condition to an external microwave signal, thus generating frequency modulated (FM) and phase modulated (PM) signals, respectively. The demodulator circuit is implemented with a GO phase synchronized to the incoming modulated signal, followed by a microwave mixer multiplying the input and the output signals of the GO and a low pass filter. The response of the system is analytically established, numerically examined and experimentally verified. The obtained results confirm that in the limit of low modulation index and in the linear range of operation of the bias tuned modulator and the phase synchronized detector, a chaos signal can be transmitted and recovered through a microwave channel using the technique of angle modulation. © 2015 World Scientific Publishing Company. Source

Sarkar B.C.,University of Burdwan | Koley C.,University of Burdwan | Guin A.K.,University of Burdwan | Sarkar S.,Burdwan Raj College
Progress In Electromagnetics Research B

The dynamics of the onset of oscillations in a wave guide cavity based Gunn Oscillator (GO) has been critically examined through numerical simulations and experimental studies. The transition of the GO from a non-oscillatory to an oscillatory state and the same in the reverse direction occurs at different critical values of the dc bias voltage applied to the GO. In presence of a weak RF field in GO cavity, oscillations with broad band continuous spectrum and multiple discrete line spectrum are observed at the GO output for different values of dc bias below the above mentioned critical values. Analysing the numerically obtained time series data, chaos quantifiers have been obtained to prove the occurrence of the chaotic oscillations in the GO. Experimental results and observations of numerical simulation show good qualitative agreement. Source

Sarkar B.C.,University of Burdwan | Koley C.,University of Burdwan | Guin A.K.,University of Burdwan | Sarkar S.,Burdwan Raj College
Progress In Electromagnetics Research B

The dynamics of a system of two bilaterally coupled chaotically oscillating X-band Gunn oscillators (GOs) has been studied by numerical simulation and by hardware experiment. The effect of variation of the coupling strengths between two oscillators in two paths has been explored. The chaotic oscillations in two GOs have become synchronized in most of the cases when coupling factors (CFs) are around 20% or more. However, the transformation of chaotic states of the GOs to quasi-periodic ones has been observed for some values of CFs. A detailed numerical analysis on the instantaneous error parameters of the GO state variables is presented to identify different steady state dynamical conditions of the system. Experimental observations of the GO output frequency power spectra and the averaged product of the two GO outputs in the coupled mode con-rm the occurrence of synchronization as well as quenching of chaotic oscillations for different values of CFs. Source

Roy D.,University of Burdwan | Khan D.,Burdwan Raj College
International Journal of Industrial Engineering Computations

In this paper, we address the optimization of an integrated line balancing process with workstation inventory management. While doing so, we have studied the interconnection between line balancing and its conversion process. Almost each and every moderate to large manufacturing industry depends on a long and integrated supply chain, consisting of inbound logistic, conversion process and outbound logistic. In this sense an approach addresses a very general problem of integrated line balancing. Research works reported in the literature so far mainly deals with minimization of cost for inbound and outbound logistic subsystems. In most of the cases conversion process has been ignored. We suggest a generic approach for linking the balancing of the line of production in the conversion area with the customers' rate of demand in the market and for configuring the related stock chambers. Thus, the main aim of this paper is to translate the underlying problem in the form of mixed nonlinear programming problem and design the optimum supply chain so that the total inventory cost and the cost of balancing loss of the conversion process is jointly minimized and ideal cycle time of the production process is determined along with ideal sizes of the stock chambers. A numerical example has been added to demonstrate the suitability of our approach. © 2010 Growing Science Ltd. All rights reserved. Source

Discover hidden collaborations